C-Mod MHD stability analysis with LHCD

NASA Astrophysics Data System (ADS)

Ebrahimi, Fatima; Bhattacharjee, A.; Delgado, L.; Scott, S.; Wilson, J. R.; Wallace, G. M.; Shiraiwa, S.; Mumgaard, R. T.

2016-10-01

In lower hybrid current drive (LHCD) experiments on the Alcator C-Mod, sawtooth activity could be suppressed as the safety factor q on axis is raised above unity. However, in some of these experiments, after applying LHCD, the onset of MHD mode activity caused the current drive efficiency to significantly drop. Here, we study the stability of these experiments by performing MHD simulations using the NIMROD code starting with experimental EFIT equilibria. First, consistent with the LHCD experiment with no signature of MHD activity, MHD mode activity was also absent in the simulations. Second, for experiments with MHD mode activity, we find that a core n=1 reconnecting mode with dominate poloidal modes of m=2,3 is unstable. This mode is a resistive current-driven mode as its growth rate scales with a negative power of the Lundquist number in the simulations. In addition, with further enhanced reversed-shear q profile in the simulations, a core double tearing mode is found to be unstable. This work is supported by U.S. DOE cooperative agreement DE-FC02-99ER54512 using the Alcator C-Mod tokamak, a DOE Office of Science user facility.

Design of practical alignment device in KSTAR Thomson diagnostic.

PubMed

Lee, J H; Lee, S H; Yamada, I

2016-11-01

The precise alignment of the laser path and collection optics in Thomson scattering measurements is essential for accurately determining electron temperature and density in tokamak experiments. For the last five years, during the development stage, the KSTAR tokamak's Thomson diagnostic system has had alignment fibers installed in its optical collection modules, but these lacked a proper alignment detection system. In order to address these difficulties, an alignment verifying detection device between lasers and an object field of collection optics is developed. The alignment detection device utilizes two types of filters: a narrow laser band wavelength for laser, and a broad wavelength filter for Thomson scattering signal. Four such alignment detection devices have been successfully developed for the KSTAR Thomson scattering system in this year, and these will be tested in KSTAR experiments in 2016. In this paper, we present the newly developed alignment detection device for KSTAR's Thomson scattering diagnostics.

Analysis of the Thermal Loads on the KSTAR Cryogenic System

NASA Astrophysics Data System (ADS)

Kim, Y. S.; Oh, Y. K.; Kim, W. C.; Park, Y. M.; Lee, Y. J.; Jin, S. B.; Sa, J. W.; Choi, C. H.; Cho, K. W.; Bak, J. S.; Lee, G. S.

2004-06-01

A large-scale helium refrigeration system is one of the key components for the KSTAR (Korea Superconducting Tokamak Advanced Research) device. In the design of the refrigeration system, an estimation of the thermal loads on the cold mass is an important issue according to the operation scenario. The cold mass of the KSTAR device is about 250 tons including 30 superconducting (SC) coils and the magnet structure. In addition to the static thermal loads, pulsed thermal loads to the refrigeration system have been considered in the operation stage. The main pulsed thermal loads on magnet system are AC losses in the SC coils and eddy current losses in the magnet structure that depend on the magnetic field variation rate. The nuclear radiation loss due to plasma pulse operation is also considered. The designed cooling capacity of the refrigeration system is estimated to be about 9 kW at 4.5 K isothermal. In this paper, calculation of the various kinds of thermal loads on KSTAR cryogenic system and design of the large-scale helium refrigeration system are presented.

Experimental characterization and modeling of non-linear coupling of the LHCD power on Tore Supra

DOE Office of Scientific and Technical Information (OSTI.GOV)

Preynas, M.; Goniche, M.; Hillairet, J.

2014-02-12

To achieve steady state operation on future tokamaks, in particular on ITER, the unique capability of a LHCD system to efficiently drive off-axis non-inductive current is needed. In this context, it is of prime importance to study and master the coupling of LH wave to the core plasma at high power density (tens of MW/m{sup 2}). In some specific conditions, deleterious effects on the LHCD coupling are sometimes observed on Tore Supra. At high power the waves may modify the edge parameters that change the wave coupling properties in a non-linear manner. In this way, dedicated LHCD experiments have beenmore » performed using the LHCD system of Tore Supra, composed of two different conceptual designs of launcher: the Fully Active Multijunction (FAM) and the new Passive Active Multijunction (PAM) antennas. A nonlinear interaction between the electron density and the electric field has been characterized in a thin plasma layer in front of the two LHCD antennas. The resulting dependence of the power reflection coefficient with the LHCD power, leading occasionally to trips in the output power, is not predicted by the standard linear theory of the LH wave coupling. Therefore, it is important to investigate and understand the possible origin of such non-linear effects in order to avoid their possible deleterious consequences. The PICCOLO-2D code, which self-consistently treats the wave propagation in the antenna vicinity and its interaction with the local edge plasma density, is used to simulate Tore Supra discharges. The simulation reproduces very well the occurrence of a non-linear behavior in the coupling observed in the LHCD experiments. The important differences and trends between the FAM and the PAM antennas, especially a larger increase in RC for the FAM, are also reproduced by the PICCOLO-2D simulation. The working hypothesis of the contribution of the ponderomotive effect in the non-linear observations of LHCD coupling is therefore validated through this

Investigation of intrinsic toroidal rotation scaling in KSTAR

NASA Astrophysics Data System (ADS)

Yoo, J. W.; Lee, S. G.; Ko, S. H.; Seol, J.; Lee, H. H.; Kim, J. H.

