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Sample records for segmented thin microstrip

  1. Thin film dielectric microstrip kinetic inductance detectors

    NASA Astrophysics Data System (ADS)

    Mazin, Benjamin A.; Sank, Daniel; McHugh, Sean; Lucero, Erik A.; Merrill, Andrew; Gao, Jiansong; Pappas, David; Moore, David; Zmuidzinas, Jonas

    2010-03-01

    Microwave kinetic inductance detectors, or MKIDs, are a type of low temperature detector that exhibit intrinsic frequency domain multiplexing at microwave frequencies. We present the first theory and measurements on a MKID based on a microstrip transmission line resonator. A complete characterization of the dielectric loss and noise properties of these resonators is performed, and agrees well with the derived theory. A competitive noise equivalent power of 5×10-17 W Hz-1/2 at 10 Hz has been demonstrated. The resonators exhibit the highest quality factors known in a microstrip resonator with a deposited thin film dielectric.

  2. Superconducting microstrip resonator for pulsed ESR of thin films.

    PubMed

    Benningshof, O W B; Mohebbi, H R; Taminiau, I A J; Miao, G X; Cory, D G

    2013-05-01

    This article describes a superconducting microstrip resonator operating at 9.5 GHz (X-band) that is specially designed for pulsed ESR on thin films. A novel configuration consisting of an array of half-wave length microstrip transmission lines generates a uniform magnetic field over a 2-D region of 100×1000 μm(2) with field homogeneity better than 5×10(-2). Using the device, we demonstrate strong coupling of the resonator to an electron spin ensemble and pulsed ESR on Si:P. PMID:23454577

  3. TEM wave propagation in a microstrip line on a substrate of circular segment cross section

    NASA Astrophysics Data System (ADS)

    Malits, P.; Haridim, M.; Chulski, S.

    2015-12-01

    TEM mode wave propagation in a microstrip transmission line on a dielectric substrate of circular segment cross section is of concern. A suggested design of a microstrip is convenient for manufacturing and allows to miniaturize microstrips since there is no lateral fringing effect of the substrate in the transmitted fundamental TEM mode. By using the bipolar orthogonal coordinates, the plane potential problem is reformulated in the form of trigonometric dual integral equations. The discontinuous integrals containing Legendre functions of complex degree and the Abel integral equation are employed to reduce the dual equations to a Fredholm equation of the second kind. The structure of the Fredholm integral equation allows to obtain a simple approximate solution. Basing on this solution, rigorous approximate formulas for the characteristic impedance are derived. The characteristic impedance of a microstrip transmission line on a silicon substrate is computed and plotted as an example.

  4. Nondestructive microwave permittivity characterization of ferroelectric thin film using microstrip dual resonator

    NASA Astrophysics Data System (ADS)

    Tan, C. Y.; Chen, Linfeng; Chong, K. B.; Ong, C. K.

    2004-01-01

    This article presents the use of a microstrip dual resonator for nondestructive permittivity characterization of a ferroelectric thin film at microwave frequencies. The dual-resonator measurement fixture consists mainly of two capacitively coupled microstrip resonators, with the ferroelectric thin film covering the gap between the two resonators. The dielectric constant and loss tangent of the ferroelectric thin film are derived from the resonant frequencies and quality factors of the dual-resonator structure. To study the electric field dependence of the ferroelectric thin film, direct current bias voltage is applied through two electrode pads on the microstrip circuit. The temperature dependence of a ferroelectric thin film was also studied using the hermetic test fixture. The measurement uncertainty of this method comes mainly from the air gap between the microstrip circuit and the ferroelectric thin film. Calibration with a sample of known dielectric constant can be used to compensate for such an error. We demonstrated the use of this method on a piece of the Ba0.5Sr0.5TiO3 thin film deposited on a LaAlO3 substrate.

  5. Coupled microstrip line microwave phase shifter using ferroelectric thin film varactors

    NASA Astrophysics Data System (ADS)

    Sheng, Su; Ong, C. K.

    2012-02-01

    This article presents a coupled microstrip line microwave phase shifter using ferroelectric thin film varactors with parallel plate electrodes integrated on high-resistivity silicon substrate. This design is proposed as a component in low-cost beam scanning phased array antennas. The phase shifter structure consists of coupled microstrip line periodically loaded with eight BaxSr1-xTiO3 (BST) varactors and two planar Marchand baluns. The planar Marchand baluns work as the transformers of odd mode excitation and a transmission stop circuit for even mode excitation as well as the impedance matching networks. A differential phase shift of 45° was obtained with a low dc bias of 20 V at frequency of 9 GHz, which corresponds to a figure of merit of ˜23°/dB. These results represent significant progress toward compact size, low loss, and ferroelectric thin film-based phase shifters at room temperature.

  6. Coupling Between Microstrip Lines With Finite Width Ground Plane Embedded in Thin Film Circuits

    NASA Technical Reports Server (NTRS)

    Ponchak, George E.; Dalton, Edan; Tentzeris, Manos M.; Papapolymerou, John

    2003-01-01

    Three-dimensional (3D) interconnects built upon multiple layers of polyimide are required for constructing 3D circuits on CMOS (low resistivity) Si wafers, GaAs, and ceramic substrates. Thin film microstrip lines (TFMS) with finite width ground planes embedded in the polyimide are often used. However, the closely spaced TFMS lines a r e susceptible to high levels of coupling, which degrades circuit performance. In this paper, Finite Difference Time Domain (FDTD) analysis and experimental measurements a r e used to show that the ground planes must be connected by via holes to reduce coupling in both the forward and backward directions. Furthermore, it is shown that coupled microstrip lines establish a slotline type mode between the two ground planes and a dielectric waveguide type mode, and that the via holes recommended here eliminate these two modes.

  7. Aperture-coupled thin-membrane microstrip array antenna for beam scanning application

    NASA Technical Reports Server (NTRS)

    Huang, John; Sadowy, Gregory; Derksen, Chuck; Del Castillo, Linda; Smith, Phil; Hoffman, Jim; Hatake, Toshiro; Moussessian, Alina

    2005-01-01

    A microstrip array using aperture-slot-coupling technique with very thin membranes has been developed at the L-band frequency for beam scanning application. This technology-demonstration array with 4 x 2 elements achieved a relatively wide bandwidth of 100 MHz (8%) and +/-45(deg) beam scan. Very narrow coupling slots were used with each having an aspect ratio of 160 (conventional slot aspect ratio is between 10 to 30) for coupling through very thin membrane (0.05mm thickness). This thin-membrane aperture-coupling technique allows the array antenna elements to be more easily integrated with transmit/receive amplifier (T/R) and phase shifter modules. This paper addresses only the radiator portion of the array. The array and active components will be presented in a separate pape.

  8. Microstrip monpulse dipole array

    NASA Astrophysics Data System (ADS)

    Miccioli, W.; Toth, J.; Sa, N.; Lewis, M.

    1985-01-01

    The development of a microstrip radiating aperture utilizing multiple microstrip dipole radiators fed by a resonant feed configuration is described. This array combines an efficient capacitively coupled radiator feeding mechanism with a planar power divider configuration to achieve an extremely thin, lightweight antenna aperture. Linear array dipole matching theory and radiator bandwidth improvement techniques are also described. A quadrant based microstrip monopulse antenna was constructed. Experimental data from this array, its subassemblies and individual components are presented and compared to analytical predictions.

  9. Tunable Microstrip Filters Using Selectively Etched Ferroelectric Thin-Film Varactors for Coupling

    NASA Technical Reports Server (NTRS)

    Mueller, Carl H.; VanKeuls, Frederick W.; Romanofsky, Robert R.; Subramanyam, Guru; Miranda, Felix A.

    2006-01-01

    We report on the use of patterned ferroelectric films to fabricate proof of concept tunable one-pole microstrip filters with excellent transmission and mismatch/reflection properties at frequencies up to 24 GHz. By controlling the electric field distribution within the coupling region between the resonator and input/output lines, sufficiently high loaded and unloaded Q values are maintained so as to be useful for microstrip filter design, with low mismatch loss. In the 23 - 24 GHz region, the filter was tunable over a 100 MHz range, the loaded and unloaded Q values were 29 and 68, respectively, and the reflection losses were below -16 dB, which demonstrates the suitability of these films for practical microwave applications.

  10. A K-band Frequency Agile Microstrip Bandpass Filter using a Thin Film HTS/Ferroelectric/dielectric Multilayer Configuration

    NASA Technical Reports Server (NTRS)

    Subramanyam, Guru; VanKeuls, Fred; Miranda, Felix A.

    1998-01-01

    We report on YBa2Cu3O(7-delta) (YBCO) thin film/SrTiO3 (STO) thin film K-band tunable bandpass filters on LaAlO3 (LAO) dielectric substrates. The 2 pole filter has a center frequency of 19 GHz and a 4% bandwidth. Tunability is achieved through the non-linear dc electric field dependence of the relative dielectric constant of STO(epsilon(sub rSTO). A large tunability ((Delta)f/f(sub 0) = (f(sub Vmax) - f(sub 0)/f(sub 0), where f(sub 0) is the center frequency of the filter at no bias and f(sub Vmax) is the center frequency of the filter at the maximum applied bias) of greater than 10% was obtained in YBCO/STO/LAO microstrip bandpass filters operating below 77 K. A center frequency shift of 2.3 GHz (i.e., a tunability factor of approximately 15%) was obtained at a 400 V bipolar dc bias, and 30 K, with minimal degradation in the insertion loss of the filter. This paper addresses design, fabrication and testing of tunable filters based on STO ferroelectric thin films. The performance of the YBCO/STO/LAO filters is compared to that of gold/STO/LAO counterparts.

  11. The local segmental dynamics of polymer thin films

    NASA Astrophysics Data System (ADS)

    Roland, C. M.; Casalini, Riccardo; Prevosto, Daniele; Labardi, Massimiliano; Zhu, Lei; Baer, Eric

    The local segmental dynamics of poly(methyl methacrylate) (PMMA) in multi-layered films with polycarbonate was investigated using dielectric spectroscopy. The segmental relaxation time decreased with layer thickness down to 4 nm. However, two measures of the cooperativity of the dynamics, the breadth of the relaxation dispersion and the dynamic correlation volume, were unaffected by the film thickness. This absence of an effect of geometric confinement on the cooperativity, even when the confinement length scale approaches the correlation length scale, requires an asymmetric correlation volume; i.e., correlating regions having a string-like nature. To further probe the effect of layering on the segmental dynamics, we measured the segmental dynamics of poly(vinylacetate) thin films in contact with variously an aluminum interface, an incompatible polymer, and air (free surface). From local dielectric relaxation measurements using an AFM tip, the dynamics were observed to be faster in all thin film configurations compared to the bulk. However, no differences were observed for the various interfaces; capping the thin films with a rigid material accelerated the segmental motions equivalently to that for an air interface. This insensitivity of the dynamics to the nature of the interface affords a means to engineer thin films while maintaining desired mechanical properties. Work at NRL supported by the Office of Naval Research.

  12. Thin membranes of new hard/soft segment copolymers

    SciTech Connect

    Ho, W.S.; Sartori, G.; Thaler, W.A.

    1996-12-31

    Thin membranes of new hard/soft segment copolymers have been synthesized for the separation of aromatics from saturates through high temperature pervaporation. In the membranes, hard segments provide temperature stability and solvent resistance, while soft segments govern aromatic/saturate selectivity and flux. We have synthesized new chlorinated polyurethane/polyester and polyimide/polyester copolymers. Based on a polyimide copolymer membrane, a new technology has been developed recently to separate heavy catalytically cracked naphtha into an aromatics-rich permeate and an aromatics-lean retentate.

  13. Thin Shell, Segmented X-Ray Mirrors

    NASA Technical Reports Server (NTRS)

    Petre, Robert

    2010-01-01

    Thin foil mirrors were introduced as a means of achieving high throughput in an X-ray astronomical imaging system in applications for which high angular resolution were not necessary. Since their introduction, their high filling factor, modest mass, relative ease of construction, and modest cost have led to their use in numerous X-ray observatories, including the Broad Band X-ray Telescope, ASCA, and Suzaku. The introduction of key innovations, including epoxy replicated surfaces, multilayer coatings, and glass mirror substrates, has led to performance improvements, and in their becoming widely used for X-ray astronomical imaging at energies above 10 keV. The use of glass substrates has also led to substantial improvement in angular resolution, and thus their incorporation into the NASA concept for the International X-ray Observatory with a planned 3 in diameter aperture. This paper traces the development of foil mirrors from their inception in the 1970's through their current and anticipated future applications.

  14. Microwave microstrip resonator measurements of Y1Ba2Cu3O(7-x) and Bi2Sr2Ca1Cu2O(8-y) thin films

    NASA Technical Reports Server (NTRS)

    Lichtenberg, Christopher L.; Wosik, Jaroslaw; Davis, Matthew; Wolfe, J. C.

    1989-01-01

    Radio frequency (RF) surface resistance measurement experiments on high T(sub c) thin films were performed. The method uses a microstrip resonator comprising a top gold conductor strip, an alumina dielectric layer, and a separate superconductivity ground plane. The surface resistance of the superconducting ground plane can be determined, with reference to a gold calibration standard, from the measured quality factor of the half-wave resonator. Initial results near 7 GHz over the temperature range from 25 to 300 K are presented for YBa2Cu3O(7-x) and Bi2Sr2CaCu2O(8-y) thin film samples deposited by an electron beam flash evaporation process. The RF surface resistance at 25 K for both materials in these samples was found to be near 25 milliohms.

  15. Coating Thin Mirror Segments for Lightweight X-ray Optics

    NASA Technical Reports Server (NTRS)

    Chan, Kai-Wing; Sharpe, Marton V.; Zhang, William; Kolosc, Linette; Hong, Melinda; McClelland, Ryan; Hohl, Bruce R.; Saha, Timo; Mazzarellam, James

    2013-01-01

    Next generations lightweight, high resolution, high throughput optics for x-ray astronomy requires integration of very thin mirror segments into a lightweight telescope housing without distortion. Thin glass substrates with linear dimension of 200 mm and thickness as small as 0.4 mm can now be fabricated to a precision of a few arc-seconds for grazing incidence optics. Subsequent implementation requires a distortion-free deposition of metals such as iridium or platinum. These depositions, however, generally have high coating stresses that cause mirror distortion. In this paper, we discuss the coating stress on these thin glass mirrors and the effort to eliminate their induced distortion. It is shown that balancing the coating distortion either by coating films with tensile and compressive stresses, or on both sides of the mirrors is not sufficient. Heating the mirror in a moderately high temperature turns out to relax the coated films reasonably well to a precision of about a second of arc and therefore provide a practical solution to the coating problem.

  16. Miniaturized microstrip multipole low-pass filters using high-temperature superconducting YBa2Cu3O7-x thin films

    NASA Astrophysics Data System (ADS)

    Kim, Jeha; Kang, Kwang-Yong; Han, Seok K.; Lee, Sang Yeol; Ahn, Dal

    1995-09-01

    We have designed the microstrip-type multipole (7-pole and 9-pole) lowpass filters consisting of both transmission lines and open stubs. The filters were fabricated on high temperature superconducting (HTS) YBa2Cu3O7-(delta ) (YBCO) thin films grown on MgO(100) substrates by pulsed laser deposition. For 7-pole lowpass filter, the measured insertion losses were within 0.5 dB, and up to 8 GHz the passband shows very flat with ripples of less than 0.05 dB. For 9-pole filter, we observed the insertion loss of 5.0 dB and the ripples of 0.64 dB. The skirt became steep and the off-band rejection increased large as the number of poles increases.

  17. Segmented sediment probe for diffusive gradient in thin films technique.

    PubMed

    Docekal, Bohumil; Gregusova, Michaela

    2012-01-21

    A new modification of a constrained sediment probe was tested for application in the diffusive gradient in thin films technique (DGT). The sediment probes packed with agarose based resin and diffusive gels were exposed under laboratory conditions to well-mixed test solutions of cadmium and nickel as model elements. The reproducibility of metal uptake in segments (strips) of resin gel with anchored 8-hydroxyquinoline functional groups (Spheron-Oxin® ion exchanger) was studied. The relative yield of uptake of metals in resin gel strips, determined as the ratio of the time-averaged DGT-measured metal concentration and the concentration of a metal in the test solution, showed that the effective sampling area was larger than the geometric area of the resin gel strip. This relative yield is in very good agreement with the theoretical value obtained by the Finite Element Method (FEM) in calculation of diffusion processes. The performance of the modified constrained probe is demonstrated by an example of uranium, iron and manganese depth profiling in a spiked sediment core. Utilization of the new segmented sediment probe in the DGT technique is very simple. Its application does not require special devices and labor-intensive procedures. It can provide sediment depth profiles of metals with the resolution down to the millimetre level. PMID:22116834

  18. Hybrid absorbers composed of Fe3O4 thin film and magnetic composite sheet and enhancement of conduction noise absorption on a microstrip line

    NASA Astrophysics Data System (ADS)

    Kim, Sung-Soo

    2015-05-01

    In response to develop wide-band noise absorbers with an improved low-frequency performance, this study investigates hybrid absorbers that are composed of conductive Fe3O4 thin film and magnetic composite sheets. The Fe3O4 films prepared via reactive sputtering exhibit a typical value of electrical resistivity of ≃10-4 Ωm. Rubber composites with flaky Fe-Si-Al particles of a high permeability and high permittivity are used as the magnetic sheet functioning as an electromagnetic shield barrier. Microstrip lines with a characteristic impedance of 50 Ω are used to measure the noise absorbing properties. For the Fe3O4 film with a low surface resistance and covered by the magnetic sheet, approximately 80% power absorption can be obtained at 1 GHz, which is significantly higher than that of the original magnetic sheet or Fe3O4 film. The high power absorption of the hybrid absorber is attributed to the enhanced ohmic loss of the Fe3O4 film through increased electric field strength bounded by the upper magnetic composite sheet. The noise absorption is further enhanced through increasing the electrical conductivity of the film containing more conductive phase (Fe3O4 + Fe), which can be prepared in a reduced oxygen partial pressure during reactive sputtering.

  19. Measurement on electrical tunability of microstrip line resonators using YBa2Cu3O7-δ/SrTiO3/MgO multilayer thin films

    NASA Astrophysics Data System (ADS)

    Han, Seok K.; Kim, Jeha; Lee, Sang Yeol; Kang, Kwang-Yong

    1995-09-01

    We have fabricated YBa2Cu3O7-(delta ) (YBCO) superconducting line resonator and tunable line resonator on ferroelectric Sr0.5Ba0.5TiO3 (SBTO) buffered MgO(100) substrate and discussed the frequency shift mechanism of superconductor as a function of temperature and bias voltage, respectively. The resonators were designed using superconducting YBCO epitaxial thin films. Optimized resonator shown the resonant frequency of 10 GHz at 77 K. The YBCO films were grown in situ by pulsed laser deposition technique at 750 degree(s)C and oxygen partial pressure of 200 mTorr. The resonators have linear microstrip line separated by a gap of 5 micrometers and 0.5 mm, respectively. A gap is intentionally introduced to generate mainly a capacitive series reactance. The equivalence circuit of line resonator is a II network consisted of three capacitances. As the series capacitance C12 of SBTO ferroelectric thin films was changed by a bias voltage applied on the strip conductors including the gap, resonance frequency was shifted about 20 MHz from the unbiased center frequency of 10 GHz. The variation of resonance peak could be explained by a serial capacitance model. To find a central frequency mechanism depending on temperature, we fit the raw data using f(T)/f(10 K) and simple power law model. The shifting of the resonant frequencies due to temperature was fit to a two-fluid model, BCS theory and empirical formula. Also the surface impedance of superconducting YBCO films as a function of temperature at 10 GHz has been estimated by a transmission line method.

  20. Pleural effusion segmentation in thin-slice CT

    NASA Astrophysics Data System (ADS)

    Donohue, Rory; Shearer, Andrew; Bruzzi, John; Khosa, Huma

    2009-02-01

    A pleural effusion is excess fluid that collects in the pleural cavity, the fluid-filled space that surrounds the lungs. Surplus amounts of such fluid can impair breathing by limiting the expansion of the lungs during inhalation. Measuring the fluid volume is indicative of the effectiveness of any treatment but, due to the similarity to surround regions, fragments of collapsed lung present and topological changes; accurate quantification of the effusion volume is a difficult imaging problem. A novel code is presented which performs conditional region growth to accurately segment the effusion shape across a dataset. We demonstrate the applicability of our technique in the segmentation of pleural effusion and pulmonary masses.

  1. Precise Alignment and Permanent Mounting of Thin and Lightweight X-ray Segments

    NASA Technical Reports Server (NTRS)

    Biskach, Michael P.; Chan, Kai-Wing; Hong, Melinda N.; Mazzarella, James R.; McClelland, Ryan S.; Norman, Michael J.; Saha, Timo T.; Zhang, William W.

    2012-01-01

    To provide observations to support current research efforts in high energy astrophysics. future X-ray telescope designs must provide matching or better angular resolution while significantly increasing the total collecting area. In such a design the permanent mounting of thin and lightweight segments is critical to the overall performance of the complete X-ray optic assembly. The thin and lightweight segments used in the assemhly of the modules are desigued to maintain and/or exceed the resolution of existing X-ray telescopes while providing a substantial increase in collecting area. Such thin and delicate X-ray segments are easily distorted and yet must be aligned to the arcsecond level and retain accurate alignment for many years. The Next Generation X-ray Optic (NGXO) group at NASA Goddard Space Flight Center has designed, assembled. and implemented new hardware and procedures mth the short term goal of aligning three pairs of X-ray segments in a technology demonstration module while maintaining 10 arcsec alignment through environmental testing as part of the eventual design and construction of a full sized module capable of housing hundreds of X-ray segments. The recent attempts at multiple segment pair alignment and permanent mounting is described along with an overview of the procedure used. A look into what the next year mll bring for the alignment and permanent segment mounting effort illustrates some of the challenges left to overcome before an attempt to populate a full sized module can begin.

  2. Bonding Thin Mirror Segments Without Distortion for the International X-Ray Observatory

    NASA Technical Reports Server (NTRS)

    Evans, Tyler C.; Chan, Kai-Wing; Saha, Timo T.

    2011-01-01

    The International X-Ray Observatory (IXO) uses thin glass optics to maximize large effective area and precise low angular resolution. The thin glass mirror segments must be transferred from their fabricated state to a permanent structure without imparting distortion. IXO will incorporate about fourteen thousand thin mirror segments to achieve the mission goal of 3.0 square meters of effective area at 1.25 keV with an angular resolution of five arcseconds. To preserve figure and alignment, the mirror segment must be bonded with sub-micron movement at each corner. Recent advances in technology development have produced significant x-ray test results of a bonded pair of mirrors. Three specific bonding cycles will be described highlighting the improvements in procedure, temperature control, and precision bonding. This paper will highlight the recent advances in alignment and permanent bonding as well as the results they have produced.

  3. Coarse alignment of thin-shell, segmented mirrors for Wolter-I telescopes

    NASA Astrophysics Data System (ADS)

    Donovan, Benjamin D.; Hertz, Edward; Marquez, Vanessa; McMuldroch, Stuart; Reid, Paul B.; Allured, Ryan

    2015-09-01

    The alignment of thin-shell, segmented mirrors for Wolter-I telescopes frequently involves the use of a Hartmann test. In order to get optical throughput in the Hartmann test, the mirrors must first be coarsely aligned to one another and to the metrology system. In the past, the coarse alignment of these mirrors at the Smithsonian Astrophysical Observatory has largely relied upon component machine tolerances and contact measurements with a coordinate measurement machine (CMM). This process takes time and does not produce reliable nor repeatable results. Thus, methods were developed to allow for the quick and reliable coarse alignment of thin- shell, segmented mirrors at their final locations in the mirror assembly. We present the coarse alignment system developed at the Smithsonian Astrophysical Observatory and its use in the alignment of thin-shell, segmented mirrors for the adjustable X-ray optics program.

  4. A Novel K-Band Tunable Microstrip Bandpass Filter Using a Thin Film HTS/Ferroelectric/ Dielectric Configuration

    NASA Technical Reports Server (NTRS)

    Subramanyam, G.; VanKeuls, F.; Miranda, F. A.

    1998-01-01

    We report on YBCO/strontium titanate (STO) thin film K-band tunable bandpass filters on lanthanum aluminate substrates. The 2 pole filters were designed for a center frequency of 19 GHz and 4% bandwidth. Tunability is achieved through the non-linear dc electric field dependence of the relative dielectric constant of STO (epsilon-rSTO). Center frequency shifts greater than 2 GHz were obtained at a 400V bipolar dc bias at temperatures below 77K, with minimum degradation in the insertion loss of the filters.

  5. Spiral Microstrip Antenna with Resistance

    NASA Technical Reports Server (NTRS)

    Shively, David G. (Inventor)

    1998-01-01

    A spiral microstrip antenna having resistor elements embedded in each of the spiral arms is provided. The antenna is constructed using a conductive back plane as a base. The back plane supports a dielectric slab having a thickness between one-sixteenth and one-quarter of an inch. A square spiral, having either two or four arms, is attached to the dielectric slab. Each arm of the spiral has resistor elements thereby dissipating an excess energy not already emitted through radiation. The entire configuration provides a thin, flat, high gain, wide bandwidth antenna which requires no underlying cavity. The configuration allows the antenna to be mounted conformably on an aircraft surface.

  6. A new intelligent method for minerals segmentation in thin sections based on a novel incremental color clustering

    NASA Astrophysics Data System (ADS)

    Izadi, Hossein; Sadri, Javad; Mehran, Nosrat-Agha

    2015-08-01

    Mineral segmentation in thin sections is a challenging, popular, and important research topic in computational geology, mineralogy, and mining engineering. Mineral segmentation in thin sections containing altered minerals, in which there are no evident and close boundaries, is a rather complex process. Most of the thin sections created in industries include altered minerals. However, intelligent mineral segmentation in thin sections containing altered minerals has not been widely investigated in the literature, and the current state of the art algorithms are not able to accurately segment minerals in such thin sections. In this paper, a novel method based on incremental learning for clustering pixels is proposed in order to segment index minerals in both thin sections with and without altered minerals. Our algorithm uses 12 color features that are extracted from thin section images. These features include red, green, blue, hue, saturation and intensity, under plane and cross polarized lights in maximum intensity situation. The proposed method has been tested on 155 igneous samples and the overall accuracy of 92.15% and 85.24% has been obtained for thin sections without altered minerals and thin sections containing altered minerals, respectively. Experimental results indicate that the proposed method outperforms the results of other similar methods in the literature, especially for segmenting thin sections containing altered minerals. The proposed algorithm could be applied in applications which require a real time segmentation or efficient identification map such as petroleum geology, petrography and NASA Mars explorations.

  7. Soft microstrip with integral ground plane aids in supercomponent integration

    NASA Astrophysics Data System (ADS)

    Faulkner, J.; Klein, G.; Sacks, F.; Woermbke, J.

    1983-11-01

    Initial 1950s microstrip circuits were based on printed circuit board technology. Problems related to very high dielectric losses and loose mechanical tolerances, led toward the use of stable ceramic materials as microstrip substrates, with subsequent development of the associated thick- and thin-film processes. In 1976, in response to the relatively high cost of ceramic substrate-based microstrip circuit technology and difficulties caused by substrate size restrictions, an American company initiated a program to develop a new class of substrate, specifically designed for lower cost large microstrip circuits. The utilization of clad soft microstrip (CSM) was found to offer numerous advantages relative to ceramic substrates. Attention is given to the properties of various dielectric substrate materials, the embedding functions, aspects of isolation enhancement, and applications of CSM.

  8. Microstrip antenna technology

    NASA Astrophysics Data System (ADS)

    Carver, K. R.; Mink, J. W.

    1981-01-01

    A survey of microstrip antenna elements is presented, with emphasis on theoretical and practical design techniques. Available substrate materials are reviewed along with the relation between dielectric constant tolerance and resonant frequency of microstrip patches. Several theoretical analysis techniques are summarized, including transmission-line and modal-expansion (cavity) techniques as well as numerical methods such as the method of moments and finite-element techniques. Practical procedures are given for both standard rectangular and circular patches, as well as variations on those designs including circularly polarized microstrip patches. The quality, bandwidth, and efficiency factors of typical patch designs are discussed. Microstrip dipole and conformal antennas are summarized. Finally, critical needs for further research and development for this antenna are identified.

  9. Wideband microstrip dipole

    NASA Astrophysics Data System (ADS)

    Dey, Supriyo; Aanandan, C. K.; Jose, K. A.; Mohanan, P.; Nair, K. G.

    1992-12-01

    A new wideband half-wave microstrip dipole antenna is described which operates in low-frequency range with more than 5 percent 2:1 VSWR bandwidth. The design is based on a stripline feeding mechanism to prevent radiation from the feeding structure and on proper end-loading of dipole arms to enhance the impedance bandwidth. It is concluded that this dipole can replace the conventional dipoles or existing microstrip antennas in phased array application.

  10. Electromagnetically coupled microstrip dipoles

    NASA Astrophysics Data System (ADS)

    Oltman, H. G.; Huebner, D. A.

    1981-01-01

    A new class of printed circuit radiator consisting of a microstrip dipole electromagnetically coupled to a microstrip feed line is described. Several configurations which differ in bandwidth, efficiency, and construction simplicity are presented. A geometry which has been found to be optimum for many applications is noted. Radiation characteristics of both isolated elements and arrays of elements are examined. Experimental and theoretical results are presented.

  11. Circularly-Polarized Microstrip Antenna

    NASA Technical Reports Server (NTRS)

    Stanton, P. H.

    1985-01-01

    Microstrip construction compact for mobile applications. Circularly polarized microstrip antenna made of concentric cylindrical layers of conductive and dielectric materials. Coaxial cable feedlines connected to horizontal and vertical subelements from inside. Vertical subelement acts as ground for horizontal subelement.

  12. Flexible Microstrip Circuits for Superconducting Electronics

    NASA Technical Reports Server (NTRS)

    Chervenak, James; Mateo, Jennette

    2013-01-01

    Flexible circuits with superconducting wiring atop polyimide thin films are being studied to connect large numbers of wires between stages in cryogenic apparatus with low heat load. The feasibility of a full microstrip process, consisting of two layers of superconducting material separated by a thin dielectric layer on 5 mil (approximately 0.13 mm) Kapton sheets, where manageable residual stress remains in the polyimide film after processing, has been demonstrated. The goal is a 2-mil (approximately 0.051-mm) process using spin-on polyimide to take advantage of the smoother polyimide surface for achieving highquality metal films. Integration of microstrip wiring with this polyimide film may require high-temperature bakes to relax the stress in the polyimide film between metallization steps.

  13. Room Temperature Thin Film Ba(x)Sr(1-x)TiO3 Ku-Band Coupled MicrostripPhase Shifters: Effects of Film Thickness, Doping, Annealing and Substrate Choice

    NASA Technical Reports Server (NTRS)

    VanKeuls, F. W.; Mueller, C. H.; Miranda, F. A.; Romanofsky, R. R.; Canedy, C. L.; Aggarwal, S.; Venkatesan, T.; Ramesh, R.; Horwitz, S.; Chang, W.

    1999-01-01

    We report on measurements taken on over twenty Ku-band coupled microstrip phase shifters (CMPS) using thin ferroelectric films of Ba(x)Sr(1-x)TiO3. This CMPS design is a recent innovation designed to take advantage of the high tunability and tolerate the high dielectric constant of ferroelectric films at Ku- and K-band frequencies. These devices are envisioned as a component in low-cost steerable beam phased area antennas, Comparisons are made between devices with differing film thickness, annealed vs unannealed, Mn-doped vs. undoped, and also substrates of LaAlO3 and MgO. A comparison between the CMPS structure and a CPW phase shifter was also made oil the same ferroelectric film.

  14. Superconducting microstrip antennas: An experimental comparison of two feeding methods

    SciTech Connect

    Richard, M.A.; Claspy, P.C. ); Bhasin, K.B. . Lewis Research Center)

    1993-07-01

    The recent discovery of high-temperature superconductors (HTS's) has generated a substantial amount of interest in microstrip antenna applications. However, the high permittivity of substrates compatible with HTS causes difficulty in feeding such antennas because of the high patch edge impedance. In this paper, two methods for feeding HTS microstrip antennas at K and Ka-band are examined. Superconducting microstrip antennas that are directly coupled and gap-coupled to a microstrip transmission line have been designed and fabricated on lanthanum aluminate substrates using Y-Ba-Cu-O superconducting thin films. Measurements from these antennas, including input impedance, bandwidth, efficiency, and patterns, are presented and compared with published models. The measured results demonstrate that usable antennas can be constructed using either of these architectures, although the antennas suffer from narrow bandwidths. In each case, the HTS antenna shows a substantial improvement over an identical antenna made with normal metals.

  15. Superconducting Microstrip Antennas: An Experimental Comparison of Two Feeding Methods

    NASA Technical Reports Server (NTRS)

    Richard, Mark A.; Claspy, Paul C.; Bhasin, Kul B.

    1993-01-01

    The recent discovery of high-temperature superconductors (HTSs) has generated a substantial amount of interest in microstrip antenna applications. However, the high permittivity of substrates compatible with HTS causes difficulty in feeding such antennas because of the high patch edge impedance. Two methods for feeding HTS microstrip antennas at K- and Ka-band are examined. Superconducting microstrip antennas that are directly coupled and gas-coupled to a microstrip transmission line have been designed and fabricated on lanthanum aluminate substrates using Y-Ba-Cu-O superconducting thin films. Measurements from these antennas, including input impedance, bandwidth, efficiency, and patterns, are presented and compared with published models. The measured results demonstrate that usable antennas can be constructed using either of these architectures, although the antennas suffer from narrow bandwidths. In each case, the HTS antenna shows a substantial improvement over an identical antenna made with normal metals

  16. Superconducting microstrip antennas - An experimental comparison of two feeding methods

    NASA Technical Reports Server (NTRS)

    Richard, M. A.; Bhasin, Kul B.; Claspy, Paul C.

    1993-01-01

    The recent discovery of high-temperature superconductors (HTSs) has generated a substantial amount of interest in microstrip antenna applications. However, the high permittivity of substrates compatible with HTS causes difficulty in feeding such antennas because of the high patch edge impedance. Two methods for feeding HTS microstrip antennas at K- and Ka-band are examined. Superconducting microstrip antennas that are directly coupled and gap-coupled to a microstrip transmission line have been designed and fabricated on lanthanum aluminate substrates using Y-Ba-Cu-O superconducting thin films. Measurements from these antennas, including input impedance, bandwidth, efficiency, and patterns, are presented and compared with published models. The measured results demonstrate that usable antennas can be constructed using either of these architectures, although the antennas suffer from narrow bandwidths. In each case, the HTS antenna shows a substantial improvement over an identical antenna made with normal metals.

  17. Microstrip antenna developments at JPL

    NASA Technical Reports Server (NTRS)

    Huang, John

    1991-01-01

    The in-house development of microstrip antennas, initiated in 1981, when a spaceborne lightweight and low-profile planar array was needed for a satellite communication system, is described. The work described covers the prediction of finite-ground-plane effects by the geometric theory of diffraction, higher-order-mode circularly polarized circular patch antennas, circularly polarized microstrip arrays with linearly polarized elements, an impedance-matching teardrop-shaped probe feed, a dual-polarized microstrip array with high isolation and low cross-polarization, a planar microstrip Yagi array, a microstrip reflectarray, a Ka-band MMIC array, and a series-fed linear arrays.

  18. Robust thin-film generator based on segmented contact-electrification for harvesting wind energy.

    PubMed

    Meng, Xian Song; Zhu, Guang; Wang, Zhong Lin

    2014-06-11

    Collecting and converting energy from ambient air flow promise to be a viable approach in developing self-powered autonomous electronics. Here, we report an effective and robust triboelectric generator that consists of an undulating thin-film membrane and an array of segmented fine-sized electrode pairs on a single substrate. Sequential processes of contact electrification and electrostatic induction generate alternating flows of free electrons when the membrane interacts with ambient air flow. Based on an optimum rational design, the segmented electrodes play an essential role in boosting the output current, leading to an enhancement of over 500% compared to the structure without the segmentation. The thin-film based generator can simultaneously and continuously light up tens of commercial light-emitting diodes. Moreover, it possesses exceptional durability, providing constant electric output after millions of operation cycles. This work offers a truly practical solution that opens the avenue to take advantage of wind energy by using the triboelectric effect. PMID:24824071

  19. Architecture of kangaroo rat inner medulla: segmentation of descending thin limb of Henle's loop.

    PubMed

    Urity, Vinoo B; Issaian, Tadeh; Braun, Eldon J; Dantzler, William H; Pannabecker, Thomas L

    2012-03-15

    We hypothesize that the inner medulla of the kangaroo rat Dipodomys merriami, a desert rodent that concentrates its urine to more than 6,000 mosmol/kgH(2)O water, provides unique examples of architectural features necessary for production of highly concentrated urine. To investigate this architecture, inner medullary nephron segments in the initial 3,000 μm below the outer medulla were assessed with digital reconstructions from physical tissue sections. Descending thin limbs of Henle (DTLs), ascending thin limbs of Henle (ATLs), and collecting ducts (CDs) were identified by immunofluorescence using antibodies that label segment-specific proteins associated with transepithelial water flux (aquaporin 1 and 2, AQP1 and AQP2) and chloride flux (the chloride channel ClC-K1); all tubules and vessels were labeled with wheat germ agglutinin. In the outer 3,000 μm of the inner medulla, AQP1-positive DTLs lie at the periphery of groups of CDs. ATLs lie inside and outside the groups of CDs. Immunohistochemistry and reconstructions of loops that form their bends in the outer 3,000 μm of the inner medulla show that, relative to loop length, the AQP1-positive segment of the kangaroo rat is significantly longer than that of the Munich-Wistar rat. The length of ClC-K1 expression in the prebend region at the terminal end of the descending side of the loop in kangaroo rat is about 50% shorter than that of the Munich-Wistar rat. Tubular fluid of the kangaroo rat DTL may approach osmotic equilibrium with interstitial fluid by water reabsorption along a relatively longer tubule length, compared with Munich-Wistar rat. A relatively shorter-length prebend segment may promote a steeper reabsorptive driving force at the loop bend. These structural features predict functionality that is potentially significant in the production of a high urine osmolality in the kangaroo rat. PMID:22237592

  20. Segments.

    ERIC Educational Resources Information Center

    Zemsky, Robert; Shaman, Susan; Shapiro, Daniel B.

    2001-01-01

    Presents a market taxonomy for higher education, including what it reveals about the structure of the market, the model's technical attributes, and its capacity to explain pricing behavior. Details the identification of the principle seams separating one market segment from another and how student aspirations help to organize the market, making…

  1. Microstrip antenna theory and design

    NASA Astrophysics Data System (ADS)

    James, J. R.; Hall, P. S.; Wood, C.

    Microstrip is the name given to a type of open waveguiding structure which is now commonly used in present-day electronics, not only as a transmission line but for circuit components such as filters, couplers, and resonators. The idea of using microstrip to construct antennas is a much more recent development. The purpose of this monograph is to present the reader with an appreciation of useful antenna design approaches and the overall state-of-the art situation. Flat-plate antenna techniques and constraints on performance are considered along with microstrip design equations and data, the radiation mechanism of an open-circuit microstrip termination and the resulting design implications, the basic methods of calculation and design of patch antennas, and linear array techniques. Attention is also given to techniques and design limitations in two-dimensional arrays, circular polarization techniques, manufacturing and operational problems of microstrip antennas, recent advances in microstrip antenna analysis, and possible future developments.

  2. Analysis of rectangular microstrip antennas

    NASA Technical Reports Server (NTRS)

    Bailey, M. C.; Deshpande, M. D.

    1984-01-01

    The problem of microstrip antennas covered by a dielectric substrate is formulated in terms of coupled integro-differential equations with the current distribution on the conducting patch as an unknown quantity. The Galerkin method is used to solve for the unknown patch current. Using the present formulation, the radiation pattern, the resonant frequency, and the bandwidth of a rectangular microstrip antenna are computed. Design data for a rectangular microstrip antenna are also presented.

  3. Microstrip Patch Antenna And Method

    NASA Technical Reports Server (NTRS)

    Fink, Patrick W. (Inventor)

    2001-01-01

    Method and apparatus are provided for a microstrip feeder structure for supplying properly phased signals to each radiator element in a microstrip antenna array that may be utilized for radiating circularly polarized electromagnetic waves. In one disclosed embodiment. the microstrip feeder structure includes a plurality of microstrip sections many or all of which preferably have an electrical length substantially equal to one-quarter wavelength at the antenna operating frequency. The feeder structure provides a low loss feed structure that may be duplicated multiple times through a set of rotations and translations to provide a radiating array of the desired size.

  4. Design of a Foldable Low-loss Microstrip Array Antenna

    NASA Technical Reports Server (NTRS)

    Christodoulou, C. G.; Wahid, P. F.; Haque, M. M.; Bailey, M. C.

    1999-01-01

    The design and analysis of a series-fed, foldable microstrip array antenna for radiometer applications is presented. The array antenna is composed of two equal sub arrays. Each sub array consists of a series of patches connected together through segments of microstrip lines. The sub arrays are fed 180 degree out of phase to ensure a symmetric radiation pattern. The design approach, is accomplished using the IE3D code that utilizes the method of moments. All experimental and simulated data are presented and discussed.

  5. Characteristic impedance of microstrip lines

    NASA Technical Reports Server (NTRS)

    Bailey, M. C.; Deshpande, M. D.

    1989-01-01

    The dyadic Green's function for a current embedded in a grounded dielectric slab is used to analyze microstrip lines at millimeter wave frequencies. The dyadic Green's function accounts accurately for fringing fields and dielectric cover over the microstrip line. Using Rumsey's reaction concept, an expression for the characteristic impedance is obtained. The numerical results are compared with other reported results.

  6. Microstrip Yagi array for MSAT vehicle antenna application

    NASA Technical Reports Server (NTRS)

    Huang, John; Densmore, Arthur; Pozar, David

    1990-01-01

    A microstrip Yagi array was developed for the MSAT system as a low-cost mechanically steered medium-gain vehicle antenna. Because its parasitic reflector and director patches are not connected to any of the RF power distributing circuit, while still contributing to achieve the MSAT required directional beam, the antenna becomes a very efficient radiating system. With the complete monopulse beamforming circuit etched on a thin stripline board, the planar microstrip Yagi array is capable of achieving a very low profile. A theoretical model using the Method of Moments was developed to facilitate the ease of design and understanding of this antenna.

  7. A 32 GHz microstrip array antenna for microspacecraft application

    NASA Technical Reports Server (NTRS)

    Huang, J.

    1994-01-01

    JPL/NASA is currently developing microspacecraft systems for future deep space applications. One of the frequency bands being investigated for microspacecraft is the Ka-band (32 GHz), which can be used with smaller equipment and provides a larger bandwidth. This article describes the successful development of a circularly polarized microstrip array with 28 dBic of gain at 32 GHz. This antenna, which is thin, flat, and small, can be surface-mounted onto the microspacecraft and, hence, takes very little volume and mass of the spacecraft. The challenges in developing this antenna are minimizing the microstrip antenna's insertion loss and maintaining a reasonable frequency bandwidth.

  8. Analytical theory of an unloaded rectangular microstrip patch

    NASA Astrophysics Data System (ADS)

    Chang, D. C.

    1981-01-01

    A graphical method for determining the size of a resonant rectangular microstrip patch for a specified frequency is given. Using an expression obtained from the reflection coefficient of a transverse electromagnetic (TEM) wave in a semi-infinite microstrip patch, the resonance condition of a given mode for a patch of finite size is derived in a manner analogous to that of a rectangular, waveguide cavity. Radiation is shown to be in the form of both surface waves and space waves and is dependent on the angles of incidence for waves impinging onto the edges of the patch. By varying the aspect ratio, it is also possible to modify the Q factor of a resonant path. Analytical expressions for the resonant frequency and the Q factor are then derived under the assumption of a very thin substrate slab, encountered frequently in the application. Design curves in the form of the 'Argand diagram' are then presented for microstrip patches with fixed aspect ratios.

  9. The study of microstrip antenna arrays and related problems

    NASA Technical Reports Server (NTRS)

    Lo, Y. T.

    1984-01-01

    The physical layout of the array elements and the proximity of the microstrip feed network makes the input impedance and radiation pattern values dependent upon the effects of mutual coupling, feedline discontinuities and feed point location. The extent of these dependences was assessed and a number of single patch and module structures were constructed and measured at an operating frequency of approximately 4.0 GHz. The empirical results were compared with the ones which were theoretically predicted by the cavity model of thin microstrip antennas. Each element was modelled as an independent radiating patch and each microstrip feedline as an independent, quasi-TEM transmission line. The effects of the feedline discontinuities are approximated by lumped L-C circuit models.

  10. Evaluation of advanced automatic PET segmentation methods using nonspherical thin-wall inserts

    SciTech Connect

    Berthon, B. Marshall, C.; Evans, M.; Spezi, E.

    2014-02-15

    Purpose: The use of positron emission tomography (PET) within radiotherapy treatment planning requires the availability of reliable and accurate segmentation tools. PET automatic segmentation (PET-AS) methods have been recommended for the delineation of tumors, but there is still a lack of thorough validation and cross-comparison of such methods using clinically relevant data. In particular, studies validating PET segmentation tools mainly use phantoms with thick plastic walls inserts of simple spherical geometry and have not specifically investigated the effect of the target object geometry on the delineation accuracy. Our work therefore aimed at generating clinically realistic data using nonspherical thin-wall plastic inserts, for the evaluation and comparison of a set of eight promising PET-AS approaches. Methods: Sixteen nonspherical inserts were manufactured with a plastic wall of 0.18 mm and scanned within a custom plastic phantom. These included ellipsoids and toroids derived with different volumes, as well as tubes, pear- and drop-shaped inserts with different aspect ratios. A set of six spheres of volumes ranging from 0.5 to 102 ml was used for a baseline study. A selection of eight PET-AS methods, written in house, was applied to the images obtained. The methods represented promising segmentation approaches such as adaptive iterative thresholding, region-growing, clustering and gradient-based schemes. The delineation accuracy was measured in terms of overlap with the computed tomography reference contour, using the dice similarity coefficient (DSC), and error in dimensions. Results: The delineation accuracy was lower for nonspherical inserts than for spheres of the same volume in 88% cases. Slice-by-slice gradient-based methods, showed particularly lower DSC for tori (DSC < 0.5), caused by a failure to recover the object geometry. The region-growing method reached high levels of accuracy for most inserts (DSC > 0.76 except for tori) but showed the largest

  11. Using sputter coated glass to stabilize microstrip gas chambers

    DOEpatents

    Gong, Wen G.

    1997-01-01

    By sputter coating a thin-layer of low-resistive, electronically-conductive glass on various substrates (including quartz and ceramics, thin-film Pestov glass), microstrip gas chambers (MSGC) of high gain stability, low leakage current, and a high rate capability can be fabricated. This design can make the choice of substrate less important, save the cost of ion-implantation, and use less glass material.

  12. Microstrip reflectarray antenna for the SCANSCAT radar application

    NASA Technical Reports Server (NTRS)

    Huang, John

    1990-01-01

    This publication presents an antenna system that has been proposed as one of the candidates for the SCANSCAT (Scanned Scatterometer) radar application. It is the mechanically steered planar microstrip reflectarray. Due to its thin, lightweight structure, the antenna's mechanical rotation will impose minimum angular momentum for the spacecraft. Since no power-dividing circuitry is needed for its many radiating microstrip patches, this electrically large array antenna demonstrates excellent power efficiency. In addition, this fairly new antenna concept can provide many significant advantages over a conventional parabolic reflector. The basic formulation for the radiation fields of the microstrip reflectarray is presented. This formulation is based on the array theory augmented by the Uniform Geometrical Theory of Diffraction (UTD). A computer code for analyzing the microstrip reflectarray's performances, such as far-field patterns, efficiency, etc., is also listed in this report. It is proposed here that a breadboard unit of this microstrip reflectarray should be constructed and tested in the future to validate the calculated performance. The antenna concept presented here can also be applied in many other types of radars where a large array antenna is needed.

  13. Tunable superconducting microstrip resonators

    NASA Astrophysics Data System (ADS)

    Adamyan, A. A.; Kubatkin, S. E.; Danilov, A. V.

    2016-04-01

    We report on a simple yet versatile design for a tunable superconducting microstrip resonator. Niobium nitride is employed as the superconducting material and aluminum oxide, produced by atomic layer deposition, as the dielectric layer. We show that the high quality of the dielectric material allows to reach the internal quality factors in the order of Qi˜104 in the single photon regime. Qi rapidly increases with the number of photons in the resonator N and exceeds 105 for N ˜10 -50 . A straightforward modification of the basic microstrip design allows to pass a current bias through the strip and to control its kinetic inductance. We achieve a frequency tuning δf =62 MHz around f0=2.4 GHz for a fundamental mode and δf =164 MHz for a third harmonic. This translates into a tuning parameter Qiδf /f0=150 . The presented design can be incorporated into essentially any superconducting circuitry operating at temperatures below 2.5 K.

  14. Front-Side Microstrip Line Feeding a Raised Antenna Patch

    NASA Technical Reports Server (NTRS)

    Hodges, Richard; Hoppe, Daniel

    2005-01-01

    An improved design concept for a printed-circuit patch antenna and the transmission line that feeds the patch calls for (1) a microstrip transmission line on the front (radiative) side of a printed-circuit board based on a thin, high-permittivity dielectric substrate; (2) using the conductor covering the back side of the circuit board as a common ground plane for both the microstrip line and the antenna patch; (3) supporting the antenna patch in front of the circuit board on a much thicker, lower-permittivity dielectric spacer layer; and (4) connecting the microstrip transmission line to the patch by use of a thin wire or narrow ribbon that extends through the thickness of the spacer and is oriented perpendicularly to the circuit-board plane. The thickness of the substrate is typically chosen so that a microstrip transmission line of practical width has an impedance between 50 and 100 ohms. The advantages of this design concept are best understood in the context of the disadvantages of prior design concepts, as explained

  15. Control of Reversible Self-Bending Behavior in Responsive Janus Microstrips.

    PubMed

    Oh, Myung Seok; Song, Young Shin; Kim, Cheolgyu; Kim, Jongmin; You, Jae Bem; Kim, Taek-Soo; Lee, Chang-Soo; Im, Sung Gap

    2016-04-01

    Here, we demonstrate a simple method to systematically control the responsive self-bending behavior of Janus hydrogel microstrips consisting of a polymeric bilayer with a high modulus contrast. The Janus hydrogel microstrips could be easily fabricated by a simple micromolding technique combined with an initiated chemical vapor deposition (iCVD) coating, providing high flexibility in controlling the physical and chemical properties of the microstrips. The fabricated Janus hydrogel microstrip is composed of a soft, pH-responsive polymer hydrogel layer laminated with a highly cross-linked, rigid thin film, generating a geometric anisotropy at a micron scale. The large difference in the elastic moduli between the two layers of the Janus microstrips leads to a self-bending behavior in response to the pH change. More specifically, the impact of the physical and chemical properties of the microstrip on the self-bending phenomena was systematically investigated by changing the thickness and composition of two layers of the microstrip, which renders high controllability in bending of the microstrips. The curvature of the Janus microstrips, formed by self-bending, highly depends on the applied acidity. A reversible, responsive self-bending/unbending exhibits a perfect resilience pattern with repeated changes in pH for 5 cycles. We envision that the Janus microstrips can be engineered to form complex 3D microstructures applicable to various fields such as soft robotics, scaffolds, and drug delivery. The reliable responsive behaviors obtained from the systematic investigation will provide critical information in bridging the gap between the theoretical mechanical analysis and the chemical properties to achieve micron-scale soft robotics. PMID:26974225

  16. High Performance Circularly Polarized Microstrip Antenna

    NASA Technical Reports Server (NTRS)

    Bondyopadhyay, Probir K. (Inventor)

    1997-01-01

    A microstrip antenna for radiating circularly polarized electromagnetic waves comprising a cluster array of at least four microstrip radiator elements, each of which is provided with dual orthogonal coplanar feeds in phase quadrature relation achieved by connection to an asymmetric T-junction power divider impedance notched at resonance. The dual fed circularly polarized reference element is positioned with its axis at a 45 deg angle with respect to the unit cell axis. The other three dual fed elements in the unit cell are positioned and fed with a coplanar feed structure with sequential rotation and phasing to enhance the axial ratio and impedance matching performance over a wide bandwidth. The centers of the radiator elements are disposed at the corners of a square with each side of a length d in the range of 0.7 to 0.9 times the free space wavelength of the antenna radiation and the radiator elements reside in a square unit cell area of sides equal to 2d and thereby permit the array to be used as a phased array antenna for electronic scanning and is realizable in a high temperature superconducting thin film material for high efficiency.

  17. Feasibility Study of Optically Transparent Microstrip Patch Antenna

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Lee, Richard Q.

    1997-01-01

    The paper presents a feasibility study on optically transparent patch antennas with microstrip line and probe feeds. The two antennas operate at 2.3 GHz and 19.5 GHz respectively. They are constructed from a thin sheet of clear polyester with an AgHT-8 optically transparent conductive coating. The experimental results show good radiation patterns and input impedance match. The antennas have potential applications in mobile wireless communications.

  18. Enhancement of conduction noise absorption by hybrid absorbers composed of indium-tin-oxide thin film and magnetic composite sheet on a microstrip line

    NASA Astrophysics Data System (ADS)

    Kim, Sun-Hong; Kim, Sung-Soo

    2014-05-01

    In order to develop wide-band noise absorbers with a focused design for low frequency performance, this study investigates hybrid absorbers that are composed of conductive indium-tin-oxide (ITO) thin film and magnetic composite sheets. The ITO films prepared via reactive sputtering exhibit a typical value of electrical resistivity of ≃10-4 Ω m. Rubber composites with flaky Fe-Si-Al particles are used as the magnetic sheet with a high permeability and high permittivity. For the ITO film with a low surface resistance and covered by the magnetic sheet, approximately 90% power absorption can be obtained at 1 GHz, which is significantly higher than that of the original magnetic sheet or ITO film. The high power absorption of the hybrid absorber is attributed to the enhanced ohmic loss of the ITO film through increased electric field strength bounded by the upper magnetic composite sheet. However, for the reverse layering sequence of the ITO film, the electric field experienced by ITO film is very weak due to the electromagnetic shielding by the under layer of magnetic sheet, which does not result in enhanced power absorption.

  19. Enhancement of conduction noise absorption by hybrid absorbers composed of indium-tin-oxide thin film and magnetic composite sheet on a microstrip line

    SciTech Connect

    Kim, Sun-Hong; Kim, Sung-Soo

    2014-05-05

    In order to develop wide-band noise absorbers with a focused design for low frequency performance, this study investigates hybrid absorbers that are composed of conductive indium-tin-oxide (ITO) thin film and magnetic composite sheets. The ITO films prepared via reactive sputtering exhibit a typical value of electrical resistivity of ≃10{sup −4} Ω m. Rubber composites with flaky Fe-Si-Al particles are used as the magnetic sheet with a high permeability and high permittivity. For the ITO film with a low surface resistance and covered by the magnetic sheet, approximately 90% power absorption can be obtained at 1 GHz, which is significantly higher than that of the original magnetic sheet or ITO film. The high power absorption of the hybrid absorber is attributed to the enhanced ohmic loss of the ITO film through increased electric field strength bounded by the upper magnetic composite sheet. However, for the reverse layering sequence of the ITO film, the electric field experienced by ITO film is very weak due to the electromagnetic shielding by the under layer of magnetic sheet, which does not result in enhanced power absorption.

  20. Designing Rectangular RHCP Microstrip Antennas

    NASA Technical Reports Server (NTRS)

    Davidson, Shayla E.

    1987-01-01

    RHCP, Right-Handed, Circularly Polarized Microstrip Antenna program, aids in design of rectangular microstrip-antenna element, given desired frequency of operation and characteristics of substrate. Begins design calculations on basis of square element with linear polarization. Effective dielectric constant and changes in electrical length due to fringing at edges of radiating element taken into account. Coaxial feed inset with 50 ohms input impedance. Placement of feed such that two orthonormal modes produced in antenna cavity, right- or left-handed circular polarization obtained. Written in FORTRAN 77.

  1. Segmentation of thin section images for grain size analysis using region competition and edge-weighted region merging

    NASA Astrophysics Data System (ADS)

    Jungmann, Matthias; Pape, Hansgeorg; Wißkirchen, Peter; Clauser, Christoph; Berlage, Thomas

    2014-11-01

    Microscopic thin section images are a major source of information on physical properties, crystallization processes, and the evolution of rocks. Extracting the boundaries of grains is of special interest for estimating the volumetric structure of sandstone. To deal with large datasets and to relieve the geologist from a manual analysis of images, automated methods are needed for the segmentation task. This paper evaluates the region competition framework, which also includes region merging. The procedure minimizes an energy functional based on the Minimum Description Length (MDL) principle. To overcome some known drawbacks of current algorithms, we present an extension of MDL-based region merging by integrating edge information between adjacent regions. In addition, we introduce a modified implementation for region competition for overcoming computational complexities when dealing with multiple competing regions. Commonly used methods are based on solving differential equations for describing the movement of boundaries, whereas our approach implements a simple updating scheme. Furthermore, we propose intensity features for reducing the amount of data. They are derived by comparing theoretical values obtained from a model function describing the intensity inside uniaxial crystals with measured data. Error, standard deviation, and phase shift between the model and intensity measurements preserve sufficient information for a proper segmentation. Additionally, identified objects are classified into quartz grains, anhydrite, and reaction fringes by these features. This grouping is, in turn, used to improve the segmentation process further. We illustrate the benefits of this approach by four samples of microscopic thin sections and quantify them in a comparison of a segmentation result and a manually obtained one.

  2. The Millimeter-Wave Properties of Superconducting Microstrip Lines

    NASA Technical Reports Server (NTRS)

    Vayonakis, A.; Luo, C.; Leduc, H. G.; Schoelkopf, R.; Zmuidzinas, J.

    2002-01-01

    We have developed a novel technique for making high quality measurements of the millimeter-wave properties of superconducting thin-film microstrip transmission lines. Our experimental technique currently covers the 75-100 GHz band. The method is based on standing wave resonances in an open ended transmission line. We obtain information on the phase velocity and loss of the microstrip. Our data for Nb/SiO/Nb lines, taken at 4.2 K and 1.6 K, can be explained by a single set of physical parameters. Our preliminary conclusion is that the loss is dominated by the SiO dielectric, with a temperature-independent loss tangent of 5.3 +/- 0.5 x 10(exp -3) for our samples.