2017-07-01

The behaviors of an intrinsic toroidal rotation without any external momentum sources are investigated in KSTAR. In these experiments, pure ohmic discharges with a wide range of plasma parameters are carefully selected and analyzed to speculate an unrevealed origin of toroidal rotation excluding any unnecessary heating sources, magnetic perturbations, and strong magneto-hydrodynamic activities. The measured core toroidal rotation in KSTAR is mostly in the counter-current direction and its magnitude strongly depends on the ion temperature divided by plasma current (Ti/IP). Especially the core toroidal rotation in the steady-state is well fitted by Ti/IP scaling with a slope of ˜-23, and the possible explanation of the scaling is compared with various candidates. As a result, the calculated offset rotation could not explain the measured core toroidal rotation since KSTAR has an extremely low intrinsic error field. For the stability conditions for ion and electron turbulences, it is hard to determine a dominant turbulence mode in this study. In addition, the intrinsic toroidal rotation level in ITER is estimated based on the KSTAR scaling since the intrinsic rotation plays an important role in stabilizing resistive wall modes for future reference.

System calibration of the 1.4 GHz and 5 GHz radiometers for soil moisture remote sensing

NASA Technical Reports Server (NTRS)

Wang, J.; Shiue, J.; Gould, W.; Fuchs, J.; Hirschmann, E.; Glazar, W.

1980-01-01

Two microwave radiometers at the frequencies of 1.4 GHz and 5 GHz were mounted on a mobile tower and used for a remote sensing of soil moisture experiment at a Beltsville Agriculture Research Center test site. The experiment was performed in October 1979 over both bare field and fields covered with grass, soybean, and corn. The calibration procedure for the radiometer systems which forms the basis of obtaining the final radiometric data product is described. It is estimated from the calibration results that the accuracy of the 1.4 GHz radiometric measurements is about + or - 3 K. The measured 5 GHz brightness temperatures over bare fields with moisture content greater than 10 percent by dry weight are about 8 K lower than those taken simultaneously at 1.4 GHz. This could be due to either (1) a 5 GHz antenna side lobe seeing the cold brightness of the sky, or (2) the thermal microwave emission from a soil being less sensitive to surface roughness at 5 GHz than at 1.4 GHz.

Design and Manufacturing of the Kstar Tokamak Helium Refrigeration System

NASA Astrophysics Data System (ADS)

Dauguet, P.; Briend, P.; Abe, I.; Fauve, E.; Bernhardt, J. M.; Andrieu, F.; Beauvisage, J.

2008-03-01

The KSTAR (Korean Superconducting Tokamak Advanced Research) project makes intensive use of superconducting (SC) magnets operated at 4.4 K. The cold components of KSTAR require a forced flow of supercritical helium for magnets and structure, boiling liquid helium for current leads, and gaseous helium for thermal shields. A helium refrigeration system has been custom-designed for this project. The purpose of this paper is to give a brief overview of the proposed cryogenic system. The specified thermal loads for the different operating modes are presented. This specification results in the definition of a design mode for the refrigerator. The design and construction of the resulting 9 kW at 4.5-K Helium Refrigeration System (HSR) are presented.

New ion source for KSTAR neutral beam injection system.

PubMed

Kim, Tae-Seong; Jeong, Seung Ho; In, Sang-Ryul

2012-02-01

The neutral beam injection system (NBI-1) of the KSTAR tokamak can accommodate three ion sources; however, it is currently equipped with only one prototype ion source. In the 2010 and 2011 KSTAR campaigns, this ion source supplied deuterium neutral beam power of 0.7-1.6 MW to the KSTAR plasma with a beam energy of 70-100 keV. A new ion source will be prepared for the 2012 KSTAR campaign with a much advanced performance compared with the previous one. The newly designed ion source has a very large transparency (∼56%) without deteriorating the beam optics, which is designed to deliver a 2 MW injection power of deuterium beams at 100 keV. The plasma generator of the ion source is of a horizontally cusped bucket type, and the whole inner wall, except the cathode filaments and plasma grid side, functions as an anode. The accelerator assembly consists of four multi-circular aperture grids made of copper and four electrode flanges made of aluminum alloy. The electrodes are insulated using PEEK. The ion source will be completed and tested in 2011.

Progress and plan of KSTAR plasma control system upgrade

DOE PAGES

Hahn, Sang-hee; Kim, Y. J.; Penaflor, B. G.; ...

2016-06-01

The plasma control system (PCS) has been one of essential systems in annual KSTAR plasma campaigns: starting from a single-process version in 2008, extensive upgrades are done through the previous 7 years in order to achieve major goals of KSTAR performance enhancement. Here, major implementations are explained in this paper. In consequences of successive upgrades, the present KSTAR PCS is able to achieve ~48 s of 500 kA plasma pulses with full real-time shaping controls and real-time NB power controls. It has become a huge system capable of dealing with 8 separate categories of algorithms, 26 actuators directly controllable duringmore » the shot, and real-time data communication units consisting of +180 analog channels and +600 digital input/outputs through the reflective memory (RFM) network. The next upgrade of the KSTAR PCS is planned in 2015 before the campaign. An overview of the upgrade layout will be given for this paper. The real-time system box is planned to use the CERN MRG-Realtime OS, an ITER-compatible standard operating system. New hardware is developed for faster real-time streaming system for future installations of actuators/diagnostics.« less

Optimizing LHCD launcher using poloidal steering on Alcator C-Mod and ADX

NASA Astrophysics Data System (ADS)

Bonoli, P.; Labombard, B.; Parker, R.; Shiraiwa, S.; Wallace, G.; Wukitch, S.; Leccacorvi, R.; Vieira, R.; Alcator C-Mod Team

2014-10-01

The poloidal location of the lower hybrid current drive (LHCD) launcher has a strong influence on the trajectory and absorption of the LH wave (poloidal steering). The physics design of an additional off-midplane launcher (LH3) for Alcator C-Mod exploits this characteristic. By shifting the launcher from the mid-plane by 25cm, it is predicted to realize strong (>80%) single pass absorption localized at about r/a = 0.7 in conjunction with the mid-plane (LH2) antenna. While LH3 is a proposal to overcome the LH density limit and to provide a unique opportunity to validate LHCD simulation codes under reactor-like conditions, poloidal steering can be used more extensively by launching waves from the high field side (HFS). On ADX, the LHCD launcher is proposed to be located on the HFS. Better accessibility due to higher magnetic field allows for using lower N//, which results in higher current drive efficiency. Also a more quiescent edge plasma may reduce the effect of N// shifts due to scattering from density fluctuations. LHCD simulations for target plasmas expected on ADX, optimization of poloidal steering, and RF simulation of high field side launcher will be presented. This work supported by USDoE awards DE-FC02-99ER54512 and DE-AC02-09CH11466.

European VLBI network observations of fourteen GHz-peaked-spectrum radio sources at 5 GHz

NASA Astrophysics Data System (ADS)

Xiang, L.; Reynolds, C.; Strom, R. G.; Dallacasa, D.

2006-08-01

We present the results of EVN polarization observations of fourteen GHz-Peaked-Spectrum (GPS) radio sources at 5 GHz. These sources were selected from bright GPS source samples and we aimed at finding Compact Symmetric Objects (CSOs). We have obtained full polarization 5 GHz VLBI observations of 14 sources providing information on their source structure and spectral indices. The results show that two core-jet sources 1433-040 and DA193, out of 14 GPS sources, exhibit integrated fractional polarizations of 3.6% and 1.0% respectively. The other 12 sources have no clear detection of pc-scale polarization. The results confirm that the GPS sources generally have very low polarization at 5 GHz. The sources 1133+432, 1824+271 and 2121-014 are confirmed as CSOs. Three new CSOs 0914+114, 1518+046 and 2322-040 (tentative) have been classified on the basis of 5 GHz images and spectral indices. The sources 1333+589, 1751+278 and 2323+790 can be classified either as compact doubles, and then they are likely CSO candidates or core-jet sources; further observations are needed for an appropriate classification; 0554-026, 1433-040 and 1509+054 are core-jet sources. In addition, we estimate that a component in the jet of quasar DA193 has superluminal motion of 3.3±0.6 h-1 c in 5.5 years.

Transport and stability analyses supporting disruption prediction in high beta KSTAR plasmas

NASA Astrophysics Data System (ADS)

Ahn, J.-H.; Sabbagh, S. A.; Park, Y. S.; Berkery, J. W.; Jiang, Y.; Riquezes, J.; Lee, H. H.; Terzolo, L.; Scott, S. D.; Wang, Z.; Glasser, A. H.

2017-10-01

KSTAR plasmas have reached high stability parameters in dedicated experiments, with normalized beta βN exceeding 4.3 at relatively low plasma internal inductance li (βN/li>6). Transport and stability analyses have begun on these plasmas to best understand a disruption-free path toward the design target of βN = 5 while aiming to maximize the non-inductive fraction of these plasmas. Initial analysis using the TRANSP code indicates that the non-inductive current fraction in these plasmas has exceeded 50 percent. The advent of KSTAR kinetic equilibrium reconstructions now allows more accurate computation of the MHD stability of these plasmas. Attention is placed on code validation of mode stability using the PEST-3 and resistive DCON codes. Initial evaluation of these analyses for disruption prediction is made using the disruption event characterization and forecasting (DECAF) code. The present global mode kinetic stability model in DECAF developed for low aspect ratio plasmas is evaluated to determine modifications required for successful disruption prediction of KSTAR plasmas. Work supported by U.S. DoE under contract DE-SC0016614.

Enhanced understanding of the MHD dynamics and ELM control experiments in KSTAR

NASA Astrophysics Data System (ADS)

Park, Hyeon K.

2013-10-01

In KSTAR, H-mode discharges have been achieved reliably at toroidal fields from 1.4 to 3.5 T with a heating power of ~ 5 MW. Using real-time plasma shape control the flattop time in H-mode has been extended to over ~ 16 s at 600 kA in the 2012 campaign and the extended plasma operation boundary has surpassed the n = 1 no-wall limit with βN /li up to 4.1. In order to achieve a high beta steady state operation in KSTAR, establishment of predictive MHD simulation and first-principle-based control of the harmful MHD are the first steps. Visualization of MHD dynamics via a 2-D Electron Cyclotron Emission Imaging (ECEI) has significantly enhanced the level of understanding of the MHD dynamics. Following the first 2-D ELM measurements in H-mode plasmas in KSTAR the measured 2-D ELM images were compared with synthetic images from the BOUT + + code. The physics of ELMs is characterized based on a wide range of measured mode numbers (n, m) local magnetic shear and pressure gradients. The observed ELM dynamics during control experiments have been enlightening and consistent with the stability models. Near the q ~ 2 surface, the island width and Δ' of the m = 2 tearing mode have been verified through the modified Rutherford model based on the 2-D images. With the aid of a second (toroidally separated) ECEI system installed in the 2012 KSTAR campaign, a 3-D reconstruction of the MHD instabilities has allowed further validation of the computed magnetic field pitch angles, rotation speeds, and toroidal asymmetries of the MHDs Work supported by NRF of Korea under contract No. 20120005920 and the U.S. DoE under contract No. DE-FG-02-99ER54531.

Design of practical alignment device in KSTAR Thomson diagnostic

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, J. H., E-mail: jhlee@nfri.re.kr; University of Science and Technology; Lee, S. H.