  3. Evaluation of an algorithm for semiautomated segmentation of thin tissue layers in high-frequency ultrasound images.

    PubMed

    Qiu, Qiang; Dunmore-Buyze, Joy; Boughner, Derek R; Lacefield, James C

    2006-02-01

    An algorithm consisting of speckle reduction by median filtering, contrast enhancement using top- and bottom-hat morphological filters, and segmentation with a discrete dynamic contour (DDC) model was implemented for nondestructive measurements of soft tissue layer thickness. Algorithm performance was evaluated by segmenting simulated images of three-layer phantoms and high-frequency (40 MHz) ultrasound images of porcine aortic valve cusps in vitro. The simulations demonstrated the necessity of the median and morphological filtering steps and enabled testing of user-specified parameters of the morphological filters and DDC model. In the experiments, six cusps were imaged in coronary perfusion solution (CPS) then in distilled water to test the algorithm's sensitivity to changes in the dimensions of thin tissue layers. Significant increases in the thickness of the fibrosa, spongiosa, and ventricularis layers, by 53.5% (p < 0.001), 88.5% (p < 0.001), and 35.1% (p = 0.033), respectively, were observed when the specimens were submerged in water. The intraobserver coefficient of variation of repeated thickness estimates ranged from 0.044 for the fibrosa in water to 0.164 for the spongiosa in CPS. Segmentation accuracy and variability depended on the thickness and contrast of the layers, but the modest variability provides confidence in the thickness measurements. PMID:16529107

  4. Investigation of certain types of microstrip arrays

    NASA Astrophysics Data System (ADS)

    Chaplin, A. F.; Iakovenko, I. G.; Iashchishin, E. M.

    Results of theoretical and experimental studies of various types of highly directional microstrip arrays are presented. Approaches to a rigorous analysis of microstrip dipole arrays are discussed. The design of three versions of microstrip arrays is considered, and the feeding of such arrays from waveguides and coaxial lines is examined. It is noted that the use of such arrays in the decimeter, centimeter, and millimeter ranges is of particular interest.

  5. Improved Dual-Polarized Microstrip Antenna

    NASA Technical Reports Server (NTRS)

    Huang, John

    1993-01-01

    Dual-polarized microstrip antenna features microstrip transmission-line feeds arranged in such configuration that cross-polarized components of radiation relatively low and degree of isolation between feed ports relatively high. V and H feed ports offset from midpoints of feed lines to obtain required opposite phases at feed-point connections to microstrip patches. Two independent beams of same frequency with electric fields polarized orthogonally to each other transmitted or received via antenna. Improved design saves space.

  6. A bandwidth enhancement method for microstrip antennas

    NASA Astrophysics Data System (ADS)

    Katehi, Pisti B.; Alexopoulos, Nicolaos G.; Hsia, I. Y.

    1987-01-01

    Bandwidth enhancement methods for electromagnetically coupled microstrip dipoles are discussed. It is demonstrated that if parasitic metallic strips are incorporated in the structure either co-planar and parallel to the embedded microstrip transmission line open end, or between the transmission line and the microstrip dipole, then substantial bandwidth enhancement results. Experimental verification of this model is introduced for a bandwidth definition based on the frequency range which satisfies a voltage standing-wave ratio of less than 2 criterion. The theoretical model which accounts for radiation from the microstrip dipole, the parasitics, and the transmission line is verified.

  7. Wideband Microstrip Antenna-Feeding Array

    NASA Technical Reports Server (NTRS)

    Huang, John

    1990-01-01

    Special impedance-matching probes help reduce feed complexity. Lightweight array of microstrip antenna elements designed to transmit and illuminate reflector antenna with circularly polarized radiation at 1,545 to 1,550 MHz and to receive circularly polarized radiation at 1,646 to 1,660 MHz. Microstrip array is cluster of 7 subarrays containing total of 28 microstrip patches. Produces cicularly polarized beam with suitable edge taper to illuminate reflector antenna. Teardrop-shaped feed probe provides gradual change of field from coaxial transmission line into microstrip substrate. Intended to be part of larger overlapping-cluster array generating multiple contiguous beams.

  8. Planar microstrip YAGI antenna array

    NASA Technical Reports Server (NTRS)

    Huang, John (Inventor)

    1993-01-01

    A directional microstrip antenna includes a driven patch surrounded by an isolated reflector and one or more coplanar directors, all separated from a ground plane on the order of 0.1 wavelength or less to provide end fire beam directivity without requiring power dividers or phase shifters. The antenna may be driven at a feed point a distance from the center of the driven patch in accordance with conventional microstrip antenna design practices for H-plane coupled or horizontally polarized signals. The feed point for E-plane coupled or vertically polarized signals is at a greater distance from the center than the first distance. This feed point is also used for one of the feed signals for circularly polarized signals. The phase shift between signals applied to feed points for circularly polarized signals must be greater than the conventionally required 90 degrees and depends upon the antenna configuration.

  9. Microstrip Yagi array antenna for mobile satellite vehicle application

    NASA Technical Reports Server (NTRS)

    Huang, John; Densmore, Arthur C.

    1991-01-01

    A novel antenna structure formed by combining the Yagi-Uda array concept and the microstrip radiator technique is discussed. This antenna, called the microstrip Yagi array, has been developed for the mobile satellite (MSAT) system as a low-profile, low-cost, and mechanically steered medium-gain land-vehicle antenna. With the antenna's active patches (driven elements) and parasitic patches (reflector and director elements) located on the same horizontal plane, the main beam of the array can be tilted, by the effect of mutual coupling, in the elevation direction providing optimal coverage for users in the continental United States. Because the parasitic patches are not connected to any of the lossy RF power distributing circuit the antenna is an efficient radiating system. With the complete monopulse beamforming and power distributing circuits etched on a single thin stripline board underneath the microstrip Yagi array, the overall L-band antenna system has achieved a very low profile for vehicle's rooftop mounting, as well as a low manufacturing cost. Experimental results demonstrate the performance of this antenna.

  10. Design of microstrip disk antenna arrays

    NASA Technical Reports Server (NTRS)

    Bailey, M. C.; Parks, F. G.

    1978-01-01

    The radio frequency characteristics and design parameters for microstrip disk antenna elements and planar arrays are presented. Two C-band model arrays (an 8 element linear and an 8 by 8 planar) were designed, fabricated, and tested to demonstrate the technique of using microstrip elements for array applications. These arrays were designed with a cosine amplitude distribution.

  11. Note: Electrical detection and quantification of spin rectification effect enabled by shorted microstrip transmission line technique

    SciTech Connect

    Soh, Wee Tee; Ong, C. K.; Peng, Bin; State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 ; Chai, Guozhi

    2014-02-15

    We describe a shorted microstrip method for the sensitive quantification of Spin Rectification Effect (SRE). SRE for a Permalloy (Ni{sub 80}Fe{sub 20}) thin film strip sputtered onto SiO{sub 2} substrate is demonstrated. Our method obviates the need for simultaneous lithographic patterning of the sample and transmission line, therefore greatly simplifying the SRE measurement process. Such a shorted microstrip method can allow different contributions to SRE (anisotropic magnetoresistance, Hall effect, and anomalous Hall effect) to be simultaneously determined. Furthermore, SRE signals from unpatterned 50 nm thick Permalloy films of area dimensions 5 mm × 10 mm can even be detected.

  12. Several Microstrip-Based Conductor/Thin Film Ferroelectric Phase Shifter Designs Using (YBa2Cu3O(7 - Delta), Au)/SrTiO3/LaAlO3 Structures

    NASA Technical Reports Server (NTRS)

    VanKeuls, F. W.; Romanofsky, R. R.; Miranda, F. A.

    1998-01-01

    We have designed, fabricated, and tested several novel microstrip-base YBa2Cu3O7-delta/SrTiO3/LaAlO3 (YBCO/STO/LAO) and Au/SrTiO3ALO3 (Au/STO/LAO) phase shifters. The first design consists of eight coupled microstrip phase shifters (CMPS) in series. This design using YBCO achieved a relative insertion phase shift (Delta f) of 484 degrees with a figure of merit of 80 degrees/dB at Vdc = 375 V, 16 GHz, and 40 K. A Delta f of 290 degrees was observed while maintaining the insertion loss below 4.5 dB. At 77 K, a Delta of 420 degrees was obtained for this phase shifter at the same bias and frequency. Both results correspond to an effective coupling length of 0.33 cm. A second compact design, consisting of an Au meander line and a CMPS section was also tested. Of the two samples tested, the best showed a figure of merit of 43 degrees/dB with Delta f = 290 degrees and 6.8 dB loss, at 40 K, 10 GHz and 400 V. Experimental and modeling results on these circuits will be discussed in the context of potential applications.

  13. Inflatable Microstrip Reflectarray Antennas At X and Ka-Band Frequencies

    NASA Technical Reports Server (NTRS)

    Huang, John; Feria, Alfonso

    1998-01-01

    Introduction: Inflatable antenna technology is being developed by JPL/NASA to enable the capabilities of low mass, high packaging efficiency, and low-cost deployment for future spacecraft high-gain and large aperture antennas. One of the technologies being considered [11 is the inflatable microstrip reflectarray. A conventional inflatable parabolic reflector antenna will offer similar advantages with the added capability of wide electrical bandwidth. However, it suffers from the difficulty of maintaining its required large, thin, and curved-parabolic surface in the space environment. Since the microstrip reflectarray has the "natural" flat reflecting surface, it is much easier to maintain the required surface tolerance using an inflatable structure. This is the primary reason, despite its narrow bandwidth characteristic, that the inflatable microstrip reflectarray is being studied. This article discusses an already-developed one-meter X-band inflatable microstrip reflectarray and a three-meter Ka-band inflatable microstrip reflectarray which is currently under development. Both antennas' RF structures are designed at JPL and their mechanical inflatable structures are designed and manufactured at ILC Dover, Inc.

  14. Inflatable Microstrip Reflectarray Antennas at X and Ka-band Frequencies

    NASA Technical Reports Server (NTRS)

    Huang, John; Feria, Alfonso

    1999-01-01

    Inflatable antenna technology is being developed by JPL/NASA to enable the capabilities of low mass, high packaging efficiency, and low-cost deployment for future spacecraft high-gain and large aperture antennas. One of the technologies being considered is the inflatable microstrip reflectarray. A conventional inflatable parabolic reflector antenna will offer similar advantages with the added capability of wide electrical bandwidth. However, it suffers from the difficulty of maintaining its required large, thin, and curved-parabolic surface in the space environment. Since the microstrip reflectarray has the "natural" flat reflecting surface, it is much easier to maintain the required surface tolerance using an inflatable structure. This is the primary reason, despite its narrow bandwidth characteristic, that the inflatable microstrip reflectarray is being studied. This article discusses an already-developed one-meter X-band inflatable microstrip reflectarray and a three-meter Ka-band inflatable microstrip reflectarray which is currently under development. Both antennas' RF structures are designed at JPL and their mechanical inflatable structures are designed and manufactured at ILC Dover, Inc.

  15. Microstrip Antenna Arrays on Multilayer LCP Substrates

    NASA Technical Reports Server (NTRS)

    Thompson, Dane; Bairavasubramanian, Ramanan; Wang, Guoan; Kingsley, Nickolas D.; Papapolymerou, Ioannis; Tenteris, Emmanouil M.; DeJean, Gerald; Li, RonglLin

    2007-01-01

    A research and development effort now underway is directed toward satisfying requirements for a new type of relatively inexpensive, lightweight, microwave antenna array and associated circuitry packaged in a thin, flexible sheet that can readily be mounted on a curved or flat rigid or semi-rigid surface. A representative package of this type consists of microwave antenna circuitry embedded in and/or on a multilayer liquid- crystal polymer (LCP) substrate. The circuitry typically includes an array of printed metal microstrip patch antenna elements and their feedlines on one or more of the LCP layer(s). The circuitry can also include such components as electrostatically actuated microelectromechanical systems (MEMS) switches for connecting and disconnecting antenna elements and feedlines. In addition, the circuitry can include switchable phase shifters described below. LCPs were chosen over other flexible substrate materials because they have properties that are especially attractive for high-performance microwave applications. These properties include low permittivity, low loss tangent, low water-absorption coefficient, and low cost. By means of heat treatments, their coefficients of thermal expansion can be tailored to make them more amenable to integration into packages that include other materials. The nature of the flexibility of LCPs is such that large LCP sheets containing antenna arrays can be rolled up, then later easily unrolled and deployed. Figure 1 depicts a prototype three- LCP-layer package containing two four-element, dual-polarization microstrip-patch arrays: one for a frequency of 14 GHz, the other for a frequency of 35 GHz. The 35-GHz patches are embedded on top surface of the middle [15-mil (approx.0.13-mm)-thick] LCP layer; the 14- GHz patches are placed on the top surface of the upper [9-mil (approx. 0.23-mm)-thick] LCP layer. The particular choice of LCP layer thicknesses was made on the basis of extensive analysis of the effects of the

  16. Design and fabrication of microstrip antenna arrays

    NASA Technical Reports Server (NTRS)

    1978-01-01

    A microstrip array project was conducted to demonstrate the feasibility of designing and fabricating simple, low cost, low sidelobe phased arrays with circular disk microstrip radiating elements. Design data were presented for microstrip elements and arrays including the effects of the protective covers, the mutual interaction between elements, and stripline feed network design. Low cost multilayer laminate fabrication techniques were also investigated. Utilizing this design data two C-band low sidelobe arrays were fabricated and tested: an eight-element linear and a sixty-four element planar array. These arrays incorporated stripline Butler matrix feed networks to produce a low sidelobe broadside beam.

  17. Passivation of micro-strip gas chambers with an interstitial germanium coating

    SciTech Connect

    Miyamoto, J.; Knoll, G.F.; Amos, N.

    1996-12-31

    Micro-strip gas chambers (MSGCs) were constructed in the Solid-State Electronics Laboratory of the University of Michigan and their performance was studied. Many efforts have been made in the past to construct MSGCs that yield high absolute gas gain and stable gas gain. Introducing a thin germanium layer has been effective for passivation but difficulties associated with the poor adhesiveness of the thin layer have been a serious obstacle. This paper reports on a new method used to overcome these difficulties. Unlike the conventional coating method the thin germanium layer was successfully deposited between the strip lines. This technique requires a careful geometric alignment of a second photomask with the original micro-strip structure. The resulting detector performance was noteworthy and an absolute gas gain of 2 {center_dot} 10{sup 4} was easily achieved by the new chamber. The chamber`s gain instability was also reduced significantly compared with those without interstitial coating.

  18. Integration of microbolometers with infrared microstrip antennas

    NASA Astrophysics Data System (ADS)

    Codreanu, Iulian; Boreman, Glenn D.

    2002-12-01

    We report on various integration schemes of infrared microbolometers with microstrip antennas. The first integration design consists of two gold (Au) rectangular microstrip patches coupled along the radiating edges by a narrow niobium (Nb) strip. Devices using silicon oxide are compared to devices using amorphous silicon as antenna substrate. An extension of the twin-patch detector design is the microstrip dipole antenna-coupled microbolometer. Two ways of connecting the device to the contact pads via narrow dc leads are presented and compared. The contribution of the dc leads to the detector response is eliminated by directly connecting the dipole to the contact pads. The thermal isolation of the microbolometer from the silicon wafer is improved by incorporating air into the antenna dielectric substrate. This leads to higher detector responsivity and shifts the resonance towards longer antennas. The implementation of a bridge microstrip dipole antenna structure is also discussed.

  19. Design Aspects of the Microstrip Reflectarray

    NASA Technical Reports Server (NTRS)

    Huang, J.

    1998-01-01

    The microstrip reflectarray has been identified as one of the enabling technologies to achieve low mass, conformal mounting, wide-angle beam scanning, etc. for NASA's future speceborne high-gain antennas.

  20. Handbook of microstrip antennas. Volumes 1 & 2

    NASA Astrophysics Data System (ADS)

    James, Jim R.; Hall, Peter S.

    The design and operation of microstrip antennas (MAs) are discussed in chapters contributed by leading experts. Topics addressed include the analysis of circular MAs, improving the frequency agility and bandwidth of patch MAs, circular polarization and bandwidth, microstrip dipoles, multilayer and parasitic MAs, wideband flat dipole and short-circuit MA patch elements and arrays, numerical analysis methods for MAs, multiport-network and transmission-line models of MAs, the design of low-cost printed MAs, printed phase-array antennas, and circularly polarized arrays. Consideration is given to MA feeds, substrate technology, measurement techniques for printed antennas, CAD of microstrip and triplate circuits, resonant MA elements and arrays for aerospace applications, MAs for mobile and satellite systems, a conical conformal microstrip tracking antenna, MA field diagnostics, MAs on a cylindrical surface, and extensions and variations of the MA concept.

  1. Microstrip monopulse antenna for land mobile communications

    NASA Technical Reports Server (NTRS)

    Garcia, Q.; Martin, C.; Delvalle, J. C.; Jongejans, A.; Rinous, P.; Travers, M. N.

    1993-01-01

    Low cost is one of the main requirements in a communication system suitable for mass production, as it is the case for satellite land mobile communications. Microstrip technology fulfills this requirement which must be supported by a low cost tracking system design. The tradeoff led us to a prototype antenna composed of microstrip patches based on electromechanical closed-loop principle; the design and the results obtained are described.

  2. Dual-Band Microstrip Antenna With Reactive Loading

    NASA Technical Reports Server (NTRS)

    Davidson, Shayla E.

    1988-01-01

    Effective but bulky coaxial stub replaced. Short-circuited microstrip transmission line serves as reactive loading element for microstrip antenna. Constructed integrally with stripline radiating element, shorted line preserves low microstrip profile and enables tuning of antenna for two-band operation.

  3. Analysis of microstrip antennas using magnetic substrates

    NASA Astrophysics Data System (ADS)

    Vakati, Venkata Jagadish Prasad

    The substrate materials play a major role in the design, production and, most importantly, the performance of the Microstrip antennas. The main goal of this thesis lies in performing a comprehensive and exhaustive study as well as an analysis of how magnetic substrates affect the performance indices of the Microstrip antennas. This project takes into consideration the fact that study of magnetic materials as substrates is a relatively uncharted territory and that a few studies into this field have shown many potential facts. This project narrows the antenna under study to a rectangular Microstrip antenna, due to both the simplicity and the versatility of this structure and the scalability of the study. The project was performed using simulation of Microstrip antenna in CST Microwave Studio with magnetic substrates, over a range of mur, and recording the performance indices of the antenna. The performance indices that were considered for the study were Directivity, Efficiency, Gain, Bandwidth, Resonant frequency and VSWR. The method followed in this study can be easily scaled further to accommodate more performance indices, if needed. The observations were later used to draw practical inferences. Also as an extension, wide band 2x2 Microstrip antenna is designed with an additional degree of freedom where changing the feed distance can cover different bands in GSM frequency.

  4. A Microstrip Reflect Array Using Crossed Dipoles

    NASA Technical Reports Server (NTRS)

    Pozar, David M.; Targonski, Stephen D.

    1998-01-01

    Microstrip reflect arrays offer a flat profile and light weight, combined with many of the electrical characteristics of reflector antennas. Previous work [1]-[7] has demonstrated a variety of microstrip reflect arrays, using different elements at a range of frequencies. In this paper we describe the use of crossed dipoles as reflecting elements in a microstrip reflectarray. Theory of the solution will be described, with experimental results for a 6" square reflectarray operating at 28 GHz. The performance of crossed dipoles will be directly compared with microstrip patches, in terms of bandwidth and loss. We also comment on the principle of operation of reflectarray elements, including crossed dipoles, patches of variable length, and patch elements with tuning stubs. This research was prompted by the proposed concept of overlaying a flat printed reflectarray on the surface of a spacecraft solar panel. Combining solar panel and antenna apertures in this way would lead to a reduction in weight and simpler deployment, with some loss of flexibility in independently pointing the solar panel and the antenna. Using crossed dipoles as reflectarray elements will minimize the aperture blockage of the solar cells, in contrast to the use of elements such as microstrip patches.

  5. Omnidirectional, circularly polarized, cylindrical microstrip antenna

    NASA Technical Reports Server (NTRS)

    Stanton, Philip H. (Inventor)

    1985-01-01

    A microstrip cylindrical antenna comprised of two concentric subelements on a ground cylinder, a vertically polarized (E-field parallel to the axis of the antenna cylinder) subelement on the inside and a horizontally polarized (E-field perpendicular to the axis) subelement on the outside. The vertical subelement is a wraparound microstrip radiator. A Y-shaped microstrip patch configuration is used for the horizontally polarized radiator that is wrapped 1.5 times to provide radiating edges on opposite sides of the cylindrical antenna for improved azimuthal pattern uniformity. When these subelements are so fed that their far fields are equal in amplitude and phased 90.degree. from each other, a circularly polarized EM wave results. By stacking a plurality of like antenna elements on the ground cylinder, a linear phased array antenna is provided that can be beam steered to the desired elevation angle.

  6. Impedance properties of circular microstrip antenna

    NASA Technical Reports Server (NTRS)

    Deshpande, M. D.; Bailey, M. C.

    1983-01-01

    A moment method solution to the input impedance of a circular microstrip antenna excited by either a microstrip feed or a coaxial probe is presented. Using the exact dyadic Green's function and the Fourier transform the problem is formulated in terms of Richmond's reaction integral equation from which the unknown patch current can be solved for. The patch current is expanded in terms of regular surface patch modes and an attachment mode (for probe excited case) which insures continuity of the current at probe/patch junction, proper polarization and p-dependance of patch current in the vicinity of the probe. The input impedance of a circular microstrip antenna is computed and compared with earlier results. Effect of attachment mode on the input impedance is also discussed.

  7. Theory and experiment for infinite microstrip arrays

    NASA Astrophysics Data System (ADS)

    Wright, S. M.; Lo, Y. T.

    1985-01-01

    Microstrip antennas are well suited for use in large scanning arrays. To obtain greater bandwidth, it is useful to use thicker substrates, which can increase the effects of mutual coupling and lead to significant mismatch or blindness for certain scan angles. Using an infinite array formulation, the impedance of a single element in an infinite array environment was solved with the method of moments. Mutual coupling is built into the solution, and the presence of surface waves is accounted for by using the periodic Green's function for the grounded dielectric substrate. Blindness in arrays of microstrip dipoles on various substrates, both with and without radomes is demonstrated.

  8. Signal integrity analysis on discontinuous microstrip line

    NASA Astrophysics Data System (ADS)

    Qiao, Qingyang; Dai, Yawen; Chen, Zipeng

    2013-03-01

    In high speed PCB design, microstirp lines were used to control the impedance, however, the discontinuous microstrip line can cause signal integrity problems. In this paper, we use the transmission line theory to study the characteristics of microstrip lines. Research results indicate that the discontinuity such as truncation, gap and size change result in the problems such as radiation, reflection, delay and ground bounce. We change the discontinuities to distributed parameter circuits, analysed the steady-state response and transient response and the phase delay. The transient response cause radiation and voltage jump.

  9. Design and fabrication of microstrip circuits

    NASA Astrophysics Data System (ADS)

    Gardiol, Fred

    1988-06-01

    This article provides an up-to-date survey of microstrip circuits. It defines the main features of microwave integrated circuits (MICs), their particular characteristics in terms of electromagnetic fields and measurements, the materials most commonly used, the techniques developed to realize and connect circuits, and the available computer software for their analysis, synthesis, optimization and for the drafting and cutting of the masks required to carry out the photolithographic process. The most accurate relations presently available to characterize microstrip lines are given, and the major models introduced to characterize discontinuities are briefly described.

  10. Multilayer Microstrip Slot And Dipole Array Antenna

    NASA Technical Reports Server (NTRS)

    Tulintseff, Ann N.

    1994-01-01

    Multilayer antenna structure contains interleaved linear subarrays of microstrip dipole and slot radiating antenna elements to provide compact, dual-band antenna. Structure also contains associated microstrip transmission lines, plus high-power amplifiers for transmission and low-noise amplifiers for reception. Overall function is to transmit in horizontal polarization at frequency of 29.634 GHz and receive in vertical polarization at 19.914 GHz, in direction 44 degrees from broadside to antenna. Antenna structure is part of apparatus described in "Steerable K/Ka-band Antenna for Land-Mobile Satellite Applications," NPO-18772.

  11. Approximate analysis of electromagnetically coupled microstrip dipoles

    NASA Astrophysics Data System (ADS)

    Kominami, M.; Yakuwa, N.; Kusaka, H.

    1990-10-01

    A new dynamic analysis model for analyzing electromagnetically coupled (EMC) microstrip dipoles is proposed. The formulation is based on an approximate treatment of the dielectric substrate. Calculations of the equivalent impedance of two different EMC dipole configurations are compared with measured data and full-wave solutions. The agreement is very good.

  12. Analysis of a microstrip dipole antenna

    NASA Astrophysics Data System (ADS)

    Rao, B. V.; Sabhnani, N. H.

    1984-02-01

    Assuming a quasi-TEM mode of wave propagation and using a conformal transformation technique, accurate and simple analytic expressions for the characteristic wave resistance and the effective dielectric constant of the microstrip dipole antenna in the mixed dielectric medium have been derived. The theoretical values are in close agreement with the experimental results.

  13. Efficient analysis for infinite microstrip dipole arrays

    NASA Astrophysics Data System (ADS)

    Wright, S. M.; Lo, Y. T.

    1983-11-01

    A moment method analysis of infinite microstrip dipole arrays which uses an efficient technique to evaluate the generalized impedance matrix is described. A particularly simple formulation is obtained through the use of the periodic Green function. Results for the reflection coefficient magnitude against scan angle are given for a typical array.

  14. Microstrip antenna arrays with parasitic elements

    NASA Technical Reports Server (NTRS)

    Lee, Kai-Fong

    1996-01-01

    This research was concerned with using parasitic elements to improve the bandwidth, gain and axial ratio characteristics of microstrip antennas and arrays. Significant improvements in these characteristics were obtained using stacked and coplanar parasitic elements. Details of the results are described in a total of 16 journal and 17 conference papers. These are listed in Section four of this report.

  15. Microstrip antenna array with parasitic elements

    NASA Technical Reports Server (NTRS)

    Lee, Kai F.; Acosta, Roberto J.; Lee, Richard Q.

    1987-01-01

    Discussed is the design of a large microstrip antenna array in terms of subarrays consisting of one fed patch and several parasitic patches. The potential advantages of this design are discussed. Theoretical radiation patterns of a subarray in the configuration of a cross are presented.

  16. Microstrip Antenna Generates Circularly Polarized Beam

    NASA Technical Reports Server (NTRS)

    Huang, J.

    1986-01-01

    Circular microstrip antenna excited with higher order transverse magnetic (TM) modes generates circularly polarized, conical radiation patterns. Found both theoretically and experimentally that peak direction of radiation pattern is varied within wide angular range by combination of mode selection and loading substrate with materials of different dielectric constants.

  17. Slotline fed microstrip antenna array modules

    NASA Technical Reports Server (NTRS)

    Lo, Y. T.; Oberhart, M. L.; Brenneman, J. S.; Aoyagi, P.; Moore, J.; Lee, R. Q. H.

    1988-01-01

    A feed network comprised of a combination of coplanar waveguide and slot transmission line is described for use in an array module of four microstrip elements. Examples of the module incorporating such networks are presented as well as experimentally obtained impedance and radiation characteristics.

  18. Investigation of DC current injection effect on the microwave characteristics of HTS YBCO microstrip resonators

    NASA Astrophysics Data System (ADS)

    Nurgaliev, T.; Blagoev, B.; Mateev, E.; Neshkov, L.; Strbik, V.; Uspenskaya, L.; Nedkov, I.; Chromik, Š.

    2014-03-01

    The DC current injection effect from a ferromagnetic (FM) La0.7Sr0.3MnO3 (LSMO) to a high temperature superconducting (HTS) Y1Ba2Cu3O7-x (YBCO) thin film was investigated by the microwave surface impedance measurements in a FM/HTS structure, formed as a microstrip resonator for improving the sensitivity of the experiments. The quality factor and the resonance frequency of this structure were found to strongly depend on the current strength, injected from the LSMO electrode into the HTS microstrip electrode. The magnetic penetration depth and the quasiparticle conductivity of the HTS component were determined to increase under DC current injection process, which in all probability stimulated breaking of Cooper pairs and led to a decrease of the superfluid concentration and an increase of the normal fluid concentration without significantly affecting the relaxation time of the quasiparticles.

  19. Thin conformal antenna array for microwave power conversions

    NASA Technical Reports Server (NTRS)

    Dickinson, R. M. (Inventor)

    1978-01-01

    A structure of a circularly polarized, thin conformal, antenna array which may be mounted integrally with the skin of an aircraft employs microstrip elliptical elements and interconnecting feed lines spaced from a circuit ground plane by a thin dielectric layer. The feed lines are impedance matched to the elliptical antenna elements by selecting a proper feedpoint inside the periphery of the elliptical antenna elements. Diodes connected between the feed lines and the ground plane rectify the microwave power, and microstrip filters (low pass) connected in series with the feed lines provide dc current to a microstrip bus. Low impedance matching strips are included between the elliptical elements and the rectifying and filtering elements.

  20. Coupling Between Microstrip Lines and Finite Ground Coplanar Lines Embedded in Polyimide Layers for 3D-MMICs on Silicon

    NASA Technical Reports Server (NTRS)

    Ponchak, G. E.; Bushyager, N.; Papapolymerou, J.; Tentzeris, E. M.; Laskar, J.

    2002-01-01

    Three-dimensional circuits built upon multiple layers of polyimide are required for constructing Si/SiGe monolithic microwave/mm-wave integrated circuits on CMOS (low resistivity) Si wafers. It is expected that these circuits will replace the ones fabricated on GaAs and reduce the overall system cost. However, the closely spaced transmission lines that are required for a high-density circuit environment are susceptible to high levels of cross-coupling, which degrades the overall circuit performance. In this paper, theoretical and experimental results on coupling and ways to reduce it are presented for two types of transmission lines: a) the microstrip line and b) the Finite Ground Coplanar (FGC) line. For microstrip lines it is shown that a fence of metalized via-holes can significantly reduce coupling, especially in the case when both lines are on the same polyimide layer or when the shielding structure extends through several polyimide layers. For closely spaced microstrip lines, coupling is lower for a metal filled trench shield than a via-hole fence. Coupling amongst microstrip lines is dependent on the ratio of line separation to polyimide thickness and is primarily due to magnetic fields. For FGC lines it is shown that they have in general low coupling that can be reduced significantly when there is even a small gap between the ground planes of each line. FGC lines have approximately 8 dB lower coupling than coupled coplanar waveguides (CPW). In addition, forward and backward characteristics of the FGC lines do not resemble those of other transmission lines such as microstrip. Therefore, the coupling mechanism of the FGC lines is different compared to thin film microstrip lines.

  1. Method for calculating longitudinal microstrip antennas in planar phased arrays

    NASA Astrophysics Data System (ADS)

    Indenbom, M. V.

    The characteristics of longitudinal microstrip antennas in a planar phased array are examined on the basis of the application of the finite element method to an integral equation for the 'charge' on the microstrip line. Microstrip dipoles, and Yagi and log-periodic antennas are examples of such radiators. The analysis takes into account the complex configuration of the conductors, both current components, and the presence of dielectric substrates and a protective coating.

  2. Microstrip dipoles on electrically thick substrates

    NASA Astrophysics Data System (ADS)

    Jackson, D. R.; Alexopoulos, N. G.

    1986-01-01

    Certain basic radiation properties of microstrip dipoles on electrically thick substrates are investigated, and a comparison is made with the case of dipoles printed on a dielectric half-space. It is concluded that the microstrip dipole radiation properties become sensitive to substrate loss as the substrate thickness increases, with the half-space properties obtained for an adequate amount of loss. Asymptotic formulas for radiated power and efficiency are given for both the thick substrate and half-space problems, showing the behavior with increasing dielectric constant. The method of moments is used to extend the analysis to center-fed strip dipoles, and a method of improving both the efficiency and gain of a printed antenna by using a superstrate layer is discussed.

  3. Dual-band reactively loaded microstrip antenna

    NASA Technical Reports Server (NTRS)

    Richards, W. F.; Long, S. A.; Davidson, S. E.

    1985-01-01

    A previously derived theory is applied to a microstrip antenna with a reactive load to produce a dual-band radiator. A model consisting of a rectangular patch radiator loaded with a variable length short-circuited coaxial stub was investigated experimentally. Comparisons of theoretical predictions and experimental data are made for the impedance and resonant frequencies as a function of the position of the load, the length of the stub, and the characteristic impedance of the stub.

  4. Characterization of bone tissue using microstrip antennas.

    PubMed

    Barros, Jannayna D; de Oliveira, Jose Josemar; da Silva, Sandro G

    2010-01-01

    The use of electromagnetic waves in the characterization of biological tissues has been conducted since the nineteenth century after the confirmation that electric and magnetic fields can interact with biological materials. In this paper, electromagnetic waves are used to characterize tissues with different levels of bone mass. In this way, one antenna array on microstrip lines was used. It can be seen that bones with different mass has different behavior in microwave frequencies. PMID:21097274

  5. Rectangular Microstrip Antenna with Slot Embedded Geometry

    NASA Astrophysics Data System (ADS)

    Ambresh, P. A.; Hadalgi, P. M.; Hunagund, P. V.; Sujata, A. A.

    2014-09-01

    In this paper, a novel design that improves the performance of conventional rectangular microstrip antenna is discussed. Design adopts basic techniques such as probe feeding technique with rectangular inverted patch structure as superstrate, air filled dielectric medium as substrate and slot embedded patch. Prototype of the proposed antenna has been fabricated and various antenna performance parameters such as impedance bandwidth, return loss, radiation pattern and antenna gain are considered for Electromagnetic-study. The antennas are designed for the wireless application operating in the frequency range of 3.3 GHz to 3.6 GHz, and UK based fixed satellite service application (3 GHz to 4 GHz), and are named as single inverted patch conventional rectangular microstrip antenna (SIP-CRMSA) and slots embedded inverted patch rectangular microstrip antenna (SEIP-RMSA), respectively. Measurement outcomes for SEIP-RMSA1 and SEIP-RMSA2 showed the satisfactory performance with an achievable impedance bandwidth of 260 MHz (7 %) and 250 MHz (6.72 %), with return loss (RL) of -11.06 dB and -17.98 dB, achieved gain of 8.17 dB and 5.17 dB with 10% and 8% size reduction in comparison with the conventional patch antenna.

  6. A simple tuning method for high temperature superconducting microstrip filters

    NASA Astrophysics Data System (ADS)

    Pal, Srikanta; Stevens, Chris; Edwards, David

    2005-07-01

    In this paper we report a simple tuning methodology of high temperature superconducting (HTS) microstrip filters. In order to establish this new tuning approach a 5 pole lumped element HTS bandpass filter, centre frequency 800 MHz, narrowband (bandwidth, 7.6 MHz), is designed and fabricated on a 2 inch (diameter) Y Ba2Cu3O6.94 thin film of thickness 700 nm and lanthanum aluminate (LaAlO3) substrate of 0.5 mm thickness. The filter was etched using conventional photolithography and a wet chemical etching process. The 5 pole lumped element filter is tested in an integrated RF-cryocooler measurement system at 65 K and also in liquid nitrogen (77 K). We demonstrate a 19.3 MHz downward shift of the centre frequency of the 5 pole filter response. This is achieved by overlaying two layers of thin dielectric tape (PTFE) (50.0 µm thickness, permittivity 3.2) over the conducting patterned part of the filter surface. A full wave electromagnetic analysis of the dielectric environment of this tuning arrangement matches the measured response closely. To improve the passband response, the filter is tuned in liquid nitrogen, placing pieces of sapphire rods over the resonators of the filter layout.

  7. Improved tunable microstrip SQUID amplifiers for the Axion Dark Matter eXperiment

    NASA Astrophysics Data System (ADS)

    O'Kelley, Sean; Hansen, Jørn; Hilton, Gene; Mol, Jan-Michael; Clarke, John; ADMX Collaboration

    2015-04-01

    We describe a series of tunable microstrip SQUID (Superconducting QUantum Interference Device) amplifiers (MSAs) used as the photon detector in the Axion Dark Matter eXperiment (ADMX). Cooled to 100mK or lower, an optimized MSA approaches the quantum limit of detection. The axion dark matter candidate would be detected via Primakoff conversion to a microwave photon in a high-Q (~ 105) tunable microwave cavity, cooled to 1.6 K or lower, in the presence of a 7-tesla magnetic field. The MSA consists of a square loop of thin Nb film, incorporating two resistively shunted Josephson tunnel junctions biased to the voltage state, flux-coupled to a resonant microstrip. The photon frequency is determined by the unknown axion mass, so the cavity and amplifier must be tunable over a broad frequency range. MSA tunability is achieved by terminating the microstrip with a GaAs varactor diode that operates at cryogenic temperatures. This voltage-controlled capacitance enables us to vary the resonant microstrip mode from nearly λ/2 to λ/4. We demonstrate gains exceeding 20 dB, at frequencies above 900 MHz. With proper design of the microwave environment, a noise temperature of 1/2 to 1/4 of the physical temperature is demonstrated. Supported by DOE Grants DE-FG02-97ER41029, DE-FG02-96ER40956, DE- AC52-07NA27344, DE-AC03-76SF00098, NSF Grant 1067242, and the Livermore LDRD program.

  8. Suspended Patch Antenna Array With Electromagnetically Coupled Inverted Microstrip Feed

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.

    2000-01-01

    The paper demonstrates a four-element suspended patch antenna array, with a parasitic patch layer and an electromagnetically coupled inverted microstrip feed, for linear polarization at K-Band frequencies. This antenna has the following advantages over conventional microstrip antennas: First, the inverted microstrip has lower attenuation than conventional microstrip; hence, conductor loss associated with the antenna corporate feed is lower resulting in higher gain and efficiency. Second, conventional proximity coupled patch antennas require a substrate for the feed and a superstrate for the patch. However, the inverted microstrip fed patch antenna makes use of a single substrate, and hence, is lightweight and low cost. Third, electromagnetic coupling results in wider bandwidth. Details regarding the design and fabrication will be presented as well as measured results including return loss, radiation patterns and cross-polarization levels.

  9. Performance of a four-element Ka-band high-temperature superconducting microstrip antenna

    NASA Technical Reports Server (NTRS)

    Richard, M. A.; Bhasin, K. B.; Gilbert, C.; Metzler, S.; Koepf, G.; Claspy, P. C.

    1992-01-01

    Superconducting four-element microstrip array antennas operating at 30 GHz have been designed and fabricated on a lanthanum aluminate (LaAlO3) substrates. The experimental performance of these thin film Y-Ba-Cu-O superconducting antennas is compared with that of identical antenna patterned with evaporated gold. Efficiency measurements of these antennas show an improvement of 2 dB at 70 K and as much as 3.5 dB at 40 K in the superconducting antenna over the gold antenna.

  10. The D0 silicon microstrip tracker

    NASA Astrophysics Data System (ADS)

    Quinn, Breese; D0 Collaboration

    2003-03-01

    The D0 collaboration has completed building a 793,000 channel silicon microstrip tracker for the D0 upgrade. The tracker consists of 768 ladder and wedge assemblies including both single- and double-sided detectors. Detector readout utilizes the SVX-IIE radiation hard chip with on-chip digitization and sparsification. A brief review of the detector design is presented along with results from the assembly and testing processes. The operation of the full readout chain and the performance of the silicon tracker are described. Finally, lessons for future production of large scale tracking systems are discussed.

  11. Microstrip amplitude-weighted wilkinson power dividers

    NASA Astrophysics Data System (ADS)

    Huck, K. D.

    1986-03-01

    Unequal-split reactive power dividers were examined for use in forming amplitude tapers for microstrip array antennas. Circuits with power ratios of up to 5.0 between arms were constructed on Rexolite substrate, for operation at 4.0 GHz and 7.5 GHz. The 4.0 GHz circuits were very accurate in forming the correct amplitude ratio between outputs, and in maintaining phase balance between outputs. Of those circuits designed for 7.5 GHz, only those with split ratios less than 2.5 worked correctly. This report includes a review of the theory, measured results, and recommendations for improved power dividers.

  12. Design of microstrip components by computer

    NASA Technical Reports Server (NTRS)

    Cisco, T. C.

    1972-01-01

    A number of computer programs are presented for use in the synthesis of microwave components in microstrip geometries. The programs compute the electrical and dimensional parameters required to synthesize couplers, filters, circulators, transformers, power splitters, diode switches, multipliers, diode attenuators and phase shifters. Additional programs are included to analyze and optimize cascaded transmission lines and lumped element networks, to analyze and synthesize Chebyshev and Butterworth filter prototypes, and to compute mixer intermodulation products. The programs are written in FORTRAN and the emphasis of the study is placed on the use of these programs and not on the theoretical aspects of the structures.

  13. RHCP- DESIGNING RECTANGULAR RIGHT-HANDED CIRCULARLY POLARIZED MICROSTRIP ANTENNAS

    NASA Technical Reports Server (NTRS)

    Davidson, S. E.

    1994-01-01

    RHCP, the Right-Handed, Circularly Polarized Microstrip Antenna program, aids in the design of a rectangular antenna element, given the desired frequency of operation and substrate characteristics. RHCP begins the design calculations based on a square element with linear polarization. The effective dielectric constant and changes in electrical length due to fringing at the radiating element edges are taken into account. A coaxial feed is inset with 50 ohms input impedance. By placing the feed such that two orthonormal modes are produced in the antenna cavity, right- or left-handed circular polarization is obtained. Input to RHCP consists of desired frequency, dielectric constant, and substrate thickness. Output consists of the final rectangular geometry, the proposed feed inset placement, and actual input impedance. RHCP has been used successfully for frequencies between 2 and 15 GHz for thin substrates. This program was used to fabricate antenna elements for the S-band quad antennas on board the Space Shuttle, and is a part of the design project for the S-band phased array antenna radiating aperture. RHCP is written in FORTRAN 77 for interactive execution and has been implemented on a DEC VAX series computer operating under VMS. This program was developed in 1985.

  14. A study of microstrip antenna elements and arrays

    NASA Astrophysics Data System (ADS)

    Lo, Y. T.; Richards, W. F.; Simon, P.

    1980-12-01

    Thin microstrip antennas have many unique and attractive properties, but their operation is much limited in bandwidth. In this report an attempt is made to develop a procedure for array design, in particular, to determine whether or not the band of operation could be broadened by using a small array of two elements of slightly different dimensions. By broadband, it is meant that the antenna must have over the bandwidth: (1) an input impedance variation within a certain prescribed SWR (say 3:1); (2) a stable pattern (in particular a stable beam-pointing direction); (3) a small variation in gain (or efficiency); and (4) in some applications, small variations in beamwidth and sidelobe level. In this work only the first two fundamental performances are considered. Insofar as the impedance is considered, the array design is essentially a circuit problem. Our theory, based on the cavity model, has previously shown that the element impedance can adequately be described by a Foster network representation, namely, a series circuit of infinitely many parallel resonant circuits, each corresponding to a mode of the cavity. For frequencies in the vicinity of a certain mode, the circuit can further be reduced to a single parallel resonant circuit of that mode in series with an inductance. Our earlier investigation has also shown that, except for very close spacings, the mutual coupling effect between elements can be ignored.

  15. Microstrip Yagi Antenna with Dual Aperture-Coupled Feed

    NASA Technical Reports Server (NTRS)

    Pogorzelski, Ronald; Venkatesan, Jaikrishna

    2008-01-01

    A proposed microstrip Yagi antenna would operate at a frequency of 8.4 GHz (which is in the X band) and would feature a mechanically simpler, more elegant design, relative to a prior L-band microstrip Yagi antenna. In general, the purpose of designing a microstrip Yagi antenna is to combine features of a Yagi antenna with those of a microstrip patch to obtain an antenna that can be manufactured at low cost, has a low profile, and radiates a directive beam that, as plotted on an elevation plane perpendicular to the antenna plane, appears tilted away from the broadside. Such antennas are suitable for flush mounting on surfaces of diverse objects, including spacecraft, aircraft, land vehicles, and computers. Stated somewhat more precisely, what has been proposed is a microstrip antenna comprising an array of three Yagi elements. Each element would include four microstrip-patch Yagi subelements: one reflector patch, one driven patch, and two director patches. To obtain circular polarization, each driven patch would be fed by use of a dual offset aperture-coupled feed featuring bow-tie-shaped apertures. The selection of the dual offset bow-tie aperture geometry is supported by results found in published literature that show that this geometry would enable matching of the impedances of the driven patches to the 50-Omega impedance of the microstrip feedline while maintaining a desirably large front-to-back lobe ratio.

  16. Swept frequency technique for dispersion measurement of microstrip lines

    NASA Technical Reports Server (NTRS)

    Lee, R. Q.

    1986-01-01

    Microstrip lines used in microwave integrated circuits are dispersive. Because a microstrip line is an open structure, the dispersion can not be derived with pure TEM, TE, or TM mode analysis. Dispersion analysis has commonly been done using a spectral domain approach, and dispersion measurement has been made with high Q microstrip ring resonators. Since the dispersion of a microstrip line is fully characterized by the frequency dependent phase velocity of the line, dispersion measurement of microstrip lines requires the measurement of the line wavelength as a function of frequency. In this paper, a swept frequency technique for dispersion measurement is described. The measurement was made using an automatic network analyzer with the microstrip line terminated in a short circuit. Experimental data for two microstrip lines on 10 and 30 mil Cuflon substrates were recorded over a frequency range of 2 to 20 GHz. Agreement with theoretical results computed by the spectral domain approach is good. Possible sources of error for the discrepancy are discussed.

  17. A CMOS readout circuit for microstrip detectors

    NASA Astrophysics Data System (ADS)

    Nasri, B.; Fiorini, C.

    2015-03-01

    In this work, we present the design and the results of a CMOS analog channel for silicon microstrips detectors. The readout circuit was initially conceived for the outer layers of the SuperB silicon vertex tracker (SVT), but can serve more generally other microstrip-based detection systems. The strip detectors considered show a very high stray capacitance and high series resistance. Therefore, the noise optimization was the first priority design concern. A necessary compromise on the best peaking time to achieve an acceptable noise level together with efficiency and timing accuracy has been investigated. The ASIC is composed by a preamplifier, shaping amplifier and a Time over Threshold (T.o.T) block for the digitalization of the signals. The chosen shaping function is the third-order semi-Gaussian function implemented with complex poles. An inverter stage is employed in the analog channel in order to operate with signals delivered from both p and n strips. The circuit includes the possibility to select the peaking time of the shaper output from four values: 250 ns, 375 ns, 500 ns and 750 ns. In this way, the noise performances and the signal occupancy can be optimized according to the real background during the experiment. The ASIC prototype has been fabricated in the 130 nm IBM technology which is considered intrinsically radiation hard. The results of the experimental characterization of a produced prototype are satisfactorily matched with simulation.

  18. Analysis of a microstrip reflectarray antenna for microspacecraft applications

    NASA Technical Reports Server (NTRS)

    Huang, J.

    1995-01-01

    A microstrip reflectarray is a flat reflector antenna that can be mounted conformally onto a spacecraft's outside structure without consuming a significant amount of spacecraft volume and mass. For large apertures (2 m or larger), the antenna's reflecting surface, being flat, can be more easily and reliably deployed than a curved parabolic reflector. This article presents the study results on a microstrip reflect-array with circular polarization. Its efficiency and bandwidth characteristics are analyzed. Numerous advantages of this antenna system are discussed. Three new concepts using this microstrip reflectarray are also proposed.

  19. A finite difference approach to microstrip antenna design

    SciTech Connect

    Barth, M.J.; Bevensee, R.M.; Pennock, S.T.

    1986-12-01

    Microstrip antennas have received increased attention in recent years, due to their size and cost advantages. Analysis of the microstrip structure has proved difficult due to the presence of the dielectric substrate, particularly for complex geometries. One possible approach to a solution is the use of a finite difference computer code to model a proposed microstrip antenna design. The models are easily constructed and altered, and code versions are available which allow input impedance or far-field patterns to be calculated. Results for some simple antenna geometries will be presented.

  20. Advanced microstrip antenna developments. Volume 2: Microstrip GPS antennas for general aviation aircraft

    NASA Astrophysics Data System (ADS)

    Sanford, G. G.; Gross, B. D.

    1982-03-01

    This report describes the application of microstrip antenna technology to the design of general aviation (G/A) aircraft antennas for use with the Global Positioning System (GPS). For most G/A aircraft, only single frequency operation will be required. However, air-carrier and some large corporate aircraft may make use of dual-frequency operation. For this reason, some dual-frequency designs have been investigated. The main effort was given to the design of antennas with broad beamwidths which could be switched or steered to compensate for aircraft maneuvers, with the goal of maintaining near-hemispherical carriage in flight. A hybrid microstrip crossed-slot and sleeve-dipole element used with a suitable combining network gives a suitable, controllable broad-beam pattern. This element and its performance are described. In addition, radiation patterns are presented using scale-model aircraft and simple crossed-slot antennas.

  1. D0 layer 0 innermost layer of silicon microstrip tracker

    SciTech Connect

    Hanagaki, K.; /Fermilab

    2006-01-01

    A new inner layer silicon strip detector has been built and will be installed in the existing silicon microstrip tracker in D0. They report on the motivation, design, and performance of this new detector.

  2. Microstrip Gas Chambers on glass and ceramic substrates

    SciTech Connect

    Gong, W.G.; Wieman, H.; Harris, J.W.; Mitchell, J.T.; Hong, W.S.; Perez-Mendez, V.

    1993-11-01

    We report developments of Microstrip Gas Chambers (MSGC) fabricated on glass and ceramic substrates with various resistivities. Low resistivity of the substrate is found to be critical for achieving stable operation of microstrip gas chambers. The microstrip pattern consists of 10 {mu}m wide anodes and 90 {mu}m wide cathodes with a 200 {mu}m anode-to-anode pitch. High-quality microstrips are fabricated using the dry etch after UV-photolithography. Our chambers are tested in an Ar(90)-CH{sub 4}(10) gas mixture at atmospheric pressure with a 100 {mu}Ci {sup 55}Fe source. An energy resolution (FWHM) of 15% has been achieved for 6 keV soft X-rays. At a rate of 5 {times} 10{sup 4} photons/sec/mm{sup 2}, gas gains are stable within a few percents. Long-term tests of gain stability and rate capability are yet to be pursued.

  3. The study of microstrip antenna arrays and related problems

    NASA Technical Reports Server (NTRS)

    Lo, Y. T.

    1986-01-01

    In February, an initial computer program to be used in analyzing the four-element array module was completed. This program performs the analysis of modules composed of four rectangular patches which are corporately fed by a microstrip line network terminated in four identical load impedances. Currently, a rigorous full-wave analysis of various types of microstrip line feed structures and patches is being performed. These tests include the microstrip line feed between layers of different electrical parameters. A method of moments was implemented for the case of a single dielectric layer and microstrip line fed rectangular patches in which the primary source is assumed to be a magnetic current ribbon across the line some distance from the patch. Measured values are compared with those computed by the program.

  4. Compact Magic-T using microstrip-slotline transitions

    NASA Technical Reports Server (NTRS)

    U-Yen, Kongpop (Inventor); Wollack, Edward J. (Inventor); Doiron, Terence (Inventor); Moseley, Samuel H. (Inventor)

    2010-01-01

    The design of a compact low-loss Magic-T is described. The planar Magic-T incorporates a compact microstrip-slotline tee junction and small microstrip-slotline transition area to reduce slotline radiation. The Magic-T produces broadband in-phase and out-of-phase power combiner/divider responses, has low in-band insertion loss, and small in-band phase and amplitude imbalance.

  5. Scattering from arbitrarily shaped microstrip patch antennas

    NASA Technical Reports Server (NTRS)

    Shively, David G.; Deshpande, Manohar D.; Cockrell, Capers R.

    1992-01-01

    The scattering properties of arbitrarily shaped microstrip patch antennas are examined. The electric field integral equation for a current element on a grounded dielectric slab is developed for a rectangular geometry based on Galerkin's technique with subdomain rooftop basis functions. A shape function is introduced that allows a rectangular grid approximation to the arbitrarily shaped patch. The incident field on the patch is expressed as a function of incidence angle theta(i), phi(i). The resulting system of equations is then solved for the unknown current modes on the patch, and the electromagnetic scattering is calculated for a given angle. Comparisons are made with other calculated results as well as with measurements.

  6. Rectenna composed of a circular microstrip antenna

    SciTech Connect

    Itoh, K.; Ohgane, T.; Ogawa, Y.

    1986-01-01

    One of the big problems in the SPS system is reradiation of the harmonic waves generated by the rectifying diode. The authors proposed the use of a circular microstrip antenna (CMSA), since the CMSA has no higher resonance-harmonic of integer multiple of the dominant resonance frequency. However, characteristics of a large rectenna array of CMSA's have not been clarified. This paper is concerned with the absorption efficiency of the rectenna composed of the CMSA. The efficiency is estimated explicitly using an infinite array model. The results show that the absorption efficiency of the infinite rectenna array composed of the CMSA is 100%. Also, this paper considers the effect of the losses of the composed of the CMSA is 100%. Also, this paper considers the effect of the losses of the CMSA. 4 references, 4 figures.

  7. Two microstrip arrays for interferometric SAR applications

    NASA Technical Reports Server (NTRS)

    Huang, J.

    1993-01-01

    Two types of C-band aircraft interferometric Synthetic Aperture Radar (SAR) are being developed at JPL to measure the ocean wave characteristics. Each type requires two identical antennas with each having a long rectangular aperture to radiate fan-shaped beam(s). One type of these radars requires each of its antennas to radiate a broadside beam that will measure the target's cross-track velocity. The other type, having each of its antennas to radiate two off-broadside pointed beams, will allow the measurement of both the cross-track and the along-track velocities of the target. Because flush mounting of the antenna on the aircraft fuselage is desirable, microstrip patch array is selected for these interferometric SAR antennas. To meet the radar system requirement, each array needs a total of 76 microstrip patches which are arranged in a 38 x 2 rectangular aperture with a physical size of 1.6m x 16.5cm. To minimize the insertion loss and physical real estate of this relatively long array, a combined series/parallel feed technique is used. Techniques to suppress cross-pol radiation and to effectively utilize the RF power are also implemented. Cross-pol level of lower than -30 dB from the co-pol peak and low insertion loss of 0.36 dB have been achieved for both types of arrays. For the type of radar that requires two off-braodside pointed beams, a simple phasing technique is used to achieve this dual-beam capability with adequate antenna gain (20 dBi) and sidelobe level (-14 dB). Both radar arrays have been flight tested on aircraft with excellent antenna performance demonstrated.

  8. Fast patterning of oriented organic microstripes for field-effect ammonia gas sensors

    NASA Astrophysics Data System (ADS)

    Wang, Binghao; Ding, Jinqiang; Zhu, Tao; Huang, Wei; Cui, Zequn; Chen, Jianmei; Huang, Lizhen; Chi, Lifeng

    2016-02-01

    A series of organic field-effect transistors (OFETs) with patterned ultra-thin films for NH3 detection are achieved via fast dip-coating. The morphology and packing structure of the ultra-thin films are greatly dependent on the surface energy of the substrates, geometry features of the patterned electrodes and evaporation atmosphere during the dip-coating process, which in turn results in a significant difference in the NH3 sensing properties. Based on the newly proposed mechanism, low-trap dielectric-semiconductor interfaces, a stripe-like morphology and an ultrathin film (as low as 2 nm) enable the OFET-based sensors to exhibit unprecedented sensitivity (~160) with a short response/recovery time. The efficient (2 mm s-1), reliable, and scalable patterning strategy opens a new route for solution-processed OFET-based gas sensors.A series of organic field-effect transistors (OFETs) with patterned ultra-thin films for NH3 detection are achieved via fast dip-coating. The morphology and packing structure of the ultra-thin films are greatly dependent on the surface energy of the substrates, geometry features of the patterned electrodes and evaporation atmosphere during the dip-coating process, which in turn results in a significant difference in the NH3 sensing properties. Based on the newly proposed mechanism, low-trap dielectric-semiconductor interfaces, a stripe-like morphology and an ultrathin film (as low as 2 nm) enable the OFET-based sensors to exhibit unprecedented sensitivity (~160) with a short response/recovery time. The efficient (2 mm s-1), reliable, and scalable patterning strategy opens a new route for solution-processed OFET-based gas sensors. Electronic supplementary information (ESI) available: Optical, SEM images of DTBDT-C6 microstripes; output characteristics of OTFTs based on DTBDT-C6 microstripes. See DOI: 10.1039/c5nr09001f

  9. A tunable microstrip SQUID amplifier for the Axion Dark Matter eXperiment (ADMX)

    NASA Astrophysics Data System (ADS)

    O'Kelley, Sean; Hansen, Jorn; Weingarten, Elan; Mueck, Michael; Hilton, Gene; Clarke, John

    2014-03-01

    We describe a microstrip SQUID (Superconducting QUantum Interference Device) amplifier (MSA) used as the photon detector in the Axion Dark Matter eXperiment (ADMX). Cooled to 100 mK or lower, an optimized MSA approaches the quantum limit of detection. The axion dark matter is detected via Primakoff conversion to a microwave photon in a high-Q (~ 105) tunable microwave cavity, currently cooled to about 1.6 K, in the presence of a 7-tesla magnetic field. The MSA consists of a square loop of thin Nb film, incorporating two Josephson tunnel junctions with resistive shunts to prevent hysteresis in the current-voltage characteristic. The microstrip is a square Nb coil deposited over an intervening insulating layer. Since the photon frequency is determined by the unknown axion mass, the cavity and amplifier must be tunable over a broad frequency range. Tunability is achieved by terminating the microstrip with a GaAs varactor diode with a voltage-controlled capacitance that enables us to vary the resonance from nearly 1/2 to 1/4 of a wavelength. With the SQUID current-biased in the voltage state, we demonstrate a gain of typically 20 dB over nearly one octave, 415 MHz to 800 MHz. Supported by DOE Grants DE-FG02-97ER41029, DE-FG02-96ER40956, DE-AC52-07NA27344, DE-AC03-76SF00098, NSF grants PHY-1067242 and PHY-1306729, and the Livermore LDRD program.

  10. Tunable microstrip SQUID amplifiers for the Gen 2 Axion Dark Matter eXperiment (ADMX)

    NASA Astrophysics Data System (ADS)

    O'Kelley, Sean; Hilton, Gene; Clarke, John; ADMX Collaboration

    2016-03-01

    We present a series of tunable microstrip SQUID (Superconducting Quantum Interference Device) amplifiers (MSAs) for installation in ADMX. The axion dark matter candidate is detected via Primakoff conversion to a microwave photon in a high-Q (~100,000) tunable microwave cavity cooled with a dilution refrigerator in a 7-tesla magnetic field. The microwave photon frequency ν is a function of the unknown axion mass, so both the cavity and amplifier must be scanned over a wide frequency range. An MSA is a linear, phase-preserving amplifier consisting of a square washer loop, fabricated from a thin Nb film, incorporating two Josephson tunnel junctions with resistive shunts to prevent hysteresis. The input is coupled via a microstrip made from a square Nb coil deposited over the washer with an intervening insulating layer. Tunability is achieved by terminating the microstrip with GaAs varactors that operate below 100 mK. By varying the varactor capacitance with a bias voltage, the resonant frequency is varied by up to a factor of 2. We demonstrate several devices operating below 100 mK, matched to the discrete operating bands of ADMX at frequencies ranging from 560 MHz to 1 GHz. The MSAs exhibit gains exceeding 20 dB and the associated noise temperatures, measured with a hot/cold load, approach the standard quantum limit (hν/kB) . Supported by DOE Grants DE - FG02 - 97ER41029, DE - FG02 - 96ER40956, DE - AC52 - 07NA27344, DE - AC03 - 76SF00098, and the Livermore LDRD program.