2016-11-15

The precise alignment of the laser path and collection optics in Thomson scattering measurements is essential for accurately determining electron temperature and density in tokamak experiments. For the last five years, during the development stage, the KSTAR tokamak’s Thomson diagnostic system has had alignment fibers installed in its optical collection modules, but these lacked a proper alignment detection system. In order to address these difficulties, an alignment verifying detection device between lasers and an object field of collection optics is developed. The alignment detection device utilizes two types of filters: a narrow laser band wavelength for laser, and a broadmore » wavelength filter for Thomson scattering signal. Four such alignment detection devices have been successfully developed for the KSTAR Thomson scattering system in this year, and these will be tested in KSTAR experiments in 2016. In this paper, we present the newly developed alignment detection device for KSTAR’s Thomson scattering diagnostics.« less

Improvement of vertical stabilization on KSTAR

NASA Astrophysics Data System (ADS)

Mueller, D.; Bak, J. G.; Boyer, M. D.; Eideitis, N.; Hahn, S. H.; Humphreys, D. A.; Kim, H. S.; Jeon, Y. M.; Lanctot, M.; Walker, M. L.

2017-10-01

The successful control of strongly shaped plasmas on the Korea Superconducting Tokamak Advanced Research (KSTAR) device requires active feedback of fast motion of the plasma vertical position by the use of internal normal conducting coils (IVC). This has required new electronics to supply relative flux loop differences, for zp, and voltage loop differences, for dzp/dt, as well as a novel technique (Zfast) to use a high-pass filter, typically 1 Hz, on the error in the signal in the feedback loop. Use of Zfast avoids the potential contention encountered when the internal coil attempts to perform control of the plasma shape which should be controlled by the slower and more powerful superconducting coils. A common problem of this contention is saturation of the IVC and loss of fast vertical control. This is eliminated by proper use of the Zfast. A Ziegler-Nichols relay feedback system was used to fine tune the required feedback gains. The selection of the magnetic sensors, filter time constants, control gains and of the Zfast control strategy which allowed vertically stable operation at a plasma elongation, kappa. of up to 2.16 at li = 1.15 and Betap = 2.4 will be discussed which is beyond the design reference of KSTAR of kappa = 2.0 at li = 1.2 and Betap = 1.9. Work Supported by U.S.D.O.E. Contract No. DE-AC02-09CH11466 and DE-SC0010685 and the KSTAR project.

Design of the klystron filament power supply control system for EAST LHCD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Zege; Wang, Mao; Hu, Huaichuan

A filament is a critical component of the klystron used to heat the cathode. There are totally 44 klystrons in experimental advanced superconducting tokamak (EAST) lower hybrid current drive (LHCD) systems. All klystron filaments are powered by AC power suppliers through isolated transformers. In order to achieve better klystron preheat, a klystron filament power supply control system is designed to obtain the automatic control of all filament power suppliers. Klystron filament current is measured by PLC and the interlock between filament current and klystron high voltage system is also implemented. This design has already been deployed in two LHCD systemsmore » and proves feasible completely.« less

Edge profile measurements using Thomson scattering on the KSTAR tokamak

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, J. H., E-mail: jhleel@nfri.re.kr; Ko, W. H.; Department of Nuclear Fusion and Plasma Science, University of Science and Technology

2014-11-15

In the KSTAR Tokamak, a “Tangential Thomson Scattering” (TTS) diagnostic system has been designed and installed to measure electron density and temperature profiles. In the edge system, TTS has 12 optical fiber bundles to measure the edge profiles with 10–15 mm spatial resolution. These 12 optical fibers and their spatial resolution are not enough to measure the pedestal width with a high accuracy but allow observations of L-H transition or H-L transitions at the edge. For these measurements, the prototype ITER edge Thomson Nd:YAG laser system manufactured by JAEA in Japan is installed. In this paper, the KSTAR TTS systemmore » is briefly described and some TTS edge profiles are presented and compared against the KSTAR Charge Exchange Spectroscopy and other diagnostics. The future upgrade plan of the system is also discussed in this paper.« less

Control advances for achieving the ITER baseline scenario on KSTAR

NASA Astrophysics Data System (ADS)

Eidietis, N. W.; Barr, J.; Hahn, S. H.; Humphreys, D. A.; in, Y. K.; Jeon, Y. M.; Lanctot, M. J.; Mueller, D.; Walker, M. L.

2017-10-01

Control methodologies developed to enable successful production of ITER baseline scenario (IBS) plasmas on the superconducting KSTAR tokamak are presented: decoupled vertical control (DVC), real-time feedforward (rtFF) calculation, and multi-input multi-output (MIMO) X-point control. DVC provides fast vertical control with the in-vessel control coils (IVCC) while sharing slow vertical control with the poloidal field (PF) coils to avoid IVCC saturation. rtFF compensates for inaccuracies in offline PF current feedforward programming, allowing reduction or removal of integral gain (and its detrimental phase lag) from the shape controller. Finally, MIMO X-point control provides accurate positioning of the X-point despite low controllability due to the large distance between coils and plasma. Combined, these techniques enabled achievement of IBS parameters (q95 = 3.2, βN = 2) with a scaled ITER shape on KSTAR. n =2 RMP response displays a strong dependence upon this shaping. Work supported by the US DOE under Award DE-SC0010685 and the KSTAR project.

Transport modeling of L- and H-mode discharges with LHCD on EAST

NASA Astrophysics Data System (ADS)

Li, M. H.; Ding, B. J.; Imbeaux, F.; Decker, J.; Zhang, X. J.; Kong, E. H.; Zhang, L.; Wei, W.; Shan, J. F.; Liu, F. K.; Wang, M.; Xu, H. D.; Yang, Y.; Peysson, Y.; Basiuk, V.; Artaud, J.-F.; Yuynh, P.; Wan, B. N.

2013-04-01

High-confinement (H-mode) discharges with lower hybrid current drive (LHCD) as the only heating source are obtained on EAST. In this paper, an empirical transport model of mixed Bohm/gyro-Bohm for electron and ion heat transport was first calibrated against a database of 3 L-mode shots on EAST. The electron and ion temperature profiles are well reproduced in the predictive modeling with the calibrated model coupled to the suite of codes CRONOS. CRONOS calculations with experimental profiles are also performed for electron power balance analysis. In addition, the time evolutions of LHCD are calculated by the C3PO/LUKE code involving current diffusion, and the results are compared with experimental observations.

Progress of long pulse operation with high performance plasma in KSTAR

NASA Astrophysics Data System (ADS)

Bae, Young; Kstar Team

2015-11-01

Recent KSTAR experiments showed the sustained H-mode operation up to the pulse duration of 46 s at the plasma current of 600 kA. The long-pulse H-mode operation has been supported by long-pulse capable neutral beam injection (NBI) system with high NB current drive efficiency attributed by highly tangential injections of three beam sources. In next phase, aiming to demonstrate the long pulse stationary high performance plasma operation, we are attempting the long pulse inductive operation at the higher performance (MA plasma current, high normalized beta, and low q95) for the final goal of demonstration of ITER-like baseline scenario in KSTAR with progressive improvement of the plasma shape control and higher neutral beam injection power. This paper presents the progress of long pulse operation and the analysis of energy confinement time and non-inductive current drive in KSTAR.

Research of Fast DAQ system in KSTAR Thomson scattering diagnostic

NASA Astrophysics Data System (ADS)

Lee, J. H.; Kim, H. J.; Yamada, I.; Funaba, H.; Kim, Y. G.; Kim, D. Y.

2017-12-01

The Thomson scattering diagnostic is one of the most important diagnostic systems in fusion plasma research. It provides reliable electron temperature and density profiles in magnetically confined plasma. A Q-switched Nd:YAG Thomson system was installed several years ago in KSTAR tokamak to measure the electron temperature and density profiles. For the KSTAR Thomson scattering system, a Charge-to-Digital Conversion (QDC) type data acquisition system was used to measure a pulse type Thomson signal. Recently, however, an error was found during the Te, ne calculation, because the QDC system had integrated the pulse Thomson signal that included a signal similar to stray light. To overcome such errors, we introduce a fast data acquisition (F-DAQ) system. To test this, we use CAEN V1742 5 GS/s, a Versa Module Eurocard Bus (VMEbus) type 12-bit switched capacitor digitizer with 32 channels. In this experiment, we compare the calculated Te results of Thomson scattering data measured simultaneously using QDC and F-DAQ. In the F-DAQ system, the shape of the pulse was restored by fitting.

47 CFR 25.136 - Licensing provisions for user transceivers in the 1.6/2.4 GHz, 1.5/1.6 GHz, and 2 GHz Mobile...

Code of Federal Regulations, 2011 CFR

2011-10-01

... Applications and Licenses Earth Stations § 25.136 Licensing provisions for user transceivers in the 1.6/2.4 GHz... specified in § 25.213, earth stations operating in the 1.6/2.4 GHz and 1.5/1.6 GHz Mobile Satellite Services... aircraft unless the earth station has a direct physical connection to the aircraft cabin or cockpit...

47 CFR 25.136 - Licensing provisions for user transceivers in the 1.6/2.4 GHz, 1.5/1.6 GHz, and 2 GHz Mobile...

Code of Federal Regulations, 2012 CFR

2012-10-01

... Applications and Licenses Earth Stations § 25.136 Licensing provisions for user transceivers in the 1.6/2.4 GHz... specified in § 25.213, earth stations operating in the 1.6/2.4 GHz and 1.5/1.6 GHz Mobile Satellite Services... aircraft unless the earth station has a direct physical connection to the aircraft cabin or cockpit...

47 CFR 25.136 - Licensing provisions for user transceivers in the 1.6/2.4 GHz, 1.5/1.6 GHz, and 2 GHz Mobile...

Code of Federal Regulations, 2013 CFR

2013-10-01

... Applications and Licenses Earth Stations § 25.136 Licensing provisions for user transceivers in the 1.6/2.4 GHz... specified in § 25.213, earth stations operating in the 1.6/2.4 GHz and 1.5/1.6 GHz Mobile-Satellite Services... aircraft unless the earth station has a direct physical connection to the aircraft cabin or cockpit...

0.5-45GHz Simultaneous Transmit and Receive (STAR) Antenna System for Electronic Attack

DTIC Science & Technology

2016-03-17

0.5-45GHz Simultaneous Transmit and Receive (STAR) Antenna System for Electronic Attack Mohamed Elmansouri, Prathap Valaleprasannakumar, Elie...Colorado, US, 80309 Abstract: A shared antenna aperture for simultaneous transmit and receive (STAR) operating from 0.5 to 45GHz with isolation...50dB over the entire band is discussed. The co-located antenna aperture system is designed across 4 overlapping bands: 0.5-2.5GHz, 2-7GHz, 6-19GHz

In-vessel visible inspection system on KSTAR

NASA Astrophysics Data System (ADS)

Chung, Jinil; Seo, D. C.

2008-08-01

To monitor the global formation of the initial plasma and damage to the internal structures of the vacuum vessel, an in-vessel visible inspection system has been installed and operated on the Korean superconducting tokamak advanced research (KSTAR) device. It consists of four inspection illuminators and two visible/H-alpha TV cameras. Each illuminator uses four 150W metal-halide lamps with separate lamp controllers, and programmable progressive scan charge-coupled device cameras with 1004×1004 resolution at 48frames/s and a resolution of 640×480 at 210frames/s are used to capture images. In order to provide vessel inspection capability under any operation condition, the lamps and cameras are fully controlled from the main control room and protected by shutters from deposits during plasma operation. In this paper, we describe the design and operation results of the visible inspection system with the images of the KSTAR Ohmic discharges during the first plasma campaign.