  11. A 10 GHz Y-Ba-Cu-O/GaAs hybrid oscillator proximity coupled to a circular microstrip patch antenna

    NASA Technical Reports Server (NTRS)

    Rohrer, Norman J.; Richard, M. A.; Valco, George J.; Bhasin, Kul B.

    1993-01-01

    A 10 GHz hybrid Y-Ba-Cu-O / GaAs microwave oscillator proximity coupled to a circular microstrip antenna was designed, fabricated and characterized. The oscillator was a reflection mode type using a GaAs MESFET as the active element. The feedline, transmission lines, RF chokes, and bias lines were all fabricated from YBa2Cu3O(7-x) superconducting thin films on a 1 cm x 1 cm lanthanum aluminate substrate. The output feedline of the oscillator was wire bonded to a superconducting feedline on a second 1 cm x 1 cm lanthanum aluminate substrate, which was in turn proximity coupled to a circular microstrip patch antenna. Antenna patterns from this active patch antenna and the performance of the oscillator measured at 77 K are reported. The oscillator had a maximum output power of 11.5 dBm at 77 K, which corresponded to an efficiency of 10 percent. In addition, the efficiency of the microstrip patch antenna together with its high temperature superconducting feedline was measured from 85 K to 30 K and was found to be 71 percent at 77 4 increasing to a maximum of 87.4 percent at 30 K.

  12. A 10 GHz Y-Ba-Cu-O/GaAs hybrid oscillator proximity coupled to a circular microstrip patch antenna

    NASA Technical Reports Server (NTRS)

    Rohrer, Norman J.; Richard, M. A.; Valco, George J.; Bhasin, Kul B.

    1993-01-01

    A 10 GHz hybrid YBCO/GaAs microwave oscillator proximity coupled to a circular microstrip antenna has been designed, fabricated, and characterized. The oscillator was a reflection mode type using a GaAs MESFET as the active element. The feedline, transmission lines, RF chokes, and bias lines were all fabricated from YBCO superconducting thin films on a 1 cm x 1 cm lanthanum aluminate substrate. The output feedline of the oscillator was wire bonded to a superconducting feedline on a second 1 cm x 1 cm lanthanum aluminate substrate, which was in turn proximity coupled to a circular microstrip patch antenna. Antenna patterns from this active patch antenna and the performance of the oscillator measured at 77 K are reported. The oscillator had a maximum output power of 11.5 dBm at 77 K, which corresponded to an efficiency of 10 percent. In addition, the efficiency of the microstrip patch antenna together with its high temperature superconducting feedline was measured from 85 K to 30 K and was found to be 71 percent at 77 K, increasing to a maximum of 87.4 percent at 30 K.

  13. Moment method analysis of microstrip antennas over a wide frequency range

    NASA Technical Reports Server (NTRS)

    Kwan, B. W.; Newman, E. H.

    1985-01-01

    Expressions for the self and mutual impedance between microstrip antenna modes on a grounded dielectric slab are presented. The mutual impedance between the microstrip modes and a vertical current filament in the dielectric is also presented. These are the quantities required in a method of moments analysis of the microstrip antenna. Entire domain expansion modes, suitable for representing the microstrip current over a broad frequency range, are used. Efficient methods for the evaluation of the mutual impedance elements are described.

  14. Three-dimensional simulation of a low-power microwave-excited microstrip plasma source

    NASA Astrophysics Data System (ADS)

    Tong, Lizhu; Saito, Keiichiro

    2016-06-01

    A low-power microwave-excited argon microstrip plasma source operated at 2.45 GHz is studied by a three-dimensional fluid model. The electrodeless microwave-excited plasmas are produced in the gas channel with the gas pressures of 50 and 100 Torr at the input power of 2 W. Simulations are performed by the plasma module of COMSOL Multiphysics@. Results show that the electric field induced by the electromagnetic wave is concentrated in the neighborhood of the inner surface of gas channel under the microstrip line. The electromagnetic wave is restricted to transit from being propagating to evanescent in a very thin zone at which the electron density is equal to the critical density. The resonance zone is solved by adding an effective collision frequency to the momentum collision frequency. The governed ions are found to be atomic argon ions (Ar+) and molecular argon ions (Ar2 +) and the latter has a wider distribution. The three-body reactions to produce Ar2 + ions become important at high gas pressures.

  15. A High-gain Circularly Polarized Ka-band Microstrip Reflectarray

    NASA Technical Reports Server (NTRS)

    Huang, J.

    1996-01-01

    A half-meter, 32 GHz, circularly polarized microstrip reflectarray antenna has been developed. Excellent efficiency, good bandwidth, and low average sideglobe and cross-pol levels are achieved. It is believed that this is electrically the largest microstrip reflectarray (6924 elements) that has ever been developed, and it is the first time that circular polarization has been demonstrated using microstrip elements.

  16. Microstrip-antenna design for hyperthermia treatment of superficial tumors.

    PubMed

    Montecchia, F

    1992-06-01

    Microstrip antennas have many different advantages over other RF/MW radiative applicators employed for superficial hyperthermia treatment. This is mainly due to their compact and body-conformable structure as well as to printed circuit board techniques, both of which allow a wide design flexibility for superficial tumor heating. Among the wide variety of radiator configurations, three microstrip antennas of increasing complexity with electromagnetic and heating characteristics potentially suitable as applicators for superficial hyperthermia have been designed, developed, and tested in different radiative conditions: a microstrip disk, a microstrip annular-slot, and a microstrip spiral. Electromagnetic design criteria are presented together with the determinations of the applicator return loss versus frequency and thermograms of the near-field heating pattern in muscle-like phantom. The results are in good agreement with theory and indicate that: i) the operating frequency is either single or multiple according to the applicator-mode, "resonant" or "traveling-wave," and can be chosen in the useful frequency range for hyperthermia (200-1000 MHz) according to the tumor cross-section and depth; ii) the heating pattern flexibility increases going from the simple geometry disk to the annular-slot and spiral applicators; iii) a distilled-water bolus is required; iv) the annular-slot applicator exhibits the highest efficiency, while the spiral applicator provides the best performance. PMID:1601439

  17. Microstrip-antenna design for hyperthermia treatment of superficial tumors

    SciTech Connect

    Montecchia, F. )

    1992-01-01

    Microstrip antennas have many different advantages over other RF/MW radiative applicators employed for superficial hyperthermia treatment. This is mainly due to their compact and body-conformable structure as well as to printed circuit board techniques, both of which allow a wide design flexibility for superficial tumor heating. Among the wide variety of radiator configurations, three microstrip antennas of increasing complexity with electromagnetic and heating characteristics potentially suitable as applicators for superficial hyperthermia have been designed, developed, and tested in different radiative condition: a microstrip disk, a microstrip annular-slot, and a microstrip spiral. Electromagnetic design criteria are presented together with the determinations of the applicator return loss versus frequency and thermograms of the near-field heating pattern in muscle-like phantom. The results are in good agreement with theory and indicated that: the operating frequency is either single or multiple according to the applicator-mode, 'resonant' or 'traveling-wave', and can be chosen in the useful frequency range for hyperthermia according to the tumor cross-section and depth; the heating pattern flexibility increases going form the simple geometry disk to the annular-slot and spiral applicators; a distilled-water bolus is required; the annular-slot applicator exhibits the highest efficiency, while the spiral applicator provides the best performance.

  18. An experimental investigation of high temperature superconducting microstrip antennas at K- and Ka-band frequencies. Ph.D. Thesis Final Report

    NASA Technical Reports Server (NTRS)

    Richard, Mark A.

    1993-01-01

    The recent discovery of high temperature superconductors (HTS) has generated a substantial amount of interest in microstrip antenna applications. However, the high permittivity of substrates compatible with HTS results in narrow bandwidths and high patch edge impedances of such antennas. To investigate the performance of superconducting microstrip antennas, three antenna architectures at K and Ka-band frequencies are examined. Superconducting microstrip antennas that are directly coupled, gap coupled, and electromagnetically coupled to a microstrip transmission line were designed and fabricated on lanthanum aluminate substrates using YBa2Cu3O7 superconducting thin films. For each architecture, a single patch antenna and a four element array were fabricated. Measurements from these antennas, including input impedance, bandwidth, patterns, efficiency, and gain are presented. The measured results show usable antennas can be constructed using any of the architectures. All architectures show excellent gain characteristics, with less than 2 dB of total loss in the four element arrays. Although the direct and gap coupled antennas are the simplest antennas to design and fabricate, they suffer from narrow bandwidths. The electromagnetically coupled antenna, on the other hand, allows the flexibility of using a low permittivity substrate for the patch radiator, while using HTS for the feed network, thus increasing the bandwidth while effectively utilizing the low loss properties of HTS. Each antenna investigated in this research is the first of its kind reported.

  19. Coupling Between Microstrip Lines with Finite Width Ground Plane Embedded in Polyimide Layers for 3D-MMICs on Si

    NASA Technical Reports Server (NTRS)

    Ponchak, George E.; Dalton, Edan; Tentzeris, Emmanouil M.; Papapolymerou, John; Williams, W. Dan (Technical Monitor)

    2001-01-01

    Three-dimensional circuits built upon multiple layers of polyimide are required for constructing Si/SiGe monolithic microwave/millimeter-wave integrated circuits on complementary metal oxide semiconductor (CMOS) (low resistivity) Si wafers. Thin film microstrip lines (TFMS) with finite width ground planes embedded in the polyimide are often used. However, the closely spaced TFMS lines are susceptible to high levels of coupling, which degrades circuit performance. In this paper, Finite Difference Time Domain (FDTD) analysis and experimental measurements are used to show that the ground planes must be connected by via holes to reduce coupling in both the forward and backward directions.

  20. Microstrip antennas on/in anisotropic material layers

    NASA Astrophysics Data System (ADS)

    Yang, Hung-Yu; Castaneda, Jesse A.; Nakatani, Akifumi

    1992-11-01

    Accurate fullwave analyses of microstrip dipoles on multi-layer substrates with generalized anisotropic permittivity and permeability have been developed. The solution to the problem of microstrip dipoles on/in gyrotropic substrates has been obtained. The potential of electronically shaped, scanned, and gain enhanced element factors with ferrite substrates has been theoretically demonstrated. The scattering and radiation problems were solved. The use of biased ferrite substrates to simultaneously reduce RCS and preserve antenna in-band gain has also been described. Infinite phased arrays of microstrip dipoles and probe-fed patches on general anisotropic multi-layer substrates have been analyzed. All the solutions involve the dyadic Green's function for the anisotropic layered structure and the application of the method of moments to an electric field integral equation.

  1. Broadband Uniplanar Microstrip to Slot-Line Transitions

    NASA Technical Reports Server (NTRS)

    Dib, Nihad I.; Simons, Rainee N.; Katehi, Linda P. B.

    1995-01-01

    New in line uniplanar microstrip-to-slotline transitions for MIC/MMIC and phased array slotline antenna applications are described. Such transactions are compact and suitable to be used in an open environment or inside a package or a multichip module. The transitions share the concept of using a balun which consists of two microstrip lines connected to a slotline through a pair of coupled microstrips. The transitions are studied theoretically using the finite difference time domain (FDTD) technique and measured experimentally using an HP8510C Network Analyzer. For a back-to-back configuration, an insertion loss of less than 1.3 dB per transition is achieved over a 40% 3-dB bandwidth with a minimum of 0.6 dB at the design frequency.

  2. Wireless OAM transmission system based on elliptical microstrip patch antenna.

    PubMed

    Chen, Jia Jia; Lu, Qian Nan; Dong, Fei Fei; Yang, Jing Jing; Huang, Ming

    2016-05-30

    The multiplexing transmission has always been a focus of attention for communication technology. In this paper, the radiation characteristics of circular microstrip patch antenna was firstly analyzed based on cavity model theory, and then spiral beams carrying orbital angular momentum (OAM) were generated, using elliptical microstrip patch antenna, with a single feed probe instead of a standard circular patch with two feedpoints. Moreover, by combining the proposed elliptic microstrip patch antenna with Universal Software Radio Peripheral (USRP), a wireless OAM transmission system was established and the real-time transmission of text, image and video in a real channel environment was realized. Since the wireless OAM transmission has the advantage of good safety and high spectrum utilization efficiency, this work has theoretical significance and potential application. PMID:27410080

  3. Microstrip dipoles for EHF and millimeter wave applications

    NASA Astrophysics Data System (ADS)

    Alexopoulos, N. G.

    1986-08-01

    This is the final report for research performed under DAAG29-83-K-0067. The research performed during the duration of this grant has made an impact in the areas of: (1) Substrate-superstrate effects on printed circuit antennas (2) Modeling electromagnetically coupled microstrip dipoles in a substrate-superstrate configuration (3) Modeling Microstrip Discontinuities and (4) Investigating substrate anisotropy effects on a variety of integrated circuit structures. During the period of research, very sophisticated algorithms were developed on Green's function methods and integral equation solutions based on a variety of numerical procedures.

  4. A microstrip array feed for MSAT spacecraft reflector antenna

    NASA Technical Reports Server (NTRS)

    Huang, John

    1988-01-01

    An L-band circularly polarized microstrip array antenna with relatively wide bandwidth has been developed. The array has seven subarrays which form a single cluster as part of a large overlapping cluster reflector feed array. Each of the seven subarrays consists of four uniquely arranged linearly polarized microstrip elements. A 7.5 percent impedance (VSWR less than 1.5) as well as axial ratio (less than 1 dB) bandwidths have been achieved by employing a relatively thick honeycomb substrate with special impedance matching feed probes.

  5. A K-Band Linear Phased Array Antenna Based on Ba(0.60)Sr(0.40)TiO3 Thin Film Phase Shifters

    NASA Technical Reports Server (NTRS)

    Romanofsky, R.; Bernhard, J.; Washington, G.; VanKeuls, F.; Miranda, F.; Cannedy, C.

    2000-01-01

    This paper summarizes the development of a 23.675 GHz linear 16-element scanning phased array antenna based on thin ferroelectric film coupled microstripline phase shifters and microstrip patch radiators.

  6. Very Long Microstrip Array Feeds of a Membrane Reflector for the Advanced Precipitation Radar

    NASA Technical Reports Server (NTRS)

    Huang, John; Rahmat-Samii, Yahya; Durden, Stephen L.; Im, Eastwood

    2005-01-01

    Very long microstrip arrays have been developed at the Ku- and Ka-band frequencies. Each array having an electrical length of about 110 free-space wavelengths is used to feed a deployable thin-membrane cylindrical reflector for a spaceborne precipitation radar application. These arrays, designed for 0(deg) and 30(deg) beam directions, achieved peak sidelobes of -20 dB and average sidelobes below -30 dB with peak cross-pol levels below -20 dB. Several unique challenges were encountered during the development of these very long arrays, such as the strong coupling between very long power divider lines, the strong leakage radiation from the lengthy transmission lines, and the lack of computer analysis capability of these electrically large arrays.

  7. Parallel and series FED microstrip array with high efficiency and low cross polarization

    NASA Technical Reports Server (NTRS)

    Huang, John (Inventor)

    1995-01-01

    A microstrip array antenna for vertically polarized fan beam (approximately 2 deg x 50 deg) for C-band SAR applications with a physical area of 1.7 m by 0.17 m comprises two rows of patch elements and employs a parallel feed to left- and right-half sections of the rows. Each section is divided into two segments that are fed in parallel with the elements in each segment fed in series through matched transmission lines for high efficiency. The inboard section has half the number of patch elements of the outboard section, and the outboard sections, which have tapered distribution with identical transmission line sections, terminated with half wavelength long open-circuit stubs so that the remaining energy is reflected and radiated in phase. The elements of the two inboard segments of the two left- and right-half sections are provided with tapered transmission lines from element to element for uniform power distribution over the central third of the entire array antenna. The two rows of array elements are excited at opposite patch feed locations with opposite (180 deg difference) phases for reduced cross-polarization.

  8. Analysis of microstrip dipoles and slots transversely coupled to a microstrip line using the FDTD method

    NASA Astrophysics Data System (ADS)

    Tulintseff, A. N.

    Printed dipole elements and their complement, linear slots, are elementary radiators that have found use in low-profile antenna arrays. Low-profile antenna arrays, in addition to their small size and low weight characteristics, offer the potential advantage of low-cost, high-volume production with easy integration with active integrated circuit components. The design of such arrays requires that the radiation and impedance characteristics of the radiating elements be known. The FDTD (Finite-Difference Time-Domain) method is a general, straight-forward implementation of Maxwell's equations and offers a relatively simple way of analyzing both printed dipole and slot elements. Investigated in this work is the application of the FDTD method to the analysis of printed dipole and slot elements transversely coupled to an infinite transmission line in a multilayered configuration. Such dipole and slot elements may be used in dipole and slot series-fed-type linear arrays, where element offsets and interelement line lengths are used to obtain the desired amplitude distribution and beam direction, respectively. The design of such arrays is achieved using transmission line theory with equivalent circuit models for the radiating elements. In an equivalent circuit model, the dipole represents a shunt impedance to the transmission line, where the impedance is a function of dipole offset, length, and width. Similarly, the slot represents a series impedance to the transmission line. The FDTD method is applied to single dipole and slot elements transversely coupled to an infinite microstrip line using a fixed rectangular grid with Mur's second order absorbing boundary conditions. Frequency-dependent circuit and scattering parameters are obtained by saving desired time-domain quantities and using the Fourier transform. A Gaussian pulse excitation is applied to the microstrip transmission line, where the resulting reflected signal due to the presence of the radiating element is used

  9. Analysis of microstrip dipoles and slots transversely coupled to a microstrip line using the FDTD method

    NASA Technical Reports Server (NTRS)

    Tulintseff, A. N.

    1993-01-01

    Printed dipole elements and their complement, linear slots, are elementary radiators that have found use in low-profile antenna arrays. Low-profile antenna arrays, in addition to their small size and low weight characteristics, offer the potential advantage of low-cost, high-volume production with easy integration with active integrated circuit components. The design of such arrays requires that the radiation and impedance characteristics of the radiating elements be known. The FDTD (Finite-Difference Time-Domain) method is a general, straight-forward implementation of Maxwell's equations and offers a relatively simple way of analyzing both printed dipole and slot elements. Investigated in this work is the application of the FDTD method to the analysis of printed dipole and slot elements transversely coupled to an infinite transmission line in a multilayered configuration. Such dipole and slot elements may be used in dipole and slot series-fed-type linear arrays, where element offsets and interelement line lengths are used to obtain the desired amplitude distribution and beam direction, respectively. The design of such arrays is achieved using transmission line theory with equivalent circuit models for the radiating elements. In an equivalent circuit model, the dipole represents a shunt impedance to the transmission line, where the impedance is a function of dipole offset, length, and width. Similarly, the slot represents a series impedance to the transmission line. The FDTD method is applied to single dipole and slot elements transversely coupled to an infinite microstrip line using a fixed rectangular grid with Mur's second order absorbing boundary conditions. Frequency-dependent circuit and scattering parameters are obtained by saving desired time-domain quantities and using the Fourier transform. A Gaussian pulse excitation is applied to the microstrip transmission line, where the resulting reflected signal due to the presence of the radiating element is used

  10. Complete and rigorous analysis of electromagnetically coupled transverse microstrip dipole

    NASA Astrophysics Data System (ADS)

    Lepeltier, P.; Floc'h, J. M.; Citerne, J.

    1987-07-01

    A rigorous and complete analysis of the electromagnetically coupled transverse microstrip dipole is presented. This new feeding process offers an alternative solution, which is especially interesting when it is necessary to excite several dipoles from the same line. The theoretical results are compared to experimental measurements in X-band for the input impedance and the radiation patterns (co- and crosspolarization).

  11. Slot-coupled excitation of microstrip dipole antennas

    NASA Astrophysics Data System (ADS)

    Ittipiboon, A.; Roscoe, D.; Cuhaci, M.; Antar, Y. M. M.

    1992-01-01

    The slot-coupled method is proposed as an alternative to the popular electromagnetically coupled technique (EMC) for feeding microstrip dipole antennas. This letter describes the basic design procedure and some key advantages of this method over EMC. Experimental results confirm the effective and practical performance of the proposed structure.

  12. Full W-band Microstrip Fed Vivaldi Antenna

    NASA Astrophysics Data System (ADS)

    Rebollo, Ainara; Gonzalo, Ramón; Ederra, Iñigo

    2016-03-01

    A full W-band Vivaldi antenna is proposed. The selected feeding technique implements a broadband slotline to microstrip transition which allows obtaining return loss higher than 10 dB in the full W-band. The proposed configuration is compatible with standard manufacturing techniques such as photo-lithography or laser milling.

  13. Stripline/Microstrip Transition in Multilayer Circuit Board

    NASA Technical Reports Server (NTRS)

    Epp, Larry; Khan, Abdur

    2005-01-01

    A stripline-to-microstrip transition has been incorporated into a multilayer circuit board that supports a distributed solid-state microwave power amplifier, for the purpose of coupling the microwave signal from a buried-layer stripline to a top-layer microstrip. The design of the transition could be adapted to multilayer circuit boards in such products as cellular telephones (for connecting between circuit-board signal lines and antennas), transmitters for Earth/satellite communication systems, and computer mother boards (if processor speeds increase into the range of tens of gigahertz). The transition is designed to satisfy the following requirements in addition to the basic coupling requirement described above: (1) The transition must traverse multiple layers, including intermediate layers that contain DC circuitry. (2) The transition must work at a frequency of 32 GHz with low loss and low reflection. (3) The power delivered by the transition to top-layer microstrip must be split equally in opposite directions along the microstrip. Referring to the figure, this amounts to a requirement that when power is supplied to input port 1, equal amounts of power flow through output ports 2 and 3. (4) The signal-line via that is necessarily a part of such a transition must not be what is known in the art as a blind via; that is, it must span the entire thickness of the circuit board.

  14. A Low Loss Microstrip Antenna for Radiometric Applications

    NASA Technical Reports Server (NTRS)

    Wahid, Parveen

    2000-01-01

    The design and analysis of a series-fed, low-loss, inverted microstrip array antenna, operating at 1.413 GHz is presented. The antenna is composed of two subarrays. Each subarray consists of an equal number of microstrip patches all connected together with microstrip lines. In the first design microstrip array for linear polarization is presented which incorporated a series feeding technique. The next design, which is capable of dual linear polarization (V-polarization and H-polarization), utilizes a corporate feed network for the V-pol and series feed arrangement for the H-pol. The first element of each subarray for H-pol is coaxially fed with a 180 deg phase difference. This approach ensures a symmetric radiation pattern on broadside in H-pol. For the V-pol two feeds are in the same phase on the two subarrays ensuring a broadside beam in V-pol. The designs presented here are simulated using the IE3D code that utilizes the method of moments. Measured results are compared with simulated results and show good agreement.

  15. Full W-band Microstrip Fed Vivaldi Antenna

    NASA Astrophysics Data System (ADS)

    Rebollo, Ainara; Gonzalo, Ramón; Ederra, Iñigo

    2016-08-01

    A full W-band Vivaldi antenna is proposed. The selected feeding technique implements a broadband slotline to microstrip transition which allows obtaining return loss higher than 10 dB in the full W-band. The proposed configuration is compatible with standard manufacturing techniques such as photo-lithography or laser milling.

  16. Use of microstrip patch antennas in grain permittivity measurement

    USGS Publications Warehouse

    El Sabbagh, M.A.; Ramahi, O.M.; Trabelsi, S.; Nelson, S.O.; Khan, L.

    2003-01-01

    In this paper, a compact size free-space setup is proposed for the measurement of complex permittivity of granular materials. The horn antennas in the conventional setup are replaced by microstrip patch antennas which is a step toward system miniaturization. The experimental results obtained are in good agreement with those obtained with horn antennas.

  17. A user's manual for the Loaded Microstrip Antenna Code (LMAC)

    NASA Technical Reports Server (NTRS)

    Forrai, D. P.; Newman, E. H.

    1988-01-01

    The use of the Loaded Microstrip Antenna Code is described. The geometry of this antenna is shown and its dimensions are described in terms of the program outputs. The READ statements for the inputs are detailed and typical values are given where applicable. The inputs of four example problems are displayed with the corresponding output of the code given in the appendices.

  18. A planar broad-band flared microstrip slot antenna

    NASA Astrophysics Data System (ADS)

    Povinelli, Mark J.

    1987-08-01

    Experimental results have been obtained on a planar multioctave bandwidth flared microstrip slot. When crossed, the element is capable of horizontal, vertical, or circular polarization. A design was fabricated and measurements were taken to define the performance. The input impedance and radiation characteristics are shown to have a broad-band response when configured as a cavity-backed element.

  19. An investigation of a novel microstrip magic-T

    NASA Astrophysics Data System (ADS)

    Katsube, M. W.

    1992-04-01

    ?he magic T device is commonly found in waveguide form and has unique power division and isolation characteristics which find wide application in the microwave field. The design of such a device in microstrip technology using aperture coupling is investigated. Aperture coupling is a recent method for coupling electromagnetic energy from one substrate layer to another. It has a number of advantages including the separate integration of top and bottom layer circuitry, whereby the ground plane provides the isolation between the respective layers. Results indicate that this working device in microstrip exhibits the required properties of a magic T. Theoretical analysis is pursued to produce ideal circuit models based on modal analysis. A first order approximation is made using the dominant mode, with Lorentz reciprocity and the Poynting theorem. Experimental findings show very good narrow band characteristics with possible broadband operation upon further optimization of the T-branch, which at this stage is the limiting factor. The slot coupling shows good characteristics from about 12 to 18 GHz. The aperture coupled microstrip magic T shows excellent potential in performance for future applications such as integration into microstrip antennas and multilayer processing systems.

  20. Nonplanar linearly tapered slot antenna with balanced microstrip feed

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Lee, Richard Q.; Perl, Thomas D.

    1992-01-01

    A nonplanar linearly tapered slot antenna (LTSA) has been fabricated and tested at frequencies from 8 to 32 giga-Hz. The LTSA is excited by a broadband balanced microstrip transformer. The measured results include the input term return loss as well as the radiation pattern of the antenna.

  1. Planar Microstrip Yagi Array with Notched Parasitic Elements

    NASA Technical Reports Server (NTRS)

    Lee, Richard Q.; Zaman, Afoz J.

    2001-01-01

    The design and radiation characteristics of a planar microstrip Yagi array with notched parasitic elements are presented. Results indicate that a directional beam 45 deg from the broadside direction with a gain over 7 dB can be achieved. Good agreements were observed between experimental and analytical results.

  2. Magic-T Junction using Microstrip/Slotline Transitions

    NASA Technical Reports Server (NTRS)

    U-yen, Kongpop; Wollack, Edward J.; Doiron, Terence

    2008-01-01

    An improved broadband planar magic-T junction that incorporates microstrip/slotline transitions has been developed. In comparison with a prior broadband magic-T junction incorporating microstrip/slotline transitions, this junction offers superior broadband performance. In addition, because this junction is geometrically simpler and its performance is less affected by fabrication tolerances, the benefits of the improved design can be realized at lower fabrication cost. There are potential uses for junctions like this one in commercial microwave communication receivers, radar and polarimeter systems, and industrial microwave instrumentation. A magic-T junction is a four-port waveguide junction consisting of a combination of an H-type and an E-type junction. An E-type junction is so named because it includes a junction arm that extends from a main waveguide in the same direction as that of the electric (E) field in the waveguide. An H-type junction is so named because it includes a junction arm parallel to the magnetic (H) field in a main waveguide. A magic-T junction includes two input ports (here labeled 1 and 2, respectively) and two output ports (here labeled E and H, respectively). In an ideal case, (1) a magic-T junction is lossless, (2) the input signals add (that is, they combine in phase with each other) at port H, and (3) the input signals subtract (that is, they combine in opposite phase) at port E. The prior junction over which the present junction is an improvement affords in-phase-combining characterized by a broadband frequency response, and features a small slotline area to minimize in-band loss. However, with respect to isolation between ports 1 and 2 and return loss at port E, it exhibits narrowband frequency responses. In addition, its performance is sensitive to misalignment of microstrip and slotline components: this sensitivity is attributable to a limited number of quarter-wavelength (lambda/4) transmission-line sections for matching impedances

  3. BI-ground microstrip array coil vs. conventional microstrip array coil for mouse imaging at 7 tesla

    NASA Astrophysics Data System (ADS)

    Hernández, Ricardo; Terrones, M. A. López; Jakob, P. M.

    2012-10-01

    At high field strengths, the need for more efficient high frequency coils has grown. Since the radiation losses and the interaction between coil and sample increase proportionally to field strength, the quality factor (Q) and the sensitivity of the coil decrease as consequence of these negative effects. Since Zhang et al proposed in 2001 a new surface coil based on the microstrip transmission line for high frequency, different Tx-Rx phased arrays based on this concept have been already introduced in animal and whole body systems at high field strengths, each of them with different modifications in order to get better field homogeneity, SNR or isolation between coil elements in the array. All these arrays for animals systems have been built for rat imaging. One of these modifications is called BI-Ground Microstrip Array Coil (BIGMAC). The implementation of a smaller two-channel BIGMAC design for mouse imaging is studied and its performance compared to a two-channel conventional Microstrip array at 7 Tesla, the higher isolation by using BIGMAC elements in comparison with conventional Microstrip elements is shown in this work.

  4. Segmental neurofibromatosis.

    PubMed

    Galhotra, Virat; Sheikh, Soheyl; Jindal, Sanjeev; Singla, Anshu

    2014-07-01

    Segmental neurofibromatosis is a rare disorder, characterized by neurofibromas or cafι-au-lait macules limited to one region of the body. Its occurrence on the face is extremely rare and only few cases of segmental neurofibromatosis over the face have been described so far. We present a case of segmental neurofibromatosis involving the buccal mucosa, tongue, cheek, ear, and neck on the right side of the face. PMID:25565748

  5. Segmental neurofibromatosis.

    PubMed

    Toy, Brian

    2003-10-01

    Segmental neurofibromatosis is a rare variant of neurofibromatosis in which skin lesions are confined to a circumscribed body segment. A case of a 72-year-old woman with this condition is presented. Clinical features and genetic evidence are reviewed. PMID:14594599

  6. Active Segmentation

    PubMed Central

    Mishra, Ajay; Aloimonos, Yiannis

    2009-01-01

    The human visual system observes and understands a scene/image by making a series of fixations. Every fixation point lies inside a particular region of arbitrary shape and size in the scene which can either be an object or just a part of it. We define as a basic segmentation problem the task of segmenting that region containing the fixation point. Segmenting the region containing the fixation is equivalent to finding the enclosing contour- a connected set of boundary edge fragments in the edge map of the scene - around the fixation. This enclosing contour should be a depth boundary. We present here a novel algorithm that finds this bounding contour and achieves the segmentation of one object, given the fixation. The proposed segmentation framework combines monocular cues (color/intensity/texture) with stereo and/or motion, in a cue independent manner. The semantic robots of the immediate future will be able to use this algorithm to automatically find objects in any environment. The capability of automatically segmenting objects in their visual field can bring the visual processing to the next level. Our approach is different from current approaches. While existing work attempts to segment the whole scene at once into many areas, we segment only one image region, specifically the one containing the fixation point. Experiments with real imagery collected by our active robot and from the known databases 1 demonstrate the promise of the approach. PMID:20686671

  7. Superconductive microstrip exhibiting negative differential resistivity

    DOEpatents

    Huebener, R.P.; Gallus, D.E.

    1975-10-28

    A device capable of exhibiting negative differential electrical resistivity over a range of values of current and voltage is formed by vapor- depositing a thin layer of a material capable of exhibiting superconductivity on an insulating substrate, establishing electrical connections at opposite ends of the deposited strip, and cooling the alloy into its superconducting range. The device will exhibit negative differential resistivity when biased in the current- induced resistive state.

  8. On the modeling and experimentation of electromagnetically coupled microstrip dipole arrays in a substrate-superstrate

    NASA Astrophysics Data System (ADS)

    Alexopoulos, Nicholaos G.; Yang, Hung-Ya

    The thrust of the research has been to develop the methodology for the modeling and design antenna arrays and microstrip discontinuities for microwave circuit applications. The thesis involves several key contributions in the subject areas of modeling microstrip discontinuities, microstrip transitions, and the synthesis of microstrip dipole arrays. This work has generated several journal publications within which one finds a fundamental contribution to the understanding of the above mentioned subjects. The analysis and the generated computer programs serve as practical tools for the design of microstrip circuits and microstrip dipole arrays. An evolution of the work has led to the understanding of microstrip discontinuity effects. In particular the theory has been extended to model microstrip bends, T-junctions, four ports, etc. In each case the algorithms account for a precise description of energy loss at discontinuities due to radiation loss and surface wave loss. These models have also been substantiated with experiment. The models are now extended to provide precise designs for microstrip corporate feeds. This will lead to the design of two dimensional transversely fed electromagnetically coupled dipole arrays.

  9. The design of microstrip dipole arrays including mutual coupling. I Theory. II - Experiment

    NASA Astrophysics Data System (ADS)

    Elliott, R. S.; Stern, G. J.

    1981-09-01

    A design technique which includes mutual coupling is formulated for use with microstrip dipole arrays. The technique is based on iterative solution of a combined design equation and requires as input foreknowledge of the self-impedances and mutual impedances of microstrip dipoles and also the link between the radiating current and the backscattered wave in the feeding line. Procedures for obtaining the input design data for microstrip dipole arrays are then described and the design of a typical array is presented. The design data indicate that mutual coupling is a significant factor which cannot be ignored in the design of small microstrip dipole arrays.

  10. Sub-terahertz and terahertz microstrip resonant-tunneling-diode oscillators

    NASA Astrophysics Data System (ADS)

    Feiginov, Michael

    2015-09-01

    We present a theoretical analysis of traveling-wave microstrip resonant-tunneling-diode (RTD) oscillators. Such oscillators are similar to terahertz (THz) quantum-cascade lasers (QCLs) with a metal-metal waveguide and with just the active part of a single QCL period (an RTD) as their active core. Assuming realistic parameters of RTDs, we show that the microstrip RTD oscillators should be working at sub-THz and THz frequencies. Contrary to the contemporary THz QCLs, RTD microstrips are room-temperature oscillators. The major loss- and gain-enhancement mechanisms in RTD microstrips are identified.

  11. Sub-terahertz and terahertz microstrip resonant-tunneling-diode oscillators

    SciTech Connect

    Feiginov, Michael

    2015-09-21

    We present a theoretical analysis of traveling-wave microstrip resonant-tunneling-diode (RTD) oscillators. Such oscillators are similar to terahertz (THz) quantum-cascade lasers (QCLs) with a metal-metal waveguide and with just the active part of a single QCL period (an RTD) as their active core. Assuming realistic parameters of RTDs, we show that the microstrip RTD oscillators should be working at sub-THz and THz frequencies. Contrary to the contemporary THz QCLs, RTD microstrips are room-temperature oscillators. The major loss- and gain-enhancement mechanisms in RTD microstrips are identified.

  12. Effect of finite substrate width on higher-order mode generation of electrically shielded symmetric microstrip

    NASA Astrophysics Data System (ADS)

    Tseng, J.-D.; Tzuang, C.-K. C.

    1992-01-01

    The effect of finite substrate width on the higher-order mode generation of an electrically shielded microstrip is investigated. By employing the full-wave mixed potential mode-matching method the microstrip on a finite-width substrate can be accurately analyzed. The dispersion characteristics of microstrip on two different substrate widths were compared in the frequency range of interest. The results indicated that the use of conventional three-dimensional simulators assuming homogeneous layered (stratified) multi-dielectric substrates may not work well above the first cutoff frequency of microstrip on a finite-width substrate.

  13. Microstrip patch antennas - Basic properties and some recent advances

    NASA Astrophysics Data System (ADS)

    Lee, Kai-Fong

    1989-10-01

    For high-speed moving vehicles, it is desirable for the antenna to be 'low profile'. One of the early low profile antennas is the slot antenna, the theory of which was developed by Professor Henry G. Booker in a classic paper published in 1946. During the last decade and a half, a relatively new class of radiators known as microstrip patch antennas has received much attention. In addition to being low profile and conformable to a shaped surface, these antennas offer the potential advantages of light weight, low cost, ruggedness, and compatibility with integrated circuit technology. The main disadvantages are narrow bandwidth and the problems associated with copper loss and spurious radiation when the elements form an array. This paper begins with a description of the basic features of microstrip patch antennas, followed by a presentation of some of the research aimed at improving the frequency response and gain, particularly those to which the author and his collaborators have made contributions.

  14. Microstrip patch antennas—basic properties and some recent advances

    NASA Astrophysics Data System (ADS)

    Kai-Fong, Lee

    1989-10-01

    For high-speed moving vehicles, it is desirable for the antenna to be "low profile". One of the early low profile antennas is the slot antenna, the theory of which was developed by Professor Henry G. Booker in a classic paper published in 1946. During the last decade and a half, a relatively new class of radiators known as microstrip patch antennas has received much attention. In addition to being low profile and conformable to a shaped surface, these antennas offer the potential advantages of light weight, low cost, ruggedness, and compatibility with integrated circuit technology. The main disadvantages are narrow bandwidth and the problems associated with copper loss and spurious radiation when the elements form an array. This paper begins with a description of the basic features of microstrip patch antennas, followed by a presentation of some of the research aimed at improving the frequency response and gain, particularly those to which the author and his collaborators have made contributions.

  15. New Optically Controlled Frequency-Agile Microstrip Antenna

    NASA Astrophysics Data System (ADS)

    Ehteshami, Nasrin; Sathi, Vahid

    2013-01-01

    A novel class of microstrip antennas composed of organic semiconductor polymer [poly(3-hexylthiophene) (P3HT)] is proposed for frequency sweeping applications. The permittivity of the P3HT film is measured using the reflective coaxial method for illuminated and nonilluminated states. Resonant frequencies of the proposed antennas instantly change on changing the optical illumination intensity from an adjustable white-light source. Two different antenna configurations (square and square ring) are designed and tested experimentally. The square ring antenna is able to sweep a broader frequency band (1.5 GHz). The gain and radiation efficiency of the proposed square antenna are compared with the corresponding copper microstrip antenna. The proposed antennas have acceptable resonant and radiation characteristics, albeit with modest radiation efficiency.

  16. Infinite phased array of microstrip dipoles in two layers

    NASA Astrophysics Data System (ADS)

    Castaneda, Jesus A.

    1989-01-01

    A method has been devised for the analysis of the infinite printed strip dipole array in a two layer microstrip substrate structure. The complete dynamic Green's function appropriate to the two-layer substrate-superstrate structure was used in the formulation of the method of moments solution. In this way all the substrate effects, including the surface wave related phenomena, have been included in the development and solution. The solution provides a means by which the most important performance characteristics of the finite-but-large phase-scanned microstrip array can be studied. Attention has been focused on the characterization of the active input impedance as a function of the equivalent scan angle.

  17. A design concept for an MMIC microstrip phased array

    NASA Technical Reports Server (NTRS)

    Lee, R. Q.; Smetana, J.; Acosta, R.

    1986-01-01

    A conceptual design for a microstrip phased array with monolithic microwave integrated circuit (MMIC) amplitude and phase controls is described. The MMIC devices used are 20 GHz variable power amplifiers and variable phase shifters recently developed by NASA contractors for applications in future Ka band advanced satellite communication antenna systems. The proposed design concept is for a general NxN element array of rectangular lattice geometry. Subarray excitation is incorporated in the MMIC phased array design to reduce the complexity of the beam forming network and the number of MMIC components required. The proposed design concept takes into consideration the RF characteristics and actual phyical dimensions of the MMIC devices. Also, solutions to spatial constraints and interconnections associated with currently available packaging designs are discussed. Finally, the design of the microstrip radiating elements and their radiation characteristics are examined.

  18. Fabrication and characterization of BYCO microstrip delay lines

    SciTech Connect

    Traek, E.K.; Hobenwarter, G.K.G.; Madhavrao, L.R.; Patt, R.; Drake, R.E.; Radparvar, M. )

    1991-03-01

    The authors have fabricated and characterized microstrip delay lines with YBCO films as the material for the strip and polished bulk copper for the ground pane. The film-carrying LaAlO{sub 3} substrate is flipped over the copper ground plane and separated from it by a polyamide laminate and acts as the microstrip dielectric. Linewidths are varied from 100 to 600 {mu}m, total length from 10 to 65 cm. Two winding shapes are evaluated, concentric circular and serpentine. For a total geometric length of 60 cm, a TDR-measured delay of 5 nanoseconds is obtained with a line impedance of 50 {omega}. This paper discusses the design constraints, fabrication and properties of these lines and the issues involved in obtaining long delays.

  19. Microstrip patch antenna receiving array operating in the Ku band

    NASA Technical Reports Server (NTRS)

    Walcher, Douglas A.

    1996-01-01

    Microstrip patch antennas were first investigated from the idea that it would be highly advantageous to fabricate radiating elements (antennas) on the same dielectric substrate as RF circuitry and transmission lines. Other advantages were soon discovered to be its lightweight, low profile, conformability to shaped surfaces, and low manufacturing costs. Unfortunately, these same patches continually exhibit narrow bandwidths, wide beamwidths, and low antenna gain. This thesis will present the design and experimental results of a microstrip patch antenna receiving array operating in the Ku band. An antenna array will be designed in an attempt to improve its performance over a single patch. Most Ku band information signals are either wide band television images or narrow band data and voice channels. An attempt to improve the gain of the array by introducing parasitic patches on top of the array will also be presented in this thesis.

  20. Dual band triangular slotted stacked microstrip antenna for wireless applications

    NASA Astrophysics Data System (ADS)

    Singh, Vinod; Ali, Zakir; Singh, Ashutosh; Ayub, Shahanaz

    2013-06-01

    In this paper stacked configuration of microstrip antenna is used to produce dual wide band which is suitable for various wireless applications. Using triangular slot and stacking of foam substrate of dielectric constant 1, two bands of bandwidth 18.70% and 12.10% is obtained. The antenna is fed by coaxial probe feeding technique. The proposed patch antenna is designed on the foam substrate and simulated on the Zeland IE3D software.

  1. A new model for broadband waveguide to microstrip transition design

    NASA Technical Reports Server (NTRS)

    Ponchak, George E.; Downey, Alan N.

    1986-01-01

    A new model is presented which permits the prediction of the resonant frequencies created by antipodal finline waveguide to microstrip transitions. The transition is modeled as a tapered transmission line in series with an infinite set of coupled resonant circuits. The resonant circuits are modeled as simple microwave resonant cavities of which the resonant frequencies are easily determined. The model is developed and the resonant frequencies determined for several different transitions. Experimental results are given to confirm the models.

  2. Operation of silicon microstrip detectors in a high radiation environment

    SciTech Connect

    Kapustinsky, J.S.; Alde, D.M.; Boissevain, J.G.; Jeppesen, R.G.; Lane, D.W.; Leitch, M.J.; Lillberg, J.W.; Lopez, T.A.; McGaughey, P.L.; Moss, J.M.; Peng, J.C. ); Brooks, B.M.; Isenhower, L.D.; Sadler, M.E. ); Lederman, L.M.; Schub, M.H. ); Brown, C.N.; Cooper, W.E.; Gounder, K.; Hsiung, Y.B.; Mishra, C.S. (Fermi National

    1990-01-01

    A Silicon Microstrip Spectrometer was recently installed and operated in an 800 GeV proton beamline at Fermilab as a major new component of experiment E789. The detectors received an estimated radiation exposure of up to 7.8 {times} 10{sup 12} minimum ionizing particles per cm{sup 2} over a period of two months. We report on the changes in detector performance that we have observed following preliminary data analysis. 5 refs., 4 figs.

  3. Silicon Microstrip Detectors for the Jlab SBS Spectrometer

    NASA Astrophysics Data System (ADS)

    de Persio, F.; Kiprich, S.; Meddi, F.; Urciuoli, G. M.

    2014-06-01

    The INFN group of Rome is developing two silicon microstrip detector planes to be part of the tracking system of the SBS spectrometer, that will be installed in the experimental Hall A of Jefferson Labortatory, in order to improve its resolution. The detector and the PCB design were the results of models simulated using PSPICE. The entire assembly process will be realized in the INFN Roma clean room CL10000 facility.

  4. Microstrip antenna modeling and measurement at high frequencies

    SciTech Connect

    Bevensee, R.M.

    1986-04-30

    This report addresses the task C(i) of the Proposal for Microstrip Antenna Modeling and Measurement at High Frequencies by the writer, July 1985. The task is: Assess the advantages and disadvantages of the three computational approaches outlined in the Proposal, including any difficulties to be resolved and an estimate of the time required to implement each approach. The three approaches are (1) Finite Difference, (2) Sommerfeld-GTD-MOM, and (3) Surface Intergral Equations - MOM. These are discussed in turn.

  5. Reducing Cross-Polarized Radiation From A Microstrip Antenna

    NASA Technical Reports Server (NTRS)

    Huang, John

    1991-01-01

    Change in configuration of feed of nominally linearly polarized microstrip-patch transmitting array antenna reduces cross-polarized component of its radiation. Patches fed on opposing sides, in opposite phases. Combination of spatial symmetry and temporal asymmetry causes copolarized components of radiation from fundamental modes of patches to reinforce each other and cross-polarized components of radiation from higher-order modes to cancel each other.

  6. Improved bandwidth of microstrip antennas using parasitic elements

    NASA Astrophysics Data System (ADS)

    Wood, C.

    1980-08-01

    A method is described of doubling the bandwidth of rectangular microstrip patch antennas by locating capacitively excited m-wavelength/4 short circuit parasitic elements at their radiating edges. The antenna characteristics are explained in terms of an antiphase mode of a pair of coupled resonators, and it is shown that the bandwidth improvement is independent of the coupling capacitance. Experimental results are presented for both linearly and circularly polarized antennas which support the theoretical predictions.

  7. A portable readout system for silicon microstrip sensors

    NASA Astrophysics Data System (ADS)

    Marco-Hernández, Ricardo

    2010-11-01

    This system can measure the collected charge in one or two microstrip silicon sensors by reading out all the channels of the sensor(s), up to 256. The system is able to operate with different types (p- and n-type) and different sizes (up to 3 cm 2) of microstrip silicon sensors, both irradiated and non-irradiated. Heavily irradiated sensors will be used at the Super Large Hadron Collider, so this system can be used to research the performance of microstrip silicon sensors in conditions as similar as possible to the Super Large Hadron Collider operating conditions. The system has two main parts: a hardware part and a software part. The hardware part acquires the sensor signals either from external trigger inputs, in case of a radioactive source setup is used, or from a synchronised trigger output generated by the system, if a laser setup is used. The software controls the system and processes the data acquired from the sensors in order to store it in an adequate format. The main characteristics of the system are described. Results of measurements acquired with n- and p-type detectors using both the laser and the radioactive source setup are also presented and discussed.

  8. Radial microstrip slotline feed network for circular mobile communications array

    NASA Astrophysics Data System (ADS)

    Simons, Rainee N.; Kelly, Eron S.; Lee, Richard Q.; Taub, Susan R.

    1994-04-01

    In mobile and satellite communications there is a need for low cost and low profile antennas which have a toroidal pattern. Antennas that have been developed for mobile communications include a L-Band electronically steered stripline phased array, a Ka-Band mechanically steered elliptical reflector antenna and a Ka-Band printed dipole. In addition, a L-Band mechanically steered microstrip array, a L-Band microstrip phased array tracking antenna for mounting on a car roof and an X-Band radial line slotted waveguide antenna have been demonstrated. In the above electronically scanned printed arrays, the individual element radiates normally to the plane of the array and hence require a phase shifter to scan the beam towards the horizon. Scanning in the azimuth is by mechanical or electronic steering. An alternate approach is to mount microstrip patch radiators on the surface of a cone to achieve the required elevation angle. The array then scans in the azimuth by beam switching.

  9. Radial microstrip slotline feed network for circular mobile communications array

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Kelly, Eron S.; Lee, Richard Q.; Taub, Susan R.

    1994-01-01

    In mobile and satellite communications there is a need for low cost and low profile antennas which have a toroidal pattern. Antennas that have been developed for mobile communications include a L-Band electronically steered stripline phased array, a Ka-Band mechanically steered elliptical reflector antenna and a Ka-Band printed dipole. In addition, a L-Band mechanically steered microstrip array, a L-Band microstrip phased array tracking antenna for mounting on a car roof and an X-Band radial line slotted waveguide antenna have been demonstrated. In the above electronically scanned printed arrays, the individual element radiates normally to the plane of the array and hence require a phase shifter to scan the beam towards the horizon. Scanning in the azimuth is by mechanical or electronic steering. An alternate approach is to mount microstrip patch radiators on the surface of a cone to achieve the required elevation angle. The array then scans in the azimuth by beam switching.

  10. High performance millimeter-wave microstrip circulators and isolators

    NASA Technical Reports Server (NTRS)

    Shih, Ming; Pan, J. J.

    1990-01-01

    Millimeter wave systems, phased array antennas, and high performance components all require wideband circulators (and isolators) to perform diplexing and switching, to improve isolation and Voltage Standing Wave Ratio (VSWR), and to construct IMPATT diode reflection amplifiers. Presently, most of the millimeter-wave circulators and isolators are available in the configurations of waveguide or stripline, both of which suffer from the shortcomings of bulky size/weight, narrow bandwidth, and poor compatibility with monolithic millimeter-wave integrated circuits (MMIC). MMW microstrip circulators/isolators can eliminate or improve these shortcomings. Stub-tuned microstrip circulator configuration were developed utilizing the electromagnetic fields perturbation technique, the adhesion problems of microstrip metallization on new ferrite substrate were overcome, the fabrication, assembly, packaging techniques were improved, and then successfully designed, fabricated a Ka band circulator which has isolation and return loss of greater than 16dB, insertion loss less than 0.7dB. To assess the steady and reliable performance of the circulator, a temperature cycling test was done over the range of -20 to +50 C for 3 continuous cycles and found no significant impact or variation of circulator performance.

  11. A dual frequency microstrip antenna for Ka band

    NASA Technical Reports Server (NTRS)

    Lee, R. Q.; Baddour, M. F.

    1985-01-01

    For fixed satellite communication systems at Ka band with downlink at 17.7 to 20.2 GHz and uplink at 27.5 to 30.0 GHz, the focused optics and the unfocused optics configurations with monolithic phased array feeds have often been used to provide multiple fixed and multiple scanning spot beam coverages. It appears that a dual frequency microstrip antenna capable of transmitting and receiving simultaneously is highly desirable as an array feed element. This paper describes some early efforts on the development and experimental testing of a dual frequency annular microstrip antenna. The antenna has potential application for use in conjunction with a monolithic microwave integrated circuit device as an active radiating element in a phased array of phased array feeds. The antenna is designed to resonate at TM sub 12 and TM sub 13 modes and tuned with a circumferential microstrip ring to vary the frequency ratio. Radiation characteristics at both the high and low frequencies are examined. Experimental results including radiating patterns and swept frequency measurements are presented.

  12. Radiation patterns of dual concentric conductor microstrip antennas for superficial hyperthermia.

    PubMed

    Stauffer, P R; Rossetto, F; Leoncini, M; Gentilli, G B

    1998-05-01

    The finite difference time domain (FDTD) method has been used to calculate electromagnetic radiation patterns from 915-MHz dual concentric conductor (DCC) microwave antennas that are constructed from thin and flexible printed circuit board (PCB) materials. Radiated field distributions are calculated in homogeneous lossy muscle tissue loads located under variable thickness coupling bolus layers. This effort extends the results of previous investigations to consider more realistic applicator configurations with smaller 2-cm-square apertures and different coupling bolus materials and thicknesses, as well as various spacings of multiple-element arrays. Results are given for practical applicator designs with microstrip feedlines etched on the backside of the PCB antenna array instead of previously tested bulky coaxial-cable feedline connections to each radiating aperture. The results demonstrate that for an optimum coupling bolus thickness of 2.5-5 mm, the thin, flexible, and lightweight DCC antennas produce effective heating to the periphery of each aperture to a depth of approximately 1 cm, and may be combined into arrays for uniform heating of large area superficial tissue regions with the 50% power deposition contour conforming closely to the outer perimeter of the array. PMID:9581059

  13. Measured and computed performance of a microstrip filter composed of semi-insulating GaAs on a fused quartz substrate

    NASA Technical Reports Server (NTRS)

    Siegel, Peter H.; Dengler, Robert J.; Oswald, John E.; Sheen, David M.; Ali, Sami M.

    1991-01-01

    The performance of a microstrip hammerhead filter that has been fabricated on an electrically thin layer of semiinsulating GaAs backed by a fused quartz substrate was measured and compared to results of a three-dimensional finite-difference time-domain (FD-TD) program used to calculate the response of the filter both with and without the GaAs layer. The program, presented by Sheen et al. (1990), discretizes the entire structure and then simulates the propagation of a Gaussian pulse through the filter. The microstrip filter is intended for applications involving ultrathin lifted-off or etched-back GaAs containing both active devices and passive microstrip circuitry backed by a much thicker mechanically rigid low-loss, low-dielectric-constant substrate. The low-pass characteristics of the hammerhead filter with the intermediate GaAs layer are compared with those of the same filter on quartz alone. Both the measured and computed data show a significant shift in cutoff frequency (about 10 percent at the 3 dB points) for a GaAs layer that is 0.007 wavelengths thick at 4 GHz.

  14. Fixed-frequency and Frequency-agile (au, HTS) Microstrip Bandstop Filters for L-band Applications

    NASA Technical Reports Server (NTRS)

    Saenz, Eileen M.; Subramanyam, Guru; VanKeuls, Fred W.; Chen, Chonglin; Miranda, Felix A.

    2001-01-01

    In this work, we report on the performance of a highly selective, compact 1.83 x 2.08 cm(exp 2) (approx. 0.72 x 0.82 in(exp 2) microstrip line bandstop filter of YBa2CU3O(7-delta) (YBCO) on LaAlO3 (LAO) substrate. The filter is designed for a center frequency of 1.623 GHz for a bandwidth at 3 dB from reference baseline of less than 5.15 MHz, and a bandstop rejection of 30 dB or better. The design and optimization of the filter was performed using Zeland's IE3D circuit simulator. The optimized design was used to fabricate gold (Au) and High-Temperature Superconductor (HTS) versions of the filter. We have also studied an electronically tunable version of the same filter. Tunability of the bandstop characteristics is achieved by the integration of a thin film conductor (Au or HTS) and the nonlinear dielectric ferroelectric SrTiO3 in a conductor/ferroelectric/dielectric modified microstrip configuration. The performance of these filters and comparison with the simulated data will be presented.

  15. Magnetic field probe for measuring surface current distributions on millimetre wave microstrip antennas

    NASA Astrophysics Data System (ADS)

    Grzybowski, R. R.; Bansal, R.

    1991-01-01

    A magnetic field probe for measuring surface current distributions on millimeter wave microstrip antennas has been designed and fabricated. This current probe was tested by measuring the surface current distributions of printed microstrip dipole antennas. The current distributions obtained compared well with the theoretically expected distributions.

  16. Broadband infrared electro-optic modulator having a buried microstrip network

    NASA Technical Reports Server (NTRS)

    Cheo, Peter K. (Inventor); Gilden, Meyer (Inventor)

    1987-01-01

    A microwave infrared modulator having a novel three dimensional structure is presented. The modulator includes a waveguide and metal base with a dielectric wafer buried therebetween. The buried wafer allows for conventional microstrip structures to be employed with larger microstrip electrode dimensions than would otherwise be possible.

  17. Broadband Via-Less Microwave Crossover Using Microstrip-CPW Transitions

    NASA Technical Reports Server (NTRS)

    Stevenson, Thomas; U-Yen, Kongpop; Wollack, Edward; Moseley, Samuel; Hsieh, Wen-Ting

    2011-01-01

    The front-to-back interface between microstrip and CPW (coplanar waveguide) typically requires complex fabrication or has high radiation loss. The microwave crossover typically requires a complex fabrication step. The prior art in microstrip-CPW transition requires a physical vias connection between the microstrip and CPW line on a separate layer. The via-less version of this transition was designed empirically and does not have a close form solution. The prior art of the micro wave crossover requires either additional substrate or wire bond as an air bridge to isolate two microwave lines at the crossing junction. The disadvantages are high radiation loss, no analytical solution to the problem, lengthy simulation time, and complex fabrication procedures to generate air bridges or via. The disadvantage of the prior crossover is a complex fabrication procedure, which also affects the device reliability and yield. This microstrip-CPW transition is visualized as two microstrip-slotline transitions combined in a way that the radiation from two slotlines cancels each other out. The invention is designed based on analytical methods; thus, it significantly reduces the development time. The crossover requires no extra layer to cross two microwave signals and has low radiation loss. The invention is simple to fabricate and design. It produces low radiation loss and can be designed with low insertion loss, with some tradeoff with signal isolation. The microstrip-CPW transition is used as an interface to connect between the device and the circuit outside the package. The via-less microwave crossover is used to allow two signals to cross without using an extra layer or fabrication processing step to enable this function. This design allows the solution to be determined entirely though analytical techniques. In addition, a planar via-less microwave crossover using this technique was proposed. The experimental results show that the proposed crossover at 5 GHz has a minimum

  18. Transformation of design formulae for feed line of triangular microstrip antenna

    NASA Astrophysics Data System (ADS)

    Mathur, Monika; Singh, Ghanshyam; Bhatnagar, S. K.; Swami, Swati; Vats, Abhijat

    2016-03-01

    In wireless communication system microstrip antenna is the key component. Popular shapes of patch for microstrip are rectangular, triangular and circular. A new transformation design formulae for feed line of rectangular microstrip antenna by using equivalent design concept were presented by the authors. That says one designed antenna for a given frequency on any substrate can be transformed into another substrate material for the same design frequency by simply multiply a factor ψ to the all dimensions of patch, length of feed line and some power of ψ for feed line width (where ψ is the square root of the ratio of dielectric constants of those two designs). This paper presents that the same formulae of that rectangular transformation feed line can also be applicable for triangular shape microstrip antenna transformation. The process was repeated for the triangular shape patch microstrip antenna as applied for rectangular shape and the simulation results were surprisingly the same for it by applying the same transformation formulae.

  19. Segmented combustor

    NASA Technical Reports Server (NTRS)

    Halila, Ely E. (Inventor)

    1994-01-01

    A combustor liner segment includes a panel having four sidewalls forming a rectangular outer perimeter. A plurality of integral supporting lugs are disposed substantially perpendicularly to the panel and extend from respective ones of the four sidewalls. A plurality of integral bosses are disposed substantially perpendicularly to the panel and extend from respective ones of the four sidewalls, with the bosses being shorter than the lugs. In one embodiment, the lugs extend through supporting holes in an annular frame for mounting the liner segments thereto, with the bosses abutting the frame for maintaining a predetermined spacing therefrom.