Measurement of vertical stability metrics in KSTAR

NASA Astrophysics Data System (ADS)

Hahn, Sang-Hee; Humphreys, D. A.; Mueller, D.; Bak, J. G.; Eidietis, N. W.; Kim, H.-S.; Ko, J. S.; Walker, M. L.; Kstar Team

2017-10-01

The paper summarizes results of multi-year ITPA experiments regarding measurement of the vertical stabilization capability of KSTAR discharges, including most recent measurements at the highest achievable elongation (κ 2.0 - 2.1). The measurements of the open-loop growth rate of VDE (γz) and the maximum controllable vertical displacement (ΔZmax) are done by the release-and-catch method. The dynamics of the vertical movement of the plasma is verified by both relevant magnetic reconstructions and non-magnetic diagnostics. The measurements of γz and ΔZmax were done for different plasma currents, βp, internal inductances, elongations and different configurations of the vessel conductors that surround the plasma as the first wall. Effects of control design choice and diagnostics noise are discussed, and comparison with the axisymmetric plasma response model is given for partial accounting for the measured control capability. This work supported by Ministry of Science, ICT, and Future Planning under KSTAR project.

Effective ion charge (Zeff) measurements and impurity behavior in KSTAR

NASA Astrophysics Data System (ADS)

Sarwar, S.; Na, H. K.; Park, J. M.

2018-04-01

A visible bremsstrahlung detector array diagnostic system has been developed on the Korea Superconducting Tokamak Advanced Research (KSTAR) to view the whole minor radius in a narrow region of the continuum free of spectral lines. The interference filters coupled with photomultiplier tubes have been employed to determine the effective charge Zeff by using visible bremsstrahlung data during neutral beam injection in the KSTAR plasma. The Zeff profiles are typically flat for L-mode plasmas and evolve to hollow profiles during the H mode in the KSTAR. A comparison of the visible bremsstrahlung emission based on the calculated Zeff profiles is consistent with measured values of Zeff from a visible spectrometer in the core plasma. The electron temperature is measured by X-ray imaging crystal spectrometry, and electron density needed for the analysis is taken by the assumption of parabolic profiles of these parameters. The line of sight averaged local bremsstrahlung emissivity is determined with low uncertainty, and the radial emissivity is obtained by using the Abel inversion technique. In addition, a dependence of effective charge Zeff on the line-averaged electron density is evaluated, and Zeff is also determined to observe the effect of boronization.

Formation of the internal transport barrier in KSTAR

NASA Astrophysics Data System (ADS)

Chung, J.; Kim, H. S.; Jeon, Y. M.; Kim, J.; Choi, M. J.; Ko, J.; Lee, K. D.; Lee, H. H.; Yi, S.; Kwon, J. M.; Hahn, S.-H.; Ko, W. H.; Lee, J. H.; Yoon, S. W.

2018-01-01

One of key objectives of tokamak experiments is the exploration of enhanced confinement regimes, and the access of the internal transport barrier (ITB) formation is dealt with an important physics issue in the most of major tokamaks. Also, the advanced tokamak scenario with ITB is expected to lead to a continuous reactor with high fusion power density. From that point of view, the formation of the ITB in KSTAR which is designed for long pulse operation capability is very important although its heating and current drive systems are not fully equipped yet. We have therefore assumed that an early injection of the full NBI power (∼5.5 MW) during the current ramp-up would give a chance to form an internal barrier if the plasma could stay in the L-mode. To avoid the H-mode transition, we have produced inboard limited plasmas with detaching from the both upper and lower divertors. Using this approach, an ITB formation during L-mode has been observed which shows improved core confinement. Ion and electron temperature profiles show the barrier clearly in the temperature, and it was sustained for about 7 s in the dedicated experiment. This is the first stationary ITB observed in a full superconducting tokamak. This operation scenario with the ITB could be an alternative way to achieve a high performance regime in KSTAR, and the length of the ITB discharge could be extended even longer. In this paper, we present the formation of the ITB using measured and simulated characteristic profiles.

MSE commissioning and other major diagnostic updates on KSTAR

NASA Astrophysics Data System (ADS)

Ko, Jinseok; Kstar Team

2015-11-01

The motional Stark effect (MSE) diagnostic based on the photoelastic-modulator (PEM) approach has been commissioned for the Korea Superconducting Tokamak Advanced Research (KSTAR). The 25-channel MSE system with the polarization-preserving front optics and precise tilt-tuning narrow bandpass filters provides the spatial resolution less than 1 cm in most of the plasma cross section and about 10 millisecond of time resolution. The polarization response curves with the daily Faraday rotation correction provides reliable pitch angle profiles for the KSTAR discharges with the MSE-optimized energy combination in the three-ion-source neutral beam injection. Some major diagnostic advances such as the poloidal charge exchange spectroscopy, the improved Thomson-scatting system, and the divertor infrared TV are reported as well. Work supported by the Ministry of Science, ICT and Future Planning, Korea.

Design of 2.5 GHz broad bandwidth microwave bandpass filter at operating frequency of 10 GHz using HFSS

NASA Astrophysics Data System (ADS)

Jasim, S. E.; Jusoh, M. A.; Mahmud, S. N. S.; Zamani, A. H.