  20. On the time-domain response of microstrip dipoles embedded in a low-loss grounded dielectric slab

    NASA Astrophysics Data System (ADS)

    Cicchetti, Renato

    1993-03-01

    An analysis based on the space-time dyadic Green's function is presented of the field radiated from printed microstrip dipoles. The numerical results show that when the time variation of the current is of the same order as the time propagation in the substrate, a strong distortion of the radiated field appears. Horizontally polarized dipoles present distortions in their electric field components that are different from each other. The phi component of the electric field is more distorted and decays to zero more slowly than the theta component. When the values of the dielectric permittivity and conductivity increases there is a decrease of the level of the radiated field and an increment of its distortions. To reduce the level of the radiated field the dipole must be embedded in a thin substrate with a high dielectric permittivity, while reducing the distortion of the radiated field requires a substrate with low permittivity.

  1. Arbitrarily oriented biaxially anisotropic media: Wave behavior and microstrip antennas

    NASA Astrophysics Data System (ADS)

    Graham, Jennifer Warzala

    This dissertation explores the electromagnetic behavior of arbitrarily oriented biaxially anisotropic media. An overview of wave behavior in biaxially anisotropic (or simply biaxial) media is presented. The reflection and transmission behaviors of electromagnetic waves from half-space and two-layer isotropic-biaxial interfaces are studied. The reflection and transmission coefficients are used in the formulation of eigenvector dyadic Green's functions. These Green's functions are employed in full-wave analyses of rectangular microstrip antennas printed on biaxial substrates. The general characteristics of electrically biaxially anisotropic (biaxial) media are presented including permittivity tensors, optic axes, orientation of the medium, and birefringence. After a detailed discussion of wave propagation, wave behavior at isotropic-biaxial interfaces is investigated. The reflection and transmission of electromagnetic waves incident upon half-space and two-layer interfaces, at which the waves may be incident from either the isotropic region or the biaxial region, are investigated. The biaxial medium considered may be aligned with the principal coordinate system or may be arbitrarily oriented. Critical angle and Brewster angle effects are analyzed for the half-space case. Once the wave behavior is well understood, the eigenvector dyadic Green's function is presented for two-layer geometries involving isotropic and biaxially anisotropic media. The symmetrical property of the dyadic Green's function is derived and used to generate an unknown Green's function from a known Green's function for the two-layer geometry of interest. This new Green's function is used to model rectangular microstrip antennas. Following the investigation of reflection and transmission, rectangular microstrip antennas are analyzed using the eigenvector dyadic Green's function and the method of moments. Galerkin's method is used to evaluate current distributions on gap-fed dipole antennas and

  2. Microstrip technology and its application to phased array compensation

    NASA Technical Reports Server (NTRS)

    Dudgeon, J. E.; Daniels, W. D.

    1972-01-01

    A systematic analysis of mutual coupling compensation using microstrip techniques is presented. A method for behind-the-array coupling of a phased antenna array is investigated as to its feasibility. The matching scheme is tried on a rectangular array of one half lambda 2 dipoles, but it is not limited to this array element or geometry. In the example cited the values of discrete components necessary were so small an L-C network is needed for realization. Such L-C tanks might limit an otherwise broadband array match, however, this is not significant for this dipole array. Other areas investigated were balun feeding and power limits of spiral antenna elements.

  3. Implantable multilayer microstrip antenna for retinal prosthesis: antenna testing.

    PubMed

    Permana, Hans; Fang, Qiang; Rowe, Wayne S T

    2012-01-01

    Retinal prosthesis has come to a more mature stage and become a very strategic answer to Retinitis Pigmentosa (RP) and Age-related Macular Degeneration (AMD) diseases. In a retinal prosthesis system, wireless link holds a great importance for the continuity of the system. In this paper, an implantable multilayer microstrip antenna was proposed for the retinal prosthesis system. Simulations were performed in High Frequency Structure Simulator (HFSS) with the surrounding material of air and Vitreous Humor fluid. The fabricated antenna was measured for characteristic validation in free space. The results showed that the real antenna possessed similar return loss and radiation pattern, while there was discrepancy with the gain values. PMID:23366231

  4. Metrology of IXO Mirror Segments

    NASA Technical Reports Server (NTRS)

    Chan, Kai-Wing

    2011-01-01

    For future x-ray astrophysics mission that demands optics with large throughput and excellent angular resolution, many telescope concepts build around assembling thin mirror segments in a Wolter I geometry, such as that originally proposed for the International X-ray Observatory. The arc-second resolution requirement posts unique challenges not just for fabrication, mounting but also for metrology of these mirror segments. In this paper, we shall discuss the metrology of these segments using normal incidence metrological method with interferometers and null lenses. We present results of the calibration of the metrology systems we are currently using, discuss their accuracy and address the precision in measuring near-cylindrical mirror segments and the stability of the measurements.

  5. Mutual coupling between microstrip dipoles in multielement arrays

    NASA Astrophysics Data System (ADS)

    Katehi, Pisti B.

    1989-03-01

    An analytical method for evaluating mutual coupling in multielement microstrip arrays is discussed. The elements of the array are strip dipoles covered by an overlayer and excited by microstrip lines embedded in the substrate. In addition, two different ways of excitation are considered to evaluate the effect of the feeding lines on the coupling between the dipoles. Throughout the analysis, the transmission line and dipole widths are taken to be a fraction of the free-space wavelength, so that the longitudinal current component is the dominant contributor to the characteristics of the array. Under this assumption, the transverse component of the current is neglected without introducing appreciable error. The current distribution along the longitudinal direction is evaluated by solving an appropriate integral equation using Galerkin's method with piecewise continuous sinusoidal functions. All possible interactions between the currents on the feeding transmission lines and dipoles are included. The method is valid in the microwave and millimeter-wave range and accounts for conductor thickness and surface wave excitation.

  6. Development and preliminary tests of resistive microdot and microstrip detectors

    NASA Astrophysics Data System (ADS)

    Fonte, P.; Nappi, E.; Martinengo, P.; Oliveira, R.; Peskov, V.; Pietropaolo, F.; Picchi, P.

    2012-12-01

    In the last few years our group has focused on developing various designs of spark-protected micropattern gaseous detectors featuring resistive electrodes instead of traditional metallic ones: resistive microstrip counters, resistive gas electron multiplier, resistive micro mesh gaseous structure. These detectors combine in one design the best features of resistive plate chamber (spark-protection) and micropattern detectors (a high position resolution). In this paper we report the progress so far made in developing other types of resistive micropattern detectors: a microdot-microhole detector and a microgap-microstrip detector. The former detector is an optimal electron amplifier for some special designs of dual phase noble liquid time projection chambers, for example with a CsI photocathode immersed inside the noble liquid. Preliminary tests of such a detector, for the first time built and investigated, are reported in this paper. The latter detector is mainly orientated towards medical imaging applications such as x-ray scanners. However, we believe that after a proper gas optimization, these detectors could also achieve a high time resolution and could thus be used in applications as time of flight positron emission tomography, detection of charged particles with simultaneously high time and position resolution etc.

  7. Broadband Microstrip-to-Coplanar Strip Double-Y Balun

    NASA Technical Reports Server (NTRS)

    Venkatesan, Jaikrishna

    2008-01-01

    A new version of the double-Y balun, transitioning from an unbalanced microstrip to a balanced coplanar strip (CPS) line, has been designed to feed a complementary spiral antenna with an input impedance of 100 Omega. The new double-Y balun transitions from a microstrip line with truncated ground plane to a CPS line. The balun does not employ CPW lines; hence, CPW bridges are not required at the junction. In addition, the balun does not exhibit CPW parasitic resonances, thereby improving passband performance. The new version of the double-Y balun is designed to feed a complementary spiral antenna. Panels on the right illustrate an expanded view of the balun junction. Preliminary voltage standing-wave ratio (VSWR) and insertion loss data are illustrated. Measured data were compared with numerical results computed using Momentum. It is seen that the balun exhibits a VSWR of less than 1.5 from 400 MHz to 8 GHz and a VSWR of less than 1.8 up to 13 GHz. The VSWR can be reduced further by reducing reflections from the balun junction and load resistor. Also, the balun is seen to exhibit an insertion loss of less than 1.5 dB up to 12 GHz. Further work involves characterizing the balun's performance when feeding a complementary spiral antenna.

  8. [Segmental neurofibromatosis].

    PubMed

    Zulaica, A; Peteiro, C; Pereiro, M; Pereiro Ferreiros, M; Quintas, C; Toribio, J

    1989-01-01

    Four cases of segmental neurofibromatosis (SNF) are reported. It is a rare entity considered to be a localized variant of neurofibromatosis (NF)-Riccardi's type V. Two cases are male and two female. The lesions are located to the head in a patient and the other three cases in the trunk. No family history nor transmission to progeny were manifested. The rest of the organs are undamaged. PMID:2502696

  9. Electrically Small Microstrip Quarter-Wave Monopole Antennas

    NASA Technical Reports Server (NTRS)

    Young, W. Robert

    2004-01-01

    Microstrip-patch-style antennas that generate monopole radiation patterns similar to those of quarter-wave whip antennas can be designed to have dimensions smaller than those needed heretofore for this purpose, by taking advantage of a feed configuration different from the conventional one. The large sizes necessitated by the conventional feed configuration have, until now, made such antennas impractical for frequencies below about 800 MHz: for example, at 200 MHz, the conventional feed configuration necessitates a patch diameter of about 8 ft (.2.4 m) . too large, for example, for mounting on the roof of an automobile or on a small or medium-size aircraft. By making it possible to reduce diameters to between a tenth and a third of that necessitated by the conventional feed configuration, the modified configuration makes it possible to install such antennas in places where they could not previously be installed and thereby helps to realize the potential advantages (concealment and/or reduction of aerodynamic drag) of microstrip versus whip antennas. In both the conventional approach and the innovative approach, a microstrip-patch (or microstrip-patch-style) antenna for generating a monopole radiation pattern includes an electrically conductive patch or plate separated from an electrically conductive ground plane by a layer of electrically insulating material. In the conventional approach, the electrically insulating layer is typically a printed-circuit board about 1/16 in. (.1.6 mm) thick. Ordinarily, a coaxial cable from a transmitter, receiver, or transceiver is attached at the center on the ground-plane side, the shield of the cable being electrically connected to the ground plane. In the conventional approach, the coaxial cable is mated with a connector mounted on the ground plane. The center pin of this connector connects to the center of the coaxial cable and passes through a hole in the ground plane and a small hole in the insulating layer and then connects

  10. A dynamic model for microstrip-slotline transition and related structures

    NASA Astrophysics Data System (ADS)

    Yang, Hung-Yu; Alexoapoulos, Nicoalaos G.

    1988-02-01

    An analysis of microstrip-to-slotline transition is presented. The method of moments is applied to the coupled integral equations. In the formulation, the Green's function for the grounded dielectric substrate, which takes into account all the radiation, surface wave, and substrate effects, is used. Meanwhile, all the mutual coupling effects are included in the method of moments solution. Certain related structures, such as slotline and microstrip discontinuities, a slot fed by a microstrip line, and a printed strip dipole fed by a slotline, can also be solved with this analysis. This approach may find applications to other related transitions in MIC (microwave integrated circuit) design.

  11. Design of a low-loss series-fed microstrip array antenna

    NASA Technical Reports Server (NTRS)

    Mahbub, M. R.; Christodoulou. C. G.; Bailey, M. C.

    1998-01-01

    The design and analysis of a series-fed, low-loss, inverted microstrip array antenna, operating at 1.413 GHz is presented. The array antenna is composed of two sub arrays. Each sub array consists of an equal number of microstrip patches all connected together through a series microstrip line. The first element of each sub array is coaxially fed but 180 degree out of phase. This approach ensures a symmetric radiation pattern. The design approach, is accomplished using the IE3D code that utilizes the method of moments. All experimental and simulated data are presented and discussed.

  12. Theoretical and Experimental Study of Microstrip-to-Slot Line Uniplanar Transition

    NASA Technical Reports Server (NTRS)

    Yook, Jong-Gwan; Dib, Nihad I.; Katehi, Linda P. B.; Simons, Rainee N.; Taub, Susan R.

    1994-01-01

    Recent advances in MMCI technology make it possible to construct transitions from CPW-to-microstrip with via hole, microstrip-to-slot line and microshield line-to-CPW all of which have potential applications in the feed network of antennas. In this study we investigate the characteristics of the microstrip-to-slot line uniplanar transition using the finite element methods (FEM) and finite difference time domain (FDTD) techniques, and compared the theoretical results with the measurements. In both cases, the results agree with the measurements within a few percent.

  13. Segmental neurofibromatosis.

    PubMed

    Sobjanek, Michał; Dobosz-Kawałko, Magdalena; Michajłowski, Igor; Pęksa, Rafał; Nowicki, Roman

    2014-12-01

    Segmental neurofibromatosis or type V neurofibromatosis is a rare genodermatosis characterized by neurofibromas, café-au-lait spots and neurofibromas limited to a circumscribed body region. The disease may be associated with systemic involvement and malignancies. The disorder has not been reported yet in the Polish medical literature. A 63-year-old Caucasian woman presented with a 20-year history of multiple, flesh colored, dome-shaped, soft to firm nodules situated in the right lumbar region. A histopathologic evaluation of three excised tumors revealed neurofibromas. No neurological and ophthalmologic symptoms of neurofibromatosis were diagnosed. PMID:25610358

  14. Segmental neurofibromatosis.

    PubMed

    Adigun, Chris G; Stein, Jennifer

    2011-01-01

    A 59-year-old man presented for evaluation and excision of non-tender, fleshy nodules that were arranged in a dermatomal distribution from the left side of the chest to the left axilla. A biopsy specimen of a nodule was consistent with a neurofibroma. Owing to the lack of other cutaneous findings, the lack of a family history of neurofibromatosis, and the dermatomal distribution of the neurofibromas, this patient met the criteria for a diagnosis of segmental neurofibromatosis (SNF) according to Riccardi's definition of SNF and classification of neurofibromatosis. Because the patient has no complications of neurofibromatosis 1 no medical treatment is required. PMID:22031651

  15. Segmental neurofibromatosis

    PubMed Central

    Dobosz-Kawałko, Magdalena; Michajłowski, Igor; Pęksa, Rafał; Nowicki, Roman

    2014-01-01

    Segmental neurofibromatosis or type V neurofibromatosis is a rare genodermatosis characterized by neurofibromas, café-au-lait spots and neurofibromas limited to a circumscribed body region. The disease may be associated with systemic involvement and malignancies. The disorder has not been reported yet in the Polish medical literature. A 63-year-old Caucasian woman presented with a 20-year history of multiple, flesh colored, dome-shaped, soft to firm nodules situated in the right lumbar region. A histopathologic evaluation of three excised tumors revealed neurofibromas. No neurological and ophthalmologic symptoms of neurofibromatosis were diagnosed. PMID:25610358

  16. A new analysis for the transmission line characteristics of the Microstrip Dipole Antenna Feed

    NASA Astrophysics Data System (ADS)

    Sabhnani, N. H.; Rao, B. V.

    1983-10-01

    The characteristic wave impedance and effective dielectric constant of a Microstrip Dipole Antenna Feed are evaluated through a conformal mapping technique. The obtained design equations are explicit, simple and yield results with an accuracy better than 2.2 percent.

  17. Design considerations for rectangular microstrip patch antenna on electromagnetic crystal substrate at terahertz frequency

    NASA Astrophysics Data System (ADS)

    Singh, G.

    2010-01-01

    The effects of 2-D electromagnetic crystal substrate on the performance of a rectangular microstrip patch antennas at THz frequencies is simulated. Electromagnetic crystal substrate is used to obtain extremely broad-bandwidth with multi-frequency band operation of the proposed microstrip antennas. Multi-frequency band microstrip patch antennas are used in modern communication systems in order to enhance their capacity through frequency reuse. The simulated 10 dB impedance bandwidth of the rectangular patch microstrip antenna is 34.3% at THz frequency (0.6-0.95 THz). The radiation efficiency, gain and directivity of the proposed antenna are presented at different THz frequencies. The simulation has been performed using CST Microwave Studio, which is a commercially available electromagnetic simulator based on finite integral technique.

  18. Bandwidth Study of Microstrip Reflectarray And A Novel Phased Reflectarray Concept

    NASA Technical Reports Server (NTRS)

    Huang, John

    1995-01-01

    A microstrip reflectarray [1,2] is a flat reflector antenna that can be conformally mounted onto its supporting structure without consuming a significant amount of real estate and without adding significant mass.

  19. Cross-polarization level in radiation from a microstrip dipole antenna

    NASA Astrophysics Data System (ADS)

    Hoorfar, Ahmad; Gupta, Kuldip C.; Chang, David C.

    1988-09-01

    A description is given of the cross-polarization level in radiation from a small horizontal electric dipole (HED) on a flat grounded dielectric substrate. The study is directed toward the design of a very low cross-polarization level in a linear array of microstrip antenna elements. Field expressions for a copolarized and crosspolarized microstrip HED for any arbitrary dipole orientation and array direction are derived.

  20. Full wave characterization of microstrip open end discontinuities patterned on anisotropic substrates using potential theory

    NASA Technical Reports Server (NTRS)

    Toncich, S. S.; Collin, R. E.; Bhasin, K. B.

    1993-01-01

    A technique for a full wave characterization of microstrip open end discontinuities fabricated on uniaxial anisotropic substrates using potential theory is presented. The substrate to be analyzed is enclosed in a cutoff waveguide, with the anisotropic axis aligned perpendicular to the air-dielectric interface. A full description of the sources on the microstrip line is included with edge conditions built in. Extention to other discontinuities is discussed.

  1. Evaluation of the Reflection Coefficient of Microstrip Elements for Reflectarray Antennas

    NASA Technical Reports Server (NTRS)

    Rengarajan, Sembiam

    2011-01-01

    Basis functions were studied and identified that provide efficient and accurate solutions for the induced patch currents and the reflection phase in microstrip reflect arrays. The integral equation of an infinite array of microstrip elements in the form of patches or crossed dipoles excited by a uniform plane wave is solved by the method-of-moments. Efficient choices of entire domain basis functions that yield accurate results have been described.

  2. Ka-band MMIC microstrip array for high rate communications

    NASA Technical Reports Server (NTRS)

    Lee, R. Q.; Raquet, C. A.; Tolleson, J. B.; Sanzgiri, S. M.

    1991-01-01

    In a recent technology assessment of alternative communication systems for the space exploration initiative (SEI), Ka-band (18 to 40 GHz) communication technology was identified to meet the mission requirements of telecommunication, navigation, and information management. Compared to the lower frequency bands, Ka-band antennas offer higher gain and broader bandwidths; thus, they are more suitable for high data rate communications. Over the years, NASA has played an important role in monolithic microwave integrated circuit (MMIC) phased array technology development, and currently, has an ongoing contract with Texas Instrument (TI) to develop a modular Ka-band MMIC microstrip subarray (NAS3-25718). The TI contract emphasizes MMIC integration technology development and stipulates using existing MMIC devices to minimize the array development cost. The objective of this paper is to present array component technologies and integration techniques used to construct the subarray modules.

  3. The silicon microstrip sensors of the ATLAS semiconductor tracker

    SciTech Connect

    ATLAS SCT Collaboration; Spieler, Helmuth G.

    2007-04-13

    This paper describes the AC-coupled, single-sided, p-in-n silicon microstrip sensors used in the Semiconductor Tracker (SCT) of the ATLAS experiment at the CERN Large Hadron Collider (LHC). The sensor requirements, specifications and designs are discussed, together with the qualification and quality assurance procedures adopted for their production. The measured sensor performance is presented, both initially and after irradiation to the fluence anticipated after 10 years of LHC operation. The sensors are now successfully assembled within the detecting modules of the SCT, and the SCT tracker is completed and integrated within the ATLAS Inner Detector. Hamamatsu Photonics Ltd. supplied 92.2percent of the 15,392 installed sensors, with the remainder supplied by CiS.

  4. The study of microstrip antenna arrays and related problems

    NASA Technical Reports Server (NTRS)

    Lo, R. Q.

    1984-01-01

    The work on rectangular microstrip antennas for dual frequency operation is reported on. The principle of this approach is based on the excitation of a patch for two or more different modes which correspond to different frequencies. However, for a given geometry, the modal frequencies have a fixed relationship; therefore, the usefulness of such a design is greatly limited. In this study three different methods have been contrived to control the frequency ratio over a wide range. First, as found prevously, if shorting pins are inserted at certain locations in the patch, the low frequency can be raised substantially. Second, if slots are cut in the patch, the high frequency can be lowered considerably. By using both techniques, the two frequency ratio can be varied approximately from 3 to 1.3. After that, the addition of more pins or slots becomes ineffective.

  5. Spiral microstrip hyperthermia applicators: technical design and clinical performance.

    PubMed

    Samulski, T V; Fessenden, P; Lee, E R; Kapp, D S; Tanabe, E; McEuen, A

    1990-01-01

    Spiral microstrip microwave (MW) antennas have been developed and adapted for use as clinical hyperthermia applicators. The design has been configured in a variety of forms including single fixed antenna applicators, multi-element arrays, and mechanically scanned single or paired antennas. The latter three configurations have been used to allow an expansion of the effective heating area. Specific absorption rate (SAR) distributions measured in phantom have been used to estimate the depth and volume of effective heating. The estimates are made using the bioheat equation assuming uniformly perfused tissue. In excess of 500 treatments of patients with advanced or recurrent localized superficial tumors have been performed using this applicator technology. Data from clinical treatments have been analyzed to quantify the heating performance and verify the suitability of these applicators for clinical use. Good microwave coupling efficiency together with the compact applicator size have proved to be valuable clinical assets. PMID:2298626

  6. SPICE analysis of signal propagation in Si microstrip detectors

    SciTech Connect

    Bacchetta, N.; Bisello, D. |; Candelori, A.; Paccagnella, A. |; Spada, M.; Vanzi, M.

    1995-08-01

    The main DC and AC characteristics of AC-coupled polysilicon-biased silicon microstrip detectors have been measured in order to determine the set of SPICE parameters of these devices based on a RC network. For this purpose each strip has been divided in 200 unit cells and simulations with 5 and 9 strips have been performed. The model is capable of calculating the interstrip and coupling impedance and phase angle in good agreement with experimental results up to a frequency of 1 MHz. The electrical propagation of a current signal simulating the charge pulse of an ionizing particle along the strips has been studied. The role of the input characteristics of the read-out electronics on the detector output signals has been addressed. The signal propagation has been studied also for anomalous working conditions of the detector, such as a strip with a break in the Al film, or disconnected from the read-out electronics.

  7. Dispersion in Nb microstrip transmission lines at submillimeter wave frequencies

    NASA Technical Reports Server (NTRS)

    Javadi, H. H. S.; Mcgrath, W. R.; Bumble, B.; Leduc, H. G.

    1992-01-01

    We have measured the effects of dispersion on the resonant mode frequencies of open-ended Nb-SiO(x)-Nb microstrip transmission lines over a frequency range from 50 to 800 GHz. Submicron Nb/Al-AlOx/Nb Josephson junctions were used as both voltage-controlled oscillators and detectors to sample the high order modes of the resonators. The resonator modes are equally spaced up to about 550 GHz where the mode spacing start to decrease gradually to a minimum above the gap frequency of about 700 GHz and then increases. Results are in good agreement with the expected theoretical behavior based on the Mattis-Bardeen conductivity of the superconductor line.

  8. Resonance in cylindrical-rectangular and wraparound microstrip structures

    NASA Technical Reports Server (NTRS)

    Ali, Sami M.; Kong, Jin AU; Habashy, Tarek M.; Kiang, Jean-Fu

    1989-01-01

    A rigorous analysis of the resonance frequency problem of both the cylindrical-rectangular and the wraparound microstrip structure is presented. The problem is formulated in terms of a set of vector integral equations. Using Galerkin's method to solve the integral equations, the complex resonance frequencies are studied with sinusoidal basis functions which incorporate the edge singularity. The complex resonance frequencies are computed using a perturbation approach. Modes suitable for resonator or antenna applications are investigated. The edge singularity of the patch current is shown to have no significant effect on the accuracy of the results. It is shown that the HE10 modes of the cylindrical-rectangular and wraparound patches are more appropriate for resonator applications. The HE01 and TE01 modes of the cylindrical-rectangular and wraparound patches, respectively, are efficient radiating modes.

  9. Characterisation of micro-strip and pixel silicon detectors before and after hadron irradiation

    NASA Astrophysics Data System (ADS)

    Allport, P. P.; Ball, K.; Casse, G.; Chmill, V.; Forshaw, D.; Hadfield, K.; Pritchard, A.; Pool, P.; Tsurin, I.

    2012-01-01

    The use of segmented silicon detectors for tracking and vertexing in particle physics has grown substantially since their introduction in 1980. It is now anticipated that roughly 50,000 six inch wafers of high resistivity silicon will need to be processed into sensors to be deployed in the upgraded experiments in the future high luminosity LHC (HL-LHC) at CERN. These detectors will also face an extremely severe radiation environment, varying with distance from the interaction point. The volume of required sensors is large and their delivery is required during a relatively short time, demanding a high throughput from the chosen suppliers. The current situation internationally, in this highly specialist market, means that security of supply for large orders can therefore be an issue and bringing additional potential vendors into the field can only be an advantage. Semiconductor companies that could include planar sensors suitable for particle physics in their product lines will, however, need to prove their products meet all the stringent technical requirements. A semiconductor company with very widespread experience of producing science grade CCDs (including deep depletion devices) has adapted their CCD process to fabricate for the first time several wafers of pixel and micro-strip radiation hard sensors, suitable for future high energy physics experiments. The results of the pre-irradiation characterization of devices fabricated with different processing parameters and the measurements of charge collection properties after different hadron irradiation doses up to those anticipated for the (larger area) outer pixel layers at the high-luminosity LHC (HL-LHC) are presented and compared with results from more established particle physics suppliers.

  10. Performance of a Micro-Strip Gas Chamber for event wise, high rate thermal neutron detection with accurate 2D position determination

    NASA Astrophysics Data System (ADS)

    Mindur, B.; Alimov, S.; Fiutowski, T.; Schulz, C.; Wilpert, T.

    2014-12-01

    A two-dimensional (2D) position sensitive detector for neutron scattering applications based on low-pressure gas amplification and micro-strip technology was built and tested with an innovative readout electronics and data acquisition system. This detector contains a thin solid neutron converter and was developed for time- and thus wavelength-resolved neutron detection in single-event counting mode, which improves the image contrast in comparison with integrating detectors. The prototype detector of a Micro-Strip Gas Chamber (MSGC) was built with a solid natGd/CsI thermal neutron converter for spatial resolutions of about 100 μm and counting rates up to 107 neutrons/s. For attaining very high spatial resolutions and counting rates via micro-strip readout with centre-of-gravity evaluation of the signal amplitude distributions, a fast, channel-wise, self-triggering ASIC was developed. The front-end chips (MSGCROCs), which are very first signal processing components, are read out into powerful ADC-FPGA boards for on-line data processing and thereafter via Gigabit Ethernet link into the data receiving PC. The workstation PC is controlled by a modular, high performance dedicated software suite. Such a fast and accurate system is crucial for efficient radiography/tomography, diffraction or imaging applications based on high flux thermal neutron beam. In this paper a brief description of the detector concept with its operation principles, readout electronics requirements and design together with the signals processing stages performed in hardware and software are presented. In more detail the neutron test beam conditions and measurement results are reported. The focus of this paper is on the system integration, two dimensional spatial resolution, the time resolution of the readout system and the imaging capabilities of the overall setup. The detection efficiency of the detector prototype is estimated as well.

  11. Utilization of amorphous silicon carbide (a-Si:C:H) as a resistive layer in gas microstrip detectors

    SciTech Connect

    Hong, W.S.; Cho, H.S.; Perez-Mendez, V.; Gong, W.G.

    1995-04-01

    Thin semiconducting films of hydrogenated amorphous silicon (a-Si:H) and its carbon alloy (a-Si:C:H) were applied to gas microstrip detectors in order to control gain instabilities due to charges on the substrate. Thin ({approximately}100nm) layers of a-Si:H or p-doped a-Si:C:H were placed either over or under the electrodes using the plasma enhanced chemical vapor deposition (PECVD) technique to provide the substrate with a suitable surface conductivity. By changing the carbon content and boron doping density, the sheet resistance of the a-Si:C:H coating could be successfully controlled in the range of 10{sup 12} {approximately} 10{sup 17} {Omega}/{four_gradient}, and the light sensitivity, which causes the resistivity to vary with ambient light conditions, was minimized. An avalanche gain of 5000 and energy resolution of 20% FWHM were achieved and the gain remained constant over a week of operation. A-Si:C:H film is an attractive alternative to ion-implanted or semiconducting glass due to the wide range of resistivities possible and the feasibility of making deposits over a large area at low cost.

  12. Utilization of amorphous silicon carbide (a-Si:C:H) as a resistive layer in gas microstrip detectors

    NASA Astrophysics Data System (ADS)

    Hong, W. S.; Cho, H. S.; Perez-Mendez, V.; Gong, W. G.

    1995-04-01

    Thin semiconducting films of hydrogenated amorphous silicon (a-Si:H) and its carbon alloy (a-Si:C:H) were applied to gas microstrip detectors in order to control gain instabilities due to charges on the substrate. Thin (approximately 100nm) layers of a-Si:H or p-doped a-Si:C:H were placed either over or under the electrodes using the plasma enhanced chemical vapor deposition (PECVD) technique to provide the substrate with a suitable surface conductivity. By changing the carbon content and boron doping density, the sheet resistance of the a-Si:C:H coating could be successfully controlled in the range of 10(exp 12) to approximately 10(exp 17) Omega/(four gradient), and the light sensitivity, which causes the resistivity to vary with ambient light conditions, was minimized. An avalanche gain of 5000 and energy resolution of 20% FWHM were achieved and the gain remained constant over a week of operation. A-Si:C:H film is an attractive alternative to ion-implanted or semiconducting glass due to the wide range of resistivities possible and the feasibility of making deposits over a large area at low cost.

  13. Receive Mode Analysis and Design of Microstrip Reflectarrays

    NASA Technical Reports Server (NTRS)

    Rengarajan, Sembiam

    2011-01-01

    Traditionally microstrip or printed reflectarrays are designed using the transmit mode technique. In this method, the size of each printed element is chosen so as to provide the required value of the reflection phase such that a collimated beam results along a given direction. The reflection phase of each printed element is approximated using an infinite array model. The infinite array model is an excellent engineering approximation for a large microstrip array since the size or orientation of elements exhibits a slow spatial variation. In this model, the reflection phase from a given printed element is approximated by that of an infinite array of elements of the same size and orientation when illuminated by a local plane wave. Thus the reflection phase is a function of the size (or orientation) of the element, the elevation and azimuth angles of incidence of a local plane wave, and polarization. Typically, one computes the reflection phase of the infinite array as a function of several parameters such as size/orientation, elevation and azimuth angles of incidence, and in some cases for vertical and horizontal polarization. The design requires the selection of the size/orientation of the printed element to realize the required phase by interpolating or curve fitting all the computed data. This is a substantially complicated problem, especially in applications requiring a computationally intensive commercial code to determine the reflection phase. In dual polarization applications requiring rectangular patches, one needs to determine the reflection phase as a function of five parameters (dimensions of the rectangular patch, elevation and azimuth angles of incidence, and polarization). This is an extremely complex problem. The new method employs the reciprocity principle and reaction concept, two well-known concepts in electromagnetics to derive the receive mode analysis and design techniques. In the "receive mode design" technique, the reflection phase is computed

  14. Detection mechanisms in microstrip dipole antenna-coupled infrared detectors

    NASA Astrophysics Data System (ADS)

    Codreanu, Iulian; Gonzalez, Francisco J.; Boreman, Glenn D.

    2003-06-01

    We compare the detection mechanisms employed in microstrip dipole antenna-coupled infrared detectors. The electrical currents induced along the antenna arms are detected by a rectangular niobium (Nb) microsensor placed at the center of the antenna. The ohmic nature of the Au-Nb contact determines the detection mechanism. Devices with linear contacts between the Au antenna arms and the Nb microsensor exhibit bolometric response. A nonlinear Au-insulator-Nb junction rectifies the induced antenna currents. Devices with nonlinear contacts also exhibit a bolometric response. The devices with nonlinear contacts are 1/ f noise limited while the devices with linear contacts are Johnson noise limited. The rectification mechanism is 5.3 times faster than the thermal detection. The current-voltage ( I- V) characteristic of the devices exhibiting bolometric response is linear, while that of the rectifying devices is cubic. For devices with nonlinear contacts excellent agreement is obtained between the measured detector response and the ratio between the second and the first derivative of the I- V characteristic.

  15. Microstrip gas detectors and a search for Xi-hypernuclei

    NASA Astrophysics Data System (ADS)

    Landry, Michael Robert

    A search for strangeness S = -2 Ξ-hypernuclei has been carried out at Brookhaven National Laboratory (BNL). Experiment 885 was conducted on the D6 beamline at the Alternating Gradient Synchrotron (AGS), using the (K-, K +) reaction on a diamond target at PK- = 1.8 GeV/c. Several novel detectors were employed, including microstrip gas chambers (MSGC) which acted as a vertex detector, and scintillating fibre (SCIFI) blocks to image decay particles. MSGC are relatively new position sensitive detectors, in which the active area of the detector is defined by a lithographed substrate, upon which electrodes are etched to collect charge from the passage of an ionizing particle. Approximately 3 × 105 (K-, K +) events were recorded, an order of magnitude greater than the existing world data set. Strangeness -2 hypernuclei are expected to form directly via the reaction K- + 12 C -->12X Be + K+. Despite limited experimental resolution (hydrogen kinematics yield 4.1 MeV/c 2 r.m.s.) that prevents resolution of discrete hypernuclear states, the missing mass spectrum was searched for evidence of bound states.

  16. Series-fed circularly polarized microstrip antennas with broad bandwidth

    NASA Astrophysics Data System (ADS)

    Mao, Shau-Gang; Chen, Shiou-Li; Yeh, Jen-Chun; Lin, Tien-Min

    2007-08-01

    A new series-fed circularly polarized antenna (SFCPA) in microstrip configuration, which consists of a traveling-wave-type crank-line antenna (CLA) and a resonant-type square-ring slot antenna (SRSA), is developed. Unlike the conventional crank-line (CL) antenna array with an open end or a resistive load, the proposed SFCPA uses the SRSA at the termination of the CLA and thus exhibits not only a broad circularly polarized (CP) bandwidth but also a large antenna gain. The characteristics of the SFCPA, including the leaky-wave radiation and the circular polarization, are examined in terms of the dispersion diagram and the current distribution. The SFCPA with the two-cell CLA and the terminated SRSA is fabricated and measured to demonstrate the 10-dB return loss and 3-dB axial ratio (AR) bandwidths of 34.3% and 30.5%, respectively. The frequency-scanning radiation patterns with a 5-7 dBi antenna gain are also presented in the operating band.

  17. UHF Microstrip Antenna Array for Synthetic- Aperture Radar

    NASA Technical Reports Server (NTRS)

    Thomas, Robert F.; Huang, John

    2003-01-01

    An ultra-high-frequency microstrippatch antenna has been built for use in airborne synthetic-aperture radar (SAR). The antenna design satisfies requirements specific to the GeoSAR program, which is dedicated to the development of a terrain-mapping SAR system that can provide information on geology, seismicity, vegetation, and other terrain-related topics. One of the requirements is for ultra-wide-band performance: the antenna must be capable of operating with dual linear polarization in the frequency range of 350 plus or minus 80 MHz, with a peak gain of 10 dB at the middle frequency of 350 MHz and a gain of at least 8 dB at the upper and lower ends (270 and 430 MHz) of the band. Another requirement is compactness: the antenna must fit in the wingtip pod of a Gulfstream II airplane. The antenna includes a linear array of microstrip-patch radiating elements supported over square cavities. Each patch is square (except for small corner cuts) and has a small square hole at its center.

  18. A compact annular ring microstrip antenna for WSN applications.

    PubMed

    Wang, Daihua; Song, Linli; Zhou, Hanchang; Zhang, Zhijie

    2012-01-01

    A compact annular ring microstrip antenna was proposed for a wireless sensor network (WSN) application in the 2.4 GHz band. In this paper the major considerations of the conformal antenna design were the compact size and the impact on antenna's performance of a steel installation base. By using a chip resistor of large resistance (120 Ω) the antenna size was reduced to 38% of that a conventional annular ring patch antenna. With the addition of the steel installation base the resonant frequency of the antenna increases about 4.2% and the bandwidth reduces from 17.5% to 11.7% by adjusting the load resistance simultaneously. Several key parameters were discussed and optimized, and the antenna was fabricated and its performance measured. The antenna is well matched at 2.4 GHz with 34.2 dB return loss and -2.5 dBi peak gain. Meanwhile, it exhibits excellent radiation patterns with very low cross-polarization levels. PMID:23012510

  19. A Compact Annular Ring Microstrip Antenna for WSN Applications

    PubMed Central

    Wang, Daihua; Song, Linli; Zhou, Hanchang; Zhang, Zhijie

    2012-01-01

    A compact annular ring microstrip antenna was proposed for a wireless sensor network (WSN) application in the 2.4 GHz band. In this paper the major considerations of the conformal antenna design were the compact size and the impact on antenna's performance of a steel installation base. By using a chip resistor of large resistance (120 Ω) the antenna size was reduced to 38% of that a conventional annular ring patch antenna. With the addition of the steel installation base the resonant frequency of the antenna increases about 4.2% and the bandwidth reduces from 17.5% to 11.7% by adjusting the load resistance simultaneously. Several key parameters were discussed and optimized, and the antenna was fabricated and its performance measured. The antenna is well matched at 2.4 GHz with 34.2 dB return loss and –2.5 dBi peak gain. Meanwhile, it exhibits excellent radiation patterns with very low cross-polarization levels. PMID:23012510

  20. A SPICE model of double-sided Si microstrip detectors

    SciTech Connect

    Candelori, A.; Paccagnella, A. |; Bonin, F.

    1996-12-31

    We have developed a SPICE model for the ohmic side of AC-coupled Si microstrip detectors with interstrip isolation via field plates. The interstrip isolation has been measured in various conditions by varying the field plate voltage. Simulations have been compared with experimental data in order to determine the values of the model parameters for different voltages applied to the field plates. The model is able to predict correctly the frequency dependence of the coupling between adjacent strips. Furthermore, we have used such model for the study of the signal propagation along the detector when a current signal is injected in a strip. Only electrical coupling is considered here, without any contribution due to charge sharing derived from carrier diffusion. For this purpose, the AC pads of the strips have been connected to a read-out electronics and the current signal has been injected into a DC pad. Good agreement between measurements and simulations has been reached for the central strip and the first neighbors. Experimental tests and computer simulations have been performed for four different strip and field plate layouts, in order to investigate how the detector geometry affects the parameters of the SPICE model and the signal propagation.

  1. Computation of self-impedance and mutual coupling of electromagnetically coupled microstrip dipoles using exact image method

    NASA Astrophysics Data System (ADS)

    Yang, Jianjun; Fang, Dagang; Sha, Kan

    In this paper, the self-impedance and mutual coupling of electromagnetically coupled microstrip dipoles are computed using recently developed, discrete, exact images. The mixed potential integral equation used for numerical analysis is solved using a moment method with rooftop subsectional basis functions. The procedure described here can be generalized to the treatment of other microstrip antennas and discontinuities and more involved multilayered structures.

  2. Automatic setae segmentation from Chaetoceros microscopic images.

    PubMed

    Zheng, Haiyong; Zhao, Hongmiao; Sun, Xue; Gao, Huihui; Ji, Guangrong

    2014-09-01

    A novel image processing model Grayscale Surface Direction Angle Model (GSDAM) is presented and the algorithm based on GSDAM is developed to segment setae from Chaetoceros microscopic images. The proposed model combines the setae characteristics of the microscopic images with the spatial analysis of image grayscale surface to detect and segment the direction thin and long setae from the low contrast background as well as noise which may make the commonly used segmentation methods invalid. The experimental results show that our algorithm based on GSDAM outperforms the boundary-based and region-based segmentation methods Canny edge detector, iterative threshold selection, Otsu's thresholding, minimum error thresholding, K-means clustering, and marker-controlled watershed on the setae segmentation more accurately and completely. PMID:24913015

  3. Investigation of broadband microstrip antenna structures for application in monolithic millimeter wave arrays

    NASA Astrophysics Data System (ADS)

    Chang, David C.; Kuester, E. F.

    1989-10-01

    The development of several ways of accurately yet efficiently modeled behavior of closely spaced microstrip antenna elements is shown. The accuracy was verified by comparison with brute force numerical procedures, and thus suggests that wideband microstrip antennas should be designable with much less difficulty than previously believed. Further, both experimental and numerical evidence was obtained for the proposition that wider bandwidth, and even lower frequency operation of a microstrip patch antenna element can be achieved by arranging many closely coupled narrow strip dipoles together in an appropriate way. An understanding of these effects is not completed; especially since there was no study of the frequency dependence of the radiation properties of these new elements. Design and optimization is also in a very primitive stage, as accurate modeling of their properties requires numerically intensive methods at this time. Questions of this nature deserve more investigation.

  4. Smaller-loss planar SPP transmission line than conventional microstrip in microwave frequencies

    PubMed Central

    Zhang, Hao Chi; Zhang, Qian; Liu, Jun Feng; Tang, Wenxuan; Fan, Yifeng; Cui, Tie Jun

    2016-01-01

    Transmission line is a basic component in all passive devices, integrated circuits, and systems. Microstrip is the most popular transmission line in the microwave and millimeter-wave frequencies, and has been widely used in current electronic devices, circuits, and systems. One of the important issues to be solved in such applications is the relatively large transmission loss of microstrip. Here, we propose a method to reduce the loss of microwave transmission line based on the designable wavenumber of spoof surface plasmon polaritons (SPPs). Using this characteristic, we analyze and experimentally demonstrate the low-loss feature of the SPP transmission line through the perturbation method and S-parameter measurements, respectively. Both simulation and experimental results show that the SPP transmission line has much smaller transmission loss than traditional microstrip with the same size in the microwave frequencies. Hence, the spoof SPP transmission line may make a big step forward in the low-loss circuits and systems. PMID:26983911

  5. Smaller-loss planar SPP transmission line than conventional microstrip in microwave frequencies.

    PubMed

    Zhang, Hao Chi; Zhang, Qian; Liu, Jun Feng; Tang, Wenxuan; Fan, Yifeng; Cui, Tie Jun

    2016-01-01

    Transmission line is a basic component in all passive devices, integrated circuits, and systems. Microstrip is the most popular transmission line in the microwave and millimeter-wave frequencies, and has been widely used in current electronic devices, circuits, and systems. One of the important issues to be solved in such applications is the relatively large transmission loss of microstrip. Here, we propose a method to reduce the loss of microwave transmission line based on the designable wavenumber of spoof surface plasmon polaritons (SPPs). Using this characteristic, we analyze and experimentally demonstrate the low-loss feature of the SPP transmission line through the perturbation method and S-parameter measurements, respectively. Both simulation and experimental results show that the SPP transmission line has much smaller transmission loss than traditional microstrip with the same size in the microwave frequencies. Hence, the spoof SPP transmission line may make a big step forward in the low-loss circuits and systems. PMID:26983911

  6. On the modeling of electromagnetically coupled microstrip antennas - The printed strip dipole

    NASA Astrophysics Data System (ADS)

    Katehi, P. B.; Alexopoulos, N. G.

    1984-11-01

    A generalized solution for a class of printed circuit antennas excited by a strip transmission line is presented. The strip transmission line may be embedded inside or printed on the substrate. As an example, microstrip dipoles electromagnetically coupled (parasitically excited) to embedded strip transmission line have been analyzed accurately, and design graphs are provided for a specific substrate material. These graphs permit the establishment of a design procedure which yields the microstrip dipole length, overlap, offset, and substrate thickness with the goal of a desired input match for a given substrate material. The method accounts for conductor thickness and for arbitrary substrate parameters. Comparison with experiment shows excellent agreement.

  7. On the modeling of electromagnetically coupled microstrip antennas: The printed strip dipole

    NASA Astrophysics Data System (ADS)

    Katehi, P. B.; Alexopoulos, N. G.

    1984-04-01

    A generalized solution for a class of printed circuit antennas, excited by a strip transmission line is presented. The strip transmission line may be embedded inside or printed on the substrate. As an example, microstrip dipoles electromagnetically coupled (parasitically excited) to embedded strip transmission line have been analyzed accurately and design graphs are provided for a specific substrate material. These graphs permit the establishment of a design procedure which yields the microstrip dipole length, overlap, offset, and substrate thickness with the goal of a desired input match for a given substrate material. The method accounts for conductor thickness and for arbitrary substrate parameters. Comparison with experiment shows excellent agreement.

  8. A generalized method for the evaluation of mutual coupling in microstrip arrays

    NASA Astrophysics Data System (ADS)

    Katehi, Pisti B.

    1987-02-01

    An analytical method for the evaluation of mutual coupling in microstrip arrays is discussed. The elements of the array are excited by microstriplines printed on or embedded in the substrate. As an example, the mutual coupling between microstrip dipoles electromagnetically coupled to embedded strip transmission lines is evaluated accurately. The present method is valid in the millimeter range as well as at microwave frequencies and does not have any substrate limitations. Also, it accounts for conductor thickness and surface wave excitation. Comparison with experimental results show excellent agreement.

  9. Design of transversely fed EMC microstrip dipole arrays including mutual coupling

    NASA Astrophysics Data System (ADS)

    Yang, Hung-Yu; Alexopoulos, Nicolaos G.; Lepeltier, Philippe M.; Stern, George J.

    1990-02-01

    Design techniques and procedures for microstrip dipole arrays transversely fed by proximity coupled microstrip lines are presented. Two design equations which include the effects of mutual coupling are developed, and the corresponding design curves are obtained by a rigorous integral equation solution. A seven-element standing wave linear array is designed to illustrate the developed design procedures. The design data are checked by a complete integral equation solution of the array, with good agreement. The measurements of radiation pattern and input impedance are found to be in good agreement with the design goal.

  10. A dispersive boundary condition for microstrip component analysis using the FD-TD method

    NASA Astrophysics Data System (ADS)

    Bi, Zhiqiang; Wu, Keli; Wu, Chen; Litva, John

    1992-04-01

    A dispersive absorbing boundary condition (DBC) is presented, which allows the dispersion characteristics of waves to be used as a criterion for designing absorbing boundary conditions. Its absorbing quality is superior to that of the presently used Mur's first order boundary condition for microstrip component analysis, and, as well, its implementation is much simpler when compared to that of the 'super boundary condition' treatment. Due to the significant performance improvement of the new boundary condition, the memory requirement can be reduced greatly when applying this boundary condition to microstrip component analysis.

  11. A Compact Low-loss Magic-T using Microstrip-Slotline Transitions

    NASA Technical Reports Server (NTRS)

    U-yen, Kongpop; Wollack, Edward J.; Moseley, Samuel H.; Papapolymerou, John; Laskar, Joy

    2007-01-01

    The design of a compact low-loss magic-T is proposed. The planar magic-T incorporates the compact microstrip-slotline tee junction and small microstrip-slotline transition area to reduce slotline radiation. The experimental results show that the magic-T produces broadband in-phase and out-of-phase power combiner/divider responses, has an average in-band insertion loss of 0.3 dB and small in-band phase and amplitude imbalance of less than plus or minus 1.6 deg. and plus or minus 0.3 dB, respectively.

  12. A large-area microstrip-gas-counter for X-ray astronomy

    NASA Astrophysics Data System (ADS)

    Ramsey, B. D.; Apple, J. A.; Austin, R. A.; Dietz, K. L.; Minamitani, T.; Kolodziejczak, J. J.; Weisskopf, M. C.

    1996-02-01

    We have developed a large-area coded-mask telescope for hard-X-ray astronomy. The heart of the instrument is an imaging microstrip-gas-counter of active area 30 cm × 30 cm and filled with 2 × 105 Pa of xenon + 2% isobutylene. Fabricated on a single sheet of borosilicate glass, 1 mm thick, the microstrip features fine anodes (10 μm) and interleaved cathodes from which the position sensing is derived. Rear pickup electrodes provide the second coordinate. Full details of the instrument and its performance are presented. A first flight, from a high-altitude balloon, is scheduled for the Spring of 1977.

  13. [Microstrip antenna design and system research of radio frequency identification temperature sensor].

    PubMed

    Yang, Hao; Yang, Xiaohe; Chen, Yuquan; Pan, Min

    2008-12-01

    Radio frequency identification sensor network, which is a product of integrating radio frequency identification (RFID) with wireless sensor network (WSN), is introduced in this paper. The principle of radio frequency identification sensor is analyzed, and the importance of the antenna is emphasized. Then three kinds of common antennae, namely coil antenna, dipole antenna and microstrip antenna, are discussed. Subsequently, according to requirement, we have designed a microstrip antenna in a wireless temperature-monitoring and controlling system. The measurement of factual effect showed the requirement was fulfilled. PMID:19166222

  14. Coupling between Microstrip Lines Embedded in Polyimide Layers for 3D-MMICs on Si

    NASA Technical Reports Server (NTRS)

    Ponchak, George E.; Tentzeris, Emmanouil M.; Papapolymerou, John

    2001-01-01

    Three-dimensional circuits built upon multiple layers of polyimide are required for constructing SilSiGe monolithic microwavdmillimeter-wave integrated circuits on CMOS (low resistivity) Si wafers. However, the closely spaced transmission lines are susceptible to high levels of coupling, which degrades circuit performance. In this paper, Finite Difference Time Domain (FDTD) analysis and measured characteristics of novel shielding structures that significantly reduce coupling between embedded microstrip lines are presented. A discussion of the electric and magnetic field distributions for the coupled microstrip lines is presented to provide a physical rationale for the presented results.

  15. Analysis of a slot loaded microstrip disk antenna for circular polarisation

    NASA Technical Reports Server (NTRS)

    Rao, Y. R.; Deshpande, Manohar D.

    1991-01-01

    A method is presented to analyze a circular microstrip disk antenna loaded with a narrow, inclined slot at its center and fed by a coaxial probe. Making use of the exact dyadic Green's functions for a grounded dielectric slab due to electric and magnetic currents, Richmond's reaction integral equation in conjunction with the method of moments (Galerkin), a generalized h-parameter equivalent network for the loaded patch is obtained. An expression for the input impedance of a slot loaded microstrip patch is obtained from the equivalent parameters. The theoretical results are compared with the experiment.

  16. Analytical and experimental procedures for determining propagation characteristics of millimeter-wave gallium arsenide microstrip lines

    NASA Technical Reports Server (NTRS)

    Romanofsky, Robert R.

    1989-01-01

    In this report, a thorough analytical procedure is developed for evaluating the frequency-dependent loss characteristics and effective permittivity of microstrip lines. The technique is based on the measured reflection coefficient of microstrip resonator pairs. Experimental data, including quality factor Q, effective relative permittivity, and fringing for 50-omega lines on gallium arsenide (GaAs) from 26.5 to 40.0 GHz are presented. The effects of an imperfect open circuit, coupling losses, and loading of the resonant frequency are considered. A cosine-tapered ridge-guide text fixture is described. It was found to be well suited to the device characterization.

  17. Reconfigurable Wideband Circularly Polarized Microstrip Patch Antenna for Wireless Applications

    NASA Astrophysics Data System (ADS)

    Khidre, Ahmed

    In this thesis, developments of rectangular microstrip patch antenna to have circular polarization agility with wideband performance, for wireless applications are presented. First, a new technique to achieve circularly polarized (CP) probe feed single-layer microstrip patch antenna with wideband characteristics is proposed. The antenna is a modified form of the popular E-shaped patch, used to broaden the impedance bandwidth of a basic rectangular patch antenna. This is established by letting the two parallel slots of the E-patch unequal. Thus, by introducing asymmetry two orthogonal currents on the patch are excited and circularly polarized fields are realized. The proposed technique exhibits the advantage of the simplicity inherent in the E-shaped patch design. It requires only slot lengths, widths, and position parameters to be determined. Also, it is suitable for later adding the reconfigurable capability. With the aid of full-wave simulator Ansoft HFSS, investigations on the effect of various dimensions of the antenna have been carried out via parametric analysis. Based on these investigations, a design procedure for a CP E-shaped patch is summarized. Various design examples with different substrate thicknesses and material types are presented and compared, with CP U-slot patch antennas, recently proposed in the literature. A prototype has been constructed following the suggested design procedure to cover the IEEE 802.11b/g WLAN band. The performance of the fabricated antenna was measured and compared with the simulation results for the reflection coefficient, axial ratio, radiation pattern, and antenna gain. Good agreement is achieved between simulation and measured results demonstrating a high gain and wideband performance. Second, a polarization reconfigurable single feed E-shaped patch antenna with wideband performance is proposed. The antenna is capable of switching from right-hand circular polarization (RHCP) to left-hand circular polarization (LHCP) and

  18. Investigation of frequency-selective devices based on a microstrip 2D photonic crystal

    NASA Astrophysics Data System (ADS)

    Belyaev, B. A.; Khodenkov, S. A.; Shabanov, V. F.

    2016-04-01

    The frequency-selective properties of structures based on a 2D microstrip photonic crystal have been investigated theoretically and experimentally. It is shown that various microwave devices, including diplexers, bandpass filters, and double bandpass filters, can be designed based on these structures.

  19. Design and characterization of a resonator-based metamaterial and its sensor application using microstrip technology

    NASA Astrophysics Data System (ADS)

    Sabah, Cumali; Nesimoglu, Tayfun

    2016-02-01

    Design of a metamaterial based on an S-shaped resonator surrounded by a ground frame and excited by using a feeding transmission line on microstrip technology is presented. Since the resonator, ground frame, and its excitation mechanism are all realized on a microstrip, its characterization can be carried out using common laboratory equipment without needing any waveguide components or plane-wave-illumination techniques. The structure presented here may be realized on any microstrip and does not require special materials. The resonator and ground frame are both on the same side of the microstrip, thus the proposed topology may also be populated with active and passive microwave components, and hybrid active, passive, or reconfigurable microwave circuits may be realized. In metamaterial designs that require plane wave illumination, usually many numbers of periodic unit cells are needed; however, in our design, only one cell is capable of achieving metamaterial properties. The constitutive parameters of the metamaterial are retrieved and compared to demonstrate the agreement between simulations and measurements. The proposed topology is also demonstrated in a sensor application, where simulated and measured results agree well. Thus, it can be realized using standard microwave technology and used for numerous applications where metamaterial properties are needed.

  20. Microstrip antenna study for Pioneer Saturn/Uranus atmosphere entry probe

    NASA Technical Reports Server (NTRS)

    Kuhlman, E. A.

    1974-01-01

    The design parameters of a microstrip antenna were studied to determine its performance characteristics as affected by an atmospheric entry probe environment. The technical literature was reviewed to identify the known design and performance characteristics. These data were used to evaluate the expected effects of mission environments on the microstrip antenna design proposed for the Saturn/Uranus Atmospheric Entry Probe (SAEP). Radiation patterns and VSWR measurements were made to evaluate the performance in the SAEP thermal environment. Results of the literature search and pattern tests confirm that the microstrip antenna is a good choice as a transmitting antenna on the SAEP. The microstrip antenna is efficient, compact, and well suited to a space environment. The pattern can be controlled with a minimum beamwidth of 60 degrees (air substrate; e.g., honeycomb structure) and a maximum on the order of 100 degrees with higher dielectric constant substrates. The power handling capacity is good and can be improved by covering the antenna with a dielectric cover.

  1. A tunable microstrip SQUID amplifier for the Axion Dark Matter eXperiment (ADMX)

    NASA Astrophysics Data System (ADS)

    O'Kelley, Sean; Weingarten, Elan; Mueck, Michael; Hansen, Jorn; Clarke, John

    2014-03-01

    We present a microstrip SQUID amplifier (MSA) with an octave of tunability for use in the ADMX collaboration. The axion dark matter candidate is detected via conversion to a microwave photon stimulated by an apparatus consisting of an 8 tesla magnet and a cryogenically cooled high-Q tunable microwave cavity. The microwave photon frequency is a function of the unknown axion mass, so the detector must scan over a broad frequency range. An MSA is constructed by flux-coupling a resonant microstrip to a resistively-shunted SQUID biased into the voltage state. We demonstrate a gain exceeding 20 dB with a tunability of nearly one octave from 415 MHz to 800 MHz. Tunability is achieved by terminating the microstrip with a low inductance GaAs varactor that operates at cryogenic temperatures, allowing a variable reflected phase of nearly 0 to π at the end of the microstrip, and thus a standing wave tunable from nearly λ/2 to λ/4.

  2. Improved tunable microstrip SQUID amplifier for the Axion Dark Matter eXperiment (ADMX)

    NASA Astrophysics Data System (ADS)

    O'Kelley, Sean; Hansen, Jorn; Mol, Jan-Michael; Hilton, Gene; Clarke, John

    2015-03-01

    We present a series of tunable microstrip SQUID amplifiers (MSAs) for use in ADMX. The axion dark matter candidate is detected via Primakoff conversion to a microwave photon in a high-Q (~ 105) tunable microwave cavity, cooled to 1.6 K or lower, in the presence of a 7-tesla magnetic field. The microwave photon frequency is a function of the unknown axion mass, so that the cavity and amplifier must be scanned over a broad frequency range. An MSA is constructed by flux-coupling a resonant microstrip to a resistively-shunted SQUID biased into the voltage state. We demonstrate gains exceeding 20 dB, at frequencies above 900 MHz. Tunability is achieved by terminating the microstrip with a low inductance GaAs varactor diode that operates at cryogenic temperatures. By varying the voltage bias of the varactor we vary its capacitance, allowing a reflected phase varying from nearly 0 to π at the end of the microstrip, and thus a standing wave tunable from nearly λ/2 to λ/4. With proper design of the microwave environment, a noise temperature of 1/2 to 1/4 of the physical temperature is demonstrated.

  3. Back-feed type circularly polarized microstrip disk antennas by one-point feed

    NASA Astrophysics Data System (ADS)

    Haneishi, M.; Yoshida, S.; Oka, N.

    1980-06-01

    A new circularly polarized microstrip disk antenna which is fed from a point on the substrate bottom surface is proposed and its radiation characteristics, element mutual conductance and radiation efficiency near resonance points are analyzed. Further, an eight-element array consisting of this disk antenna as an element is introduced and its effectiveness is discussed.

  4. Ultra-wideband miniaturized microstrip patch antennas for wireless communications: Design guidelines and modeling

    NASA Astrophysics Data System (ADS)

    Dandu, Varun Kumar

    The number of wireless communication applications continue to increase steadily, leading to competition for currently allocated frequency bands. Capacity issues in form of data rate and latency have always been a bottleneck for broadband wireless-communication usage. New communication systems like ultra-wideband (UWB) require larger bandwidth than what is normally utilized with traditional antenna techniques. The interest for compact consumer electronics is growing in the meantime, creating a demand on efficient and low profile antennas which can be integrated on a printed circuit board. The main objective of this thesis is to study, design, analyze and implement UWB low profile microstrip patch antenna that satisfy UWB technology requirements. Some methods to extend the bandwidth and other antenna parameters associated with wideband usages are studied. Several techniques are used for optimal UWB bandwidth performance of the UWB microstrip patch antenna. The performance parameters such as VSWR, Gain and radiation pattern of the UWB microstrip patch antenna is extensively investigated with simulations using FEKO. A set of simple design guidelines is proposed to provide approximate rules that result in optimum "first-pass" designs of probe-fed, miniaturized, low profile, microstrip UWB antennas using different bandwidth-enhancement techniques to satisfy UWB bandwidth that require minimal tuning.