2018-04-01

Development of low losses, small size and broad bandwidth microwave bandpass filter operating at higher frequencies is an active area of research. This paper presents a new route used to design and simulate microwave bandpass filter using finite element modelling and realized broad bandwidth, low losses, small dimension microwave bandpass filter operating at 10 GHz frequency using return loss method. The filter circuit has been carried out using Computer Aid Design (CAD), Ansoft HFSS software and designed with four parallel couple line model and small dimension (10 × 10 mm2) using LaAlO3 substrate. The response of the microwave filter circuit showed high return loss -50 dB at operating frequency at 10.4 GHz and broad bandwidth of 2.5 GHz from 9.5 to 12 GHz. The results indicate the filter design and simulation using HFSS is reliable and have the opportunity to transfer from lab potential experiments to the industry.

ECH-assisted startup at KSTAR

NASA Astrophysics Data System (ADS)

Bae, Y. S.; Jeong, J. H.; Park, S. I.; Cho, M. H.; Namkung, W.; Jackson, G. L.; Joung, M.; Yoon, S. W.; Kim, J. H.; Hahn, S. H.; Kim, W. C.; Yang, H. L.; Oh, Y. K.; Humphreys, D.; Walker, M. L.; Gorelov, Y.; Leuer, J. A.; Hyatt, A. W.; Eidietis, N. W.; Mueller, D.; Bak, J. S.; Kwon, M.

2009-11-01

The electron cyclotron heating (ECH)-assisted startup was successful in the Korea Superconducting Tokamak Advanced Research (KSTAR) first plasma campaign completed in June, 2008. It was observed that the second harmonic EC wave of 0.35 MW was sufficient to achieve breakdown in the ECH pre-ionization phase, to allow burn through, and to sustain the plasma during the current ramp with a low loop voltage of 2.0 V. This corresponds to a toroidal electric field of 0.24 Vm-1 at the innermost vacuum vessel wall (R = 1.3 m). Since there is no feedback control of the plasma radial position in the initial phase of the KSTAR first plasma campaign, wall contact caused the plasma current fall to zero soon after the ECH beam was turned off. Extending pulse duration of the ECH power to 190 ms allowed the plasma current to rise up to more than 100 kA with a ramp-up rate of 0.8 MA/s and the pulse duration of 210 ms. Later in the first plasma campaign, the plasma was sustained up to 865 ms with the help of additional heating of 350-ms long ECH beam and with the help of the plasma radial position feedback control. The plasma current in the pre-ionization phase was observed and it is considered to be pressure-driven Pfirsch-Schlüter current.

Physics validation for design change of KSTAR passive stabilizer

NASA Astrophysics Data System (ADS)

Jeon, Y. M.; Kim, J. Y.; Oh, Y. K.; Yang, H. L.; Kim, W. C.; Kim, H. K.; Sabbagh, S. A.; Bialek, J. M.; Humphreys, D. A.; Welander, A. S.; Walker, M. L.

2009-11-01

Recently, the design of the passive stabilizer in KSTAR has been changed to improve controllability of the active control system and reduce the possibility of producing an additional error field. Originally the passive stabilizer in KSTAR was designed for RWM and vertical instability (or VDE) stabilizations and plasma startup efficiency, so that current bridges were designed and combined through 3D saddle-loop connections. Since the key design change is removing the current bridges, it's essential to assure satisfactory control performance for these instabilities under the design change. Control capability for n=1 RWM and achievable βN will be addressed as a primary goal of the passive stabilizer together with vertical instability control and effects on plasma startup. In addition, the changes in electro-magnetic force on conducting structures will be discussed qualitatively as a key engineering issue of the design change.

Radiometric measurements over bare and vegetated fields at 1.4 GHz and 5 GHz frequencies. [Beltsville Agricultural Research Center, Maryland

NASA Technical Reports Server (NTRS)

Wang, J. R.; Mcmurtrey, J. E., III; Engman, E. T.; Jackson, T. J.; Schmugge, T. J.; Gould, W. I.; Glazar, W. S.; Fuchs, J. E. (Principal Investigator)

1981-01-01

Microwave emission from bare and vegetated fields was measured with dual polarized radiometers at 1.4 GHz and 5 GHz frequencies. The measured brightness temperatures over bare fields are shown to compare favorably with those calculated from radiative transfer theory with two constant parameters characterizing surface roughness effect. The presence of vegetation cover is found to reduce the sensitivity to soil moisture variation. This sensitivity reduction is generally pronounced the denser, the vegetation cover and the higher the frequency of observation. The effect of vegetation cover is also examined with respect to the measured polarization factor at both frequencies. With the exception of dry corn fields, the measured polarization factor over vegetated fields is found appreciably reduced compared to that over bare fields. A much larger reduction in this factor is found at 5GHz than at 1.4GHz frequency.

LETTER: ECH pre-ionization and assisted startup in the fully superconducting KSTAR tokamak using second harmonic

NASA Astrophysics Data System (ADS)

Bae, Y. S.; Jeong, J. H.; Park, S. I.; Joung, M.; Kim, J. H.; Hahn, S. H.; Yoon, S. W.; Yang, H. L.; Kim, W. C.; Oh, Y. K.; England, A. C.; Namkung, W.; Cho, M. H.; Jackson, G. L.; Bak, J. S.; KSTAR Team

2009-02-01

This letter reports on the successful demonstration of the second harmonic electron cyclotron heating (ECH)-assisted startup in the first plasma experiments recently completed in the fully superconducting Korea Superconducting Tokamak Advanced Research (KSTAR) device whose major and minor radii are 1.8 m and 0.5 m, respectively. For the second harmonic ECH-assisted startup, an 84 GHz EC wave at 0.35 MW was launched before the onset of the toroidal electric field of the Ohmic system. And it was observed that this was sufficient to achieve breakdown in the ECH pre-ionization phase, allow burn-through and sustain the plasma during the current ramp with a low loop voltage of 2.0 V and a corresponding toroidal electric field of 0.24 V m-1at the innermost vacuum vessel wall (R = 1.3 m). This is a lower value than 0.3 Vm-1 which is the maximum electric field in ITER. Due to the limited volt-seconds and the loop voltage of the Ohmic power system, the extended pulse duration of the ECH power up to 180 ms allowed the plasma current to rise up to more than 100 kA with a ramp-up rate of 0.8 MA s-1.