  5. Segment alignment control system

    NASA Technical Reports Server (NTRS)

    Aubrun, JEAN-N.; Lorell, Ken R.

    1988-01-01

    The segmented primary mirror for the LDR will require a special segment alignment control system to precisely control the orientation of each of the segments so that the resulting composite reflector behaves like a monolith. The W.M. Keck Ten Meter Telescope will utilize a primary mirror made up of 36 actively controlled segments. Thus the primary mirror and its segment alignment control system are directly analogous to the LDR. The problems of controlling the segments in the face of disturbances and control/structures interaction, as analyzed for the TMT, are virtually identical to those for the LDR. The two systems are briefly compared.

  6. Automated retinal layer segmentation and characterization

    NASA Astrophysics Data System (ADS)

    Luisi, Jonathan; Briley, David; Boretsky, Adam; Motamedi, Massoud

    2014-05-01

    Spectral Domain Optical Coherence Tomography (SD-OCT) is a valuable diagnostic tool in both clinical and research settings. The depth-resolved intensity profiles generated by light backscattered from discrete layers of the retina provide a non-invasive method of investigating progressive diseases and injury within the eye. This study demonstrates the application of steerable convolution filters capable of automatically separating gradient orientations to identify edges and delineate tissue boundaries. The edge maps were recombined to measure thickness of individual retinal layers. This technique was successfully applied to longitudinally monitor changes in retinal morphology in a mouse model of laser-induced choroidal neovascularization (CNV) and human data from age-related macular degeneration patients. The steerable filters allow for direct segmentation of noisy images, while novel recombination of weaker segmentations allow for denoising post-segmentation. The segmentation before denoising strategy allows the rapid detection of thin retinal layers even under suboptimal imaging conditions.

  7. Scanning and Defocusing Properties of Microstrip Reflectarray Antennas

    NASA Technical Reports Server (NTRS)

    Rengarajan, Sembiam

    2011-01-01

    A symmetric reflectarray, consisting of variable-size square patch elements with a commonly used mathematical model for the horn in the form of a cosine function, has been designed using the transmit mode technique for different f/D ratios with 10 dB edge taper. Subsequently, the antennas were analyzed for the radiation pattern and gain. The infinite array model was used to determine the reflection phase of each patch element in the design and analysis codes. By displacing the feed laterally, the scan characteristics were obtained, such as the beam deviation factor, gain loss, and pattern degradation. The properties of reflect arrays were compared to those of the conventional paraboloidal reflectors. The same procedure was used to study the scan properties of offset reflectarrays. There is no cross-polarized radiation in the principal planes for a symmetric system. Cross-polarized radiation exists in non-principal planes off broadside in symmetric systems, with greater levels for larger values of subtended angles. Such cross-polarized radiation level increases with subtended angle just as cross-polarization level increases with decreasing values of f/D ratios for symmetric paraboloids in non-principal planes. Pattern distortions and gain loss were found to be more severe in the case of a microstrip reflectarray compared to the conventional parabolic reflector. The scan performance of the reflect arrays was found to improve with f/D ratios as is true for paraboloids. In general, scanning by means of displaced feed is limited to a few beam - widths in reflectarrays. Feed displacement in the axial direction of a symmetric reflectarray was investigated and compared to that of paraboloids. The gain loss due to the defocused feed of a reflectarray was found to be nearly the same as that of a paraboloid of the same subtended angle for larger values of f/D, and for displacements away from the antenna. The gain loss of an axially defocused reflectarray was found to be

  8. Sipunculans and segmentation

    PubMed Central

    Kristof, Alen; Brinkmann, Nora

    2009-01-01

    Comparative molecular, developmental and morphogenetic analyses show that the three major segmented animal groups—Lophotrochozoa, Ecdysozoa and Vertebrata—use a wide range of ontogenetic pathways to establish metameric body organization. Even in the life history of a single specimen, different mechanisms may act on the level of gene expression, cell proliferation, tissue differentiation and organ system formation in individual segments. Accordingly, in some polychaete annelids the first three pairs of segmental peripheral neurons arise synchronously, while the metameric commissures of the ventral nervous system form in anterior-posterior progression. Contrary to traditional belief, loss of segmentation may have occurred more often than commonly assumed, as exemplified in the sipunculans, which show remnants of segmentation in larval stages but are unsegmented as adults. The developmental plasticity and potential evolutionary lability of segmentation nourishes the controversy of a segmented bilaterian ancestor versus multiple independent evolution of segmentation in respective metazoan lineages. PMID:19513266

  9. Segmented trapped vortex cavity

    NASA Technical Reports Server (NTRS)

    Grammel, Jr., Leonard Paul (Inventor); Pennekamp, David Lance (Inventor); Winslow, Jr., Ralph Henry (Inventor)

    2010-01-01

    An annular trapped vortex cavity assembly segment comprising includes a cavity forward wall, a cavity aft wall, and a cavity radially outer wall there between defining a cavity segment therein. A cavity opening extends between the forward and aft walls at a radially inner end of the assembly segment. Radially spaced apart pluralities of air injection first and second holes extend through the forward and aft walls respectively. The segment may include first and second expansion joint features at distal first and second ends respectively of the segment. The segment may include a forward subcomponent including the cavity forward wall attached to an aft subcomponent including the cavity aft wall. The forward and aft subcomponents include forward and aft portions of the cavity radially outer wall respectively. A ring of the segments may be circumferentially disposed about an axis to form an annular segmented vortex cavity assembly.

  10. [Bilateral segmental neurofibromatosis].

    PubMed

    Rose, I; Vakilzadeh, F

    1991-12-01

    Segmental neurofibromatosis is a rare type of neurofibromatosis. We report a case of bilateral manifestation, review the literature on this extremely uncommon variant, and discuss the possible causative mechanisms and the genetic risk of segmental neurofibromatosis. PMID:1765491

  11. Station Tour: Russian Segment

    NASA Video Gallery

    Expedition 33 Commander Suni Williams concludes her tour of the International Space Station with a visit to the Russian segment, which includes Zarya, the first segment of the station launched in 1...

  12. Possible and Impossible Segments.

    ERIC Educational Resources Information Center

    Walker, Rachel; Pullum, Geoffrey K.

    1999-01-01

    Examines the relationship between phonetic possibility and phonological permissibility of segment types. Specific focus is on whether there are any phonetically impossible segments phonologically permissible, and whether there are any phonetically possible segments phonologically impermissable. Examines the case of nasality spreading in Sudanese…

  13. Automatic Contrail Detection and Segmentation

    NASA Technical Reports Server (NTRS)

    Weiss, John M.; Christopher, Sundar A.; Welch, Ronald M.

    1998-01-01

    Automatic contrail detection is of major importance in the study of the atmospheric effects of aviation. Due to the large volume of satellite imagery, selecting contrail images for study by hand is impractical and highly subject to human error. It is far better to have a system in place that will automatically evaluate an image to determine 1) whether it contains contrails and 2) where the contrails are located. Preliminary studies indicate that it is possible to automatically detect and locate contrails in Advanced Very High Resolution Radiometer (AVHRR) imagery with a high degree of confidence. Once contrails have been identified and localized in a satellite image, it is useful to segment the image into contrail versus noncontrail pixels. The ability to partition image pixels makes it possible to determine the optical properties of contrails, including optical thickness and particle size. In this paper, we describe a new technique for segmenting satellite images containing contrails. This method has good potential for creating a contrail climatology in an automated fashion. The majority of contrails are detected, rejecting clutter in the image, even cirrus streaks. Long, thin contrails are most easily detected. However, some contrails may be missed because they are curved, diffused over a large area, or present in short segments. Contrails average 2-3 km in width for the cases studied.

  14. Suspended Rectangular/Circular Patch Antennas with Electromagnetically Coupled Inverted Microstrip Feed for Dual Polarization/Frequency

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.

    2000-01-01

    The paper demonstrates suspended rectangular and circular patch antennas with electromagnetically coupled inverted microstrip feed for linear as well as dual linear polarization/frequency applications. The measured results include the return loss and the impedance bandwidth of the antennas.

  15. Multi-segment detector

    NASA Technical Reports Server (NTRS)

    George, Peter K. (Inventor)

    1978-01-01

    A plurality of stretcher detector segments are connected in series whereby detector signals generated when a bubble passes thereby are added together. Each of the stretcher detector segments is disposed an identical propagation distance away from passive replicators wherein bubbles are replicated from a propagation path and applied, simultaneously, to the stretcher detector segments. The stretcher detector segments are arranged to include both dummy and active portions thereof which are arranged to permit the geometry of both the dummy and active portions of the segment to be substantially matched.

  16. A general approach of the active concept of microstrip antennas and arrays based on the loaded scatterer theory

    NASA Astrophysics Data System (ADS)

    Gillard, Raphael; Legay, Herve; Floch, Jean-Marie; Citerne, Jacques

    1991-06-01

    A quantitative and general approach of the active antenna concept concretized in planar type microstrip technologies is proposed using integral equation techniques associated with the multiport representation of loaded scatterers. Two configurations based on this concept, involving an electromagnetically fed microstrip dipole combined with either passive loads simulating a monolithic switch or active loads simulating a monolithic amplifier, are computed to illustrate the extended capacities of this new approach. Theoretical results on matching characteristics are compared to measurements achieved in X band.

  17. Experimental Verification of the Use of Metal Filled Via Hole Fences for Crosstalk Control of Microstrip Lines in LTCC Packages

    NASA Technical Reports Server (NTRS)

    Ponchak, George E.; Chun, Donghoon; Katehi, Linda P. B.; Yook, Jong-Gwan

    1999-01-01

    Coupling between microstrip lines in dense RF packages is a common problem that degrades circuit performance. Prior 3D-FEM electromagnetic simulations have shown that metal filled via hole fences between two adjacent microstrip lines actually increases coupling between the lines; however, if the top of the via posts are connected by a metal Strip, coupling is reduced. In this paper, experimental verification of the 3D-FEM simulations Is demonstrated for commercially fabricated LTCC packages.

  18. Color image segmentation

    NASA Astrophysics Data System (ADS)

    McCrae, Kimberley A.; Ruck, Dennis W.; Rogers, Steven K.; Oxley, Mark E.

    1994-03-01

    The most difficult stage of automated target recognition is segmentation. Current segmentation problems include faces and tactical targets; previous efforts to segment these objects have used intensity and motion cues. This paper develops a color preprocessing scheme to be used with the other segmentation techniques. A neural network is trained to identify the color of a desired object, eliminating all but that color from the scene. Gabor correlations and 2D wavelet transformations will be performed on stationary images; and 3D wavelet transforms on multispectral data will incorporate color and motion detection into the machine visual system. The paper will demonstrate that color and motion cues can enhance a computer segmentation system. Results from segmenting faces both from the AFIT data base and from video taped television are presented; results from tactical targets such as tanks and airplanes are also given. Color preprocessing is shown to greatly improve the segmentation in most cases.

  19. Ferroelectric/Semiconductor Tunable Microstrip Patch Antenna Developed

    NASA Technical Reports Server (NTRS)

    Romanofsky, Robert R.

    2001-01-01

    A lithographically printed microwave antenna that can be switched and tuned has been developed. The structure consists of a rectangular metallic "patch" radiator patterned on a thin ferroelectric film that was grown on high-resistivity silicon. Such an antenna may one day enable a single-phased array aperture to transmit and receive signals at different frequencies, or it may provide a simple way to reconfigure fractal arrays for communications and radar applications.

  20. Manipulation of propagating spin waves in straight and curved magnetic microstrips

    NASA Astrophysics Data System (ADS)

    Haldar, Arabinda; Liu, Hau-Jian; Schultheiss, Helmut; Vogt, Katrin; Hoffmann, Axel; Buchanan, Kristen

    2012-02-01

    The main challenges in realizing magnonics devices are the generation, manipulation and detection of spin waves, especially in metallic magnetic materials where the length scales are of interest for applications. We have studied the propagation of spin waves in transversely magnetized Permalloy (Py) microstrips of different shapes using micro-Brillouin light scattering. The Py stripe was 30-nm thick, several micrometers wide and >50 μm long. Spin waves were excited in the Py strip using a 2-μm wide antenna. We compare the spin wave propagation along a straight wire to the propagation along a magnetic microstrip with a smooth bend. We will also discuss the use of a current through a gold wire under the Permalloy to provide a local magnetic field to maintain a transverse magnetization around the bend.

  1. Surface wave and related effects on the RCS of microstrip dipoles printed on magnetodielectric substrates

    NASA Astrophysics Data System (ADS)

    Antilla, George E.; Alexopoulos, Nicolaos G.

    1991-12-01

    The scattering cross section of microstrip dipoles is examined. The primary emphasis is to demonstrate the effects of surface waves on the scattering cross section, and to provide a simple physical understanding of the surface wave mechanism. The electric field integral equation is solved in the spatial domain using the method of moments. Special techniques used to speed up the evaluation of the Sommerfeld integrals will be explained. The radar cross section for several microstrip dipole configurations is presented. The mechanism for generation of surface waves plays a major role in the scattering behavior of the dipoles, and a physically intuitive interpretation of this mechanism is used to successfully explain the pattern structure. For generality, magnetodielectric substrates with and without loss are considered.

  2. The RCS of a microstrip dipole deduced from an expansion of pole singularities

    NASA Astrophysics Data System (ADS)

    Hanson, George W.; Nyquist, Dennis P.

    1993-03-01

    The SEM is applied to the steady-state analysis of plane wave scattering from microstrip dipoles. The current induced on the antenna is expanded in a series of natural modes, where the amplitude of each term in the expansion is expressed as a coupling coefficient weighted by a simple frequency pole. Natural modes occur at pole singularities of the antenna current in the complex frequency plane, and are found by a numerical root search of a homogeneous matrix equation. This formulation results in an accurate and efficient calculation of the radar cross section of microstrip dipoles which exhibit some appreciable resonant characteristics, where it is found that the current resonance dominates the response of the antenna. The SEM applied here yields good physical insight into the scattering behavior of such antennas. Results obtained with the SEM analysis are compared with a full-wave method of moments solution.

  3. Resonant frequencies of irregularly shaped microstrip antennas using method of moments

    NASA Technical Reports Server (NTRS)

    Deshpande, Manohar D.; Shively, David G.; Cockrell, C. R.

    1993-01-01

    This paper describes an application of the method of moments to determine resonant frequencies of irregularly shaped microstrip patches embedded in a grounded dielectric slab. For analysis, the microstrip patch is assumed to be excited by a linearly polarized plane wave that is normal to the patch. The surface-current density that is induced on the patch because of the incident field is expressed in terms of subdomain functions by dividing the patch into identical rectangular subdomains. The amplitudes of the subdomain functions, as a function of frequency, are determined using the electric-field integral equation (EFIE) approach in conjunction with the method of moments. The resonant frequencies of the patch are then obtained by selecting the frequency at which the amplitude of the surface-current density is real. The resonant frequencies of the equilateral triangular and other nonrectangular patches are computed using the present technique, and these frequencies are compared with measurements and other independent calculations.

  4. Gap Excitations and Series Loads in Microstrip Lines: Equivalent Network Characterization with Application to THz Circuits

    NASA Technical Reports Server (NTRS)

    Neto, Andrea; Siegel, Peter H.

    2001-01-01

    At submillimeter wavelengths typical gap discontinuities in microstrip, CPW lines or at antenna terminals, which might contain diodes or active elements, cannot be viewed as simple quasi statically evaluated lumped elements. Planar Schottky diodes at 2.5 THz, for example, have a footprint that is comparable to a wavelength. Thus, apart from modelling the diodes themselves, the connection with their exciting elements (antennas or microstrip) gives rise to parasitics. Full wave or strictly numeric approaches can be used to account for these parasitics but at the expense of generality of the solution and the CPU time of the calculation. In this paper an equivalent network is derived that accurately accounts for large gap discontinuities (with respect to a wavelength) without suffering from the limitations of available numeric techniques.

  5. Gain Improvement of Microstrip Patch Antenna Using CLS Split Ring Resonator Metamaterial

    NASA Astrophysics Data System (ADS)

    Katiyar, Pankaj Rameshchandra; Wan Mahadi, Wan Nor Liza Binti

    2015-03-01

    Metamaterials are artificial materials with negative permittivity and permeability. Metamaterials due to their unique negative parameter are capable of focusing the electromagnetic energy incident upon them. This focusing of electromagnetic energy is used to increase the gain of microstrip patch antenna. A capacitive loaded strip (CLS)-loaded split ring resonator is used to form a multilayer array of metamaterial and used in front of microstrip patch antenna to enhance far-field gain of antenna. An accurate simulation model is created and analyzed using CST. The simulated model is then fabricated and measured in fully anechoic chamber for validation. The far-field gain of regular patch antenna with and without metamaterial is measured in anechoic chamber. The increase in gain by 4 dB is measured at 95 mm from antenna. The beam focusing property is also evident from 3 dB beamwidth of antenna which is reduced to 42.01°.

  6. A Stacked Microstrip Patch Antenna Loaded With U-Shaped Slots

    NASA Astrophysics Data System (ADS)

    Tiwari, Harshvardhan; Kartikeyan, Machavazam V.

    2011-07-01

    In this work, an extensive design study of a stacked U-slot microstrip patch antenna for dual band operation will be presented. This antenna consists of two stacked microstrip patches, both having U-slots embedded in them. Two feeding techniques namely probe-feeding and co-planar waveguide feeding have been used and the results compared. The antennas were simulated using CST Microwave Studio's Transient Solver which is based on the Finite Integral Technique (FIT) and particle swarm optimization was used to optimize the antenna parameters for both the cases. The simulated and measured results indicate that using co-planar waveguide feeding results in a tremendous increase in bandwidth when compared with probe feeding, however degradation in gain is observed.

  7. Quality Factor Effect on the Wireless Range of Microstrip Patch Antenna Strain Sensors

    PubMed Central

    Daliri, Ali; Galehdar, Amir; Rowe, Wayne S. T.; John, Sabu; Wang, Chun H.; Ghorbani, Kamran

    2014-01-01

    Recently introduced passive wireless strain sensors based on microstrip patch antennas have shown great potential for reliable health and usage monitoring in aerospace and civil industries. However, the wireless interrogation range of these sensors is limited to few centimeters, which restricts their practical application. This paper presents an investigation on the effect of circular microstrip patch antenna (CMPA) design on the quality factor and the maximum practical wireless reading range of the sensor. The results reveal that by using appropriate substrate materials the interrogation distance of the CMPA sensor can be increased four-fold, from the previously reported 5 to 20 cm, thus improving considerably the viability of this type of wireless sensors for strain measurement and damage detection. PMID:24451457

  8. Wide-band, forward-coupling microstrip hybrids with high directivity

    NASA Astrophysics Data System (ADS)

    Ikalainen, Pertti K.; Matthaei, George L.

    1987-08-01

    The common forms of microstrip hybrids are either 'backward couplers', formed using parallel lines, or branch-line or rat-race hybrids. All of these tend to have degraded performance due to discontinuities, junction effects, or unequal even- and odd-mode velocities. In contrast, coupled-line microstrip forward couplers do not require any discontinuities or junctions and utilize the unequal mode velocities. As a result, forward couplers can tolerate unusually thick substrates and still achieve high directivity and very little radiation. Though they are relatively long, designs with sizable coupling gaps have reasonable lengths for many applications, particularly at millimeter-wave frequencies. A trial symmetrical design yielded a bandwidth of 15 percent for 1-dB maximum unbalance. By use of asymmetrical design, a bandwidth of 57 percent was achieved for this same tolerance. Either quadrature or 'magic-T hybrid performance can be approximated. Directivities of 37 dB or more were readily achieved.

  9. An antenna-coupled bolometer with an integrated microstrip bandpass filter

    NASA Astrophysics Data System (ADS)

    Myers, Michael J.; Holzapfel, William; Lee, Adrian T.; O'Brient, Roger; Richards, P. L.; Tran, Huan T.; Ade, Peter; Engargiola, Greg; Smith, Andy; Spieler, Helmuth

    2005-03-01

    We describe the fabrication and testing of antenna-coupled superconducting transition-edge bolometers for use at millimeter wavelengths. The design uses a double-slot dipole antenna connected to superconducting niobium microstrip. Band defining filters are implemented in the microstrip, which is then terminated with a load resistor. The power dissipated in the load resistor is measured by a superconducting transition-edge sensor (TES). The load resistor and TES are thermally well connected and are supported by a silicon nitride substrate. The substrate is suspended by four narrow silicon nitride legs for thermal isolation. The bolometers have been optically characterized and the spectral response is presented. This detector is a prototype element for use in an array designed for studies of the cosmic microwave background polarization.

  10. The bipolar silicon microstrip detector: A proposal for a novel precision tracking device

    NASA Astrophysics Data System (ADS)

    Horisberger, R.

    1990-03-01

    It is proposed to combine the technology of fully depleted silicon microstrip detectors fabricated on n doped high resistivity silicon with the concept of the bipolar transistor. This is done by adding a n ++ doped region inside the normal p + implanted region of the reverse biased p + n diode. Teh resulting structure has amplifying properties and is referred to as bipolar pixel transistor. The simplest readout scheme of a bipolar pixel array by an aluminium strip bus leads to the bipolar microstrip detector. The bipolar pixel structure is expected to give a better signal-to-noise performance for the detection of minimum ionizing charged particle tracks than the normal silicon diode strip detector and therefore should allow in future the fabrication of thinner silicon detectors for precision tracking.

  11. Input impedance of a probe-fed circular microstrip antenna with thick substrate

    NASA Technical Reports Server (NTRS)

    Davidovitz, M.; Lo, Y. T.

    1986-01-01

    A method of computing the input impedance for the probe fed circular microstrip antenna with thick dielectric substrate is presented. Utilizing the framework of the cavity model, the fields under the microstrip patch are expanded in a set of modes satisfying the boundary conditions on the eccentrically located probe, as well as on the cavity magnetic wall. A mode-matching technique is used to solve for the electric field at the junction between the cavity and the coaxial feed cable. The reflection coefficient of the transverse electromagnetic (TEM) mode incident in the coaxial cable is determined, from which the input impedance of the antenna is computed. Measured data are presented to verify the theoretical calculations. Results of the computation of various losses for the circular printed antenna as a function of substrate thickness are also included.

  12. Quality factor effect on the wireless range of microstrip patch antenna strain sensors.

    PubMed

    Daliri, Ali; Galehdar, Amir; Rowe, Wayne S T; John, Sabu; Wang, Chun H; Ghorbani, Kamran

    2014-01-01

    Recently introduced passive wireless strain sensors based on microstrip patch antennas have shown great potential for reliable health and usage monitoring in aerospace and civil industries. However, the wireless interrogation range of these sensors is limited to few centimeters, which restricts their practical application. This paper presents an investigation on the effect of circular microstrip patch antenna (CMPA) design on the quality factor and the maximum practical wireless reading range of the sensor. The results reveal that by using appropriate substrate materials the interrogation distance of the CMPA sensor can be increased four-fold, from the previously reported 5 to 20 cm, thus improving considerably the viability of this type of wireless sensors for strain measurement and damage detection. PMID:24451457

  13. High-Tc superconducting rectangular microstrip patch covered with a dielectric layer

    NASA Astrophysics Data System (ADS)

    Bedra, Sami; Fortaki, Tarek

    2016-05-01

    This paper presents a full-wave method to calculate the resonant characteristics of rectangular microstrip antenna with and without dielectric cover, to explain the difference of performance with temperature between superconducting and normal conducting antenna. Especially the characteristics of high temperature superconducting (HTS) antenna were almost ideal around the critical temperature (Tc). The dyadic Green's functions of the considered structure are efficiently determined in the vector Fourier transform domain. The effect of the superconductivity of the patch is taken into account using the concept of the complex resistive boundary condition. The computed results are found to be in good agreement with results obtained using other methods. Also, the effects of the superstrate on the resonant frequency and bandwidth of rectangular microstrip patch in a substrate-superstrate configuration are investigated. This type of configuration can be used for wider bandwidth by proper selection of superstrate thickness and its dielectric constants.

  14. Estimation of Resonant Frequency of a Circular Microstrip Antenna Using Artificial Neural Network

    NASA Astrophysics Data System (ADS)

    Singh, Jagtar; Singh, A. P.; Kamal, T. S.

    2012-03-01

    In recent years the art of using artificial neural networks for wireless communication engineers has been gaining momentum. In this paper a general procedure is suggested for estimating the resonant frequency of circular microstrip patch antenna using artificial neural networks. The method of moments (MOM) based IE3D software was used to generate data dictionary for training and validation set of ANN. The proposed technique uses multilayer feed-forward back-propagation artificial neural network with one hidden layers for estimating the resonant frequency of a circular microstrip antenna. A relative performance of the different training algorithms is carried out for estimating the resonant frequency with particular attention paid to the speed of computation and accuracy achieved. This type of performance comparison has not been attempted so far.

  15. Dual frequency, dual polarized, multi-layered microstrip slot and dipole array antenna

    NASA Technical Reports Server (NTRS)

    Tulintseff, Ann N. (Inventor)

    1995-01-01

    An antenna array system is disclosed which uses subarrays of slots and subarrays of dipoles on separate planes. The slots and dipoles respectively are interleaved, which is to say there is minimal overlap between them. Each subarray includes a microstrip transmission line and a plurality of elements extending perpendicular thereto. The dipoles form the transmission elements and the slots form the receive elements. The plane in which the slots are formed also forms a ground plane for the dipoles--hence the feed to the dipole is on the opposite side of this ground plane as the feed to the slots. HPAs are located adjacent the dipoles on one side of the substrate and LNAs are located adjacent the slots on the other side of the substrate. The dipoles and slots are tuned by setting different offsets between each element and the microstrip transmission line.

  16. Radiation tolerance studies of neutron irradiated double sided silicon microstrip detectors

    NASA Astrophysics Data System (ADS)

    Singla, M.; Larionov, P.; Balog, T.; Heuser, J.; Malygina, H.; Momot, I.; Sorokin, I.; Sturm, C.

    2016-07-01

    Radiation tolerance studies were made on double-sided silicon microstrip detectors for the Silicon Tracking System of the Compressed Baryonic Matter experiment at FAIR. The prototype detectors from two different vendors were irradiated to twice the highest expected fluence (1 ×1014 1 MeVneqcm-2) in the CBM experimental runs of several years. Test results from these prototype detectors both before and after irradiations have been discussed.

  17. Characteristics of microstrip dipole antennas in a periodic structure with dielectric layers

    NASA Astrophysics Data System (ADS)

    Grinev, A. Iu.; Kotov, Iu. V.

    Microstrip dipole antennas in a periodic antenna array with dielectric layers are analyzed on the basis of a rigorous solution of an integral equation of the first kind with respect to the electric-field distribution on the dipole. Numerical results are presented on the partial radiation pattern of the antenna, the total input impedance, and the amplitude-phase distribution of the electric current on the dipole. The optimization of the antenna is considered.

  18. A new model for broadband waveguide-to-microstrip transition design

    NASA Technical Reports Server (NTRS)

    Ponchak, George E.; Downey, Alan N.

    1988-01-01

    A new model is presented which permits the prediction of the resonant frequencies created by antipodal finline waveguide to microstrip transitions. The transition is modeled as a tapered transmission line in series with an infinite set of coupled resonant circuits. The resonant circuits are modeled as simple microwave resonant cavities of which the resonant frequencies are easily determined. The model is developed and the resonant frequencies determined for several different transitions. Experimental results are given to confirm the models.

  19. The design and fabrication of microstrip omnidirectional array antennas for aerospace applications

    NASA Technical Reports Server (NTRS)

    Campbell, T. G.; Appleton, M. W.; Lusby, T. K.

    1976-01-01

    A microstrip antenna design concept was developed that will provide quasi-omnidirectional radiation pattern characteristics about cylindrical and conical aerospace structures. L-band and S-band antenna arrays were designed, fabricated, and, in some cases, flight tested for rocket, satellite, and aircraft drone applications. Each type of array design is discussed along with a thermal cover design that was required for the sounding rocket applications.

  20. Coupling Between Microstrip Lines Embedded in Polyimide Layers for 3D-MMICs on Si

    NASA Technical Reports Server (NTRS)

    Ponchak, George E.; Tentzeris, Emmanouil M.; Papapolymerou, John

    2001-01-01

    Three-dimensional circuits built upon multiple layers of polyimide are required for constructing Si/SiGe monolithic microwave/millimeter-wave integrated circuits on CMOS (low resistivity) Si wafers. However, the closely spaced transmission lines are susceptible to high levels of coupling, which degrades circuit performance. In this paper, Finite Difference Time Domain (FDTD) analysis and measured characteristics of novel shielding structures that significantly reduce coupling between embedded microstrip lines are presented.

  1. The finite ground plane effect on the microstrip antenna radiation patterns

    NASA Technical Reports Server (NTRS)

    Huang, J.

    1983-01-01

    The uniform geometrical theory of diffraction (GTD) is employed for calculating the edge diffracted fields from the finite ground plane of a microstrip antenna. The source field from the radiating patch is calculated by two different methods: the slot theory and the modal expansion theory. Many numerical and measured results are presented to demonstrate the accuracy of the calculations and the finite ground plane edge effect.

  2. Effective side length formula for resonant frequency of equilateral triangular microstrip antenna

    NASA Astrophysics Data System (ADS)

    Guney, Kerim; Kurt, Erhan

    2016-02-01

    A novel and accurate expression is obtained by employing the differential evolution algorithm for the effective side length (ESL) of the equilateral triangular microstrip antenna (ETMA). This useful formula allows the antenna engineers to accurately calculate the ESL of the ETMA. The computed resonant frequencies (RFs) show very good agreement with the experimental RFs when this accurate ESL formula is utilised for the computation of the RFs for the first five modes.

  3. Performance characteristics and radiation damage results from the Fermilab E706 silicon microstrip detector system

    NASA Astrophysics Data System (ADS)

    Engels, E.; Mani, S.; Orris, D.; Shepard, P. F.; Weerasundara, P. D.; Choudhary, B. C.; Joshi, U.; Kapoor, V.; Shivpuri, R.; Baker, W.; Berg, D.; Carey, D.; Johnstone, C.; Nelson, C.; Bromberg, C.; Brown, D.; Huston, J.; Miller, R.; Nguyen, A.; Benson, R.; Lukens, P.; Ruddick, K.; Alverson, G.; Faissler, W.; Garelick, D.; Glaubman, M.; Kourbanis, I.; Lirakis, C.; Pothier, E.; Sinanidis, A.; Wu, G.-H.; Yasuda, T.; Yosef, C.; Easo, S.; Hartman, K.; Oh, B. Y.; Toothacker, W.; Whitmore, J.; Ballocchi, G.; Debarbaro, L.; Desoi, W.; Fanourakis, G.; Ferbel, T.; Ginther, G.; Gutierrez, P.; Lanaro, A.; Lobkowicz, F.; Mansour, J.; Pedeville, G.; Prebys, E.; Skow, D.; Slattery, P.; Varelas, N.; Zielinski, M.

    1989-07-01

    A charged particle spectrometer containing a 7120-channel silicon microstrip detector system, one component of Fermilab experiment E706 to study direct photon production in hadron-hadron collisions, was utilized in a run in which 6 million events were recorded. We describe the silicon system, provide early results of track and vertex reconstruction, and present data on the radiation damage to the silicon wafers resulting from the narrow high intensity beam.

  4. Accurate Analysis and Computer Aided Design of Microstrip Dual Mode Resonators and Filters.

    NASA Astrophysics Data System (ADS)

    Grounds, Preston Whitfield, III

    1995-01-01

    Microstrip structures are of interest due to their many applications in microwave circuit design. Their small size and ease of connection to both passive and active components make them well suited for use in systems where size and space is at a premium. These include satellite communication systems, radar systems, satellite navigation systems, cellular phones and many others. In general, space is always a premium for any mobile system. Microstrip resonators find particular application in oscillators and filters. In typical filters each microstrip patch corresponds to one resonator. However, when dual mode patches are employed, each patch acts as two resonators and therefore reduces the amount of space required to build the filter. This dissertation focuses on the accurate electromagnetic analysis of the components of planar dual mode filters. Highly accurate analyses are required so that the resonator to resonator coupling and the resonator to input/output can be predicted with precision. Hence, filters can be built with a minimum of design iterations and tuning. The analysis used herein is an integral equation formulation in the spectral domain. The analysis is done in the spectral domain since the Green's function can be derived in closed form, and the spatial domain convolution becomes a simple product. The resulting set of equations is solved using the Method of Moments with Galerkin's procedure. The electromagnetic analysis is applied to range of problems including unloaded dual mode patches, dual mode patches coupled to microstrip feedlines, and complete filter structures. At each step calculated results are compared to measured results and good agreement is found. The calculated results are also compared to results from the circuit analysis program HP EESOF^{ rm TM} and again good agreement is found. A dual mode elliptic filter is built and good performance is obtained.

  5. Radiation tolerance studies of silicon microstrip sensors for the CBM Silicon Tracking System

    NASA Astrophysics Data System (ADS)

    Momot, I.; Singla, M.; Teklishyn, M.; Pugatch, V.; Heuser, J.

    2016-01-01

    Double-sided silicon microstrip sensors will be used in the Silicon Tracking System of the CBM experiment. During experimental run they will be exposed to a radiation field of up to 1x1014 1 MeV neq cm-2. Radiation tolerance studies were made on prototypes from two different vendors. Results from these prototype detectors before and after irradiation to twice that neutron fluence are discussed.

  6. Impact assisted segmented cutterhead

    DOEpatents

    Morrell, Roger J.; Larson, David A.; Ruzzi, Peter L.

    1992-01-01

    An impact assisted segmented cutterhead device is provided for cutting various surfaces from coal to granite. The device comprises a plurality of cutting bit segments deployed in side by side relationship to form a continuous cutting face and a plurality of impactors individually associated with respective cutting bit segments. An impactor rod of each impactor connects that impactor to the corresponding cutting bit segment. A plurality of shock mounts dampening the vibration from the associated impactor. Mounting brackets are used in mounting the cutterhead to a base machine.

  7. Stripline feed for a microstrip array of patch elements with teardrop shaped probes

    NASA Technical Reports Server (NTRS)

    Huang, John (Inventor)

    1989-01-01

    A circularly polarized microstrip array antenna utilizing a honeycomb substrate made of dielectric material to support on one side the microstrip patch elements in an array, and on the other side a stripline circuit for feeding the patch elements in subarray groups of four with angular orientation and phase for producing circularly polarized radiation, preferably at a 0, 90, 180, and 270 degree relationship is described. The probe used for coupling each feed point in the stripline circuit to a microstrip patch element is teardrop shaped in order to introduce capacitance between the coupling probe and the metal sheet of the stripline circuit that serves as an antenna ground plane. The capacitance thus introduced tunes out inductance of the probe. The shape of the teardrop probe is not critical. The probe capacitance required is controlled by the maximum diameter for the teardrop shaped probe, which can be empirically determined for the operating frequency. An aluminum baffle around each subarray blocks out surface wave between subarrays.

  8. Annealing studies of silicon microstrip detectors irradiated at high neutron fluences

    NASA Astrophysics Data System (ADS)

    Miñano, M.; Balbuena, J. P.; García, C.; González, S.; Lacasta, C.; Lacuesta, V.; Lozano, M.; Martí i Garcia, S.; Pellegrini, G.; Ullán, M.

    2008-06-01

    Silicon p-type detectors are being investigated for the development of radiation-tolerant detectors for the luminosity upgrade of the CERN large hadron collider (Super-LHC (sLHC)). Microstrip detectors have been fabricated by CNM-IMB with an n-side read-out on p-type high-resistivity float zone substrates. They have been irradiated with neutrons at the TRIGA Mark II nuclear reactor in Ljubljana. The irradiation fluxes match with the expected doses for the inner tracker at the sLHC (up to 10 16 equivalent 1 MeV neutrons cm -2). The macroscopic properties of the irradiated prototypes after irradiation were characterized at the IFIC-Valencia laboratory. The charge collection studies were carried out by means of a radioactive source setup as well as by an infrared laser illumination. The annealing behavior was studied in detail on a microstrip detector irradiated with a flux of 10 15 equivalent 1 MeV neutrons cm -2. Collected charge measurements were made after accelerated annealing times at 80 °C up to an equivalent annealing time of several years at room temperature. This note reports on the recorded results from the annealing of the irradiated p-type microstrip sensor.

  9. Effect of Weaving Direction of Conductive Yarns on Electromagnetic Performance of 3D Integrated Microstrip Antenna

    NASA Astrophysics Data System (ADS)

    Xu, Fujun; Yao, Lan; Zhao, Da; Jiang, Muwen; Qiu, Yipping

    2013-10-01

    A three-dimensionally integrated microstrip antenna (3DIMA) is a microstrip antenna woven into the three-dimensional woven composite for load bearing while functioning as an antenna. In this study, the effect of weaving direction of conductive yarns on electromagnetic performance of 3DIMAs are investigated by designing, simulating and experimental testing of two microstrip antennas with different weaving directions of conductive yarns: one has the conductive yarns along the antenna feeding direction (3DIMA-Exp1) and the other has the conductive yarns perpendicular the antenna feeding direction (3DIMA-Exp2). The measured voltage standing wave ratio (VSWR) of 3DIMA-Exp1 was 1.4 at the resonant frequencies of 1.39 GHz; while that of 3DIMA-Exp2 was 1.2 at the resonant frequencies of 1.35 GHz. In addition, the measured radiation pattern of the 3DIMA-Exp1 has smaller back lobe and higher gain value than those of the 3DIMA-Exp2. This result indicates that the waving direction of conductive yarns may have a significant impact on electromagnetic performance of textile structural antennas.

  10. Signal of microstrip scanning near-field optical microscope in far- and near-field zones.

    PubMed

    Morozov, Yevhenii M; Lapchuk, Anatoliy S

    2016-05-01

    An analytical model of interference between an electromagnetic field of fundamental quasi-TM(EH)00-mode and an electromagnetic field of background radiation at the apex of a near-field probe based on an optical plasmon microstrip line (microstrip probe) has been proposed. The condition of the occurrence of electromagnetic energy reverse flux at the apex of the microstrip probe was obtained. It has been shown that the nature of the interference depends on the length of the probe. Numerical simulation of the sample scanning process was conducted in illumination-reflection and illumination-collection modes. Results of numerical simulation have shown that interference affects the scanning signal in both modes. However, in illumination-collection mode (pure near-field mode), the signal shape and its polarity are practically insensible to probe length change; only signal amplitude (contrast) is slightly changed. However, changing the probe length strongly affects the signal amplitude and shape in the illumination-reflection mode (the signal formed in the far-field zone). Thus, we can conclude that even small background radiation can significantly influence the signal in the far-field zone and has practically no influence on a pure near-field signal. PMID:27140358

  11. Stripline feed for a microstrip array of patch elements with teardrop shaped probes

    NASA Technical Reports Server (NTRS)

    Huang, John (Inventor)

    1990-01-01

    A circularly polarized microstrip array antenna utilizing a honeycomb substrate made of dielectric material to support on one side the microstrip patch elements in an array, and on the other side a stripline circuit for feeding the patch elements in subarray groups of four with angular orientation and phase for producing circularly polarized radiation, preferably at a 0.degree., 90.degree., 180.degree. and 270.degree. relationship. The probe used for coupling each feed point in the stripline circuit to a microstrip patch element is teardrop shaped in order to introduce capacitance between the coupling probe and the metal sheet of the stripline circuit that serves as an antenna ground plane. The capacitance thus introduced tunes out inductance of the probe. The shape of the teardrop probe is not critical. The probe capacitance required is controlled by the maximum diameter for the teardrop shaped probe, which can be empirically determined for the operating frequency. An aluminum baffle around each subarray blocks out surface waves between subarrays.

  12. Design of Miniaturized Dual-Band Microstrip Antenna for WLAN Application

    PubMed Central

    Yang, Jiachen; Wang, Huanling; Lv, Zhihan; Wang, Huihui

    2016-01-01

    Wireless local area network (WLAN) is a technology that combines computer network with wireless communication technology. The 2.4 GHz and 5 GHz frequency bands in the Industrial Scientific Medical (ISM) band can be used in the WLAN environment. Because of the development of wireless communication technology and the use of the frequency bands without the need for authorization, the application of WLAN is becoming more and more extensive. As the key part of the WLAN system, the antenna must also be adapted to the development of WLAN communication technology. This paper designs two new dual-frequency microstrip antennas with the use of electromagnetic simulation software—High Frequency Structure Simulator (HFSS). The two antennas adopt ordinary FR4 material as a dielectric substrate, with the advantages of low cost and small size. The first antenna adopts microstrip line feeding, and the antenna radiation patch is composed of a folded T-shaped radiating dipole which reduces the antenna size, and two symmetrical rectangular patches located on both sides of the T-shaped radiating patch. The second antenna is a microstrip patch antenna fed by coaxial line, and the size of the antenna is diminished by opening a stepped groove on the two edges of the patch and a folded slot inside the patch. Simulation experiments prove that the two designed antennas have a higher gain and a favourable transmission characteristic in the working frequency range, which is in accordance with the requirements of WLAN communication. PMID:27355954

  13. Hybrid perturbation scheme for wide beamwidth circularly polarized stacked patch microstrip antenna for satellite communication

    NASA Astrophysics Data System (ADS)

    Hossain, Mohammad Shakawat

    Circularly polarized microstrip antennas are popular for satellite communications due to their circularly polarized orientation. They are used frequently in modern day satellite communication. In order to achieve wide angular coverage in satellite communication, a wide beamwidth is required from the antenna. Traditional single layer microstrip antenna inherently demonstrates low angular beamwidth of approximately 600 to 800and thereby lacks wide angular coverage when used for satellite communication. The objective of this thesis is to design a single-fed stacked microstrip antenna using different perturbation techniques in order to achieve a wide angular beamwidth. This thesis presents a new design for a circularly polarized antenna based on the hybrid perturbation scheme. First, a method of stacked patch-ring with negative perturbation was used to generate a significantly larger beamwidth of 1060. The axial ratio (AR) bandwidth obtained is also significantly larger compared to the case when square rings are used as parasitic and driven rings with a single feed. A simulated impedance bandwidth (S11< - 10 dB) of 16%, 3 dB AR bandwidth of 8% and a peak gain of 8.65 dBic are obtained from this design. Next, a new design of stacked hybrid antenna is presented, which uses hybrid perturbations to generate circular polarization radiation. An enhanced beamwidth of 1260 was obtained. The simulation results are confirmed by the measured results.

  14. Microstrip Antenna for Remote Sensing of Soil Moisture and Sea Surface Salinity

    NASA Technical Reports Server (NTRS)

    Ramhat-Samii, Yahya; Kona, Keerti; Manteghi, Majid; Dinardo, Steven; Hunter, Don; Njoku, Eni; Wilson, Wiliam; Yueh, Simon

    2009-01-01

    This compact, lightweight, dual-frequency antenna feed developed for future soil moisture and sea surface salinity (SSS) missions can benefit future soil and ocean studies by lowering mass, volume, and cost of the antenna system. It also allows for airborne soil moisture and salinity remote sensors operating on small aircraft. While microstrip antenna technology has been developed for radio communications, it has yet to be applied to combined radar and radiometer for Earth remote sensing. The antenna feed provides a key instrument element enabling high-resolution radiometric observations with large, deployable antennas. The design is based on the microstrip stacked-patch array (MSPA) used to feed a large, lightweight, deployable, rotating mesh antenna for spaceborne L-band (approximately equal to 1 GHz) passive and active sensing systems. The array consists of stacked patches to provide dual-frequency capability and suitable radiation patterns. The stacked-patch microstrip element was designed to cover the required L-band center frequencies at 1.26 GHz (lower patch) and 1.413 GHz (upper patch), with dual-linear polarization capabilities. The dimension of patches produces the required frequencies. To achieve excellent polarization isolation and control of antenna sidelobes for the MSPA, the orientation of each stacked-patch element within the array is optimized to reduce the cross-polarization. A specialized feed-distribution network was designed to achieve the required excitation amplitude and phase for each stacked-patch element.

  15. Electric-field distribution near rectangular microstrip radiators for hyperthermia heating: theory versus experiment in water.

    PubMed

    Underwood, H R; Peterson, A F; Magin, R L

    1992-02-01

    A rectangular microstrip antenna radiator is investigated for its near-zone radiation characteristics in water. Calculations of a cavity model theory are compared with the electric-field measurements of a miniature nonperturbing diode-dipole E-field probe whose 3 mm tip was positioned by an automatic three-axis scanning system. These comparisons have implications for the use of microstrip antennas in a multielement microwave hyperthermia applicator. Half-wavelength rectangular microstrip patches were designed to radiate in water at 915 MHz. Both low (epsilon r = 10) and high (epsilon r = 85) dielectric constant substrates were tested. Normal and tangential components of the near-zone radiated electric field were discriminated by appropriate orientation of the E-field probe. Low normal to transverse electric-field ratios at 3.0 cm depth indicate that the radiators may be useful for hyperthermia heating with an intervening water bolus. Electric-field pattern addition from a three-element linear array of these elements in water indicates that phase and amplitude adjustment can achieve some limited control over the distribution of radiated power. PMID:1612617

  16. Electric-field distribution near rectangular microstrip radiators for hyperthermia heating: Theory versus experiment in water

    SciTech Connect

    Underwood, H.R. ); Peterson, A.F. ); Magin, R.L. )

    1992-02-01

    A rectangular microstrip antenna radiator is investigated for its near-zone radiation characteristics in water. Calculations of a cavity model theory are compared with the electric-field measurements of a miniature nonperturbing diode dipole E-field probe whose 3 mm tip was positioned by an automatic three-axis scanning system. These comparisons have implications for the use of microstrip antennas in a multielement microwave hyperthermia applicator. Half-wavelength rectangular microstrip patches were designed to radiate in water at 915 MHz. Both low ([epsilon][sub r] = 10) and high ([epsilon][sub r] = 85) dielectric constant substrates were tested. Normal and tangential components of the near-zone radiated electric field were discriminated by appropriate orientation of the E-field probe. Low normal to transverse electric-field ratios ar 3.0 cm depth indicate that the radiators may be useful for hyperthermia heating with an intervening water bolus. Electric-field pattern addition from a three-element linear array of these elements in water indicates that phase and amplitude adjustment can achieve some limited control over the distribution of radiated power.

  17. Design of Miniaturized Dual-Band Microstrip Antenna for WLAN Application.

    PubMed

    Yang, Jiachen; Wang, Huanling; Lv, Zhihan; Wang, Huihui

    2016-01-01

    Wireless local area network (WLAN) is a technology that combines computer network with wireless communication technology. The 2.4 GHz and 5 GHz frequency bands in the Industrial Scientific Medical (ISM) band can be used in the WLAN environment. Because of the development of wireless communication technology and the use of the frequency bands without the need for authorization, the application of WLAN is becoming more and more extensive. As the key part of the WLAN system, the antenna must also be adapted to the development of WLAN communication technology. This paper designs two new dual-frequency microstrip antennas with the use of electromagnetic simulation software-High Frequency Structure Simulator (HFSS). The two antennas adopt ordinary FR4 material as a dielectric substrate, with the advantages of low cost and small size. The first antenna adopts microstrip line feeding, and the antenna radiation patch is composed of a folded T-shaped radiating dipole which reduces the antenna size, and two symmetrical rectangular patches located on both sides of the T-shaped radiating patch. The second antenna is a microstrip patch antenna fed by coaxial line, and the size of the antenna is diminished by opening a stepped groove on the two edges of the patch and a folded slot inside the patch. Simulation experiments prove that the two designed antennas have a higher gain and a favourable transmission characteristic in the working frequency range, which is in accordance with the requirements of WLAN communication. PMID:27355954

  18. Development of a ridged microstrip microwave interferometer for plasma electron density measurements

    NASA Astrophysics Data System (ADS)

    Hsieh, C. H.; Liang, Y. W.; Jeng, J. Y.; Chiou, J. S.; Leou, K. C.; Lin, C.

    2015-06-01

    Here we report the development of a microwave interferometer based on a ridged microstrip transmission line structure for the monitoring of plasma density in plasma processing tools. A special ridged shaped microstrip structure with a quartz dielectric is adopted for yielding a large phase shift of the microwave, and thus a higher sensitivity of the interferometer. During operation, the plasma density sensor is installed on the chamber wall where the microstrip transmission line is immersed in plasma and a microwave is launched from one end of the line and exits through the other end. As in conventional microwave interferometers, the plasma density is determined by the phase shift of the microwave propagating through the transmission line. 3D electromagnetic numerical simulations, where plasma is treated as a dielectric medium having a plasma permittivity determined by plasma density and microwave frequency, were employed to determine the phase shift/plasma density relation of this sensor. The sensor is designed to operate at 2.4 GHz microwave frequency, with a compact size and materials that are compatible with most plasma processing tools. Measurement results show that plasma density measured by the sensor, although placed at the chamber wall, does reflect the variations of the plasma density near the chamber center. In the real-time plasma etch process, the dependence of plasma densities on source powers and pressures measured by the sensor is also consistent with the results of ion current on the wafer electrode obtained from an impedance meter.

  19. Patterning of visible/infrared dual-band microstrip filter arrays for multispectral imaging application

    NASA Astrophysics Data System (ADS)

    Lai, Jian-Jun; Liang, Hua-Feng; Zhou, Zhi-Ping; Fang, Guo-Jia; Li, Li

    2009-08-01

    Visible/infrared dual-band microstrip filter arrays have been developed to be integrated with 512 × 512 PtSi CCD imaging sensor chips for multispectral imaging when it operates in the front-illumination mode. A high visible transmittance and high infrared reflectance ZAO (ZnO:Al) based coating for visible passband and an interference absorbing filter film for a mid-infrared passband have been designed and deposited on sapphire substrates. An effective double-layer lift-off technique that is compatible with high temperature deposition has been developed to create thick microstrip infrared film. The infrared passband film using germanium and yttrium fluoride as high and low refractive indices materials have been deposited by ion-beam-assisted electron beam evaporation. Tested optical performance results reveal that the visible and near-infrared transmittance of the infrared passband film is very low, which makes it ideal for mid-infrared imaging. Environmental durability testing shows that the microstrip arrays have good mechanical and thermal performances for practical applications.

  20. Tilted Microstrip Phased Arrays With Improved Electromagnetic Decoupling for Ultrahigh-Field Magnetic Resonance Imaging

    PubMed Central

    Pang, Yong; Wu, Bing; Jiang, Xiaohua; Vigneron, Daniel B.; Zhang, Xiaoliang

    2014-01-01

    Abstract One of the technical challenges in designing a dedicated transceiver radio frequency (RF) array for MR imaging in humans at ultrahigh magnetic fields is how to effectively decouple the resonant elements of the array. In this work, we propose a new approach using tilted microstrip array elements for improving the decoupling performance and potentially parallel imaging capability. To investigate and validate the proposed design technique, an 8-channel volume array with tilted straight-type microstrip elements was designed, capable for human imaging at the ultrahigh field of 7 Tesla. In this volume transceiver array, its electromagnetic decoupling behavior among resonant elements, RF field penetration to biological samples, and parallel imaging performance were studied through bench tests and in vivo MR imaging experiments. In this specific tilted element array design, decoupling among array elements changes with the tilted angle of the elements and the best decoupling can be achieved at certain tilted angle. In vivo human knee MR images were acquired using the tilted volume array at 7 Tesla for method validation. Results of this study demonstrated that the electromagnetic decoupling between array elements and the B1 field strength can be improved by using the tilted element method in microstrip RF coil array designs at the ultrahigh field of 7T. PMID:25526481

  1. Tunable microstrip SQUID amplifiers for the Gen 2 Axion Dark Matter eXperiment (ADMX)

    NASA Astrophysics Data System (ADS)

    O'Kelley, Sean; Hilton, Gene; Clarke, John

    We present a series of tunable microstrip SQUID amplifiers (MSAs) for installation in ADMX. The axion dark matter candidate is detected via Primakoff conversion to a microwave photon in a high-Q (~100,000) tunable microwave cavity cooled with a dilution refrigerator in the presence of a 7-tesla magnetic field. The microwave photon frequency ν is a function of the unknown axion mass, so both the cavity and amplifier must be scanned over a wide frequency range. An MSA is a linear, phase-preserving amplifier consisting of a superconducting, resonant microstrip flux-coupled to a resistively-shunted dc SQUID biased into the voltage state. Tunability is achieved by terminating the microstrip with low inductance GaAs varactor diodes that operate below 100 mK. By varying the bias voltage of the varactors we vary their capacitance, allowing a reflected phase varying from nearly 0 to π, thus achieving a tunability close to a factor of 2. We demonstrate several devices operating below 100 mK, matched to the discrete operating bands of ADMX at frequencies ranging from 560 MHz to 1 GHz, that exhibit gains exceeding 20 dB. The associated noise temperatures, measured with a hot/cold load, approach the standard quantum limit (hν/kB) for a linear phase-preserving amplifier.

  2. The 20 GHz circularly polarized, high temperature superconducting microstrip antenna array

    NASA Technical Reports Server (NTRS)

    Morrow, Jarrett D.; Williams, Jeffery T.; Long, Stuart A.; Wolfe, John C.

    1994-01-01

    The primary goal was to design and characterize a four-element, 20 GHz, circularly polarized microstrip patch antenna fabricated from YBa2Cu3O(x) superconductor. The purpose is to support a high temperature superconductivity flight communications experiment between the space shuttle orbiter and the ACTS satellite. This study is intended to provide information into the design, construction, and feasibility of a circularly polarized superconducting 20 GHz downlink or cross-link antenna. We have demonstrated that significant gain improvements can be realized by using superconducting materials for large corporate fed array antennas. In addition, we have shown that when constructed from superconducting materials, the efficiency, and therefore the gain, of microstrip patches increases if the substrate is not so thick that the dominant loss mechanism for the patch is radiation into the surface waves of the conductor-backed substrate. We have considered two design configurations for a superconducting 20 GHz four-element circularly polarized microstrip antenna array. The first is the Huang array that uses properly oriented and phased linearly polarized microstrip patch elements to realize a circularly polarized pattern. The second is a gap-coupled array of circularly polarized elements. In this study we determined that although the Huang array operates well on low dielectric constant substrates, its performance becomes extremely sensitive to mismatches, interelement coupling, and design imperfections for substrates with high dielectric constants. For the gap-coupled microstrip array, we were able to fabricate and test circularly polarized elements and four-element arrays on LaAlO3 using sputtered copper films. These antennas were found to perform well, with relatively good circular polarization. In addition, we realized a four-element YBa2Cu3O(x) array of the same design and measured its pattern and gain relative to a room temperature copper array. The patterns were

  3. Measurement of loss in superconducting microstrip at millimeter-wave frequencies

    NASA Astrophysics Data System (ADS)

    Gao, Jiansong; Vayonakis, Anastasios; Noroozian, Omid; Zmuidzinas, Jonas; Day, Peter K.; Leduc, Henry G.

    2009-12-01

    We have developed a new technique for accurate measurement of the loss of superconducting microstrips at mm-wave frequencies. In this technique, we optically couple power to slot antenna, which is connected to one port of a hybrid coupler. One of the output ports of the hybrid delivers power to a series of mm-wave microstrip resonators which are capacitively coupled to a feedline followed by an MKID (microwave kinetic inductance detector) that measures the transmitted power. Two other MKIDs are connected to the remaining ports of the hybrid to measure the total incident optical power and the power reflected from the mm-wave resonators, allowing |S21|2 and |S11|2 to be accurately determined and resonance frequency fr and quality factor Q to be retrieved. We have fabricated such a Nb/SiO2/Nb microstrip loss test device which contains several mm- wave resonators with fr˜100 GHz and measured it at 30 mK. All the resonators have shown internal quality factor Qi˜500-2000, suggesting a loss tangent of ˜5×10-4-2×10-3 for the SiO2 in use. For comparison, we have also fabricated a 5 GHz microstrip resonator on the same chip and measured it with a network analyzer. The loss tangent at 5 GHz derived from fitting the f0 and Q data to the two-level system (TLS) model is 6×10-4, about the same as from the mm-wave measurement. This suggests that the loss at both microwave and mm-wave frequencies is probably dominated by the TLS in SiO2. Our results are of direct interest to mm/submm direct detection applications which use microstrip transmission lines (such as antenna-coupled MKIDs and transition-edge sensors), and other applications (such as on-chip filters). Our measurement technique is applicable up to approximately 1 THz and can be used to investigate a range of dielectrics.

  4. Pancreas and cyst segmentation

    NASA Astrophysics Data System (ADS)

    Dmitriev, Konstantin; Gutenko, Ievgeniia; Nadeem, Saad; Kaufman, Arie

    2016-03-01

    Accurate segmentation of abdominal organs from medical images is an essential part of surgical planning and computer-aided disease diagnosis. Many existing algorithms are specialized for the segmentation of healthy organs. Cystic pancreas segmentation is especially challenging due to its low contrast boundaries, variability in shape, location and the stage of the pancreatic cancer. We present a semi-automatic segmentation algorithm for pancreata with cysts. In contrast to existing automatic segmentation approaches for healthy pancreas segmentation which are amenable to atlas/statistical shape approaches, a pancreas with cysts can have even higher variability with respect to the shape of the pancreas due to the size and shape of the cyst(s). Hence, fine results are better attained with semi-automatic steerable approaches. We use a novel combination of random walker and region growing approaches to delineate the boundaries of the pancreas and cysts with respective best Dice coefficients of 85.1% and 86.7%, and respective best volumetric overlap errors of 26.0% and 23.5%. Results show that the proposed algorithm for pancreas and pancreatic cyst segmentation is accurate and stable.

  5. Chain and Segmental Dynamics of Poly(2-vinlylpyridine)

    SciTech Connect

    Holt, Adam P; Sangoro, Joshua R; Wang, Yangyang; Agapov, Alexander L; Sokolov, Alexei P

    2013-01-01

    The influence of different oxide nanoparticles on segmental and chain dynamics of poly(2-vinylpyridine) is investigated by broadband dielectric spectroscopy (BDS), dynamic mechanical measurements, and calorimetry. While significant changes in rheological properties are observed with increasing nanoparticle loading, only weak effects are found in the glass transition temperature, the segmental mobility, and fragility. These results are discussed in the context of recent controversies in studies of polymer nanocomposites and polymer thin films.

  6. Aperture-Coupled Thin-Membrane L-Band Antenna

    NASA Technical Reports Server (NTRS)

    Huang, John

    2007-01-01

    The upper part of the figure depicts an aperture-coupled L-band antenna comprising patterned metal conductor films supported on two thin polyimide membranes separated by an air gap. In this antenna, power is coupled from a microstrip line on the lower surface of the lower membrane, through a slot in a metal ground plane on the upper surface of the lower membrane, to a radiating metal patch on the upper surface of the upper membrane. The two-membrane configuration of this antenna stands in contrast to a three-membrane configuration heretofore considered as the basis for developing arrays of dual-polarization, wideband microwave antennas that could be thin and could be, variously, incorporated into, or supported on, thin structures, including inflatable structures. By reducing the number of membranes from three to two, the present design simplifies the problems of designing and fabricating such antennas or arrays of such antennas, including the problems of integrating such antennas or arrays with thin-membrane-mounted transmit/ receive modules. In addition, the use of aperture (slot) coupling eliminates the need for rigid coaxial feed pins and associated solder connections on thin membranes, making this antenna more mechanically reliable, relative to antennas that include coaxial feed pins. This antenna is designed for a nominal frequency of 1.26 GHz. The polyimide membranes are 0.05 mm thick and have a relative permittivity of 3.4. The radiating patch is square, 8.89 cm on each side. This radiating patch lies 1.27 cm above the ground plane. The feeding microstrip line is 0.12 mm wide and has a characteristic impedance of 50 . The aperture-coupling slot, etched in the ground plane, is 0.48 mm wide and 79.5 mm long. In order to maximize coupling, the microstrip line is extended beyond the middle of the slot by a length of 36 mm, which corresponds to a transmission- line electrical length of about a quarter wavelength. The other end of the microstrip line is

  7. Segmented ion thruster

    NASA Technical Reports Server (NTRS)

    Brophy, John R. (Inventor)

    1993-01-01

    Apparatus and methods for large-area, high-power ion engines comprise dividing a single engine into a combination of smaller discharge chambers (or segments) configured to operate as a single large-area engine. This segmented ion thruster (SIT) approach enables the development of 100-kW class argon ion engines for operation at a specific impulse of 10,000 s. A combination of six 30-cm diameter ion chambers operating as a single engine can process over 100 kW. Such a segmented ion engine can be operated from a single power processor unit.

  8. Design and analysis of an electronically steerable microstrip patch and a novel Coplanar Waveguide (CPW) fed slot antenna array

    NASA Astrophysics Data System (ADS)

    Aldossary, Hamad

    Conformal Phased Array Antennas (CPAAs) are very attractive for their high gain, low profile, and beam scanning ability while being conformal to their mounting surface. Among them are microstrip patch phased arrays and wideband slot phased arrays which are of particular significance. In this work, first the study, design, and implementation of a conformal microstrip patch phased array is presented which consists of a high gain beam scanning array implemented using microstrip delay lines controlled using GaAs SPDT switches. Then the study and design of a wideband Coplanar Waveguide (CPW)-fed slot phased array antenna is presented. In both cases the array beam scanning properties are elucidated by incorporating the measured delay line scattering parameters inside Ansys Designer simulation models and then computing and presenting their full-wave radiation characteristics.

  9. Experimental Verification of the Use of Metal Filled Via Hole Fences for Crosstalk Control of Microstrip Lines in LTCC Packages

    NASA Technical Reports Server (NTRS)

    Ponchak, George E.; Chun, Donghoon; Yook, Jong-Gwan; Katehi, Linda P. B.

    2001-01-01

    Coupling between microstrip lines in dense RF packages is a common problem that degrades circuit performance. Prior three-dimensional-finite element method (3-D-FEM) electromagnetic simulations have shown that metal filled via hole fences between two adjacent microstrip lines actually Increases coupling between the lines: however, if the top of the via posts are connected by a metal strip, coupling is reduced. In this paper, experimental verification of the 3-D-FEM simulations is demonstrated for commercially fabricated low temperature cofired ceramic (LTCC) packages. In addition, measured attenuation of microstrip lines surrounded by the shielding structures is presented and shows that shielding structures do not change the attenuation characteristics of the line.

  10. A microstrip silicon telescope for high performance particle tracking

    NASA Astrophysics Data System (ADS)

    Lietti, D.; Berra, A.; Prest, M.; Vallazza, E.

    2013-11-01

    Bent crystals are thin silicon/germanium devices that act as a bulk dipole magnet and thus are able to deflect relativistic charged particle beams with high efficiency (up to 98%). To study their behavior on extracted beamlines in terms of deflection capability and efficiency, a fast and high position resolution telescope is needed such as the INSULAB telescope. It consists in several modules equipped with double or single side silicon detectors readout by different ASICs. The Data Acquisition system is designed to work with pulsed beams minimizing the dead time to allow the collection of a large statistics in a short time. It is based on custom VME readout/memory boards for the data storage and 12 bit ADC custom boards for the signal digitization; the present maximum DAQ rate is 6 kHz. A detailed description of the detectors, the ASICs and the readout system together with the results obtained at the SPS H4 and PS T9 CERN beamlines in terms of spatial resolution and charge sharing are presented.

  11. Image segmentation survey

    NASA Technical Reports Server (NTRS)

    Haralick, R. M.

    1982-01-01

    The methodologies and capabilities of image segmentation techniques are reviewed. Single linkage schemes, hybrid linkage schemes, centroid linkage schemes, histogram mode seeking, spatial clustering, and split and merge schemes are addressed.

  12. Segmentation of SAR images

    NASA Technical Reports Server (NTRS)

    Kwok, Ronald

    1989-01-01

    The statistical characteristics of image speckle are reviewed. Existing segmentation techniques that have been used for speckle filtering, edge detection, and texture extraction are sumamrized. The relative effectiveness of each technique is briefly discussed.

  13. Adjacent segment disease.

    PubMed

    Virk, Sohrab S; Niedermeier, Steven; Yu, Elizabeth; Khan, Safdar N

    2014-08-01

    EDUCATIONAL OBJECTIVES As a result of reading this article, physicians should be able to: 1. Understand the forces that predispose adjacent cervical segments to degeneration. 2. Understand the challenges of radiographic evaluation in the diagnosis of cervical and lumbar adjacent segment disease. 3. Describe the changes in biomechanical forces applied to adjacent segments of lumbar vertebrae with fusion. 4. Know the risk factors for adjacent segment disease in spinal fusion. Adjacent segment disease (ASD) is a broad term encompassing many complications of spinal fusion, including listhesis, instability, herniated nucleus pulposus, stenosis, hypertrophic facet arthritis, scoliosis, and vertebral compression fracture. The area of the cervical spine where most fusions occur (C3-C7) is adjacent to a highly mobile upper cervical region, and this contributes to the biomechanical stress put on the adjacent cervical segments postfusion. Studies have shown that after fusion surgery, there is increased load on adjacent segments. Definitive treatment of ASD is a topic of continuing research, but in general, treatment choices are dictated by patient age and degree of debilitation. Investigators have also studied the risk factors associated with spinal fusion that may predispose certain patients to ASD postfusion, and these data are invaluable for properly counseling patients considering spinal fusion surgery. Biomechanical studies have confirmed the added stress on adjacent segments in the cervical and lumbar spine. The diagnosis of cervical ASD is complicated given the imprecise correlation of radiographic and clinical findings. Although radiological and clinical diagnoses do not always correlate, radiographs and clinical examination dictate how a patient with prolonged pain is treated. Options for both cervical and lumbar spine ASD include fusion and/or decompression. Current studies are encouraging regarding the adoption of arthroplasty in spinal surgery, but more long

  14. Segmented pyroelector detector

    DOEpatents

    Stotlar, S.C.; McLellan, E.J.

    1981-01-21

    A pyroelectric detector is described which has increased voltage output and improved responsivity over equivalent size detectors. The device comprises a plurality of edge-type pyroelectric detectors which have a length which is much greater than the width of the segments between the edge-type electrodes. External circuitry connects the pyroelectric detector segments in parallel to provide a single output which maintains 50 ohm impedance characteristics.

  15. Squaring a Circular Segment

    ERIC Educational Resources Information Center

    Gordon, Russell

    2008-01-01

    Consider a circular segment (the smaller portion of a circle cut off by one of its chords) with chord length c and height h (the greatest distance from a point on the arc of the circle to the chord). Is there a simple formula involving c and h that can be used to closely approximate the area of this circular segment? Ancient Chinese and Egyptian…

  16. Segmental neurofibromatosis and malignancy.

    PubMed

    Dang, Julie D; Cohen, Philip R

    2010-01-01

    Segmental neurofibromatosis is an uncommon variant of neurofibromatosis type I characterized by neurofibromas and/or café-au-lait macules localized to one sector of the body. Although patients with neurofibromatosis type I have an associated increased risk of certain malignancies, malignancy has only occasionally been reported in patients with segmental neurofibromatosis. The published reports of patients with segmental neurofibromatosis who developed malignancy were reviewed and the characteristics of these patients and their cancers were summarized. Ten individuals (6 women and 4 men) with segmental neurofibromatosis and malignancy have been reported. The malignancies include malignant peripheral nerve sheath tumor (3), malignant melanoma (2), breast cancer (1), colon cancer (1), gastric cancer (1), lung cancer (1), and Hodgkin lymphoma (1). The most common malignancies in patients with segmental neurofibromatosis are derived from neural crest cells: malignant peripheral nerve sheath tumor and malignant melanoma. The incidence of malignancy in patients with segmental neurofibromatosis may approach that of patients with neurofibromatosis type I. PMID:21137621

  17. Size Optimization for Mirror Segments for X-Ray Optics

    NASA Technical Reports Server (NTRS)

    Biskach, Michael P.; McClelland, Ryan S.; Saha, Timo; Zhang, William W.

    2011-01-01

    The flight mirror assemblies (FMA) for X-ray telescopes similar to that of the International X-ray Observatory (IXO) concept consist of several thousands of individual mirror segments. The size, shape, and location of these mirrors affect many characteristics of the telescope design. Mission requirements among other factors in turn restrict mirror segment parameters such as thickness, axial- length, azimuthal span, and mass density. This paper provides an overview of the critical relationships relating to mirror segment size and configuration throughout the design and analysis of an X-ray mirror assembly. A computational analysis is presented in the form of ray tracing pairs of thin X-ray mirror segments of varying sizes aligned in gravity and supported using kinematic constraints with corresponding self weight distortions calculated using finite element analysis (FEA). The work in this paper may be used as a starting point for determining mirror segment sizes for X-ray missions like that of IXO and beyond.

  18. Compact ultra wide band microstrip bandpass filter based on multiple-mode resonator and modified complementary split ring resonator.

    PubMed

    Marcotegui, J Antonio; Illescas, Jesús Miguel; Estevez, Aritz; Falcone, Francisco

    2013-01-01

    A new class of broadband microstrip filters for Ultra Wide Band (UWB) applications is proposed. In the design, different stages of parallel-coupled microstrip line and other stages with a Modified Complementary Split Ring Resonator (MCSRR)-a concept proposed here for the first time-are adjusted to obtain the desired response with broadband, sharp rejection, low insertion loss, and low return loss. Full wave simulation results as well as measurement results from fabricated prototypes are presented, showing good agreement. The proposed technique offers a new alternative to implement low-cost high-performance filter devices, applicable to a wide range of communication systems. PMID:24319366

  19. Compact Ultra Wide Band Microstrip Bandpass Filter Based on Multiple-Mode Resonator and Modified Complementary Split Ring Resonator

    PubMed Central

    Marcotegui, J. Antonio; Illescas, Jesús Miguel; Estevez, Aritz

    2013-01-01

    A new class of broadband microstrip filters for Ultra Wide Band (UWB) applications is proposed. In the design, different stages of parallel-coupled microstrip line and other stages with a Modified Complementary Split Ring Resonator (MCSRR)—a concept proposed here for the first time—are adjusted to obtain the desired response with broadband, sharp rejection, low insertion loss, and low return loss. Full wave simulation results as well as measurement results from fabricated prototypes are presented, showing good agreement. The proposed technique offers a new alternative to implement low-cost high-performance filter devices, applicable to a wide range of communication systems. PMID:24319366

  20. Analysis of microstrip lines with alternative implementation of conductors and superconductors

    NASA Technical Reports Server (NTRS)

    Kong, K.-S.; Lee, H.-Y.; Itoh, T.; Chorey, C. M.; Bhasin, K. B.

    1990-01-01

    An analysis of microstrip line structures in which either the strip or the ground plane or both are made of a high Tc superconductor is presented. The effect of implementation of a superconductor to the strip and the ground plane is explained with the calculation of a conductor loss of the structure by the Phenomenological Loss Equivalence Method (PEM). The theoretical values are compared with the experimental results from a ring resonator which is made of a gold ground plane and a high Tc superconductor, YBa2Cu3O(7-x), strip.

  1. Influence of dielectric substrate on the responsivity of microstrip dipole-antenna-coupled infrared microbolometers

    NASA Astrophysics Data System (ADS)

    Codreanu, Iulian; Boreman, Glenn D.

    2002-04-01

    We report on the influence of the dielectric substrate on the performance of microstrip dipole-antenna-coupled microbolometers. The location, the width, and the magnitude of the resonance of a printed dipole are altered when the dielectric substrate is backed by a ground plane. A thicker dielectric substrate shifts the antenna resonance toward shorter dipole lengths and leads to a stronger and slower detector response. The incorporation of an air layer into the antenna substrate further increases thermal impedance, leading to an even stronger response and shifting the antenna resonance toward longer dipole lengths.

  2. Development of a silicon micro-strip detector for tracking high intensity secondary beams

    NASA Astrophysics Data System (ADS)

    Kiuchi, R.; Asano, H.; Hasegawa, S.; Honda, R.; Ichikawa, Y.; Imai, K.; Joo, C. W.; Nakazawa, K.; Sako, H.; Sato, S.; Shirotori, K.; Sugimura, H.; Tanida, K.; Watabe, T.

    2014-11-01

    A single-sided silicon micro-strip detector (SSD) has been developed as a tracking detector for hadron experiments at J-PARC where secondary meson beams with intensities of up to 108 Hz are available. The performance of the detector has been investigated and verified in a series of test beam experiments in the years 2009-2011. The hole mobility was deduced from the analysis of cluster events. The beam rate dependence was measured in terms of timing resolution, signal-to-noise ratio, and hit efficiency. This paper describes the detector with its read-out system, details of the test experiments, and discusses the performance achieved.

  3. An Inline Microstrip-to-Waveguide Transition Operating in the Full W-Band

    NASA Astrophysics Data System (ADS)

    Rebollo, Ainara; Gonzalo, Ramón; Ederra, Iñigo

    2015-08-01

    An inline microstrip-to-waveguide transition covering the full W-Band is presented in this article. The verification of the simulation results has been carried out by means of a back-to-back transition measurement. Experimental results show good return losses above 15 dB in the entire W-Band and also low insertion losses. Specifically, the measured insertion losses are 0.71 dB at the central frequency of W-Band, i.e., 92.5 GHz, and below 1.1 dB in the full W-band.

  4. (abstract) A Ka-Band 0.5 m Circularily Polarized Microstrip Reflectarray

    NASA Technical Reports Server (NTRS)

    Huang, John

    1997-01-01

    The microstrip reflectarray antenna, being in the form of a flat reflector, has recently been investigated by several antenna researchers. This antenna, when compared to the conventional parabolic reflector, not only has the potential advantages of achieving smaller mass, smaller volume, simpler deployment mechanism, but also has the capability of scanning its main beam to larger angles from the broadside direction. Without any power divider and its associated large insertion loss, a phased reflectarray may not need the high cost T/R modules and can still remain to be an efficient array antenna.

  5. A fast position sensitive microstrip-gas-chamber detector at high count rate operation

    NASA Astrophysics Data System (ADS)

    Dolbnya, I. P.; Alberda, H.; Hartjes, F. G.; Udo, F.; Bakker, R. E.; Konijnenburg, M.; Homan, E.; Cerjak, I.; Goedtkindt, P.; Bras, W.

    2002-11-01

    Testing of a newly developed position sensitive high count rate microstrip gas chamber (MSGC) detector at high count rate operation has been carried out at the Dutch-Belgian x-ray scattering beamline at the European Synchrotron Radiation Facility (Grenoble, France) with a high intensity x-ray beam. The measurements show local count rate capabilities up to approx4.5 x105 counts/s/channel. Experimental data taken with this detector are also shown. These tests show that both time resolution down to 1.5 ms/frame and a reliable operation at high counting rates can be achieved.

  6. Influence of dielectric substrate on the responsivity of microstrip dipole-antenna-coupled infrared microbolometers.

    PubMed

    Codreanu, Iulian; Boreman, Glenn D

    2002-04-01

    We report on the influence of the dielectric substrate on the performance of microstrip dipole-antenna-coupled microbolometers. The location, the width, and the magnitude of the resonance of a printed dipole are altered when the dielectric substrate is backed by a ground plane. A thicker dielectric substrate shifts the antenna resonance toward shorter dipole lengths and leads to a stronger and slower detector response. The incorporation of an air layer into the antenna substrate further increases thermal impedance, leading to an even stronger response and shifting the antenna resonance toward longer dipole lengths. PMID:11936778

  7. Compact, Lightweight Dual- Frequency Microstrip Antenna Feed for Future Soil Moisture and Sea Surface Salinity Missions

    NASA Technical Reports Server (NTRS)

    Yueh, Simon H.; Wilson, William J.; Njoku, Eni; Hunter, Don; Dinardo, Steve; Kona, Keerti S.; Manteghi, Majid; Gies, Dennis; Rahmat-Samii, Yahya

    2004-01-01

    The development of a compact, lightweight, dual frequency antenna feed for future soil moisture and sea surface salinity (SSS) missions is described. The design is based on the microstrip stacked-patch array (MSPA) to be used to feed a large lightweight deployable rotating mesh antenna for spaceborne L-band (approx. 1 GHz) passive and active sensing systems. The design features will also enable applications to airborne sensors operating on small aircrafts. This paper describes the design of stacked patch elements, 16-element array configuration and power-divider beam forming network The test results from the fabrication of stacked patches and power divider were also described.

  8. Influence of solar heating on the performance of integrated solar cell microstrip patch antennas

    SciTech Connect

    Roo-Ons, M.J.; Shynu, S.V.; Ammann, M.J.; Seredynski, M.; McCormack, S.J.; Norton, B.

    2010-09-15

    The integration of microstrip patch antennas with photovoltaics has been proposed for applications in autonomous wireless communication systems located on building facades. Full integration was achieved using polycrystalline silicon solar cells as both antenna ground plane and direct current power generation in the same device. An overview of the proposed photovoltaic antenna designs is provided and the variation characterised of the electromagnetic properties of the device with temperature and solar radiation. Measurements for both copper and solar antennas are reported on three different commercial laminates with contrasting values for thermal coefficient of the dielectric constant. (author)

  9. Operation and performance of the ATLAS silicon micro-strip tracker

    SciTech Connect

    Pylypchenko, Y.

    2011-07-01

    The Semiconductor Tracker (SCT) is the key precision tracking device in ATLAS, made from silicon micro-strip detectors processed in the planar p-in-n technology. The completed SCT has been installed inside the ATLAS experimental hall since 2007 and has been operational since then. In this paper the current status of the Semiconductor Tracker is reviewed, including results from the data-taking periods in 2009 and 2010, and from the detector alignment. The emphasis is given to the performance of the Semiconductor Tracker with the LHC in collision mode and to the performance of individual electronic components. (authors)

  10. A design concept for an MMIC (Monolithic Microwave Integrated Circuit) microstrip phased array

    NASA Technical Reports Server (NTRS)

    Lee, Richard Q.; Smetana, Jerry; Acosta, Roberto

    1987-01-01

    A conceptual design for a microstrip phased array with monolithic microwave integrated circuit (MMIC) amplitude and phase controls is described. The MMIC devices used are 20 GHz variable power amplifiers and variable phase shifters recently developed by NASA contractors for applications in future Ka proposed design, which concept is for a general NxN element array of rectangular lattice geometry. Subarray excitation is incorporated in the MMIC phased array design to reduce the complexity of the beam forming network and the number of MMIC components required.

  11. Microstrip Hairpin Bandpass Filter Using Modified Minkowski Fractal-Shape for Suppression of Second Harmonic

    NASA Astrophysics Data System (ADS)

    Lalbakhsh, Ali; Lotfi Neyestanak, Abbas Ali; Naser-Moghaddasi, Mohammad

    In this paper, a novel microstrip hairpin-line bandpass filter which employs a modified Minkowski fractal shape is proposed. Although conventional hairpin-line filters are popular for RF front ends, they suffer from undesired spurious responses located at the second harmonic, which causes asymmetry in the upper skirt band. By proper design, the second harmonic of fractal filters can be significantly suppressed through the use of fractal shape. To validate this novel geometry, the proposed filters are fabricated and measured. Simulated results are in good agreement with measured results.

  12. Electrical production testing of the D0 Silicon microstrip tracker detector modules

    SciTech Connect

    D0, SMT Production Testing Group; /Fermilab

    2006-03-01

    The D0 Silicon Microstrip Tracker (SMT) is the innermost system of the D0 detector in Run 2. It consists of 912 detector units, corresponding to 5 different types of assemblies, which add up to a system with 792,576 readout channels. The task entrusted to the Production Testing group was to thoroughly debug, test and grade each detector module before its installation in the tracker. This note describes the production testing sequence and the procedures by which the detector modules were electrically tested and characterized at the various stages of their assembly.

  13. Rediscovering market segmentation.

    PubMed

    Yankelovich, Daniel; Meer, David

    2006-02-01

    In 1964, Daniel Yankelovich introduced in the pages of HBR the concept of nondemographic segmentation, by which he meant the classification of consumers according to criteria other than age, residence, income, and such. The predictive power of marketing studies based on demographics was no longer strong enough to serve as a basis for marketing strategy, he argued. Buying patterns had become far better guides to consumers' future purchases. In addition, properly constructed nondemographic segmentations could help companies determine which products to develop, which distribution channels to sell them in, how much to charge for them, and how to advertise them. But more than 40 years later, nondemographic segmentation has become just as unenlightening as demographic segmentation had been. Today, the technique is used almost exclusively to fulfill the needs of advertising, which it serves mainly by populating commercials with characters that viewers can identify with. It is true that psychographic types like "High-Tech Harry" and "Joe Six-Pack" may capture some truth about real people's lifestyles, attitudes, self-image, and aspirations. But they are no better than demographics at predicting purchase behavior. Thus they give corporate decision makers very little idea of how to keep customers or capture new ones. Now, Daniel Yankelovich returns to these pages, with consultant David Meer, to argue the case for a broad view of nondemographic segmentation. They describe the elements of a smart segmentation strategy, explaining how segmentations meant to strengthen brand identity differ from those capable of telling a company which markets it should enter and what goods to make. And they introduce their "gravity of decision spectrum", a tool that focuses on the form of consumer behavior that should be of the greatest interest to marketers--the importance that consumers place on a product or product category. PMID:16485810

  14. Fault rupture segmentation

    NASA Astrophysics Data System (ADS)

    Cleveland, Kenneth Michael

    A critical foundation to earthquake study and hazard assessment is the understanding of controls on fault rupture, including segmentation. Key challenges to understanding fault rupture segmentation include, but are not limited to: What determines if a fault segment will rupture in a single great event or multiple moderate events? How is slip along a fault partitioned between seismic and seismic components? How does the seismicity of a fault segment evolve over time? How representative are past events for assessing future seismic hazards? In order to address the difficult questions regarding fault rupture segmentation, new methods must be developed that utilize the information available. Much of the research presented in this study focuses on the development of new methods for attacking the challenges of understanding fault rupture segmentation. Not only do these methods exploit a broader band of information within the waveform than has traditionally been used, but they also lend themselves to the inclusion of even more seismic phases providing deeper understandings. Additionally, these methods are designed to be fast and efficient with large datasets, allowing them to utilize the enormous volume of data available. Key findings from this body of work include demonstration that focus on fundamental earthquake properties on regional scales can provide general understanding of fault rupture segmentation. We present a more modern, waveform-based method that locates events using cross-correlation of the Rayleigh waves. Additionally, cross-correlation values can also be used to calculate precise earthquake magnitudes. Finally, insight regarding earthquake rupture directivity can be easily and quickly exploited using cross-correlation of surface waves.

  15. Segment-to-segment contact elements for modelling joint interfaces in finite element analysis

    NASA Astrophysics Data System (ADS)

    Mayer, M. H.; Gaul, L.

    2007-02-01

    This paper presents an efficient approach to model contact interfaces of joints in finite element analysis (FEA) with segment-to-segment contact elements like thin layer or zero thickness elements. These elements originate from geomechanics and have been applied recently in modal analysis as an efficient way to define the contact stiffness of fixed joints for model updating. A big advantage of these elements is that no global contact search algorithm is employed as used in master-slave contacts. Contact search algorithms are not necessary for modelling contact interfaces of fixed joints since the interfaces are always in contact and restricted to small relative movements, which saves much computing time. We first give an introduction into the theory of segment-to-segment contact elements leading to zero thickness and thin layer elements. As a new application of zero thickness elements, we demonstrate the implementation of a structural contact damping model, derived from a Masing model, as non-linear constitutive laws for the contact element. This damping model takes into account the non-linear influence of frictional microslip in the contact interface of fixed joints. With this model we simulate the non-linear response of a bolted structure. This approach constitutes a new way to simulate multi-degree-of-freedom systems with structural joints and predict modal damping properties.

  16. A compact, higher order, high temperature superconductor microstrip bandpass filter on a two-inch lanthanum aluminate substrate for personal communication service applications

    NASA Astrophysics Data System (ADS)

    Pal, Srikanta; Stevens, Chris; Edwards, David

    2005-10-01

    A practical design methodology for a compact parallel-coupled microstrip bandpass filter structure with steep attenuation is introduced using a computer-aided full wave electromagnetic simulation based on the method of moments. The structure consists of an array of fully aligned half-wavelength spiral meander line resonators. Aimed at application in the front-end receiver of digital cellular communication service, a 12-pole high temperature superconductor filter with 2.27% fractional bandwidth at 883.0 MHz was designed. The filter is fabricated using thallium-barium-calcium-copper oxide (TBCCO) thin films on a two-inch lanthanum aluminate (LaAlO3) wafer. The S-parameter measurements show a good agreement with the simulated results. At 70 K, the 12-pole filter shows less than 0.4 dB insertion loss, 0.3 dB passband ripple, better than 12 dB return loss. The out of band rejection at 3 MHz below the passband edges is more than 60.0 dB. In order to estimate the power handling capability of the filter, the third-order intermodulation distortion was measured. A sensitivity analysis for the observed frequency shift in the filter is reported. Also from this analysis an approach for using the same design in 0.5% FBW applications is discussed.

  17. Bootstrapping structured page segmentation

    NASA Astrophysics Data System (ADS)

    Ma, Huanfeng; Doermann, David S.

    2003-01-01

    In this paper, we present an approach to the bootstrap learning of a page segmentation model. The idea evolves from attempts to segment dictionaries that often have a consistent page structure, and is extended to the segmentation of more general structured documents. In cases of highly regular structure, the layout can be learned from examples of only a few pages. The system is first trained using a small number of samples, and a larger test set is processed based on the training result. After making corrections to a selected subset of the test set, these corrected samples are combined with the original training samples to generate bootstrap samples. The newly created samples are used to retrain the system, refine the learned features and resegment the test samples. This procedure is applied iteratively until the learned parameters are stable. Using this approach, we do not need to initially provide a large set of training samples. We have applied this segmentation to many structured documents such as dictionaries, phone books, spoken language transcripts, and obtained satisfying segmentation performance.

  18. Scorpion image segmentation system

    NASA Astrophysics Data System (ADS)

    Joseph, E.; Aibinu, A. M.; Sadiq, B. A.; Bello Salau, H.; Salami, M. J. E.

    2013-12-01

    Death as a result of scorpion sting has been a major public health problem in developing countries. Despite the high rate of death as a result of scorpion sting, little report exists in literature of intelligent device and system for automatic detection of scorpion. This paper proposed a digital image processing approach based on the floresencing characteristics of Scorpion under Ultra-violet (UV) light for automatic detection and identification of scorpion. The acquired UV-based images undergo pre-processing to equalize uneven illumination and colour space channel separation. The extracted channels are then segmented into two non-overlapping classes. It has been observed that simple thresholding of the green channel of the acquired RGB UV-based image is sufficient for segmenting Scorpion from other background components in the acquired image. Two approaches to image segmentation have also been proposed in this work, namely, the simple average segmentation technique and K-means image segmentation. The proposed algorithm has been tested on over 40 UV scorpion images obtained from different part of the world and results obtained show an average accuracy of 97.7% in correctly classifying the pixel into two non-overlapping clusters. The proposed 1system will eliminate the problem associated with some of the existing manual approaches presently in use for scorpion detection.

  19. Cooperative processes in image segmentation

    NASA Technical Reports Server (NTRS)

    Davis, L. S.

    1982-01-01

    Research into the role of cooperative, or relaxation, processes in image segmentation is surveyed. Cooperative processes can be employed at several levels of the segmentation process as a preprocessing enhancement step, during supervised or unsupervised pixel classification and, finally, for the interpretation of image segments based on segment properties and relations.

  20. Lightweight, Segmented, Mostly Silicon Telescope Mirror

    NASA Technical Reports Server (NTRS)

    Yang, Eui-Hyeok

    2006-01-01

    A document presents the concept of a curved telescope primary reflector structure, made mostly of silicon, that would have an areal mass density 1 kg/m2 and would be deployed in outer space, where it would be operated at a temperature in the cryogenic range. The concept provides for adjustment of the shape of the mirror to maintain the required precise optical surface figure despite the flexibility inherent in the ultra-lightweight design. The structure would include a thin mirror layer divided into hexagonal segments supported by flexure hinges on a lightweight two-layer backing structure. Each segment would also be supported at three points by sets of piezoelectric linear microactuators that could impose small displacements along the optical axis. The excitations applied to the aforementioned microactuators would be chosen to effect fine adjustments of the axial positions and the orientations of the segments relative to the supporting structure. Other piezoelectric linear microactuators embedded in the backing structure would enable control of the displacements of the segments along the hexagonal axes; they would also enable control of the curvature of the backing structure and, thus, additional control of the curvature of the reflector.

  1. Phasing a segmented telescope

    NASA Astrophysics Data System (ADS)

    Paykin, Irina; Yacobi, Lee; Adler, Joan; Ribak, Erez N.

    2015-02-01

    A crucial part of segmented or multiple-aperture systems is control of the optical path difference between the segments or subapertures. In order to achieve optimal performance we have to phase subapertures to within a fraction of the wavelength, and this requires high accuracy of positioning for each subaperture. We present simulations and hardware realization of a simulated annealing algorithm in an active optical system with sparse segments. In order to align the optical system we applied the optimization algorithm to the image itself. The main advantage of this method over traditional correction methods is that wave-front-sensing hardware and software are no longer required, making the optical and mechanical system much simpler. The results of simulations and laboratory experiments demonstrate the ability of this optimization algorithm to correct both piston and tip-tilt errors.

  2. Segmented annular combustor

    DOEpatents

    Reider, Samuel B.

    1979-01-01

    An industrial gas turbine engine includes an inclined annular combustor made up of a plurality of support segments each including inner and outer walls of trapezoidally configured planar configuration extents and including side flanges thereon interconnected by means of air cooled connector bolt assemblies to form a continuous annular combustion chamber therebetween and wherein an air fuel mixing chamber is formed at one end of the support segments including means for directing and mixing fuel within a plenum and a perforated header plate for directing streams of air and fuel mixture into the combustion chamber; each of the outer and inner walls of each of the support segments having a ribbed lattice with tracks slidably supporting porous laminated replaceable panels and including pores therein for distributing combustion air into the combustion chamber while cooling the inner surface of each of the panels by transpiration cooling thereof.

  3. Phasing a segmented telescope.

    PubMed

    Paykin, Irina; Yacobi, Lee; Adler, Joan; Ribak, Erez N

    2015-02-01

    A crucial part of segmented or multiple-aperture systems is control of the optical path difference between the segments or subapertures. In order to achieve optimal performance we have to phase subapertures to within a fraction of the wavelength, and this requires high accuracy of positioning for each subaperture. We present simulations and hardware realization of a simulated annealing algorithm in an active optical system with sparse segments. In order to align the optical system we applied the optimization algorithm to the image itself. The main advantage of this method over traditional correction methods is that wave-front-sensing hardware and software are no longer required, making the optical and mechanical system much simpler. The results of simulations and laboratory experiments demonstrate the ability of this optimization algorithm to correct both piston and tip-tilt errors. PMID:25768631

  4. Head segmentation in vertebrates

    PubMed Central

    Kuratani, Shigeru; Schilling, Thomas

    2008-01-01

    Classic theories of vertebrate head segmentation clearly exemplify the idealistic nature of comparative embryology prior to the 20th century. Comparative embryology aimed at recognizing the basic, primary structure that is shared by all vertebrates, either as an archetype or an ancestral developmental pattern. Modern evolutionary developmental (Evo-Devo) studies are also based on comparison, and therefore have a tendency to reduce complex embryonic anatomy into overly simplified patterns. Here again, a basic segmental plan for the head has been sought among chordates. We convened a symposium that brought together leading researchers dealing with this problem, in a number of different evolutionary and developmental contexts. Here we give an overview of the outcome and the status of the field in this modern era of Evo-Devo. We emphasize the fact that the head segmentation problem is not fully resolved, and we discuss new directions in the search for hints for a way out of this maze. PMID:20607135

  5. Generation of microstripe cylindrical and toroidal mirrors by localized laser evaporation of fused silica.

    PubMed

    Wlodarczyk, Krystian L; Thomson, Ian J; Baker, Howard J; Hall, Denis R

    2012-09-10

    We report a new technique for the rapid fabrication of microstripe cylindrical and toroidal mirrors with a high ratio (>10) of the two principal radii of curvature (RoC(1)/RoC(2)), and demonstrate their effectiveness as mode-selecting resonator mirrors for high-power planar waveguide lasers. In this process, the larger radius of curvature (RoC(1)) is determined by the planar or cylindrical shape of the fused silica substrate selected for laser processing, whilst the other (RoC(2)) is produced by controlled CO(2) laser-induced vaporization of the glass. The narrow stripe mirror aperture is achieved by applying a set of partially overlapped laser scans, with the incident laser power, the number of laser scans, and their spacing being used to control the curvature produced by laser evaporation. In this work, a 1 mm diameter laser spot is used to produce grooves of cylindrical/toroidal shape with 240 μm width and 16 mm length. After high reflectance coating, these grooves are found to provide excellent mode selectivity as resonator mirrors for a 150 μm core Yb:YAG planar waveguide laser, producing high brightness output at more than 300 W. The results show clearly that the laser-generated microstripe mirrors can improve the optical performance of high-power planar waveguide lasers when applied in a low-loss mode-selective resonator configuration. PMID:22968274

  6. Ultrahigh frequency tunability of aperture-coupled microstrip antenna via electric-field tunable BST

    NASA Astrophysics Data System (ADS)

    Du, Hong-Lei; Xue, Qian; Gao, Xiao-Yang; Yao, Feng-Rui; Lu, Shi-Yang; Wang, Ye-Long; Liu, Chun-Heng; Zhang, Yong-Cheng; Lü, Yue-Guang; Li, Shan-Dong

    2015-12-01

    A composite ceramic with nominal composition of 45.0 wt%(Ba0.5Sr0.5)TiO3-55.0 wt%MgO (acronym is BST-MgO) is sintered for fabricating a frequency reconfigurable aperture-coupled microstrip antenna. The calcined BST-MgO composite ceramic exhibits good microwave dielectric properties at X-band with appropriate dielectric constant ɛr around 85, lower dielectric loss tan δ about 0.01, and higher permittivity tunability 14.8% at 8.33 kV/cm. An ultrahigh E-field tunability of working frequency up to 11.0% (i.e., from 9.1 GHz to 10.1 GHz with a large frequency shift of 1000 MHz) at a DC bias field from 0 to 8.33 kV/cm and a considerably large center gain over 7.5 dB are obtained in the designed frequency reconfigurable microstrip antenna. These results demonstrate that BST materials are promising for the frequency reconfigurable antenna. Project supported by the National Natural Science Foundation of China (Grant No. 11074040) and the Key Project of Shandong Provincial Department of Science and Technology, China (Grant No. ZR2012FZ006).

  7. Investigation of New Microstrip Bandpass Filter Based on Patch Resonator with Geometrical Fractal Slot

    PubMed Central

    Mezaal, Yaqeen S.; Eyyuboglu, Halil T.

    2016-01-01

    A compact dual-mode microstrip bandpass filter using geometrical slot is presented in this paper. The adopted geometrical slot is based on first iteration of Cantor square fractal curve. This filter has the benefits of possessing narrower and sharper frequency responses as compared to microstrip filters that use single mode resonators and traditional dual-mode square patch resonators. The filter has been modeled and demonstrated by Microwave Office EM simulator designed at a resonant frequency of 2 GHz using a substrate of εr = 10.8 and thickness of h = 1.27 mm. The output simulated results of the proposed filter exhibit 22 dB return loss, 0.1678 dB insertion loss and 12 MHz bandwidth in the passband region. In addition to the narrow band gained, miniaturization properties as well as weakened spurious frequency responses and blocked second harmonic frequency in out of band regions have been acquired. Filter parameters including insertion loss, return loss, bandwidth, coupling coefficient and external quality factor have been compared with different values of perturbation dimension (d). Also, a full comparative study of this filter as compared with traditional square patch filter has been considered. PMID:27054755

  8. Investigation of New Microstrip Bandpass Filter Based on Patch Resonator with Geometrical Fractal Slot.

    PubMed

    Mezaal, Yaqeen S; Eyyuboglu, Halil T

    2016-01-01

    A compact dual-mode microstrip bandpass filter using geometrical slot is presented in this paper. The adopted geometrical slot is based on first iteration of Cantor square fractal curve. This filter has the benefits of possessing narrower and sharper frequency responses as compared to microstrip filters that use single mode resonators and traditional dual-mode square patch resonators. The filter has been modeled and demonstrated by Microwave Office EM simulator designed at a resonant frequency of 2 GHz using a substrate of εr = 10.8 and thickness of h = 1.27 mm. The output simulated results of the proposed filter exhibit 22 dB return loss, 0.1678 dB insertion loss and 12 MHz bandwidth in the passband region. In addition to the narrow band gained, miniaturization properties as well as weakened spurious frequency responses and blocked second harmonic frequency in out of band regions have been acquired. Filter parameters including insertion loss, return loss, bandwidth, coupling coefficient and external quality factor have been compared with different values of perturbation dimension (d). Also, a full comparative study of this filter as compared with traditional square patch filter has been considered. PMID:27054755

  9. Multi-Channel Microstrip Transceiver Arrays Using Harmonics for High Field MR Imaging in Humans

    PubMed Central

    Wu, Bing; Wang, Chunsheng; Lu, Jonathan; Pang, Yong; Nelson, Sarah J; Vigneron, Daniel B; Zhang, Xiaoliang

    2012-01-01

    RF transceiver array design using primary and higher order harmonics for in-vivo parallel MR imaging and spectroscopic imaging is proposed. The improved electromagnetic decoupling performance, unique magnetic field distributions and high-frequency operation capabilities of higher-order harmonics of resonators would benefit transceiver arrays for parallel MRI, especially for ultrahigh field parallel MRI. To demonstrate this technique, microstrip transceiver arrays using first and second harmonic resonators were developed for human head parallel imaging at 7T. Phantom and human head images were acquired and evaluated using the GRAPPA reconstruction algorithm. The higher-order harmonic transceiver array design technique was also assessed numerically using FDTD simulation. Compared with regular primary-resonance transceiver designs, the proposed higher-order harmonic technique provided an improved g-factor and increased decoupling among resonant elements without using dedicated decoupling circuits, which would potentially lead to a better parallel imaging performance and ultimately faster and higher quality imaging. The proposed technique is particularly suitable for densely spaced transceiver array design where the increased mutual inductance among the elements becomes problematic. In addition, it also provides a simple approach to readily upgrade the channels of a conventional primary resonator microstrip array to a larger number for faster imaging. PMID:21878410

  10. Effective relative permittivity and characteristic impedance of graphene loaded microstrip line by scalar S-parameters

    NASA Astrophysics Data System (ADS)

    Patel, Kamlesh; Neha, Tyagi, Pawan K.

    2016-05-01

    Graphene film has particular applications at the microwave frequencies because as the number of layers increases, the permittivity and conductivity are modulated. Particularly, an effective relative permittivity of graphene is of high interest. In the present work, effective relative permittivity and characteristic impedance for three kind of structures where microstrip line is either in air or loaded by glass or by graphene film on the glass substrate have been determined. The scalar S-parameters have been measured by adopting both transmission-reflection and short-open methods. The propagation constant and effective relative permittivity have been calculated and found to be nearly same for the both methods with maximum difference of 0.27% and 1.87%, respectively. However, the characteristic impedance values have significant variations as high as 12.13%. Enhanced effective relative permittivity in the range of 3.7 to 4.12 has been observed in the frequency range 1 to 8 GHz, if graphene film on the glass substrate has been loaded on top of the microstrip line. In this value the contribution of stripline substrate includes. Relative permittivity of only monolayer graphene film on the glass substrate is determined in the range of 1.62 to 4.05, and dispersive in nature.

  11. Method and apparatus for magnetic resonance imaging and spectroscopy using microstrip transmission line coils

    DOEpatents

    Zhang, Xiaoliang; Ugurbil, Kamil; Chen, Wei

    2006-04-04

    Apparatus and method for MRI imaging using a coil constructed of microstrip transmission line (MTL coil) are disclosed. In one method, a target is positioned to be imaged within the field of a main magnetic field of a magnet resonance imaging (MRI) system, a MTL coil is positioned proximate the target, and a MRI image is obtained using the main magnet and the MTL coil. In another embodiment, the MRI coil is used for spectroscopy. MRI imaging and spectroscopy coils are formed using microstrip transmission line. These MTL coils have the advantageous property of good performance while occupying a relatively small space, thus allowing MTL coils to be used inside restricted areas more easily than some other prior art coils. In addition, the MTL coils are relatively simple to construct of inexpensive components and thus relatively inexpensive compared to other designs. Further, the MTL coils of the present invention can be readily formed in a wide variety of coil configurations, and used in a wide variety of ways. Further, while the MTL coils of the present invention work well at high field strengths and frequencies, they also work at low frequencies and in low field strengths as well.

  12. Phase-slip states in the normal-superconducting relaxation of current-biased microstrips

    SciTech Connect

    Butler, D.P.; Hsiang, T.Y.

    1987-03-01

    The authors have solved the generalized time-dependent Ginzburg-Landau (TDGL) equations of Kramer and Watts-Tobin numerically. The solutions are used to predict the relaxation behavior of a microstrip biased below its dc critical current and excited into the resistive state by the application of a supercritical current pulse of a fixed duration. They have studied the relaxation behavior of the gap parameter and voltage along the microstrip as a function of the current pulse amplitude and bias magnitude. The relaxation is found to occur through a succession of phase-slip oscillations. The relaxation behavior is determined by the initial phase-slip state created by the current pulse. The maximum resistance attained increases rapidly, then saturates at a value less than the normal state resistance. The numerical solutions exhibit a region in which a relaxation time anomaly occurs with respect to the current pulse amplitude. In this region, the more highly excited states were found to relax faster. These features of the resistive relaxation behavior are found to be in qualitative agreement with their previous experimental measurements.

  13. Bandwidth Enhancement of a Dual Band Planar Monopole Antenna Using Meandered Microstrip Feeding

    PubMed Central

    Ahsan, M. R.; Islam, M. T.; Habib Ullah, M.; Misran, N.

    2014-01-01

    A meandered-microstrip fed circular shaped monopole antenna loaded with vertical slots on a high dielectric material substrate (εr = 15) is proposed in this paper. The performance criteria of the proposed antenna have been experimentally verified by fabricating a printed prototype. The experimental results show that the proposed antenna has achieved wider bandwidth with satisfactory gain by introducing meandered-microstrip feeding in assistant of partial ground plane. It is observed that, the −10 dB impedance bandwidth of the proposed antenna at lower band is 44.4% (600 MHz–1 GHz) and at upper band is 28% (2.25 GHz–2.95 GHz). The measured maximum gains of −1.18 dBi and 4.87 dBi with maximum radiation efficiencies have been observed at lower band and upper band, respectively. The antenna configuration and parametric study have been carried out with the help of commercially available computer-aided EM simulator, and a good accordance is perceived in between the simulated and measured results. The analysis of performance criteria and almost consistent radiation pattern make the proposed antenna a suitable candidate for UHF RFID, WiMAX, and WLAN applications. PMID:24723832

  14. A Dual Polarized Ultra-Wideband Slot Antenna Using Stepped Microstrip Feed Structure

    NASA Astrophysics Data System (ADS)

    Ram Krishna, R. V. S.; Kumar, Raj

    2015-11-01

    In this paper, a printed slot antenna for ultra-wideband dual polarization is proposed and experimentally demonstrated. The slot is L-shape and its two arms are individually microstrip fed for producing the orthogonal polarizations. The slot arms and the microstrip feed lines are step sectioned for wideband impedance matching. For isolation purpose, a slant narrow metallic stub is inserted at the junction of the slot arms. The antenna has an impedance bandwidth of 118% (3.1-12 GHz) and isolation of around 20 dB over most of the band. The radiation patterns are nearly omnidirectional with a peak gain varying from 3 to 6 dBi. For assessing the diversity performance of the antenna, the envelope correlation coefficients are computed from the simulated and measured S-parameters and found to be within acceptable limits. With a compact, single substrate design, the antenna is expected to be useful for printed circuit ultra wideband applications requiring dual polarization features.

  15. Bandwidth enhancement of a dual band planar monopole antenna using meandered microstrip feeding.

    PubMed

    Ahsan, M R; Islam, M T; Habib Ullah, M; Misran, N

    2014-01-01

    A meandered-microstrip fed circular shaped monopole antenna loaded with vertical slots on a high dielectric material substrate (ε r = 15) is proposed in this paper. The performance criteria of the proposed antenna have been experimentally verified by fabricating a printed prototype. The experimental results show that the proposed antenna has achieved wider bandwidth with satisfactory gain by introducing meandered-microstrip feeding in assistant of partial ground plane. It is observed that, the -10 dB impedance bandwidth of the proposed antenna at lower band is 44.4% (600 MHz-1 GHz) and at upper band is 28% (2.25 GHz-2.95 GHz). The measured maximum gains of -1.18 dBi and 4.87 dBi with maximum radiation efficiencies have been observed at lower band and upper band, respectively. The antenna configuration and parametric study have been carried out with the help of commercially available computer-aided EM simulator, and a good accordance is perceived in between the simulated and measured results. The analysis of performance criteria and almost consistent radiation pattern make the proposed antenna a suitable candidate for UHF RFID, WiMAX, and WLAN applications. PMID:24723832

  16. Dielectric parameter estimation of novel magneto-dielectric substrate based microstrip antenna

    NASA Astrophysics Data System (ADS)

    Saini, Ashish; Kumar, P.; Ravelo, B.; Thakur, Atul; Thakur, Preeti

    2016-05-01

    The effective relative permittivity and effective relative permeability of magneto-dielectric materials when used as substrate for microstrip antenna shows interdependency. This dependency was analyzed through simulation and verified by synthesizing nano composite ferrite. The 40nm nano crystallite size particles were synthesized using a co- precipitation method. Matching values of complex permittivity (ɛ* = 4.2-0.1j) and complex permeability (μ* = 4.3-0.2j) at 1 GHz were obtained from the electromagnetic characterization. The microstrip antenna with coaxial feed was fabricated and the interdependence of relative permittivity and relative permeability was verified. An error of 7% in the drawn length was observed for ɛr and μr of the order of 4. The magneto-dielectric material with composition Mn0.5Zn0.3Co0.2Fe2O4+BaFe12O19 proposed in this paper definitely can be proposed as a substrate material for miniaturized antenna. The antenna with desired resonant frequency can be fabricated by calculating the effective medium parameters as discussed in the paper.

  17. A SPICE model for Si microstrip detectors and read-out electronics

    SciTech Connect

    Bacchetta, N.; Candelori, A.; Bisello, D. |; Calgarotto, C.; Paccagnella, A. |

    1996-06-01

    The authors have developed a SPICE model of silicon microstrip detector and its read-out electronics. The SPICE model of an AC-coupled single-sided polysilicon-biased silicon microstrip detector has been implemented by using a RC network containing up to 19 strips. The main parameters of this model have been determined by direct comparison with DC and AC measurements. The simulated interstrip and coupling impedance and phase angle are in good agreement with experimental results, up to a frequency of 1 MHz. The authors have used the PreShape 32 as the read-out chip for both the simulation and the measurements. It consists of a charge sensitive preamplifier followed by a shaper and a buffer. The SPICE parameters have been adjusted to fit the experimental results obtained for the configuration where every strip is connected to the read-out electronics and kept the same for the different read-out configurations they have considered. By adding 2 further capacitances simulating the parasitic contributions between the read-out channels of the PS32 chip, a satisfactory matching between the experimental data and the simulated curves has been reached on both rising and trailing edges of the signal. Such agreement deteriorates only for strips far from the strip where the signal has been applied.

  18. Breakdown Features of Various Microstrip-Type Gas Counter Designs and Their Improvements

    NASA Technical Reports Server (NTRS)

    Peskov, V.; Ramsey, B. D.; Fonte, P.

    1998-01-01

    Breakdown mechanisms and spurious pulses, the precursors to some breakdowns, were studied experimentally for both uncoated and coated Microstrip Gas Counters (MSGCs) of different geometries, as well as for MicroGap Counters (MGCs) and for the "Compteur A Trou" (CAT). It was found that in all cases the breakdowns occurred through surface streamers, although the exact mechanism of streamer formation depended on the particular detector design. Based on these studies, new designs of microstrip detectors, in which the role of the substrate was minimized, were elaborated and tested. In some of these detectors, especially with large pitches (greater than 2mm), gains up to 2-3 x 10(exp 5) were achieved together with good rate characteristics. The ultimate gain limit in all geometries was still set by spark-inducing streamers which appeared at some critical charge density in the avalanche. To avoid this, and particularly to enhance the performance of small-pitch MSGCs, preamplification structures can be used. Utilizing a parallel plate avalanche chamber as a front end to an MSGC resulted in an overall gain of approximately 10(exp 6), limited in this case only by charge saturation.

  19. Test beam results of a low-pressure micro-strip gas chamber with a secondary-electron emitter

    SciTech Connect

    Kwan, S.; Anderson, D.F.; Zimmerman, J.; Sbarra, C.; Salomon, M.

    1994-10-01

    We present recent results, from a beam test, on the angular dependence of the efficiency and the distribution of the signals on the anode strips of a low-pressure microstrip gas chamber with a thick CsI layer as a secondary-electron emitter. New results of CVD diamond films as secondary-electron emitters are discussed.

  20. Design and performance of a 4.5GHz circularly polarized YBa 2Cu 3O 7 microstrip antenna

    NASA Astrophysics Data System (ADS)

    Zhu, M. H.; Cao, B. S.; Zhang, X. X.; Li, W. H.; Yuan, H. J.; Wang, Y. J.; Zhang, L. W.; Dong, D. J.; Liu, M. L.; Cui, D. F.; He, M.; Zhou, Y. L.; Liu, T. J.

    1997-08-01

    A 4.5GHz circularly polarized YBCO microstrip antenna was designed and fabricated. Measurements showed that at 77K the superconducting antenna had about 3dB gain improvement over the comparable silver antenna, in agreement with the calculated results using the modified Green function method.

  1. Automatic brain tumor segmentation

    NASA Astrophysics Data System (ADS)

    Clark, Matthew C.; Hall, Lawrence O.; Goldgof, Dmitry B.; Velthuizen, Robert P.; Murtaugh, F. R.; Silbiger, Martin L.

    1998-06-01

    A system that automatically segments and labels complete glioblastoma-multiform tumor volumes in magnetic resonance images of the human brain is presented. The magnetic resonance images consist of three feature images (T1- weighted, proton density, T2-weighted) and are processed by a system which integrates knowledge-based techniques with multispectral analysis and is independent of a particular magnetic resonance scanning protocol. Initial segmentation is performed by an unsupervised clustering algorithm. The segmented image, along with cluster centers for each class are provided to a rule-based expert system which extracts the intra-cranial region. Multispectral histogram analysis separates suspected tumor from the rest of the intra-cranial region, with region analysis used in performing the final tumor labeling. This system has been trained on eleven volume data sets and tested on twenty-two unseen volume data sets acquired from a single magnetic resonance imaging system. The knowledge-based tumor segmentation was compared with radiologist-verified `ground truth' tumor volumes and results generated by a supervised fuzzy clustering algorithm. The results of this system generally correspond well to ground truth, both on a per slice basis and more importantly in tracking total tumor volume during treatment over time.

  2. [Toxic anterior segment syndrome].

    PubMed

    Cornut, P-L; Chiquet, C

    2011-01-01

    Toxic anterior segment syndrome (TASS) is a general term used to describe acute, sterile postoperative inflammation due to a non-infectious substance that accidentally enters the anterior segment at the time of surgery and mimics infectious endophthalmitis. TASS most commonly occurs acutely following anterior segment surgery, typically 12-72h after cataract extraction. Anterior segment inflammation is usually quite severe with hypopyon. Endothelial cell damage is common, resulting in diffuse corneal edema. No bacterium is isolated from ocular samples. The causes of TASS are numerous and difficult to isolate. Any device or substance used during the surgery or in the immediate postoperative period may be implicated. The major known causes include: preservatives in ophthalmic solutions, denatured ophthalmic viscosurgical devices, bacterial endotoxin, and intraocular lens-induced inflammation. Clinical features of infectious and non-infectious inflammation are initially indistinguishable and TASS is usually diagnosed and treated as acute endophthalmitis. It usually improves with local steroid treatment but may result in chronic elevation of intraocular pressure or irreversible corneal edema due to permanent damage of trabecular meshwork or endothelial cells. PMID:21176994

  3. Segmentation of stereo terrain images

    NASA Astrophysics Data System (ADS)

    George, Debra A.; Privitera, Claudio M.; Blackmon, Theodore T.; Zbinden, Eric; Stark, Lawrence W.

    2000-06-01

    We have studied four approaches to segmentation of images: three automatic ones using image processing algorithms and a fourth approach, human manual segmentation. We were motivated toward helping with an important NASA Mars rover mission task -- replacing laborious manual path planning with automatic navigation of the rover on the Mars terrain. The goal of the automatic segmentations was to identify an obstacle map on the Mars terrain to enable automatic path planning for the rover. The automatic segmentation was first explored with two different segmentation methods: one based on pixel luminance, and the other based on pixel altitude generated through stereo image processing. The third automatic segmentation was achieved by combining these two types of image segmentation. Human manual segmentation of Martian terrain images was used for evaluating the effectiveness of the combined automatic segmentation as well as for determining how different humans segment the same images. Comparisons between two different segmentations, manual or automatic, were measured using a similarity metric, SAB. Based on this metric, the combined automatic segmentation did fairly well in agreeing with the manual segmentation. This was a demonstration of a positive step towards automatically creating the accurate obstacle maps necessary for automatic path planning and rover navigation.

  4. Insect segmentation: Genes, stripes and segments in "Hoppers".

    PubMed

    French, V

    2001-11-13

    Recent work has revealed that orthologues of several segmentation genes are expressed in the grasshopper embryo, in patterns resembling those shown in Drosophila. This suggests that, despite great differences between the embryos, a hierarchy of gap/pair-rule/segment polarity gene function may be a shared and ancestral feature of insect segmentation. PMID:11719236

  5. Globus pallidus internal segment.

    PubMed

    Nambu, Atsushi

    2007-01-01

    The internal segment of the globus pallidus (GP(i)) gathers many bits of information including movement-related activity from the striatum, external segment of the globus pallidus (GP(e)), and subthalamic nucleus (STN), and integrates them. The GP(i) receives rich GABAergic inputs from the striatum and GP(e), and gamma-aminobutyric acid (GABA) receptors are distributed in the GP(i) in a specific manner. Thus, inputs from the striatum and GP(e) may control GP(i) activity in a different way. The GP(i) finally conveys processed information outside the basal ganglia. Changes in GABAergic neurotransmission have been reported in movement disorders and suggested to play an important role in the pathophysiology of the symptoms. PMID:17499112

  6. Segmented vortex flaps

    NASA Technical Reports Server (NTRS)

    Rao, D. M.

    1983-01-01

    Segmented vortex flaps were suggested as a means of delaying the vortex spill-over causing thrust loss over the outboard region of single-panel flaps. Also proposed was hinge-line setback for exploiting leading-edge suction in conjunction with vortex flaps to improve the overall thrust per unit flap area. These two concepts in combination were tested on a 60-deg cropped delta wing model. Significant improvement in flap efficiency was indicated by a reduction of the flap/wing area from 11.4% of single-panel flap to 6.3% of a two segment delta flap design, with no lift/drag penalty at lift coefficients between 0.5 and 0.7. The more efficient vortex flap arrangement of this study should benefit the performance attainable with flaps of given area on wings of moderate leading-edge sweep.

  7. Segmented Thermal Barrier Coating

    NASA Technical Reports Server (NTRS)

    Smialek, James L. (Inventor)

    2001-01-01

    The article has a macro-segmented thermal barrier coating due to the presence of a pattern of three-dimensional features. The features may be a series of raised ribs formed on the substrate surface and being spaced from 0.05 inches to 0.30 apart. The ribs have a width ranging from 0.005 inches to 0.02 inches, and a height ranging from 25% to 100% of the thickness of the barrier coating. Alternately, the features may be a similar pattern of grooves formed in the surface of the substrate. Other embodiments provide segmentation by grooves or ribs in the bond coat or alternately grooves formed in the thermal barrier layer.

  8. Wood adhesion cell segmentation scheme based on GVF-Snake model

    NASA Astrophysics Data System (ADS)

    Zhao, Lei; Ma, Yan

    2010-08-01

    In order to extract the characteristic parameters of the wood cells accurately, this paper presents an efficient scheme for wood cell segmentation. This scheme is mainly based on GVF-Snake model and the method of image thinning. Firstly, computing the Category Roundness of every connectivity domain is done in order to get the degree of adhesion. Secondly, image thinning helps to get the skeleton of the cell. Finally, according to the location coordinates of skeleton and contour, it can determine the location of segmentation. Experimental results demonstrate the scheme for precise extraction with limited human intervention; it can also determine the correct edge of segmentation. Comparatively speaking, the inaccuracy is rather limited.

  9. Example based lesion segmentation

    NASA Astrophysics Data System (ADS)

    Roy, Snehashis; He, Qing; Carass, Aaron; Jog, Amod; Cuzzocreo, Jennifer L.; Reich, Daniel S.; Prince, Jerry; Pham, Dzung

    2014-03-01

    Automatic and accurate detection of white matter lesions is a significant step toward understanding the progression of many diseases, like Alzheimer's disease or multiple sclerosis. Multi-modal MR images are often used to segment T2 white matter lesions that can represent regions of demyelination or ischemia. Some automated lesion segmentation methods describe the lesion intensities using generative models, and then classify the lesions with some combination of heuristics and cost minimization. In contrast, we propose a patch-based method, in which lesions are found using examples from an atlas containing multi-modal MR images and corresponding manual delineations of lesions. Patches from subject MR images are matched to patches from the atlas and lesion memberships are found based on patch similarity weights. We experiment on 43 subjects with MS, whose scans show various levels of lesion-load. We demonstrate significant improvement in Dice coefficient and total lesion volume compared to a state of the art model-based lesion segmentation method, indicating more accurate delineation of lesions.

  10. Novel Compact Mushroom-Type EBG Structure for Electromagnetic Coupling Reduction of Microstrip Antenna array

    NASA Astrophysics Data System (ADS)

    Hu, Lizhong; Wang, Guangming; Liang, Jiangang; Zhang, Chenxin

    2015-03-01

    A novel compact electromagnetic bandgap (EBG) structure consisting of two turns complementary spiral resonator (CSR) and conventional mushroom EBG (CM-EBG) structure is introduced to suppress the mutual coupling in antenna arrays for multiple-input and multiple-output (MIMO) applications. Eigenmode calculation is used to investigate the proposed CSR-loaded mushroom-type EBG (MT-EBG), which proved to exhibit bandgap property and a miniaturization of 48.9% is realized compared with the CM-EBG. By inserting the proposed EBG structure between two E-plane coupled microstrip antennas, a mutual coupling reduction of 8.13 dB has been achieved numerically and experimentally. Moreover, the EBG-loaded antenna has better far-field radiation patterns compared with the reference antenna. Thus, this novel EBG structure with advantages of compactness and high decoupling efficiency opens an avenue to new types of antennas with super performances.

  11. Analysis of an infinite array of rectangular microstrip patches with idealized probe feeds

    NASA Technical Reports Server (NTRS)

    Pozar, D. M.; Schaubert, D. H.

    1984-01-01

    A solution is presented to the problem of an infinite array of microstrip patches fed by idealized current probes. The input reflection coefficient is calculated versus scan angle in an arbitrary scan plane, and the effects of substrate parameters and grid spacing are considered. It is pointed out that even when a Galerkin method is used the impedance matrix is not symmetric due to phasing through a unit cell, as required for scanning. The mechanism by which scan blindness can occur is discussed. Measurement results are presented for the reflection coefficient magnitude variation with angle for E-plane, H-plane, and D-plane scans, for various substrate parameters. Measured results from waveguide simulators are also presented, and the scan blindness phenomenon is observed and discussed in terms of forced surface waves and a modified grating lobe diagram.

  12. RF Pulse Signal Integrity Analysis for Nonlinear Ended Microstrip Line Atom-Probe Tomography

    NASA Astrophysics Data System (ADS)

    Zhao, L.; Delamare, A.; Normand, A.; Delaroche, F.; Latry, O.; Vurpillot, F.; Ravelo, B.

    2016-03-01

    A signal integrity (SI) analysis of high voltage rectangular short pulses for the atom- probe system is explored in this paper. The operated RF transient pulse is considered for exciting on material sample inside an ultra-high vacuum (UHV) cryogenic chamber. The ns- duration pulse signal is injected into the cryogenic analysis chamber through the transmitting system mainly constituted by a microstrip interconnect line ended by optical controlled nonlinear load. The whole system frequency characterization is performed based on the S- parameter measurements. As expected, a challenging ultra-short rectangular shape pulse is exhibited by the pulser. Promising experimental results with the improvement of ion mass spectrum is demonstrated with the designed RF pulser.

  13. Microstrip electrode readout noise for load-dominated long shaping-time systems

    NASA Astrophysics Data System (ADS)

    Collier, Kelsey; Cunnington, Taylor; Crosby, Sean; Fadeyev, Vitaliy; Martinez-McKinney, Forest; Mistry, Khilesh; Schumm, Bruce A.; Spencer, Edwin; Taylor, Aaron; Wilder, Max

    2013-11-01

    In cases such as that of the proposed International Linear Collider (ILC), for which the beam-delivery and detector-occupancy characteristics permit a long shaping-time readout of the microstrip sensors, it is possible to envision long (∼1 meter) daisy-chained ‘ladders’ of fine-pitch sensors read out by a single front-end amplifier. In this study, a long shaping-time (∼2 μsec) front-end amplifier has been used to measure readout noise as a function of detector load. Comparing measured noise to that expected from lumped and distributed models of the load network, it is seen that network effects significantly mitigate the amount of readout noise contributed by the detector load. Further reduction in noise is demonstrated for the case that the sensor load is read out from its center rather than its end.

  14. Bandwidth optimization of compact microstrip antenna for PCS/DCS/bluetooth application

    NASA Astrophysics Data System (ADS)

    Singh, Vinod; Ali, Zakir; Ayub, Shahanaz; Singh, Ashutosh

    2014-09-01

    A novel compact broadband microstrip patch antenna is presented for various wireless applications. The proposed antenna has been fabricated and the impedance bandwidth and radiation pattern are measured. The simulated and measured antenna characteristics along with radiation pattern and gain are presented. It is stated that the proposed designed antenna can completely cover the required band widths of Digital communication system (DCS 1.71-1.88 GHz), Personal communication system (PCS 1.85-1.88 GHz) and IEEE 802.11b/g (2.4-2.485 GHz) with satisfactory radiation characteristics. The Experimental result shows that the proposed antenna presents a bandwidth 60.25% covering the range of 1.431-2.665 GHz with the maximum radiation efficiency 90%.

  15. Computing resonant frequency of C-shaped compact microstrip antennas by using ANFIS

    NASA Astrophysics Data System (ADS)

    Akdagli, Ali; Kayabasi, Ahmet; Develi, Ibrahim

    2015-03-01

    In this work, the resonant frequency of C-shaped compact microstrip antennas (CCMAs) operating at UHF band is computed by using the adaptive neuro-fuzzy inference system (ANFIS). For this purpose, 144 CCMAs with various relative dielectric constants and different physical dimensions were simulated by the XFDTD software package based on the finite-difference time domain (FDTD) method. One hundred and twenty-nine CCMAs were employed for training, while the remaining 15 CCMAs were used for testing of the ANFIS model. Average percentage error (APE) values were obtained as 0.8413% and 1.259% for training and testing, respectively. In order to demonstrate its validity and accuracy, the proposed ANFIS model was also tested over the simulation data given in the literature, and APE was obtained as 0.916%. These results show that ANFIS can be successfully used to compute the resonant frequency of CCMAs.

  16. Dual-band bandpass terahertz wave filter based on microstrip resonant structure

    NASA Astrophysics Data System (ADS)

    Liu, Yu-hang; Li, Jiu-sheng

    2011-11-01

    The terahertz (THz) band, which refers to the spectral region between 0.1 and 10THz, covers the fingerprints of many chemical and biological materials. Within the past few years, there are increasing demands for experiments in terahertz frequencies, in different areas such as biotechnology, nanotechnology, space science, security, chemical and biological sensing, terahertz wave communications, and medical diagnostics. For potential applications, the functional devices, such as beam polarizers, switchs and filters, are crucial components for a terahertz system. Terahertz wave filter based on two kinds of microstrip resonant structures, has been characterized by terahertz time-domain spectroscopy in the region from 0.1 to 3THz. The experimental results for the frequency dependence of the transmittance of the terahertz wave filter show that the terahertz wave transmittance peak is of 79.5% at 0.5THz and 82.5% at 0.81THz.

  17. Dual-band bandpass terahertz wave filter based on microstrip resonant structure

    NASA Astrophysics Data System (ADS)

    Liu, Yu-hang; Li, Jiu-sheng

    2012-03-01

    The terahertz (THz) band, which refers to the spectral region between 0.1 and 10THz, covers the fingerprints of many chemical and biological materials. Within the past few years, there are increasing demands for experiments in terahertz frequencies, in different areas such as biotechnology, nanotechnology, space science, security, chemical and biological sensing, terahertz wave communications, and medical diagnostics. For potential applications, the functional devices, such as beam polarizers, switchs and filters, are crucial components for a terahertz system. Terahertz wave filter based on two kinds of microstrip resonant structures, has been characterized by terahertz time-domain spectroscopy in the region from 0.1 to 3THz. The experimental results for the frequency dependence of the transmittance of the terahertz wave filter show that the terahertz wave transmittance peak is of 79.5% at 0.5THz and 82.5% at 0.81THz.

  18. A new inner layer silicon micro-strip detector for D0

    SciTech Connect

    Weber, Michael S.; /Fermilab

    2006-01-01

    The D{O} experiment at the Fermilab Tevatron is building a new inner layer detector (Layer-0) to be installed inside the existing D{O} Silicon Micro-strip Tracker (SMT). The Layer-0 detector is based on R&D performed for the RunIIb silicon upgrade, which was canceled in the fall of 2003. Layer-0 will be installed between the bean pipe and the the 2.2cm radius opening available in the SMT support structure. The radius of the first sampling will be reduced from 2.7cm to 1.6cm. Layer-0 will be radiation harder than the current SMT, thus ensuring that the silicon tracker remains viable through Tevatron RunII.

  19. Radiative and non-radiative recombinations in tensile strained Ge microstrips: Photoluminescence experiments and modeling

    SciTech Connect

    Virgilio, M.; Schroeder, T.; Yamamoto, Y.; Capellini, G.

    2015-12-21

    Tensile germanium microstrips are candidate as gain material in Si-based light emitting devices due to the beneficial effect of the strain field on the radiative recombination rate. In this work, we thoroughly investigate their radiative recombination spectra by means of micro-photoluminescence experiments at different temperatures and excitation powers carried out on samples featuring different tensile strain values. For sake of comparison, bulk Ge(001) photoluminescence is also discussed. The experimental findings are interpreted in light of a numerical modeling based on a multi-valley effective mass approach, taking in to account the depth dependence of the photo-induced carrier density and of the self-absorption effect. The theoretical modeling allowed us to quantitatively describe the observed increase of the photoluminescence intensity for increasing values of strain, excitation power, and temperature. The temperature dependence of the non-radiative recombination time in this material has been inferred thanks to the model calibration procedure.

  20. Triple-band high-temperature superconducting microstrip filter based on multimode split ring resonator

    NASA Astrophysics Data System (ADS)

    Liu, Hai-Wen; Wang, Yan; Fan, Yi-Chao; Guan, Xue-Hui; He, Yusheng

    2013-09-01

    A compact triple-band high-temperature superconducting (HTS) YBa2Cu3Oy microstrip bandpass filter using multimode split ring resonator (SRR) is presented in this letter. Also, its properties and equivalent circuit models are investigated by even- and odd-mode analysis. Moreover, design method of the proposed triple-band HTS filter for the applications of global positioning system at 1.57 GHz, worldwide interoperability for microwave access at 3.5 GHz, and wireless local area networks at 5.8 GHz is discussed. The centre frequencies and the bandwidths of the three passbands can be allocated properly choosing the dimension parameters of the multimode SRR. In addition, four transmission zeros are produced to improve the selectivity of this filter.

  1. Dual band multi frequency rectangular patch microstrip antenna with flyswatter shaped slot for wireless systems

    NASA Astrophysics Data System (ADS)

    Bhardwaj, Dheeraj; Saraswat, Shriti; Gulati, Gitansh; Shekhar, Snehanshu; Joshi, Kanika; Sharma, Komal

    2016-03-01

    In this paper a dual band planar antenna has been proposed for IEEE 802.16 Wi-MAX /IEEE 802.11 WLAN/4.9 GHz public safety applications. The antenna comprises a frequency bandwidth of 560MHz (3.37GHz-3.93GHz) for WLAN and WiMAX and 372MHz (4.82GHz-5.192GHz) for 4.9 GHz public safety applications and Radio astronomy services (4.8-4.94 GHz). The proposed antenna constitutes of a single microstrip patch reactively loaded with three identical steps positioned in a zig-zag manner towards the radiating edges of the patch. The coaxially fed patch antenna characteristics (radiation pattern, antenna gain, antenna directivity, current distribution, S11) have been investigated. The antenna design is primarily focused on achieving a dual band operation.

  2. Full wave analysis and miniaturization of microstrip antenna on ferrimagnetics substrates

    NASA Astrophysics Data System (ADS)

    Lavor, Otávio Paulino; Fernandes, Humberto Cesar Chaves

    2016-02-01

    This paper presents the miniaturization of the microstrip antenna on ferrimagnetic substrate for operate at a frequency of 2.5 GHz, where the full wave method Transverse Transmission Line-TTL is used it for obtain resonance frequency. For validate this method in these substrates, the results as function of DC magnetic field are shown. When the field is 132.6 AT/m, the value of reference is 151.7 MHz and the value of TTL is 151.3 MHz. The dimensions are obtained for the frequency of 2.5 GHz and a comparison is done with ferrites and conventional substrate, showing a reduction in volume of the antenna of 2808.96 mm3 for 0.39 mm3 when the ferrites are used.

  3. Clutter sensitivity test under controlled field conditions Resonant Microstrip Patch Antenna (RMPA) sensor technology

    SciTech Connect

    1996-06-27

    Theoretical research, controlled laboratory tests, and these field test results show that nonmetallic (and metallic) shallowly buried objects can be detected and imaged with the Resonant Microstrip Patch Antenna (RMPA) sensor. The sensor can be modeled as a high Q cavity which capitalizes on its resonant condition sensitivity to scattered waves from buried objects. When the RMPA sensor is swept over a shallowly buried object, the RMPA fed-point impedance (resistance), measured with a Maxwell bridge, changes by tens of percent. The significant change in unprocessed impedance data can be presented in two-dimensional and three-dimensional graphical displays over the survey area. This forms silhouette images of the objects without the application of computationally intensive data processing algorithms. Because RMPA employed electromagnetic waves to illuminate the shallowly buried object, a number of questions and issues arise in the decision to fund or deny funding of the reconfiguration of the RMPA technology into a nonmetallic (metallic) land mine detector.

  4. Compact double-p slotted inset-fed microstrip patch antenna on high dielectric substrate.

    PubMed

    Ahsan, M R; Islam, M T; Habib Ullah, M; Mahadi, W N L; Latef, T A

    2014-01-01

    This paper presents a compact sized inset-fed rectangular microstrip patch antenna embedded with double-P slots. The proposed antenna has been designed and fabricated on ceramic-PTFE composite material substrate of high dielectric constant value. The measurement results from the fabricated prototype of the antenna show -10 dB reflection coefficient bandwidths of 200 MHz and 300 MHz with center resonant frequency of 1.5 GHz and 4 GHz, respectively. The fabricated antenna has attained gains of 3.52 dBi with 81% radiation efficiency and 5.72 dBi with 87% radiation efficiency for lower band and upper band, respectively. The measured E- and H-plane radiation patterns are also presented for better understanding. Good agreement between the simulation and measurement results and consistent radiation patterns make the proposed antenna suitable for GPS and C-band applications. PMID:25165750

  5. Onset of dispersion in Nb microstrip transmission lines at submillimeter wave frequencies

    NASA Technical Reports Server (NTRS)

    Javadi, H. H. S.; Mcgrath, William R.; Bumble, B.; Leduc, Henry G.

    1992-01-01

    We have measured the dispersion in phase velocity of a Nb-SiO(x)-Nb microstrip transmission line resonator over a frequency range from 50 GHz to 800 GHz. A submicron Nb/Al-AlO(x)/Nb Josephson junction was used as a voltage-controlled oscillator to excite the high order modes in the resonator. The same junction is used as a direct detector resulting in a series of step-like structures in the DC current-voltage characteristic at the position of each mode frequency. The transmission line is dispersionless up to about 500 GHz where the phase velocity begins to decrease. This is well below the gap frequency f(sub g) approx. equals 700 GHz. Results agree qualitatively with the expected theoretical behavior near f(sub g). This onset of dispersion and loss in Nb transmission lines will have a significant impact on the design of submillimeter wave RF circuits.

  6. Compact Microstrip Low-pass Filter with Wide Stop-band and Sharp Roll-off

    NASA Astrophysics Data System (ADS)

    Hayati, Mohsen; Vaziri, Hamid Sherafat

    2013-09-01

    This paper presents a novel compact microstrip low-pass filter with wide stop-band and sharp roll-off. The structure consists of a transmission line, loaded with coupled novel Hairpin units. The cut-off frequency of the proposed filter is 2.9 GHz. The measured results show good LPF performance such as sharp roll-off skirt, low insertion-loss, high return-loss in the pass-band and wide upper stop-band of 3.2 to 16.1 GHz with an insertion-loss higher than 20.0 dB. The measured values and the EM-simulation results are in good agreement.

  7. Automated quality assurance for silicon microstrip sensors of the CBM Silicon Tracking System

    NASA Astrophysics Data System (ADS)

    Larionov, P.

    2016-01-01

    The Silicon Tracking System (STS) is the main tracking detector of the upcoming fixed-target Compressed Baryonic Matter (CBM) experiment which aims to explore the phase diagram of the strongly interacting matter in a region of high net baryonic densities and moderate temperatures. The STS will be used for the reconstruction of tracks of charged particles and determination of their momenta. The system comprises 8 tracking stations located 30 cm downstream the target and will be mounted with 300 μm thick double-sided silicon microstrip sensors in three different sizes. In this paper, the Quality Assurance (QA) procedures for the STS sensors are overviewed highlighting the automated QA testing procedure for a single strip defect identification.

  8. Alignment and Integration of Lightweight Mirror Segments

    NASA Technical Reports Server (NTRS)

    Evans, Tyler; Biskach, Michael; Mazzarella, Jim; McClelland, Ryan; Saha, Timo; Zhang, Will; Chan, Kai-Wing

    2011-01-01

    The optics for the International X-Ray Observatory (IXO) require alignment and integration of about fourteen thousand thin mirror segments to achieve the mission goal of 3.0 square meters of effective area at 1.25 keV with an angular resolution of five arc-seconds. These mirror segments are 0.4 mm thick, and 200 to 400 mm in size, which makes it difficult not to impart distortion at the sub-arc-second level. This paper outlines the precise alignment, permanent bonding, and verification testing techniques developed at NASA's Goddard Space Flight Center (GSFC). Improvements in alignment include new hardware and automation software. Improvements in bonding include two module new simulators to bond mirrors into, a glass housing for proving single pair bonding, and a Kovar module for bonding multiple pairs of mirrors. Three separate bonding trials were x-ray tested producing results meeting the requirement of sub ten arc-second alignment. This paper will highlight these recent advances in alignment, testing, and bonding techniques and the exciting developments in thin x-ray optic technology development.

  9. Design and fabrication of low-cost reconfigurable microstrip antenna using photodiode as optical switching

    NASA Astrophysics Data System (ADS)

    Kusumawati, E. R.; Pramono, Y. H.; Rubiyanto, A.

    2014-09-01

    Design, fabrication, and characterization prototype of reconfigurable dipole microstrip antenna using photodiode as optical switching have been conducted in the Laboratory for Optical and Microwave Physics Department Faculty of ITS. This paper presents a new reconfigurable antenna design using photodiode as optical switching. In order to be optical switching, photodiode must be illuminated by optical source. The optical source used is Infrared with power 8 mW. Antenna is fabricated in FR-4 substrate which has 1.6 mm thick and 4.8 relative permittivity value. The dimension of the substrate is 131 mm × 21.5 mm × 1.6 mm. The structure of antenna is Coplanar Stripline (CPS) dipole. Measurement is conducted in two state. First state is photodiodes unilluminated Infrared and the second state is illuminated. The measurement result indicate that if condition is not illuminated by Infrared (OFF-state) antenna has resonance frequency of 2010 MHz and 2120 MHz. At frequency 2010 MHz, S11 value -35.7 dB and bandwidth 57 MHz, meanwhile at frequency 2120 MHz, S11 value -17.3 dB and bandwidth 42 MHz. Then if photodiode was illuminated by infrared (ON-state), antenna work at frequency 2007 MHz with S11 value -41.8 dB and bandwidth 61 MHz and 2113 MHz with S11 value -19.4 and bandwidth 47 MHz. There was frequency shifting from 2010 MHz to 2007 MHz and 2120 MHz to 2113 MHz of 5 MHz. At ON state, S11 value also was shifting. There was 6.1 dB and 2.1 dB. Bandwidth at ON-state is wider than OFF state. Microstrip antenna with a reconfigurable optical switching photodiode has several advantages. The advantages are more easily fabricated and the cost is relatively cheaper than the other techniques of optical switching.

  10. Contact flexible microstrip applicators (CFMA) in a range from microwaves up to short waves.

    PubMed

    Gelvich, Edward A; Mazokhin, Vladimir N

    2002-09-01

    Contact flexible microstrip applicator (CFMA) is a new light-weight microstrip applicator type for superficial and deep local hyperthermia. Typical specimens are developed for operation at frequencies of 434, 70, 40, and 27 MHz. The main common features of CFMA, namely, their flexibility and light weight, as well as their aperture dimensions slightly depend on the operating frequency. Two antenna types are used in CFMAs: inductive antennas with a radiating plane electrical dipole at microwaves, and coplanar capacitive antennas, providing depression of the normal component of the electrical field in the very high-frequency (VHF) and high-frequency (HF) range. The flexibility of the applicators enables one to conform them with curved surfaces. In a bent state of the applicators there arises a focusing effect of energy deposition in deeper located tissues due to linear polarization of the irradiated electromagnetic (EM) field, inherent in CFMA. All CFMA are integrated with silicon water boluses which serve as a matching element, so as a skin cooling agent. Due to this and to the predominance of the tangential electrical component in the radiated EM field, no fat overheating effects are noticed, as a rule. The aperture of the developed applicators overlap the range 160-630 cm2 providing effective heating field sizes (EFSs) 64-400 cm2, respectively. The most bulky CFMAs with an aperture of (21 x 29) cm2 operating at the frequency of 434 MHz weigh 0.8 kg and 2.5 kg at 27 MHz. Phenomenological analysis of the radiating systems, as well as experimental evaluation of the applicators are presented. CFMAs operating at frequencies of 434 and 40 MHz are used in clinical practice. CFMA at 70 and 27 MHz are subjected to laboratory clinical investigations. PMID:12214873

  11. Effective Permeability and Miniaturization Estimation of Ferrite-loaded Microstrip Patch Antenna

    NASA Astrophysics Data System (ADS)

    Saini, Ashish; Thakur, Atul; Thakur, Preeti

    2016-08-01

    Miniaturization of a microstrip patch antenna using composite nanosized ferrite material is proposed in this paper. Detailed simulations were performed to analyze the effect of increase in relative permeability of substrate material on physical size and efficiency of a microstrip antenna. An analytical expression for estimation of the effective relative permeability is established here on the basis of the detailed simulation. Composite nano ferrite (Mn0.5Zn0.35Co0.15Fe2O4 + SrFe12O19) with an average crystallite size of 72 nm was synthesized and characterized for electromagnetic properties. The substrate material was prepared by the co-precipitation method. Matching values of complex permittivity ( ɛ* = 4.1-0.1j) and complex permeability ( μ* = 3.72-0.28j) up to 1 GHz were obtained from the electromagnetic characterization. Measurement of the resonant frequency of the fabricated antenna validates the derived expression of effective relative permeability. It reduces the error in calculation of resonant frequency from 10% to 1%. Simulation and measurement results also confirm that an antenna fabricated with the above parameters can reduce the patch size by almost 44% and increases -10 dB reflection loss bandwidth over a pure dielectric FR4 substrate. Therefore, we propose here an analytical expression for estimation of effective relative permeability and Mn0.5Zn0.35Co0.15Fe2O4 + SrFe12O19 composite nano ferrites as suitable candidate for a high-bandwidth miniaturized antenna in the microwave frequency range.

  12. Effective Permeability and Miniaturization Estimation of Ferrite-loaded Microstrip Patch Antenna

    NASA Astrophysics Data System (ADS)

    Saini, Ashish; Thakur, Atul; Thakur, Preeti

    2016-05-01

    Miniaturization of a microstrip patch antenna using composite nanosized ferrite material is proposed in this paper. Detailed simulations were performed to analyze the effect of increase in relative permeability of substrate material on physical size and efficiency of a microstrip antenna. An analytical expression for estimation of the effective relative permeability is established here on the basis of the detailed simulation. Composite nano ferrite (Mn0.5Zn0.35Co0.15Fe2O4 + SrFe12O19) with an average crystallite size of 72 nm was synthesized and characterized for electromagnetic properties. The substrate material was prepared by the co-precipitation method. Matching values of complex permittivity (ɛ* = 4.1-0.1j) and complex permeability (μ* = 3.72-0.28j) up to 1 GHz were obtained from the electromagnetic characterization. Measurement of the resonant frequency of the fabricated antenna validates the derived expression of effective relative permeability. It reduces the error in calculation of resonant frequency from 10% to 1%. Simulation and measurement results also confirm that an antenna fabricated with the above parameters can reduce the patch size by almost 44% and increases -10 dB reflection loss bandwidth over a pure dielectric FR4 substrate. Therefore, we propose here an analytical expression for estimation of effective relative permeability and Mn0.5Zn0.35Co0.15Fe2O4 + SrFe12O19 composite nano ferrites as suitable candidate for a high-bandwidth miniaturized antenna in the microwave frequency range.

  13. Segmenting the Adult Education Market.

    ERIC Educational Resources Information Center

    Aurand, Tim

    1994-01-01

    Describes market segmentation and how the principles of segmentation can be applied to the adult education market. Indicates that applying segmentation techniques to adult education programs results in programs that are educationally and financially satisfying and serve an appropriate population. (JOW)

  14. Market Segmentation for Information Services.

    ERIC Educational Resources Information Center

    Halperin, Michael

    1981-01-01

    Discusses the advantages and limitations of market segmentation as strategy for the marketing of information services made available by nonprofit organizations, particularly libraries. Market segmentation is defined, a market grid for libraries is described, and the segmentation of information services is outlined. A 16-item reference list is…

  15. Functional Segments in Tongue Movement

    ERIC Educational Resources Information Center

    Stone, Maureen; Epstein, Melissa A.; Iskarous, Khalil

    2004-01-01

    The tongue is a deformable object, and moves by compressing or expanding local functional segments. For any single phoneme, these functional tongue segments may move in similar or opposite directions, and may reach target maximum synchronously or not. This paper will discuss the independence of five proposed segments in the production of speech.…

  16. Microstrip Antennas with Polarization Diversity across a Wide Frequency Range and Phased Array Antennas for Radar and Satellite Communications

    NASA Astrophysics Data System (ADS)

    Ho, Kevin Ming-Jiang

    The thesis comprises of 3 projects; an L-band microstrip antenna with frequency agility and polarization diversity, X-band phased array antennas incorporating commercially packaged RFIC phased array chips, and studies for Ku/Ka-band shared aperture antenna array. The first project features the use of commercially packaged RF-MEMS SPDT switches, that boasts of high reliability, high linearity, low losses, hermetically packaged and fully compatible for SMTA processes for mass-assembly and production. Using the switches in a novel manner for the feed network, microstrip antennas with polarization diversity are presented. Frequency agility is achieved with the use of tuning diodes to provide capacitive loading to the antenna element. Additional inductance effects from surface-mounted capacitors, and its impact, is introduced. Theoretical cross-polarization of probe-fed antenna elements is presented for both linear and circular polarized microstrip antennas. Designs and measurements are presented, for microstrip antennas with polarization diversity, wide frequency tuning range, and both features. Replacement of the tuning diodes with commercially-packaged high Q RF MEMS tunable capacitors will allow for significant improvements to the radiation efficiency. In another project, multi-channel CMOS RFIC phased-array receiver chips are assembled in QFN packages and directly integrated on the same multi-layered PCB stack-up with the antenna arrays. Problems of isolation from the PCB-QFN interface, and potential performance degradation on antenna array from the use of commercial-grade laminates for assembly requirements, namely potential scan blindness and radiation efficiency, are presented. Causes for apparent drift of dielectric constant for microstrip circuits, and high conductor losses observed in measurements, are introduced. Finally, studies are performed for the design of a Ku/Ka-Band shared aperture array. Different approaches for developing dual-band shared apertures

  17. Interactive explorations of hierarchical segmentations

    NASA Technical Reports Server (NTRS)

    Tilton, James C.

    1992-01-01

    The authors report on the implementation of an interactive tool, called HSEGEXP, to interactively explore the hierarchical segmentation produced by the iterative parallel region growing (IPRG) algorithm to select the best segmentation result. This combination of the HSEGEXP tool with the IPRG algorithm amounts to a computer-assisted image segmentation system guided by human interaction. The initial application of the HSEGEXP tool is in the refinement of ground reference data based on the IPRG/HSEGEXP segmentation of the corresponding remotely sensed image data. The HSEGEXP tool is being used to help evaluate the effectiveness of an automatic 'best' segmentation process under development.

  18. Segmentation of Unstructured Datasets

    NASA Technical Reports Server (NTRS)

    Bhat, Smitha

    1996-01-01

    Datasets generated by computer simulations and experiments in Computational Fluid Dynamics tend to be extremely large and complex. It is difficult to visualize these datasets using standard techniques like Volume Rendering and Ray Casting. Object Segmentation provides a technique to extract and quantify regions of interest within these massive datasets. This thesis explores basic algorithms to extract coherent amorphous regions from two-dimensional and three-dimensional scalar unstructured grids. The techniques are applied to datasets from Computational Fluid Dynamics and from Finite Element Analysis.

  19. Enhanced bandwidth of a microstrip antenna using a parasitic mushroom-like metamaterial structure for multi-robot cooperative navigation

    NASA Astrophysics Data System (ADS)

    Lee, Cherl-Hee; Lee, Jonghun; Kim, Yoon-Gu; An, Jinung

    2015-01-01

    The broadband design of a microstrip patch antenna is presented and experimentally studied for multi-robot cooperation. A parasitic mushroom-like metamaterial (MTM) patch close to a microstrip top patch is excited through gap-coupling, thereby producing a resonance frequency. Because of the design, the resonance frequency of the parasitic MTM patch is adjacent to that of the main patch, and the presented antenna can achieve an enhanced bandwidth of 450 MHz, which is about two times the bandwidth of a conventional patch antenna without the MTM parasitic patch. The error rate of packet transmissions for measuring the distance between a leader robot and a follower robot was also improved by almost two-fold.

  20. Development of a High-Stability Microstrip-based L-band Radiometer for Ocean Salinity Measurements

    NASA Technical Reports Server (NTRS)

    Pellerano, Fernando A.; Horgan, Kevin A.; Wilson, William J.; Tanner, Alan B.

    2004-01-01

    The development of a microstrip-based L-band Dicke radiometer with the long-term stability required for future ocean salinity measurements to an accuracy of 0.1 psu is presented. This measurement requires the L-band radiometers to have calibration stabilities of less than or equal to 0.05 K over 2 days. This research has focused on determining the optimum radiometer requirements and configuration to achieve this objective. System configuration and component performance have been evaluated with radiometer test beds at both JPL and GSFC. The GSFC testbed uses a cryogenic chamber that allows long-term characterization at radiometric temperatures in the range of 70 - 120 K. The research has addressed several areas including component characterization as a function of temperature and DC bias, system linearity, optimum noise diode injection calibration, and precision temperature control of components. A breadboard radiometer, utilizing microstrip-based technologies, has been built to demonstrate this long-term stability.

  1. Dual-band operation of a microstrip patch antenna on a Duroid 5870 substrate for Ku- and K-bands.

    PubMed

    Islam, M M; Islam, M T; Faruque, M R I

    2013-01-01

    The dual-band operation of a microstrip patch antenna on a Duroid 5870 substrate for Ku- and K-bands is presented. The fabrication of the proposed antenna is performed with slots and a Duroid 5870 dielectric substrate and is excited by a 50 Ω microstrip transmission line. A high-frequency structural simulator (HFSS) is used which is based on the finite element method (FEM) in this research. The measured impedance bandwidth (2 : 1 VSWR) achieved is 1.07 GHz (15.93 GHz-14.86 GHz) on the lower band and 0.94 GHz (20.67-19.73 GHz) on the upper band. A stable omnidirectional radiation pattern is observed in the operating frequency band. The proposed prototype antenna behavior is discussed in terms of the comparisons of the measured and simulated results. PMID:24385878

  2. A wide-band dual-polarized VHF microstrip antenna for global sensing of sea ice thickness

    NASA Technical Reports Server (NTRS)

    Huang, John; Hussein, Ziad; Petros, Argy

    2005-01-01

    A VHF microstrip patch antenna was developed to achieve a bandwidth of 45 MHz (30%) from 127 MHz to 172 MHz with dual-linear-polarization capability. This microstrip antenna used foam substrates and dual stacked patches with capacitive probe feeds to achieve wide bandwidth. Four such capacitive feeds were used to achieve dual polarizations with less than -20 dB of cross-polarization level. Twenty-four shorting pins were used on the lower patch to achieve acceptable isolation between the four feed probes. This antenna has a measured gain of 8.5 dB at 137 MHz and 10 dB at 162 MHz. By using the Method of Moments technique, multipath scattering patterns were calculated when the antenna is mounted on the outside of a Twin Otter aircraft.

  3. Dual-Band Operation of a Microstrip Patch Antenna on a Duroid 5870 Substrate for Ku- and K-Bands

    PubMed Central

    Islam, M. M.; Islam, M. T.; Faruque, M. R. I.

    2013-01-01

    The dual-band operation of a microstrip patch antenna on a Duroid 5870 substrate for Ku- and K-bands is presented. The fabrication of the proposed antenna is performed with slots and a Duroid 5870 dielectric substrate and is excited by a 50 Ω microstrip transmission line. A high-frequency structural simulator (HFSS) is used which is based on the finite element method (FEM) in this research. The measured impedance bandwidth (2 : 1 VSWR) achieved is 1.07 GHz (15.93 GHz–14.86 GHz) on the lower band and 0.94 GHz (20.67–19.73 GHz) on the upper band. A stable omnidirectional radiation pattern is observed in the operating frequency band. The proposed prototype antenna behavior is discussed in terms of the comparisons of the measured and simulated results. PMID:24385878

  4. LDR segmented mirror technology assessment study

    NASA Technical Reports Server (NTRS)

    Krim, M.; Russo, J.

    1983-01-01

    In the mid-1990s, NASA plans to orbit a giant telescope, whose aperture may be as great as 30 meters, for infrared and sub-millimeter astronomy. Its primary mirror will be deployed or assembled in orbit from a mosaic of possibly hundreds of mirror segments. Each segment must be shaped to precise curvature tolerances so that diffraction-limited performance will be achieved at 30 micron (nominal operating wavelength). All panels must lie within 1 micron on a theoretical surface described by the optical precipitation of the telescope's primary mirror. To attain diffraction-limited performance, the issues of alignment and/or position sensing, position control of micron tolerances, and structural, thermal, and mechanical considerations for stowing, deploying, and erecting the reflector must be resolved. Radius of curvature precision influences panel size, shape, material, and type of construction. Two superior material choices emerged: fused quartz (sufficiently homogeneous with respect to thermal expansivity to permit a thin shell substrate to be drape molded between graphite dies to a precise enough off-axis asphere for optical finishing on the as-received a segment) and a Pyrex or Duran (less expensive than quartz and formable at lower temperatures). The optimal reflector panel size is between 1-1/2 and 2 meters. Making one, two-meter mirror every two weeks requires new approaches to manufacturing off-axis parabolic or aspheric segments (drape molding on precision dies and subsequent finishing on a nonrotationally symmetric dependent machine). Proof-of-concept developmental programs were identified to prove the feasibility of the materials and manufacturing ideas.

  5. A compact cylindrical-shape microstrip structure with cloaking properties for mutual coupling reduction in array antennas

    NASA Astrophysics Data System (ADS)

    Naqvi, Syed Aftab

    A cylindrical-shaped microstrip structure with cloaking properties is presented as a shielding device to reduce the mutual coupling between two patch antennas. The surface comprises of a number of 2-port microstrip (2-PM) elements printed on individual substrates and, to enclose a particular region, several 2-PM elements are interconnected into a cylindrical shape. Each 2-PM element has the capability of coupling an incident EM field on the surface to the adjacent interconnected elements. Then, because the 2-PM elements are connected into a cylindrical shape, the incident EM field is re-radiated from the other interconnected 2-PM elements in a direction away from the transmitter; achieving a behavior similar to a cloak. The prototypes in this dissertation illustrates that this surface has the additional benefit of overcoming many of the manufacturing difficulties of traditional cloaks because microstrip structures are used. To demonstrate this concept, a cylindrical surface operating at 3.89 GHz and a frequency reconfigurable surface (consisting of 2-port frequency reconfigurable microstrip elements (2-PFRM)) operating at 3.68 GHz and 3.89 GHz is simulated in HFSS, manufactured and measured in a full anechoic chamber. Moreover, as an application, the cylindrical surface operating at 3.89 GHz is used to reduce the mutual coupling between two patch antennas operating simultaneously at 3.89 GHz. The radiation pattern and the gain of a 2-element array is measured to demonstrate the negligible effects of a cylindrical surface on the far field antenna array parameters. Simulation and measurement results are in good agreement and validate the proposed EM cloak-based surface for applications such as antenna array shielding, radar cross section and communications in complex EM environments.

  6. Segmented Target Design

    NASA Astrophysics Data System (ADS)

    Merhi, Abdul Rahman; Frank, Nathan; Gueye, Paul; Thoennessen, Michael; MoNA Collaboration

    2013-10-01

    A proposed segmented target would improve decay energy measurements of neutron-unbound nuclei. Experiments like this have been performed at the National Superconducting Cyclotron Laboratory (NSCL) located at Michigan State University. Many different nuclei are produced in such experiments, some of which immediately decay into a charged particle and neutron. The charged particles are bent by a large magnet and measured by a suite of charged particle detectors. The neutrons are measured by the Modular Neutron Array (MoNA) and Large Multi-Institutional Scintillation Array (LISA). With the current target setup, a nucleus in a neutron-unbound state is produced with a radioactive beam impinged upon a beryllium target. The resolution of these measurements is very dependent on the target thickness since the nuclear interaction point is unknown. In a segmented target using alternating layers of silicon detectors and Be-targets, the Be-target in which the nuclear reaction takes place would be determined. Thus the experimental resolution would improve. This poster will describe the improvement over the current target along with the status of the design. Work supported by Augustana College and the National Science Foundation grant #0969173.

  7. The design and analysis of a phased array microstrip antenna for a low earth orbit communication satellite

    NASA Astrophysics Data System (ADS)

    Barfield, William L.

    1994-06-01

    A Naval Postgraduate School spacecraft design class proposed a multiple beam, phased array, microstrip antenna as part of the preliminary design of a low earth orbit communication satellite. The antenna must provide coverage over the satellite's entire field of view while both uplink and down-link operate simultaneously on the same 1-band frequency. This thesis assesses the feasibility of the antenna proposed in that preliminary design. Design tradeoffs for a microstrip array constrained by both available surface area and a limited mass budget are examined. Two different substrate materials are considered in terms of weight and performance. Microstrip patch theory is applied to array element design and layout and antenna array theory is applied to determine phase and amplitude coefficients. The focus of the design is on obtaining the desired beam shape and orientation, given antenna size constraints. A corporate feed method is discussed and a general design presented. Antenna performance is predicted through the use of a computer model based on Modal Expansion theory and results are plotted in a series of graphs which demonstrate the limitations of the proposed design.

  8. Automatic colonic fold segmentation for computed tomography colonography

    NASA Astrophysics Data System (ADS)

    Zhu, Hongbin; Barish, Matthew; Li, Lihong; Song, Bowen; Harrington, Donald; Pickhardt, Perry; Liang, Zhengrong

    2012-03-01

    Human colon has complex structures mostly because of the haustral folds. Haustral folds are thin flat protrusions on the colon wall, which inherently attached on the colon wall. These structures may complicate the shape analysis for computer-aided detection of colonic polyps (CADpolyp); however, they can serve as solid reference during image interpretation in computed tomographic colonography (CTC). Therefore, in this study, based on a clear model of the haustral fold boundaries, we employ level set method to automatically segment the fold surfaces. We believe the segmented folds have the potential to significantly benefit various post-procedures in CTC, e.g., supine-prone registration, synchronized image interpretation, automatic polyp matching, CADpolyp, teniae coli extraction, etc. For the first time, with assistance from physician experts, we established the ground truth of haustral fold boundaries of 15 real patient data from two medical centers, based on which we evaluated our algorithm. The results demonstrated that about 92.7% of the folds are successfully detected. Furthermore, we explored the segmented area ratio (SAR), i.e., the ratio between the areas of the intersection and the union of the expert-drawn and the automatically-segmented folds, to measure the accuracy of the segmentation algorithm. The averaged result of SAR=86.2% shows a good match between the ground truth and our segmentation results.

  9. Image segmentation using random features

    NASA Astrophysics Data System (ADS)

    Bull, Geoff; Gao, Junbin; Antolovich, Michael

    2014-01-01

    This paper presents a novel algorithm for selecting random features via compressed sensing to improve the performance of Normalized Cuts in image segmentation. Normalized Cuts is a clustering algorithm that has been widely applied to segmenting images, using features such as brightness, intervening contours and Gabor filter responses. Some drawbacks of Normalized Cuts are that computation times and memory usage can be excessive, and the obtained segmentations are often poor. This paper addresses the need to improve the processing time of Normalized Cuts while improving the segmentations. A significant proportion of the time in calculating Normalized Cuts is spent computing an affinity matrix. A new algorithm has been developed that selects random features using compressed sensing techniques to reduce the computation needed for the affinity matrix. The new algorithm, when compared to the standard implementation of Normalized Cuts for segmenting images from the BSDS500, produces better segmentations in significantly less time.

  10. Segmented rail linear induction motor

    DOEpatents

    Cowan, Jr., Maynard; Marder, Barry M.

    1996-01-01

    A segmented rail linear induction motor has a segmented rail consisting of a plurality of nonferrous electrically conductive segments aligned along a guideway. The motor further includes a carriage including at least one pair of opposed coils fastened to the carriage for moving the carriage. A power source applies an electric current to the coils to induce currents in the conductive surfaces to repel the coils from adjacent edges of the conductive surfaces.

  11. Segmented rail linear induction motor

    DOEpatents

    Cowan, M. Jr.; Marder, B.M.

    1996-09-03

    A segmented rail linear induction motor has a segmented rail consisting of a plurality of nonferrous electrically conductive segments aligned along a guideway. The motor further includes a carriage including at least one pair of opposed coils fastened to the carriage for moving the carriage. A power source applies an electric current to the coils to induce currents in the conductive surfaces to repel the coils from adjacent edges of the conductive surfaces. 6 figs.

  12. Multiple-Segment Climbing Robots

    NASA Technical Reports Server (NTRS)

    Kerley, James; May, Edward; Eklund, Wayne

    1994-01-01

    Multiple-segment climbing robots developed to perform such tasks as inspection, sandblasting, welding, and painting on towers and other structures. Look and move like caterpillars. Video camera mounted on one of segments rotated to desired viewing angle. Used in remote inspection of structure, to view motion of robot and/or provides video feedback for control of motion, and/or to guide operation of head mounted on foremost segment with motorized actuators.

  13. Partially segmented deformable mirror

    DOEpatents

    Bliss, Erlan S.; Smith, James R.; Salmon, J. Thaddeus; Monjes, Julio A.

    1991-01-01

    A partially segmented deformable mirror is formed with a mirror plate having a smooth and continuous front surface and a plurality of actuators to its back surface. The back surface is divided into triangular areas which are mutually separated by grooves. The grooves are deep enough to make the plate deformable and the actuators for displacing the mirror plate in the direction normal to its surface are inserted in the grooves at the vertices of the triangular areas. Each actuator includes a transducer supported by a receptacle with outer shells having outer surfaces. The vertices have inner walls which are approximately perpendicular to the mirror surface and make planar contacts with the outer surfaces of the outer shells. The adhesive which is used on these contact surfaces tends to contract when it dries but the outer shells can bend and serve to minimize the tendency of the mirror to warp.

  14. Partially segmented deformable mirror

    DOEpatents

    Bliss, E.S.; Smith, J.R.; Salmon, J.T.; Monjes, J.A.

    1991-05-21

    A partially segmented deformable mirror is formed with a mirror plate having a smooth and continuous front surface and a plurality of actuators to its back surface. The back surface is divided into triangular areas which are mutually separated by grooves. The grooves are deep enough to make the plate deformable and the actuators for displacing the mirror plate in the direction normal to its surface are inserted in the grooves at the vertices of the triangular areas. Each actuator includes a transducer supported by a receptacle with outer shells having outer surfaces. The vertices have inner walls which are approximately perpendicular to the mirror surface and make planar contacts with the outer surfaces of the outer shells. The adhesive which is used on these contact surfaces tends to contract when it dries but the outer shells can bend and serve to minimize the tendency of the mirror to warp. 5 figures.

  15. Segmented field OFFGEL® electrophoresis.

    PubMed

    Tobolkina, Elena; Cortés-Salazar, Fernando; Momotenko, Dmitry; Maillard, Julien; Girault, Hubert H

    2012-11-01

    A multielectrode setup for protein OFFGEL electrophoresis that significantly improves protein separation efficiency has been developed. Here, the electric field is applied by segments between seven electrodes connected in series to six independent power supplies. The aim of this strategy is to distribute evenly the electric field along the multiwell system, and as a consequence to enhance electrophoresis in terms of separation time, resolution, and protein collection efficiency, while minimizing the overall potential difference and therefore the Joule heating. The performances were compared to a standard two-electrode setup for OFFGEL fractionation of a protein mixture, using UV-Vis spectroscopy for quantification and MALDI-MS for identification. The electrophoretic separation process was simulated, and optimized by solving the time-dependent Nernst-Planck differential equation. PMID:23086720

  16. Probabilistic retinal vessel segmentation

    NASA Astrophysics Data System (ADS)

    Wu, Chang-Hua; Agam, Gady

    2007-03-01

    Optic fundus assessment is widely used for diagnosing vascular and non-vascular pathology. Inspection of the retinal vasculature may reveal hypertension, diabetes, arteriosclerosis, cardiovascular disease and stroke. Due to various imaging conditions retinal images may be degraded. Consequently, the enhancement of such images and vessels in them is an important task with direct clinical applications. We propose a novel technique for vessel enhancement in retinal images that is capable of enhancing vessel junctions in addition to linear vessel segments. This is an extension of vessel filters we have previously developed for vessel enhancement in thoracic CT scans. The proposed approach is based on probabilistic models which can discern vessels and junctions. Evaluation shows the proposed filter is better than several known techniques and is comparable to the state of the art when evaluated on a standard dataset. A ridge-based vessel tracking process is applied on the enhanced image to demonstrate the effectiveness of the enhancement filter.

  17. Segmented heat exchanger

    DOEpatents

    Baldwin, Darryl Dean; Willi, Martin Leo; Fiveland, Scott Byron; Timmons, Kristine Ann

    2010-12-14

    A segmented heat exchanger system for transferring heat energy from an exhaust fluid to a working fluid. The heat exchanger system may include a first heat exchanger for receiving incoming working fluid and the exhaust fluid. The working fluid and exhaust fluid may travel through at least a portion of the first heat exchanger in a parallel flow configuration. In addition, the heat exchanger system may include a second heat exchanger for receiving working fluid from the first heat exchanger and exhaust fluid from a third heat exchanger. The working fluid and exhaust fluid may travel through at least a portion of the second heat exchanger in a counter flow configuration. Furthermore, the heat exchanger system may include a third heat exchanger for receiving working fluid from the second heat exchanger and exhaust fluid from the first heat exchanger. The working fluid and exhaust fluid may travel through at least a portion of the third heat exchanger in a parallel flow configuration.

  18. A microwave microstrip ring resonator as a moisture sensor for biomaterials: application to wheat grains

    NASA Astrophysics Data System (ADS)

    Abegaonkar, Mahesh P.; Karekar, R. N.; Aiyer, R. C.

    1999-03-01

    A miniaturized, non-destructive sensor employing a microwave microstrip ring resonator (MRR, 0957-0233/10/3/014/img1 GHz, mean diameter 3.69 mm) was developed for estimating the moisture content of a single wheat ( Triticum aestivum L) grain. A single wheat grain with a known amount of moisture was placed on the MRR at two different orientations (0957-0233/10/3/014/img2 and 0957-0233/10/3/014/img3) with respect to the feedline. The resonance frequency 0957-0233/10/3/014/img4, bandwidth (B) and quality factor 0957-0233/10/3/014/img5 of the MRR were calibrated against the moisture content. The measurements were made with a scalar network analyser. The sensor was studied in the normal useful moisture range of 11-32% (on a wet-weight basis), the actual moisture values being obtained by an oven-drying method. The 0957-0233/10/3/014/img2 orientation was more sensitive to moisture than was the 0957-0233/10/3/014/img3 orientation. The total changes in 0957-0233/10/3/014/img8 for a 21% change in moisture content for 0957-0233/10/3/014/img2 and 900957-0233/10/3/014/img10 orientations were 235 and 150 MHz, respectively. The errors in moisture estimation with 0957-0233/10/3/014/img8 for 0957-0233/10/3/014/img2 and 0957-0233/10/3/014/img3 were 0957-0233/10/3/014/img14% and 0957-0233/10/3/014/img15%, respectively. The corresponding values with B and 0957-0233/10/3/014/img16 for 0957-0233/10/3/014/img3 orientation were 0957-0233/10/3/014/img18% and 0957-0233/10/3/014/img19%, respectively. The proposed sensor is more sensitive than a reported waveguide resonator and is easy to operate, for the microstrip offers an open structure, thereby facilitating easy loading and unloading of the samples.

  19. Current Status of Thin Film (Ba,Sr) TiO3 Tunable Microwave Components for RF Communications

    NASA Technical Reports Server (NTRS)

    VanKeuls, F. W.; Romananofsky, R. R.; Mueller, C. H.; Warner, J. D.; Canedy, C. L.; Ramesh, R.; Miranda, F. A.

    2000-01-01

    The performance of proof-of-concept ferroelectric microwave devices has been moving steadily closer to the level needed for satellite and other rf communications applications. This paper will review recent progress at NASA Glenn in developing thin film Ba(x)Sr(1-x)TiO3 tunable microwave components for these applications. Phase shifters for phased array antennas, tunable filters and tunable oscillators employing microstrip and coupled microstrip configurations will be presented. Tunabilities, maximum dielectric constants, and phase shifter parameters will be discussed (e.g., coupled microstrip phase shifters with phase shift over 200 deg. at 18 GHz and a figure of merit of 74.3 deg./dB). Issues of postannealing, Mn-doping and Ba(x)Sr(1-x)TiO3 growth on sapphire and alumina substrates will be covered. The challenges of incorporating these devices into larger systems, such as yield, variability in phase shift and insertion loss, and protective coatings will also be addressed.

  20. Asteroid Redirect Mission: Robotic Segment

    NASA Video Gallery

    This concept animation illustrates the robotic segment of NASA's Asteroid Redirect Mission. The Asteroid Redirect Vehicle, powered by solar electric propulsion, travels to a large asteroid to robot...

  1. Compatibility of segmented thermoelectric generators

    NASA Technical Reports Server (NTRS)

    Snyder, J.; Ursell, T.

    2002-01-01

    It is well known that power generation efficiency improves when materials with appropriate properties are combined either in a cascaded or segmented fashion across a temperature gradient. Past methods for determining materials used in segmentation weremainly concerned with materials that have the highest figure of merit in the temperature range. However, the example of SiGe segmented with Bi2Te3 and/or various skutterudites shows a marked decline in device efficiency even though SiGe has the highest figure of merit in the temperature range. The origin of the incompatibility of SiGe with other thermoelectric materials leads to a general definition of compatibility and intrinsic efficiency. The compatibility factor derived as = (Jl+zr - 1) a is a function of only intrinsic material properties and temperature, which is represented by a ratio of current to conduction heat. For maximum efficiency the compatibility factor should not change with temperature both within a single material, and in the segmented leg as a whole. This leads to a measure of compatibility not only between segments, but also within a segment. General temperature trends show that materials are more self compatible at higher temperatures, and segmentation is more difficult across a larger -T. The compatibility factor can be used as a quantitative guide for deciding whether a material is better suited for segmentation orcascading. Analysis of compatibility factors and intrinsic efficiency for optimal segmentation are discussed, with intent to predict optimal material properties, temperature interfaces, and/or currentheat ratios.

  2. Automated medical image segmentation techniques

    PubMed Central

    Sharma, Neeraj; Aggarwal, Lalit M.

    2010-01-01

    Accurate segmentation of medical images is a key step in contouring during radiotherapy planning. Computed topography (CT) and Magnetic resonance (MR) imaging are the most widely used radiographic techniques in diagnosis, clinical studies and treatment planning. This review provides details of automated segmentation methods, specifically discussed in the context of CT and MR images. The motive is to discuss the problems encountered in segmentation of CT and MR images, and the relative merits and limitations of methods currently available for segmentation of medical images. PMID:20177565

  3. Performance Enhancement of Tunable Bandpass Filters Using Selective Etched Ferroelectric Thin Films

    NASA Technical Reports Server (NTRS)

    Miranda, Felix A.; Mueller, Carl H.; VanKeuls, Fred W.; Subramanyam, Guru; Vignesparamoorthy, Sivaruban

    2003-01-01

    The inclusion of voltage-tunable barium strontium titanate (BSTO) thin films into planar band pass filters offers tremendous potential to increase their versatility. The ability to tune the passband so as to correct for minor deviations in manufacturing tolerances, or to completely reconfigure the operating frequencies of a microwave communication system, are highly sought-after goals. However, use of ferroelectric films in these devices results in higher dielectric losses, which in turn increase the insertion loss and decrease the quality factors of the filters. This study explores the use of patterned ferroelectric layers to minimize dielectric losses without degrading tunability. Patterning the ferroelectric layers enables us to constrict the width of the ferroelectric layers between the coupled microstrip lines, and minimize losses due to ferroelectric layers. Coupled one-pole microstrip bandpass filters with fundamental resonances at approx. 7.2 GHz and well defined harmonic resonances at approx. 14.4 and approx. 21.6 GHz, were designed, simulated and tested. For one of the filters, experimental results verified that its center frequency was tunable by 528 MHz at a center frequency of 21.957 GHz, with insertion losses varying from 4.3 to 2.5 dB, at 0 and 3.5 V/micron, respectively. These data demonstrate that the tuning-to-loss figure of merit of tunable microstrip filters can be greatly improved using patterned ferroelectric thin films as the tuning element, and tuning can be controlled by engineering the ferroelectric constriction in the coupled sections.

  4. Segmenting Words from Natural Speech: Subsegmental Variation in Segmental Cues

    ERIC Educational Resources Information Center

    Rytting, C. Anton; Brew, Chris; Fosler-Lussier, Eric

    2010-01-01

    Most computational models of word segmentation are trained and tested on transcripts of speech, rather than the speech itself, and assume that speech is converted into a sequence of symbols prior to word segmentation. We present a way of representing speech corpora that avoids this assumption, and preserves acoustic variation present in speech. We…

  5. Automatic Jet Contrail Detection and Segmentation

    NASA Technical Reports Server (NTRS)

    Weiss, J.; Christopher, S. A.; Welch, R. M.

    1997-01-01

    Jet contrails are an important subset of cirrus clouds in the atmosphere, and thin cirrus are thought to enhance the greenhouse effect due to their semi-transparent nature. They are nearly transparent to the solar energy reaching the surface, but they reduce the planetary emission to space due to their cold ambient temperatures. Having 'seeded' the environment, contrails often elongate and widen into cirrus-like features. However, there is great uncertainty regarding the impact of contrails on surface temperature and precipitation. With increasing numbers of subsonic aircraft operating in the upper troposphere, there is the possibility of increasing cloudiness which could lead to changes in the radiation balance. Automatic detection and seg- mentation of jet contrails in satellite imagery is important because (1) it is impractical to compile a contrail climatology by hand, and (2) with the segmented images it will be possible to retrieve contrail physical properties such as optical thickness, effective ice crystal diameter and emissivity.

  6. A Compact and Broadband Differential Microstrip Line to Rectangular Waveguide Transition Using Dipole Antenna

    NASA Astrophysics Data System (ADS)

    Yang, Ziqiang; Yang, Tao; Liu, Yu; Peng, Hao

    2016-02-01

    In this paper, a compact full Ka-band differential microstrip line (DML) to rectangular waveguide transition is proposed. The dipole antenna with semi-elliptic arms is introduced to transform the differential mode of DML to the TE10 mode of the rectangular waveguide directly. The two arms of the dipole antenna are connected together by a shorting strip to reduce the size of the dipole. Compared with the DML-to-waveguide transition using the fin-line topology, the size of the proposed transition has been reduced by 86 %. To verify this transition, a back-to-back structure is fabricated and tested. It provides a return loss of better than 15.2 dB and an insertion loss of 0.73 to 1.07 dB within a wide frequency range from 26.5 to 40 GHz. The measurement results show good agreement with the simulation results. Furthermore, a tolerance analysis is also performed via the simulation to prove that this transition is robust in the fabrication and mechanical assembly.

  7. Compact microstrip lowpass filter with wide stopband and sharp roll-off using tapered resonator

    NASA Astrophysics Data System (ADS)

    Hayati, Mohsen; Shama, Farzin; Abbasi, Hamed

    2013-12-01

    In this article, a novel microstrip lowpass filter (LPF) with specifications such as sharp cut-off, wide stopband, low insertion loss and high return loss using tapered resonator is presented. The LPF has cut-off frequency of 1.11 GHz, where unwanted harmonics are suppressed by novel tapered cells. The bandwidth is enhanced, and the size is reduced as compared to the conventional tapered filter. The transition band is approximately 0.29 GHz from 1.11 to 1.4 GHz with corresponding attenuation levels of -3 and -20 dB, respectively. The stopband with greater than -20 dB rejection is from 1.4 to 8.9 GHz, insertion loss in the passband is less than 0.1 dB, return loss is less than -18 dB and the overall size of the filter is 0.12 × 0.073 λg. The proposed filter is fabricated and measured. The simulation and measurement results are in good agreement. This LPF is designed for microwave communication applications, especially wireless video transmitters.

  8. Wideband Gap Coupled Assembly of Rectangular Microstrip Patches for Wi-Max Applications

    NASA Astrophysics Data System (ADS)

    Sharma, Vijay; Sharma, M. M.

    2014-01-01

    This paper presents a wideband gap coupled assembly of rectangular microstrip patches applicable in lower and upper band of Wi-Max applications utilizing six directly and parasitically coupled patches. Considered assembly of patches on glass epoxy FR4 substrate has overall dimension of 40.0 mm by 52.88 mm. The proposed antenna is designed to function in the lower band (2.4-2.69 GHz) and upper band (5.25-5.85 GHz) of Wi-Max systems. The antenna is simulated using IE3D simulation software in view of the Wi-Max standards adopted by IEEE 802.16 working group. The simulated and measured results are well in agreement and show that antenna resonates in two bands proposed for wireless communication applications and successfully achieves the bandwidth of 11.2% (at VSWR: 1.5) with respect to the center frequency of 2.84 GHz in lower band and 9.7% with respect to the center frequency of 5.39 GHz in upper band. Gain and efficiency of antenna in these two bands are however low due to lossy substrate but radiation patterns in each of these two bands are identical in shape in entire bandwidth region. In lower band maximum radiations may be achieved normal to patch geometry but in upper band, direction of maximum radiations is inclined at θ = 60° perhaps due to the generation of higher mode.

  9. Design of cross-coupled planar microstrip band-pass filters using a novel adjustment method

    NASA Astrophysics Data System (ADS)

    Alkafaji, Muhammed S. S.

    2015-02-01

    In this paper the design of a cross-coupled planar microwave band-pass filter using open-loop square microstrip resonators, with two symmetrically placed attenuation poles, is presented. The design starts from the following specifications: central frequency 3GHz, 150MHz bandwidth, 1dB ripple in the pass-band corresponding to return loss of 6.8dB.The adjustment method using additional ports placed on each resonator of the filter is used, allowing the interconnection of the filter structure with external lumped elements. Connecting a reactive element (capacitor) from such an additional port to ground allows a fine tuning of the resonator. Connecting a reactive element between two such additional ports allows a fine change in the coupling coefficient between these resonators. After adding four extra ports and connecting the external elements (capacitors), it is possible to use fast circuit simulation software to optimize the filter's response. Then all these capacitors have to be gradually eliminated, by compensating their effects through fine changes back in the layouts. If some specific issues are properly handled, this procedure improves considerably the quality of the final design of the filter. After a thorough optimization of the layout, the filter was fabricated and measured. The results of measurements are in good agreement with the specifications of the filter, showing this way the efficiency of the applied optimization method.

  10. Domain wall dynamics of periodic magnetic domain patterns in Co2MnGe-Heusler microstripes

    NASA Astrophysics Data System (ADS)

    Gross, K.; Westerholt, K.; Zabel, H.

    2016-03-01

    Highly symmetric periodic domain patterns were obtained in Co2MnGe-Heusler microstripes as a result of the competition between growth-induced in-plane magnetic anisotropy and shape anisotropy. Zero field magnetic configurations and magnetic field-induced domain wall (DW) motion were studied by magnetic force microscopy-image technique for two different cases: dominant uniaxial- and dominant cubic in-plane anisotropy. We implemented a magneto-optical Kerr effect susceptometer to investigate the DW dynamics of periodic domain structures by measuring the in-phase and out-of-phase components of the Kerr signal as a function of magnetic field frequency and amplitude. The DW dynamics for fields applied transversally to the long stripe axis was found to be dominated by viscous slide motion. We used the inherent symmetry/periodicity properties of the magnetic domain structure to fit the experimental results with a theoretical model allowing to extract the DW mobility for the case of transverse DWs (μ TDW = 1.1 m s-1 Oe-1) as well as for vortex-like DWs (μ VDW = 8.7 m s-1 Oe-1). Internal spin structure transformations may cause a reduction of DW mobility in TDWs as observed by OMMFF simulations.

  11. The design of a microstrip antenna array for a UHF space telemetry link

    NASA Technical Reports Server (NTRS)

    Post, R. E.; Stephenson, D. T.

    1981-01-01

    An array of microstrip antenna panels was designed for use on a small instrumented satellite as part of a 400-MHz telemetry link between that satellite and NASA's shuttle spacecraft. A roughly omnidirectional phi-plane pattern was desired. The 1.4-wavelength diameter of the satellite and the various ports and structures on its surface presented strong constraints on the antenna array design. Eight antennas, each one a quarter-wavelength panel with one radiating and one shorted edge, were chosen. A phi-plane pattern ripple of 4.4 dB and a gain of at least 0.1 dB relative to a half-wavelength dipole were realized. The design technique used for the individual antenna panels included the study of feed-point location for impedance matching and the effect of losses in the dielectric. A superposition method was used to synthesize the radiation patterns for different numbers and different excitations of antennas on the satellite.

  12. Precision Electron-Beam Polarimetry at 1 GeV Using Diamond Microstrip Detectors

    NASA Astrophysics Data System (ADS)

    Narayan, A.; Jones, D.; Cornejo, J. C.; Dalton, M. M.; Deconinck, W.; Dutta, D.; Gaskell, D.; Martin, J. W.; Paschke, K. D.; Tvaskis, V.; Asaturyan, A.; Benesch, J.; Cates, G.; Cavness, B. S.; Dillon-Townes, L. A.; Hays, G.; Ihloff, E.; Jones, R.; King, P. M.; Kowalski, S.; Kurchaninov, L.; Lee, L.; McCreary, A.; McDonald, M.; Micherdzinska, A.; Mkrtchyan, A.; Mkrtchyan, H.; Nelyubin, V.; Page, S.; Ramsay, W. D.; Solvignon, P.; Storey, D.; Tobias, A.; Urban, E.; Vidal, C.; Waidyawansa, B.; Wang, P.; Zhamkotchyan, S.

    2016-01-01

    We report on the highest precision yet achieved in the measurement of the polarization of a low-energy, O (1 GeV ) , continuous-wave (CW) electron beam, accomplished using a new polarimeter based on electron-photon scattering, in Hall C at Jefferson Lab. A number of technical innovations were necessary, including a novel method for precise control of the laser polarization in a cavity and a novel diamond microstrip detector that was able to capture most of the spectrum of scattered electrons. The data analysis technique exploited track finding, the high granularity of the detector, and its large acceptance. The polarization of the 180 -μ A , 1.16-GeV electron beam was measured with a statistical precision of <1 % per hour and a systematic uncertainty of 0.59%. This exceeds the level of precision required by the Qweak experiment, a measurement of the weak vector charge of the proton. Proposed future low-energy experiments require polarization uncertainty <0.4 %, and this result represents an important demonstration of that possibility. This measurement is the first use of diamond detectors for particle tracking in an experiment. It demonstrates the stable operation of a diamond-based tracking detector in a high radiation environment, for two years.

  13. The silicon micro-strip detector plane for the LOFT/wide-field monitor

    NASA Astrophysics Data System (ADS)

    Goldwurm, A.; Ferrando, P.; Götz, D.; Laurent, P.; Lebrun, F.; Limousin, O.; Basa, S.; Bertoli, W.; Delagnes, Eric; Dolgorouky, Y.; Gevin, O.; Gros, A.; Gouiffes, C.; Jeanneau, F.; Lachaud, C.; Llored, M.; Olivetto, C.; Prevot, G.; Renaud, D.; Rodriguez, J.; Rossin, C.; Schanne, S.; Soldi, S.; Varniere, P.

    2012-09-01

    The main objective of the Wide Field Monitor (WFM) on the LOFT mission is to provide unambiguous detection of the high-energy sources in a large field of view, in order to support science operations of the LOFT primary instrument, the LAD. The monitor will also provide by itself a large number of results on the timing and spectral behavior of hundreds of galactic compact objects, Active Galactic Nuclei and Gamma-Ray Bursts. The WFM is based on the coded aperture concept where a position sensitive detector records the shadow of a mask projected by the celestial sources. The proposed WFM detector plane, based on Double Sided micro-Strip Silicon Detectors (DSSD), will allow proper 2-dimensional recording of the projected shadows. Indeed the positioning of the photon interaction in the detector with equivalent fine resolution in both directions insures the best imaging capability compatible with the allocated budgets for this telescope on LOFT. We will describe here the overall configuration of this 2D-WFM and the design and characteristics of the DSSD detector plane including its imaging and spectral performances. We will also present a number of simulated results discussing the advantages that this configuration offers to LOFT. A DSSD-based WFM will in particular reduce significantly the source confusion experienced by the WFM in crowded regions of the sky like the Galactic Center and will in general increase the observatory science capability of the mission.

  14. Afterglow of a microwave microstrip plasma as an ion source for mass spectrometry

    NASA Astrophysics Data System (ADS)

    Pfeuffer, Kevin P.; White, Allen; Broekaert, José A. C.; Hieftje, Gary M.

    2015-01-01

    A microwave-induced plasma that was previously used for optical emission spectrometry has been repurposed as an afterglow ion source for mass spectrometry. This compact microwave discharge, termed the microstrip plasma (MSP), is operated at 20-50 W and 2.45 GHz in helium at a flow of 300 mL/min. The primary background ions present in the afterglow are ionized and protonated water clusters. An exponential dilution chamber was used to introduce volatile organic compounds into the MSP afterglow and yielded limits of detection in the 40 ppb to 7 ppm range (v/v). A hydride-generation system was also utilized for detection of volatile hydride-forming elements (arsenic, antimony, tin) in the afterglow and produced limits of detection in the 10-100 ppb range in solution. The MSP afterglow was found capable of desorption and ionization of analyte species directly from a solid substrate, suggesting its use as an ion source for ambient desorption/ionization mass spectrometry.

  15. Tests of Radiation-Hard Silicon Microstrip Sensors for CMS in S-LHC

    SciTech Connect

    Luukka, Panja; Maenpaa, Teppo; Tuovinen, Esa; Spiegel, Lenny; Flight, Robert; /Rochester U.

    2011-02-21

    The tests are to study the performance of various silicon microstrip sensors that are sufficiently radiation-hard to be considered as candidates for the CMS outer (R > 25cm) tracker in the second phase of the currently envisioned S-LHC upgrade. The main goal of the beam test is to test Float Zone (FZ) and Magnetic Czochralski (MCz) silicon sensors that have been procured from Hamamatsu by the CMS collaboration as possible replacements for the CMS outer tracker for phase 2 operations. The detectors under test (DUT) will be isntalled in a cold box that contains 10 slots for modules based on CMS Tracker hybrids. Slots 1-4 and 7-10 are occupied by reference planes and slots 5 and 6 are reserved for DUTs. The box is cooled by Peltier elements in thermal contact with the top and bottom aluminum baseplates and is typically operated at around -25 C. A PCI based version of the CMS DAQ is used to read out the 10 slots based on triggers provided by beam scintillation counters. Given the low rate of beam particles the hybrid APVs will be operated in Peak mode, which maximizes the signal-to-noise performance of the readout chips. The internal clock operates at the LHC frequency of 40 MHz.

  16. Development of a silicon-microstrip super module prototype for the high luminosity LHC

    NASA Astrophysics Data System (ADS)

    Clark, A.; Barbier, G.; Cadoux, F.; Endo, M.; Favre, Y.; Ferrere, D.; Gonzalez-Sevilla, S.; Hanagaki, K.; Hara, K.; Iacobucci, G.; Ikegami, Y.; Koriki, T.; La Marra, D.; Pohl, M.; Takubo, Y.; Terada, S.; Unno, Y.; Weber, M.

    2013-01-01

    Following the Phase II upgrade of the CERN Large Hadron Collider (LHC) currently foreseen in 2022-2023, the High Luminosity LHC (HL-LHC) is expected to deliver a peak luminosity in excess of 5×1034 cm-2 s-1 and an integrated luminosity of order 3000 fb-1 until 2033. The ATLAS Collaboration plans to replace the existing Inner Tracking Detector by a new tracker, with readout electronics as well as silicon pixel and strip sensor technology capable of maintaining the excellent tracking performance of the existing tracker in the severe radiation and high collision rate environment of the HL-LHC. The promising super-module integration concept extends the proven design of the existing barrel silicon strip tracker to the HL-LHC, with double-sided stereo silicon micro-strip modules assembled into a low mass local support structure. The Super-Module R&D program is described, with reference to HL-LHC requirements, and key prototype results are summarized.

  17. Boron imaging with a microstrip silicon detector for applications in BNCT

    NASA Astrophysics Data System (ADS)

    Mattera, A.; Basilico, F.; Bolognini, D.; Borasio, P.; Cappelletti, P.; Chiari, P.; Conti, V.; Frigerio, M.; Gelosa, S.; Giannini, G.; Hasan, S.; Mascagna, V.; Mauri, P.; Monti, A. F.; Mozzanica, A.; Ostinelli, A.; Prest, M.; Scazzi, S.; Vallazza, E.; Zanini, A.

    2009-06-01

    Boron Neutron Capture Therapy (BNCT) is a radiotherapic technique exploiting the α particles produced after the irradiation of the isotope 10 of boron with thermal neutrons in the capture reaction B(n,α)710Li. It is used to treat tumours that for their features (radioresistance, extension, localization near vital organs) cannot be treated through conventional photon-beams radiotherapy. One of the main limitations of this technique is the lack of specificity (i.e. the ability of localizing in tumour cells, saving the healthy tissues) of the compounds used to carry the 10B isotope in the organs to be treated. This work, developed in the framework of the INFN PhoNeS project, describes the possibility of boron imaging performed exploiting the neutrons photoproduced by a linac (the Clinac 2100C/D of the S. Anna Hospital Radiotherapy Unit in Como, Italy) and detecting the α s with a non-depleted microstrip silicon detector: the result is a 1D scan of the boron concentration. Several boron doped samples have been analysed, from solutions of H3BO3 (reaching a minimum detectable amount of 25 ng of 10B) to biological samples of urine containing BPA and BSH (the two molecules currently used for the clinical trials in BNCT) in order to build kinetic curves (showing the absolute 10B concentration as a function of time). Further measurements are under way to test the imaging system with 10BPA-Fructose complex perfused human lung samples.

  18. Bistability and hysteresis in the emergence of pulses in microstrip Gunn-diode circuits

    SciTech Connect

    Yurchenko, V. B.; Yurchenko, L. V.

    2014-12-15

    We develop time-domain simulations of microwave and THz radiation sources built as arrays of active devices when the radiation wavelength is small as compared to spacing between electronic components. We pursue an approach when the system is represented by equations with time-delay feedback that could generate chaos and other forms of complicated dynamics. The approach simplifies simulations of ultra-wideband effects and exceeds capabilities of frequency-domain methods. As a model case, we simulated a microstrip circuit with Gunn diode and a remote resonator emitting the radiation towards infinity. We observed the emergence of either the continuous waves or the trains of high-frequency pulses depending on the bias conditions. We found bistability and hysteresis in the onset of different oscillation modes that depends on the way of driving the bias voltage into the domain of instability of the given system. The results would allow one to improve the design of THz radiation sources with time-delay coupling between components.

  19. Low-Cost Dielectric Substrate for Designing Low Profile Multiband Monopole Microstrip Antenna

    PubMed Central

    Ahsan, M. R.; Islam, M. T.; Habib Ullah, M.; Arshad, H.; Mansor, M. F.

    2014-01-01

    This paper proposes a small sized, low-cost multiband monopole antenna which can cover the WiMAX bands and C-band. The proposed antenna of 20 × 20 mm2 radiating patch is printed on cost effective 1.6 mm thick fiberglass polymer resin dielectric material substrate and fed by 4 mm long microstrip line. The finite element method based, full wave electromagnetic simulator HFSS is efficiently utilized for designing and analyzing the proposed antenna and the antenna parameters are measured in a standard far-field anechoic chamber. The experimental results show that the prototype of the antenna has achieved operating bandwidths (voltage stand wave ratio (VSWR) less than 2) 360 MHz (2.53–2.89 GHz) and 440 MHz (3.47–3.91 GHz) for WiMAX and 1550 MHz (6.28–7.83 GHz) for C-band. The simulated and measured results for VSWR, radiation patterns, and gain are well matched. Nearly omnidirectional radiation patterns are achieved and the peak gains are of 3.62 dBi, 3.67 dBi, and 5.7 dBi at 2.66 GHz, 3.65 GHz, and 6.58 GHz, respectively. PMID:25136648

  20. Wide Bandpass and Narrow Bandstop Microstrip Filters based on Hilbert fractal geometry: design and simulation results.

    PubMed

    Mezaal, Yaqeen S; Eyyuboglu, Halil T; Ali, Jawad K

    2014-01-01

    This paper presents new Wide Bandpass Filter (WBPF) and Narrow Bandstop Filter (NBSF) incorporating two microstrip resonators, each resonator is based on 2nd iteration of Hilbert fractal geometry. The type of filter as pass or reject band has been adjusted by coupling gap parameter (d) between Hilbert resonators using a substrate with a dielectric constant of 10.8 and a thickness of 1.27 mm. Numerical simulation results as well as a parametric study of d parameter on filter type and frequency responses are presented and studied. WBPF has designed at resonant frequencies of 2 and 2.2 GHz with a bandwidth of 0.52 GHz, -28 dB return loss and -0.125 dB insertion loss while NBSF has designed for electrical specifications of 2.37 GHz center frequency, 20 MHz rejection bandwidth, -0.1873 dB return loss and 13.746 dB insertion loss. The proposed technique offers a new alternative to construct low-cost high-performance filter devices, suitable for a wide range of wireless communication systems. PMID:25536436

  1. Low-cost dielectric substrate for designing low profile multiband monopole microstrip antenna.

    PubMed

    Ahsan, M R; Islam, M T; Habib Ullah, M; Arshad, H; Mansor, M F

    2014-01-01

    This paper proposes a small sized, low-cost multiband monopole antenna which can cover the WiMAX bands and C-band. The proposed antenna of 20 × 20 mm(2) radiating patch is printed on cost effective 1.6 mm thick fiberglass polymer resin dielectric material substrate and fed by 4 mm long microstrip line. The finite element method based, full wave electromagnetic simulator HFSS is efficiently utilized for designing and analyzing the proposed antenna and the antenna parameters are measured in a standard far-field anechoic chamber. The experimental results show that the prototype of the antenna has achieved operating bandwidths (voltage stand wave ratio (VSWR) less than 2) 360 MHz (2.53-2.89 GHz) and 440 MHz (3.47-3.91 GHz) for WiMAX and 1550 MHz (6.28-7.83 GHz) for C-band. The simulated and measured results for VSWR, radiation patterns, and gain are well matched. Nearly omnidirectional radiation patterns are achieved and the peak gains are of 3.62 dBi, 3.67 dBi, and 5.7 dBi at 2.66 GHz, 3.65 GHz, and 6.58 GHz, respectively. PMID:25136648

  2. Compact Double-P Slotted Inset-Fed Microstrip Patch Antenna on High Dielectric Substrate

    PubMed Central

    Ahsan, M. R.; Islam, M. T.; Habib Ullah, M.; Mahadi, W. N. L.; Latef, T. A.

    2014-01-01

    This paper presents a compact sized inset-fed rectangular microstrip patch antenna embedded with double-P slots. The proposed antenna has been designed and fabricated on ceramic-PTFE composite material substrate of high dielectric constant value. The measurement results from the fabricated prototype of the antenna show −10 dB reflection coefficient bandwidths of 200 MHz and 300 MHz with center resonant frequency of 1.5 GHz and 4 GHz, respectively. The fabricated antenna has attained gains of 3.52 dBi with 81% radiation efficiency and 5.72 dBi with 87% radiation efficiency for lower band and upper band, respectively. The measured E- and H-plane radiation patterns are also presented for better understanding. Good agreement between the simulation and measurement results and consistent radiation patterns make the proposed antenna suitable for GPS and C-band applications. PMID:25165750

  3. Wide Bandpass and Narrow Bandstop Microstrip Filters Based on Hilbert Fractal Geometry: Design and Simulation Results

    PubMed Central

    Mezaal, Yaqeen S.; Eyyuboglu, Halil T.; Ali, Jawad K.

    2014-01-01

    This paper presents new Wide Bandpass Filter (WBPF) and Narrow Bandstop Filter (NBSF) incorporating two microstrip resonators, each resonator is based on 2nd iteration of Hilbert fractal geometry. The type of filter as pass or reject band has been adjusted by coupling gap parameter (d) between Hilbert resonators using a substrate with a dielectric constant of 10.8 and a thickness of 1.27 mm. Numerical simulation results as well as a parametric study of d parameter on filter type and frequency responses are presented and studied. WBPF has designed at resonant frequencies of 2 and 2.2 GHz with a bandwidth of 0.52 GHz, −28 dB return loss and −0.125 dB insertion loss while NBSF has designed for electrical specifications of 2.37 GHz center frequency, 20 MHz rejection bandwidth, −0.1873 dB return loss and 13.746 dB insertion loss. The proposed technique offers a new alternative to construct low-cost high-performance filter devices, suitable for a wide range of wireless communication systems. PMID:25536436

  4. A Compact and Broadband Differential Microstrip Line to Rectangular Waveguide Transition Using Dipole Antenna

    NASA Astrophysics Data System (ADS)

    Yang, Ziqiang; Yang, Tao; Liu, Yu; Peng, Hao

    2016-06-01

    In this paper, a compact full Ka-band differential microstrip line (DML) to rectangular waveguide transition is proposed. The dipole antenna with semi-elliptic arms is introduced to transform the differential mode of DML to the TE10 mode of the rectangular waveguide directly. The two arms of the dipole antenna are connected together by a shorting strip to reduce the size of the dipole. Compared with the DML-to-waveguide transition using the fin-line topology, the size of the proposed transition has been reduced by 86 %. To verify this transition, a back-to-back structure is fabricated and tested. It provides a return loss of better than 15.2 dB and an insertion loss of 0.73 to 1.07 dB within a wide frequency range from 26.5 to 40 GHz. The measurement results show good agreement with the simulation results. Furthermore, a tolerance analysis is also performed via the simulation to prove that this transition is robust in the fabrication and mechanical assembly.

  5. Design of Compact Penta-Band and Hexa-Band Microstrip Antennas

    NASA Astrophysics Data System (ADS)

    Srivastava, Kunal; Kumar, Ashwani; Kanaujia, Binod K.

    2016-03-01

    This paper presents the design of two multi-band microstrip antennas. The antenna-1 gives Penta-Band and antenna-2 gives Hexa-band in the WLAN band. The frequency bands of the antenna-1 are Bluetooth 2.47 GHz (2.43 GHz-2.54 GHz), WiMax band 3.73 GHz (3.71 GHz-3.77 GHz), WLAN 5.1 GHz (4.99 GHz-5.13 GHz), upper WLAN 6.36 GHz (6.29 GHz-6.43 GHz), C band band 7.42 GHz (7.32 GHz-7.50 GHz) and the antenna-2 are WLAN band 2.6 GHz (2.56 GHz-2.63 GHz), 3.0 GHz (2.94 GHz-3.05 GHz), WiMax band 3.4 GHz (3.34 GHz-3.55 GHz), 4.85 GHz (4.81 GHz-4.92 GHz), WLAN 5.3 GHz (5.27 GHz-5.34 GHz) and upper WLAN 6.88 GHz. Both the antennas are fabricated and their measured results are presented to validate the simulated results. Proposed antennas have compact sizes and good radiation performances.

  6. High pressure multiwire proportional and gas microstrip chambers for medical radiology

    NASA Astrophysics Data System (ADS)

    Babichev, E. A.; Baru, S. E.; Khabakhpashev, A. G.; Kolachev, G. M.; Neustroev, V. V.; Pestov, Yu. N.; Ponomarev, O. A.; Savinov, G. M.; Shekhtman, L. I.; Martinez-Davalos, A.; Speller, R. D.; Miller, D. J.

    1995-02-01

    Application of MultiWire Proportional Chambers (MWPC) and MicroStrip Gas Chambers (MSGC) in medical radiography is discussed. These detectors are capable of detecting X-rays in counting mode with high efficiency, thus giving essential dose reduction compared to film/screen techniques. This was demonstrated on several Digital Radiographic Devices (DRD) with one-dimensional MWPC and scanning in the orthogonal direction. Effective pixel sizes of 1 mm and 0.5 mm for different devices with highly parallel readout systems has been achieved. The counting rate capability of DRDs is ˜ 500 kHz/pixel, which is enough to get high statistics of X-rays with a short exposure. Dose saving factors from 1 to 2 orders of magnitude for several common examinations were demonstrated. Further development of this approach can be made with MSGC which reproduce operation of MWPC in a much smaller scale. First tests of prototype chambers with 200 μm pitch of strips at high pressure have shown the possibility to reach a gain of ˜ 10 4 in a 6 bar Xe mixture. A proper choice of substrate material permits one to avoid charging problems at high fluxes. These features allow, one to build a counting device with 0.2 mm pixels for the detection of X-rays of 20-60 keV.

  7. SPICE evaluation of the S/N ratio for Si microstrip detectors

    SciTech Connect

    Candelori, A.; Paccagnella, A.; Nardi, F.; Bacchetta, N.; Bisello, D.

    1999-10-01

    SPICE simulations of ac-coupled single-sided Si microstrip detectors connected to the PreShape 32 read-out chip have been performed in order to determine the geometrical characteristics (i.e., the strip pitch p and width w) which maximize the signal-to-noise ratio. All of the resistive and capacitive elements of the detector have been determined as a function of the w/p ratio by considering experimental and simulated data available in literature. The SPICE model the authors propose in this work takes into account all the main noise sources in the detector and read-out electronics. The minimum ionizing particle current signal shape has been introduced in the simulations. Two read-out configurations (every strip or every second strip) have been investigated for 6.4- and 12.8-cm-long detectors. The equivalent noise charge as determined by the simulations has been compared with analytical calculations, in order to determine the limits and the corrections to a simplified analytical noise model. Finally, general guidelines for the detector design have been proposed, based on the simulation results.

  8. Planar architecture for microstrip interfaced packaging of coplanar-waveguide-based radio frequency microelectromechanical system switches

    NASA Astrophysics Data System (ADS)

    Singh, Shailendra; Giridhar, Malalahalli Sreenivasamurthy; Rao, Cheemalamarri Venkata Narasimha; Bhalke, Sangam; Islam, Rifqul

    2015-01-01

    This paper describes the architecture of microstrip (MS) interfaced packaging of a coplanar-waveguide (CPW)-based radio frequency microelectromechanical systems (RF MEMS) switch in a hermetic metal-ceramic RF package. The switch is integrated along with CPW to MS (CPW-MS) transitions within the package itself. This makes the MS interfaced packaged switch module readily mountable on MS based RF boards and subsystems. The CPW-MS transition for the package was designed as a separate off-chip entity on an alumina substrate and utilizes via hole. The integrated three-dimensional model of the package consisting of the RF MEMS switch and the transitions was simulated using high frequency structure simulator. The realized module shows an insertion loss of 0.2 and 1.1 dB at 100 MHz and 7 GHz, respectively. The measured isolation is better than 60 dB at 100 MHz and 30 dB at 7 GHz. The return loss is better than 15 dB up to 7 GHz. The estimated packaging and transitioning loss is 0.5 dB at 5 GHz. This packaging architecture is a planar solution for the MS interfaced packaging of CPW based RF MEMS switches for designers who do not have access to high-end technologies, such as zero-level packaging, through silicon via or low temperature co-fired ceramics.

  9. Segmentation: Slicing the Urban Pie.

    ERIC Educational Resources Information Center

    Keim, William A.

    1981-01-01

    Explains market segmentation and defines undifferentiated, concentrated, and differentiated marketing strategies. Describes in detail the marketing planning process at the Metropolitan Community Colleges. Focuses on the development and implementation of an ongoing recruitment program designed for the market segment composed of business employees.…

  10. Market Segmentation: An Instructional Module.

    ERIC Educational Resources Information Center

    Wright, Peter H.

    A concept-based introduction to market segmentation is provided in this instructional module for undergraduate and graduate transportation-related courses. The material can be used in many disciplines including engineering, business, marketing, and technology. The concept of market segmentation is primarily a transportation planning technique by…

  11. The Importance of Marketing Segmentation

    ERIC Educational Resources Information Center

    Martin, Gillian

    2011-01-01

    The rationale behind marketing segmentation is to allow businesses to focus on their consumers' behaviors and purchasing patterns. If done effectively, marketing segmentation allows an organization to achieve its highest return on investment (ROI) in turn for its marketing and sales expenses. If an organization markets its products or services to…

  12. Optimal segmentation and packaging process

    DOEpatents

    Kostelnik, Kevin M.; Meservey, Richard H.; Landon, Mark D.

    1999-01-01

    A process for improving packaging efficiency uses three dimensional, computer simulated models with various optimization algorithms to determine the optimal segmentation process and packaging configurations based on constraints including container limitations. The present invention is applied to a process for decontaminating, decommissioning (D&D), and remediating a nuclear facility involving the segmentation and packaging of contaminated items in waste containers in order to minimize the number of cuts, maximize packaging density, and reduce worker radiation exposure. A three-dimensional, computer simulated, facility model of the contaminated items are created. The contaminated items are differentiated. The optimal location, orientation and sequence of the segmentation and packaging of the contaminated items is determined using the simulated model, the algorithms, and various constraints including container limitations. The cut locations and orientations are transposed to the simulated model. The contaminated items are actually segmented and packaged. The segmentation and packaging may be simulated beforehand. In addition, the contaminated items may be cataloged and recorded.

  13. Risk segmentation: goal or problem?

    PubMed

    Feldman, R; Dowd, B

    2000-07-01

    This paper traces the evolution of economists' views about risk segmentation in health insurance markets. Originally seen as a desirable goal, risk segmentation has come to be viewed as leading to abnormal profits, wasted resources, and inefficient limitations on coverage and services. We suggest that risk segmentation may be efficient if one takes an ex post view (i.e., after consumers' risks are known). From this perspective, managed care may be a much better method for achieving risk segmentation than limitations on coverage. The most serious objection to risk segmentation is the ex ante concern that it undermines long-term insurance contracts that would protect consumers against changes in lifetime risk. PMID:11010237

  14. Vascular active contour for vessel tree segmentation.

    PubMed

    Shang, Yanfeng; Deklerck, Rudi; Nyssen, Edgard; Markova, Aneta; de Mey, Johan; Yang, Xin; Sun, Kun

    2011-04-01

    In this paper, a novel active contour model is proposed for vessel tree segmentation. First, we introduce a region competition-based active contour model exploiting the gaussian mixture model, which mainly segments thick vessels. Second, we define a vascular vector field to evolve the active contour along its center line into the thin and weak vessels. The vector field is derived from the eigenanalysis of the Hessian matrix of the image intensity in a multiscale framework. Finally, a dual curvature strategy, which uses a vesselness measure-dependent function selecting between a minimal principal curvature and a mean curvature criterion, is added to smoothen the surface of the vessel without changing its shape. The developed model is used to extract the liver and lung vessel tree as well as the coronary artery from high-resolution volumetric computed tomography images. Comparisons are made with several classical active contour models and manual extraction. The experiments show that our model is more accurate and robust than these classical models and is, therefore, more suited for automatic vessel tree extraction. PMID:21138795

  15. The LOFT ground segment

    NASA Astrophysics Data System (ADS)

    Bozzo, E.; Antonelli, A.; Argan, A.; Barret, D.; Binko, Pavel; Brandt, S.; Cavazzuti, E.; Courvoisier, T.; den Herder, J. W.; Feroci, M.; Ferrigno, C.; Giommi, P.; Götz, D.; Guy, L.; Hernanz, M.; in't Zand, J. J. M.; Klochkov, D.; Kuulkers, Erik; Motch, C.; Lumb, D.; Papitto, A.; Pittori, Carlotta; Rohlfs, R.; Santangelo, A.; Schmid, C.; Schwope, A. D.; Smith, P. J.; Webb, N. A.; Wilms, J.; Zane, S.

    2014-07-01

    LOFT, the Large Observatory For X-ray Timing, was one of the ESA M3 mission candidates that completed their assessment phase at the end of 2013. LOFT is equipped with two instruments, the Large Area Detector (LAD) and the Wide Field Monitor (WFM). The LAD performs pointed observations of several targets per orbit (~90 minutes), providing roughly ~80 GB of proprietary data per day (the proprietary period will be 12 months). The WFM continuously monitors about 1/3 of the sky at a time and provides data for about ~100 sources a day, resulting in a total of ~20 GB of additional telemetry. The LOFT Burst alert System additionally identifies on-board bright impulsive events (e.g., Gamma-ray Bursts, GRBs) and broadcasts the corresponding position and trigger time to the ground using a dedicated system of ~15 VHF receivers. All WFM data are planned to be made public immediately. In this contribution we summarize the planned organization of the LOFT ground segment (GS), as established in the mission Yellow Book1. We describe the expected GS contributions from ESA and the LOFT consortium. A review is provided of the planned LOFT data products and the details of the data flow, archiving and distribution. Despite LOFT was not selected for launch within the M3 call, its long assessment phase ( >2 years) led to a very solid mission design and an efficient planning of its ground operations.

  16. Temperature dependence dynamical permeability characterization of magnetic thin film using near-field microwave microscopy.

    PubMed

    Hung, Le Thanh; Phuoc, Nguyen N; Wang, Xuan-Cong; Ong, C K

    2011-08-01

    A temperature dependence characterization system of microwave permeability of magnetic thin film up to 5 GHz in the temperature range from room temperature up to 423 K is designed and fabricated as a prototype measurement fixture. It is based on the near field microwave microscopy technique (NFMM). The scaling coefficient of the fixture can be determined by (i) calibrating the NFMM with a standard sample whose permeability is known; (ii) by calibrating the NFMM with an established dynamic permeability measurement technique such as shorted microstrip transmission line perturbation method; (iii) adjusting the real part of the complex permeability at low frequency to fit the value of initial permeability. The algorithms for calculating the complex permeability of magnetic thin films are analyzed. A 100 nm thick FeTaN thin film deposited on Si substrate by sputtering method is characterized using the fixture. The room temperature permeability results of the FeTaN film agree well with results obtained from the established short-circuited microstrip perturbation method. Temperature dependence permeability results fit well with the Landau-Lifshitz-Gilbert equation. The temperature dependence of the static magnetic anisotropy H(K)(sta), the dynamic magnetic anisotropy H(K)(dyn), the rotational anisotropy H(rot), together with the effective damping coefficient α(eff), ferromagnetic resonance f(FMR), and frequency linewidth Δf of the thin film are investigated. These temperature dependent magnetic properties of the magnetic thin film are important to the high frequency applications of magnetic devices at high temperatures. PMID:21895260

  17. Thin Clouds

    Atmospheric Science Data Center

    2013-04-18

    ... of this montage is a natural-color view of the Caribbean Sea east of the Yucatan Peninsula as seen by MISR's most steeply ... - Thin, feathery clouds of ice crystals over the Caribbean Sea. project:  MISR category:  gallery ...

  18. A Segmental Framework for Representing Signs Phonetically

    ERIC Educational Resources Information Center

    Johnson, Robert E.; Liddell, Scott K.

    2011-01-01

    The arguments for dividing the signing stream in signed languages into sequences of phonetic segments are compelling. The visual records of instances of actually occurring signs provide evidence of two basic types of segments: postural segments and trans-forming segments. Postural segments specify an alignment of articulatory features, both manual…

  19. Position sensors for segmented mirror

    NASA Astrophysics Data System (ADS)

    Rozière, Didier; Buous, Sébastien; Courteville, Alain

    2004-09-01

    There are currently several projects for giant telescopes with segmented mirrors under way. These future telescopes will have their primary mirror made of several thousand segments. The main advantage of segmentation is that it enables the active control of the whole mirror, so as to suppress the deformations of the support structure due to the wind, gravity, thermal inhomogeneities etc. ..., thus getting the best possible stigmatism. However, providing active control of segmented mirrors requires numerous accurate edges sensors. It is acknowledged that capacitance-based technology nowadays offers the best metrological performances-to-cost ratio. As the leader in capacitive technology, FOGALE nanotech offers an original concept which reduces the cost of instrumentation, sensors and electronics, while keeping a very high level of performances with a manufacturing process completely industrialised. We present here the sensors developed for the Segment Alignment Measurement System (SAMS) of the Southern African Large Telescope (SALT). This patented solution represents an important improvement in terms of cost, to market the Position Sensors for Segmented Mirrors of ELTs, whilst maintaining a very high performance level. We present here the concept, the laboratory qualification, and the first trials on the 7 central segments of SALT. The laboratory results are good, and we are now working on the on-site implementation to improve the immunity of the sensors to environment.

  20. Multiatlas segmentation as nonparametric regression.

    PubMed

    Awate, Suyash P; Whitaker, Ross T

    2014-09-01

    This paper proposes a novel theoretical framework to model and analyze the statistical characteristics of a wide range of segmentation methods that incorporate a database of label maps or atlases; such methods are termed as label fusion or multiatlas segmentation. We model these multiatlas segmentation problems as nonparametric regression problems in the high-dimensional space of image patches. We analyze the nonparametric estimator's convergence behavior that characterizes expected segmentation error as a function of the size of the multiatlas database. We show that this error has an analytic form involving several parameters that are fundamental to the specific segmentation problem (determined by the chosen anatomical structure, imaging modality, registration algorithm, and label-fusion algorithm). We describe how to estimate these parameters and show that several human anatomical structures exhibit the trends modeled analytically. We use these parameter estimates to optimize the regression estimator. We show that the expected error for large database sizes is well predicted by models learned on small databases. Thus, a few expert segmentations can help predict the database sizes required to keep the expected error below a specified tolerance level. Such cost-benefit analysis is crucial for deploying clinical multiatlas segmentation systems. PMID:24802528

  1. Direct volume estimation without segmentation

    NASA Astrophysics Data System (ADS)

    Zhen, X.; Wang, Z.; Islam, A.; Bhaduri, M.; Chan, I.; Li, S.

    2015-03-01

    Volume estimation plays an important role in clinical diagnosis. For example, cardiac ventricular volumes including left ventricle (LV) and right ventricle (RV) are important clinical indicators of cardiac functions. Accurate and automatic estimation of the ventricular volumes is essential to the assessment of cardiac functions and diagnosis of heart diseases. Conventional methods are dependent on an intermediate segmentation step which is obtained either manually or automatically. However, manual segmentation is extremely time-consuming, subjective and highly non-reproducible; automatic segmentation is still challenging, computationally expensive, and completely unsolved for the RV. Towards accurate and efficient direct volume estimation, our group has been researching on learning based methods without segmentation by leveraging state-of-the-art machine learning techniques. Our direct estimation methods remove the accessional step of segmentation and can naturally deal with various volume estimation tasks. Moreover, they are extremely flexible to be used for volume estimation of either joint bi-ventricles (LV and RV) or individual LV/RV. We comparatively study the performance of direct methods on cardiac ventricular volume estimation by comparing with segmentation based methods. Experimental results show that direct estimation methods provide more accurate estimation of cardiac ventricular volumes than segmentation based methods. This indicates that direct estimation methods not only provide a convenient and mature clinical tool for cardiac volume estimation but also enables diagnosis of cardiac diseases to be conducted in a more efficient and reliable way.

  2. Non-invasive characterization and quality assurance of silicon micro-strip detectors using pulsed infrared laser

    NASA Astrophysics Data System (ADS)

    Ghosh, P.

    2016-01-01

    The Compressed Baryonic Matter (CBM) experiment at FAIR is composed of 8 tracking stations consisting of roughly 1300 double sided silicon micro-strip detectors of 3 different dimensions. For the quality assurance of prototype micro-strip detectors a non-invasive detector charaterization is developed. The test system is using a pulsed infrared laser for charge injection and characterization, called Laser Test System (LTS). The system is aimed to develop a set of characterization procedures which are non-invasive (non-destructive) in nature and could be used for quality assurances of several silicon micro-strip detectors in an efficient, reliable and reproducible way. The procedures developed (as reported here) uses the LTS to scan sensors with a pulsed infra-red laser driven by step motor to determine the charge sharing in-between strips and to measure qualitative uniformity of the sensor response over the whole active area. The prototype detector modules which are tested with the LTS so far have 1024 strips with a pitch of 58 μm on each side. They are read-out using a self-triggering prototype read-out electronic ASIC called n-XYTER. The LTS is designed to measure sensor response in an automatized procedure at several thousand positions across the sensor with focused infra-red laser light (spot size ≈ 12 μm, wavelength = 1060 nm). The pulse with a duration of ≈ 10 ns and power ≈ 5 mW of the laser pulse is selected such, that the absorption of the laser light in the 300 μm thick silicon sensor produces ≈ 24000 electrons, which is similar to the charge created by minimum ionizing particles (MIP) in these sensors. The laser scans different prototype sensors and various non-invasive techniques to determine characteristics of the detector modules for the quality assurance is reported.

  3. Multiple solution of linear algebraic systems by an iterative method with recomputed preconditioner in the analysis of microstrip structures

    NASA Astrophysics Data System (ADS)

    Ahunov, Roman R.; Kuksenko, Sergey P.; Gazizov, Talgat R.

    2016-06-01

    A multiple solution of linear algebraic systems with dense matrix by iterative methods is considered. To accelerate the process, the recomputing of the preconditioning matrix is used. A priory condition of the recomputing based on change of the arithmetic mean of the current solution time during the multiple solution is proposed. To confirm the effectiveness of the proposed approach, the numerical experiments using iterative methods BiCGStab and CGS for four different sets of matrices on two examples of microstrip structures are carried out. For solution of 100 linear systems the acceleration up to 1.6 times, compared to the approach without recomputing, is obtained.

  4. Compact, Lightweight Dual-Frequency Microstrip Antenna Feed for Future Soil Moisture and Sea Surface Salinity Missions

    NASA Technical Reports Server (NTRS)

    Yueh, Simon; Wilson, William J.; Njoku, Eni; Dinardo, Steve; Hunter, Don; Rahmat-Samii, Yahya; Kona, Keerti S.; Manteghi, Majid

    2006-01-01

    The development of a compact, lightweight, dual-frequency antenna feed for future soil moisture and sea surface salinity (SSS) missions is described. The design is based on the microstrip stacked-patch array (MSPA) to be used to feed a large lightweight deployable rotating mesh antenna for spaceborne L-band (approx.1 GHz) passive and active sensing systems. The design features will also enable applications to airborne soil moisture and salinity remote sensing sensors operating on small aircrafts. This paper describes the design of stacked patch elements and 16-element array configuration. The results from the return loss, antenna pattern measurements and sky tests are also described.

  5. Demonstration of an X-Band Multilayer Yagi-Like Microstrip Patch Antenna With High Directivity and Large Bandwidth

    NASA Technical Reports Server (NTRS)

    Nessel, James A.; Zaman, Afroz; Lee, Richard Q.; Lambert, Kevin

    2005-01-01

    The feasibility of obtaining large bandwidth and high directivity from a multilayer Yagi-like microstrip patch antenna at 10 GHz is investigated. A measured 10-dB bandwidth of approximately 20 percent and directivity of approximately 11 dBi is demonstrated through the implementation of a vertically-stacked structure with three parasitic directors, above the driven patch, and a single reflector underneath the driven patch. Simulated and measured results are compared and show fairly close agreement. This antenna offers the advantages of large bandwidth, high directivity, and symmetrical broadside patterns, and could be applicable to satellite as well as terrestrial communications.

  6. Metasurface Reflector (MSR) Loading for High Performance Small Microstrip Antenna Design.

    PubMed

    Ahsan, Md Rezwanul; Islam, Mohammad Tariqul; Ullah, Mohammad Habib; Singh, Mandeep Jit; Ali, Mohd Tarmizi

    2015-01-01

    A meander stripline feed multiband microstrip antenna loaded with metasurface reflector (MSR) structure has been designed, analyzed and constructed that offers the wireless communication services for UHF/microwave RFID and WLAN/WiMAX applications. The proposed MSR assimilated antenna comprises planar straight forward design of circular shaped radiator with horizontal slots on it and 2D metasurface formed by the periodic square metallic element that resembles the behavior of metamaterials. A custom made high dielectric bio-plastic substrate (εr = 15) is used for fabricating the prototype of the MSR embedded planar monopole antenna. The details of the design progress through numerical simulations and experimental results are presented and discussed accordingly. The measured impedance bandwidth, radiation patterns and gain of the proposed MSR integrated antenna are compared with the obtained results from numerical simulation, and a good compliance can be observed between them. The investigation shows that utilization of MSR structure has significantly broadened the -10 dB impedance bandwidth than the conventional patch antenna: from 540 to 632 MHz (17%), 467 to 606 MHz (29%) and 758 MHz to 1062 MHz (40%) for three distinct operating bands centered at 0.9, 3.5 and 5.5 GHz. Additionally, due to the assimilation of MSR, the overall realized gains have been upgraded to a higher value of 3.62 dBi, 6.09 dBi and 8.6 dBi for lower, middle and upper frequency band respectively. The measured radiation patterns, impedance bandwidths (S11<-10 dB) and gains from the MSR loaded antenna prototype exhibit reasonable characteristics that can satisfy the requirements of UHF/microwave (5.8 GHz) RFID, WiMAX (3.5/5.5 GHz) and WLAN (5.2/5.8 GHz) applications. PMID:26018795

  7. Metasurface Reflector (MSR) Loading for High Performance Small Microstrip Antenna Design

    PubMed Central

    Ahsan, Md Rezwanul; Islam, Mohammad Tariqul; Ullah, Mohammad Habib; Singh, Mandeep Jit; Ali, Mohd Tarmizi

    2015-01-01

    A meander stripline feed multiband microstrip antenna loaded with metasurface reflector (MSR) structure has been designed, analyzed and constructed that offers the wireless communication services for UHF/microwave RFID and WLAN/WiMAX applications. The proposed MSR assimilated antenna comprises planar straight forward design of circular shaped radiator with horizontal slots on it and 2D metasurface formed by the periodic square metallic element that resembles the behavior of metamaterials. A custom made high dielectric bio-plastic substrate (εr = 15) is used for fabricating the prototype of the MSR embedded planar monopole antenna. The details of the design progress through numerical simulations and experimental results are presented and discussed accordingly. The measured impedance bandwidth, radiation patterns and gain of the proposed MSR integrated antenna are compared with the obtained results from numerical simulation, and a good compliance can be observed between them. The investigation shows that utilization of MSR structure has significantly broadened the -10dB impedance bandwidth than the conventional patch antenna: from 540 to 632 MHz (17%), 467 to 606 MHz (29%) and 758 MHz to 1062 MHz (40%) for three distinct operating bands centered at 0.9, 3.5 and 5.5 GHz. Additionally, due to the assimilation of MSR, the overall realized gains have been upgraded to a higher value of 3.62 dBi, 6.09 dBi and 8.6 dBi for lower, middle and upper frequency band respectively. The measured radiation patterns, impedance bandwidths (S11<-10 dB) and gains from the MSR loaded antenna prototype exhibit reasonable characteristics that can satisfy the requirements of UHF/microwave (5.8 GHz) RFID, WiMAX (3.5/5.5 GHz) and WLAN (5.2/5.8 GHz) applications. PMID:26018795

  8. A new micro-strip tracker for the new generation of experiments at hadron colliders

    SciTech Connect

    Dinardo, Mauro E

    2005-12-01

    This thesis concerns the development and characterization of a prototype Silicon micro-strip detector that can be used in the forward (high rapidity) region of a hadron collider. These detectors must operate in a high radiation environment without any important degradation of their performance. The innovative feature of these detectors is the readout electronics, which, being completely data-driven, allows for the direct use of the detector information at the lowest level of the trigger. All the particle hits on the detector can be readout in real-time without any external trigger and any particular limitation due to dead-time. In this way, all the detector information is available to elaborate a very selective trigger decision based on a fast reconstruction of tracks and vertex topology. These detectors, together with the new approach to the trigger, have been developed in the context of the BTeV R&D program; our aim was to define the features and the design parameters of an optimal experiment for heavy flavour physics at hadron colliders. Application of these detectors goes well beyond the BTeV project and, in particular, involves the future upgrades of experiments at hadron colliders, such as Atlas, CMS and LHCb. These experiments, indeed, are already considering for their future high-intensity runs a new trigger strategy a la BTeV. Their aim is to select directly at trigger level events containing Bhadrons, which, on several cases, come from the decay of Higgs bosons, Z{sup o}'s or W{sup {+-}}'s; the track information can also help on improving the performance of the electron and muon selection at the trigger level. For this reason, they are going to develop new detectors with practically the same characteristics as those of BTeV. To this extent, the work accomplished in this thesis could serve as guide-line for those upgrades.

  9. Coupled microstrip line transverse electromagnetic resonator model for high-field magnetic resonance imaging.

    PubMed

    Bogdanov, G; Ludwig, R

    2002-03-01

    The performance modeling of RF resonators at high magnetic fields of 4.7 T and more requires a physical approach that goes beyond conventional lumped circuit concepts. The treatment of voltages and currents as variables in time and space leads to a coupled transmission line model, whereby the electric and magnetic fields are assumed static in planes orthogonal to the length of the resonator, but wave-like along its longitudinal axis. In this work a multiconductor transmission line (MTL) model is developed and successfully applied to analyze a 12-element unloaded and loaded microstrip line transverse electromagnetic (TEM) resonator coil for animal studies. The loading involves a homogeneous cylindrical dielectric insert of variable radius and length. This model formulation is capable of estimating the resonance spectrum, field distributions, and certain types of losses in the coil, while requiring only modest computational resources. The boundary element method is adopted to compute all relevant transmission line parameters needed to set up the transmission line matrices. Both the theoretical basis and its engineering implementation are discussed and the resulting model predictions are placed in context with measurements. A comparison between a conventional lumped circuit model and this distributed formulation is conducted, showing significant departures in the resonance response at higher frequencies. This MTL model is applied to simulate two small-bore animal systems: one of 7.5-cm inner diameter, tuned to 200 MHz (4.7 T for proton imaging), and one of 13.36-cm inner diameter, tuned to both 200 and 300 MHz (7 T). PMID:11870846

  10. Thin Film?

    NASA Astrophysics Data System (ADS)

    Kariper, İ. Afşin

    2014-09-01

    This study focuses on the critical surface tension of lead sulfite (PbSO3) crystalline thin film produced with chemical bath deposition on substrates (commercial glass).The PbSO3 thin films were deposited at room temperature at different deposition times. The structural properties of the films were defined and examined according to X-ray diffraction (XRD) and the XRD results such as dislocation density, average grain size, and no. of crystallites per unit area. Atomic force microscopy was used to measure the film thickness and the surface properties. The critical surface tension of the PbSO3 thin films was measured with an optical tensiometer instrument and calculated using the Zisman method. The results indicated that the critical surface tension of films changed in accordance with the average grain size and film thickness. The film thickness increased with deposition time and was inversely correlated with surface tension. The average grain size increased according to deposition time and was inversely correlated with surface tension.

  11. Morphing of Segmented Bimorph Mirrors

    NASA Astrophysics Data System (ADS)

    Rodrigues, Gonçalo; Bastaits, Renaud; Preumont, André

    2010-08-01

    Atmospheric turbulence compensation for the next generation of terrestrial telescopes (30-40 m diameter) will require deformable mirrors of increasing size and a number of actuators reaching several thousands. However, the mere extrapolation of existing designs leads to complicated and extremely expensive mirrors. This article discusses an alternative solution based on the use of segmented identical hexagonal bimorph mirrors. This allows to indefinitely increase the degree of correction while maintaining the first mechanical resonance at the level of a single segment, and shows an increase in price only proportional to the number of segments. Extensive simulations using random turbulent screens show that the segmentation produces only moderate reductions of the Strehl number, compared to a monolithic bimorph mirror with the same number of actuators (S = 0.86 instead of S = 0.89 in this study).

  12. Segmentation Of Polarimetric SAR Data

    NASA Technical Reports Server (NTRS)

    Rignot, Eric J. M.; Chellappa, Rama

    1994-01-01

    Report presents one in continuing series of studies of segmentation of polarimetric synthetic-aperture-radar, SAR, image data into regions. Studies directed toward refinement of method of automated analysis of SAR data.

  13. Bayesian segmentation of hyperspectral images

    NASA Astrophysics Data System (ADS)

    Mohammadpour, Adel; Féron, Olivier; Mohammad-Djafari, Ali

    2004-11-01

    In this paper we consider the problem of joint segmentation of hyperspectral images in the Bayesian framework. The proposed approach is based on a Hidden Markov Modeling (HMM) of the images with common segmentation, or equivalently with common hidden classification label variables which is modeled by a Potts Markov Random Field. We introduce an appropriate Markov Chain Monte Carlo (MCMC) algorithm to implement the method and show some simulation results.

  14. Segmental neurofibromatosis [NF type - v].

    PubMed

    Arfan-ul-Bari; Simeen-ber-Rahman

    2003-12-01

    Segmental neurofibromatosis is a rare variant of neurofibromatosis in which skin lesions are confined to a circumscribed body segment. A case of a 39-year-old man with this condition is presented, who was having multiple soft skin tumours over a localized area of back with no associated cafe au lait spots, axillary freckles or lish nodules. Histology confirmed the diagnosis of neurofibroma. PMID:15569561

  15. The Envisat-1 ground segment

    NASA Astrophysics Data System (ADS)

    Harris, Ray; Ashton, Martin

    1995-03-01

    The European Space Agency (ESA) Earth Remote Sensing Satellite (ERS-1 and ERS-2) missions will be followed by the Polar Orbit Earth Mission (POEM) program. The first of the POEM missions will be Envisat-1. ESA has completed the design phase of the ground segment. This paper presents the main elements of that design. The main part of this paper is an overview of the Payload Data Segment (PDS) which is the core of the Envisat-1 ground segment, followed by two further sections which describe in more detail the facilities to be offered by the PDS for archiving and for user servcies. A further section describes some future issues for ground segment development. Logica was the prime contractor of a team of 18 companies which undertook the ESA financed architectural design study of the Envisat-1 ground segment. The outputs of the study included detailed specifications of the components that will acquire, process, archive and disseminate the payload data, together with the functional designs of the flight operations and user data segments.

  16. Efficient threshold for volumetric segmentation

    NASA Astrophysics Data System (ADS)

    Burdescu, Dumitru D.; Brezovan, Marius; Stanescu, Liana; Stoica Spahiu, Cosmin; Ebanca, Daniel

    2015-07-01

    Image segmentation plays a crucial role in effective understanding of digital images. However, the research on the existence of general purpose segmentation algorithm that suits for variety of applications is still very much active. Among the many approaches in performing image segmentation, graph based approach is gaining popularity primarily due to its ability in reflecting global image properties. Volumetric image segmentation can simply result an image partition composed by relevant regions, but the most fundamental challenge in segmentation algorithm is to precisely define the volumetric extent of some object, which may be represented by the union of multiple regions. The aim in this paper is to present a new method to detect visual objects from color volumetric images and efficient threshold. We present a unified framework for volumetric image segmentation and contour extraction that uses a virtual tree-hexagonal structure defined on the set of the image voxels. The advantage of using a virtual tree-hexagonal network superposed over the initial image voxels is that it reduces the execution time and the memory space used, without losing the initial resolution of the image.

  17. Segmentation of endpoint trajectories does not imply segmented control.

    PubMed

    Sternad, D; Schaal, S

    1999-01-01

    While it is generally assumed that complex movements consist of a sequence of simpler units, the quest to define these units of action, or movement primitives, remains an open question. In this context, two hypotheses of movement segmentation of endpoint trajectories in three-dimensional human drawing movements are reexamined: (1) the stroke-based segmentation hypothesis based on the results that the proportionality coefficient of the two-thirds power law changes discontinuously with each new "stroke," and (2) the segmentation hypothesis inferred from the observation of piecewise planar endpoint trajectories of three-dimensional drawing movements. In two experiments human subjects performed a set of elliptical and figure eight patterns of different sizes and orientations using their whole arm in three dimensions. The kinematic characteristics of the endpoint trajectories and the seven joint angles of the arm were analyzed. While the endpoint trajectories produced similar segmentation features to those reported in the literature, analyses of the joint angles show no obvious segmentation but rather continuous oscillatory patterns. By approximating the joint angle data of human subjects with sinusoidal trajectories, and by implementing this model on a 7-degree-of-freedom (DOF) anthropomorphic robot arm, it is shown that such a continuous movement strategy can produce exactly the same features as observed by the above segmentation hypotheses. The origin of this apparent segmentation of endpoint trajectories is traced back to the nonlinear transformations of the forward kinematics of human arms. The presented results demonstrate that principles of discrete movement generation may not be reconciled with those of rhythmic movement as easily as has been previously suggested, while the generalization of nonlinear pattern generators to arm movements can offer an interesting alternative to approach the question of units of action. PMID:9928796

  18. Semi-automatic segmentation of major aorto-pulmonary collateral arteries (MAPCAs) for image guided procedures

    NASA Astrophysics Data System (ADS)

    Rivest-Hénault, David; Duong, Luc; Lapierre, Chantale; Desch"nes, Sylvain; Cheriet, Mohamed

    2010-02-01

    Manual segmentation of pre-operative volumetric dataset is generally time consuming and results are subject to large inter-user variabilities. Level-set methods have been proposed to improve segmentation consistency by finding interactively the segmentation boundaries with respect to some priors. However, in thin and elongated structures, such as major aorto-pulmonary collateral arteries (MAPCAs), edge-based level set methods might be subject to flooding whereas region-based level set methods may not be selective enough. The main contribution of this work is to propose a novel expert-guided technique for the segmentation of the aorta and of the attached MAPCAs that is resilient to flooding while keeping the localization properties of an edge-based level set method. In practice, a two stages approach is used. First, the aorta is delineated by using manually inserted seed points at key locations and an automatic segmentation algorithm. The latter includes an intensity likelihood term that prevents leakage of the contour in regions of weak image gradients. Second, the origins of the MAPCAs are identified by using another set of seed points, then the MAPCAs' segmentation boundaries are evolved while being constrained by the aorta segmentation. This prevents the aorta to interfere with the segmentation of the MAPCAs. Our preliminary results are promising and constitute an indication that an accurate segmentation of the aorta and MAPCAs can be obtained with reasonable amount of effort.

  19. Near- and Far-Field Characterization of Planar mm-Wave Antenna Arrays with Waveguide-to-Microstrip Transition

    NASA Astrophysics Data System (ADS)

    Salhi, Mohammed Adnan; Kazemipour, Alireza; Gentille, Gennaro; Spirito, Marco; Kleine-Ostmann, Thomas; Schrader, Thorsten

    2016-04-01

    We present the design and characterization of planar mm-wave patch antenna arrays with waveguide-to-microstrip transition using both near- and far-field methods. The arrays were designed for metrological assessment of error sources in antenna measurement. One antenna was designed for the automotive radar frequency range at 77 GHz, while another was designed for the frequency of 94 GHz, which is used, e.g., for imaging radar applications. In addition to the antennas, a simple transition from rectangular waveguide WR-10 to planar microstrip line on Rogers 3003™ substrate has been designed based on probe coupling. For determination of the far-field radiation pattern of the antennas, we compare results from two different measurement methods to simulations. Both a far-field antenna measurement system and a planar near-field scanner with near-to-far-field transformation were used to determine the antenna diagrams. The fabricated antennas achieve a good matching and a good agreement between measured and simulated antenna diagrams. The results also show that the far-field scanner achieves more accurate measurement results with regard to simulations than the near-field scanner. The far-field antenna scanning system is built for metrological assessment and antenna calibration. The antennas are the first which were designed to be tested with the measurement system.

  20. Near- and Far-Field Characterization of Planar mm-Wave Antenna Arrays with Waveguide-to-Microstrip Transition

    NASA Astrophysics Data System (ADS)

    Salhi, Mohammed Adnan; Kazemipour, Alireza; Gentille, Gennaro; Spirito, Marco; Kleine-Ostmann, Thomas; Schrader, Thorsten

    2016-09-01

    We present the design and characterization of planar mm-wave patch antenna arrays with waveguide-to-microstrip transition using both near- and far-field methods. The arrays were designed for metrological assessment of error sources in antenna measurement. One antenna was designed for the automotive radar frequency range at 77 GHz, while another was designed for the frequency of 94 GHz, which is used, e.g., for imaging radar applications. In addition to the antennas, a simple transition from rectangular waveguide WR-10 to planar microstrip line on Rogers 3003™ substrate has been designed based on probe coupling. For determination of the far-field radiation pattern of the antennas, we compare results from two different measurement methods to simulations. Both a far-field antenna measurement system and a planar near-field scanner with near-to-far-field transformation were used to determine the antenna diagrams. The fabricated antennas achieve a good matching and a good agreement between measured and simulated antenna diagrams. The results also show that the far-field scanner achieves more accurate measurement results with regard to simulations than the near-field scanner. The far-field antenna scanning system is built for metrological assessment and antenna calibration. The antennas are the first which were designed to be tested with the measurement system.