VizieR Online Data Catalog: 2FGL sources observed between 5-9GHz (Schinzel+, 2015)

NASA Astrophysics Data System (ADS)

Schinzel, F. K.; Petrov, L.; Taylor, G. B.; Mahony, E. K.; Edwards, P. G.; Kovalev, Yu. Y.

2015-04-01

A list of 216 target fields were observed with the Very Large Array (VLA). The instantaneous bandwidth was split into two parts, with one half centered at 5.0GHz (4.5-5.5GHz) and the other centered at 7.3GHz (6.8-7.8GHz); on 2012 October 26 and 2012 November 3. See section 2.1 During the first campaign with the Australia Telescope Compact Array (ATCA), from 2012 September 19-20, we observed 411 2FGL unassociated sources in a decl. range of [-90°, +10°] at 5.5 and 9GHz. The details of that observing campaign and results have been reported by Petrov et al. (2013, J/MNRAS/432/1294). We detected a total of 424 point sources. In a second ATCA campaign on 2013 September 25-28, we re-observed sources that were detected at 5GHz, but were not detected at 9GHz. See section 2.2. Follow-up observations of 149 targets selected from the VLA and ATCA survey above -30° decl. were conducted with the Very Long Baseline Array (VLBA) between 2013 Feb-Aug (VCS7 project; 4.128-4.608 and 7.392-7.872GHz simultaneously) and in 2013 Jun-Dec (campaign S5272; 7.392-7.872GHz only). See section 2.3. For sources with decl. below -30° we added 21 objects to the on-going LCS campaign (Petrov et al. 2011, J/MNRAS/414/2528) in 2013 Mar-2013 Jun at 8.200-8.520GHz. See section 2.4. (7 data files).

A comprehensive study on rotation reversal in KSTAR: experimental observations and modelling

NASA Astrophysics Data System (ADS)

Na, D. H.; Na, Yong-Su; Angioni, C.; Yang, S. M.; Kwon, J. M.; Jhang, Hogun; Camenen, Y.; Lee, S. G.; Shi, Y. J.; Ko, W. H.; Lee, J. A.; Hahm, T. S.; KSTAR Team

2017-12-01

Dedicated experiments have been performed in KSTAR Ohmic plasmas to investigate the detailed physics of the rotation reversal phenomena. Here we adapt the more general definition of rotation reversal, a large change of the intrinsic toroidal rotation gradient produced by minor changes in the control parameters (Camenen et al 2017 Plasma Phys. Control. Fusion 59 034001), which is commonly observed in KSTAR regardless of the operating conditions. The two main phenomenological features of the rotation reversal are the normalized toroidal rotation gradient ({{u}\\prime} ) change in the gradient region and the existence of an anchor point. For the KSTAR Ohmic plasma database including the experiment results up to the 2016 experimental campaign, both features were investigated. First, the observations show that the locations of the gradient and the anchor point region are dependent on {{q}95} . Second, a strong dependence of {{u}\\prime} on {νeff} is clearly observed in the gradient region, whereas the dependence on R/{{L}{{Ti}}} , R/{{L}{{Te}}} , and R/{{L}{{ne}}} is unclear considering the usual variation of the normalized gradient length in KSTAR. The experimental observations were compared against several theoretical models. The rotation reversal might not occur due to the transition of the dominant turbulence from the trapped electron mode to the ion temperature gradient mode or the neoclassical equilibrium effect in KSTAR. Instead, it seems that the profile shearing effects associated with a finite ballooning tilting well reproduce the experimental observations of both the gradient region and the anchor point; the difference seems to be related to the magnetic shear and the q value. Further analysis implies that the increase of {{u}\\prime} in the gradient region with the increase of the collisionality would occur when the reduction of the momentum diffusivity is comparatively larger than the reduction of the residual stress. It is supported by the perturbative

Operating characteristics of a new ion source for KSTAR neutral beam injection system.

PubMed

Kim, Tae-Seong; Jeong, Seung Ho; Chang, Doo-Hee; Lee, Kwang Won; In, Sang-Ryul

2014-02-01

A new positive ion source for the Korea Superconducting Tokamak Advanced Research neutral beam injection (KSTAR NBI-1) system was designed, fabricated, and assembled in 2011. The characteristics of the arc discharge and beam extraction were investigated using hydrogen and helium gas to find the optimum operating parameters of the arc power, filament voltage, gas pressure, extracting voltage, accelerating voltage, and decelerating voltage at the neutral beam test stand at the Korea Atomic Energy Research Institute in 2012. Based on the optimum operating condition, the new ion source was then conditioned, and performance tests were primarily finished. The accelerator system with enlarged apertures can extract a maximum 65 A ion beam with a beam energy of 100 keV. The arc efficiency and optimum beam perveance, at which the beam divergence is at a minimum, are estimated to be 1.0 A/kW and 2.5 uP, respectively. The beam extraction tests show that the design goal of delivering a 2 MW deuterium neutral beam into the KSTAR Tokamak plasma is achievable.

Contemporaneous VLBA 5 GHz Observations of Large Area Telescope Detected Blazars

DTIC Science & Technology

2012-01-10

Polarimetry Survey (VIPS) have been included in the sample, as well as 142 sources not found in VIPS. This very large, 5 GHz flux-limited sample of active...observing runs were follow-up observations on 90 sources in the VLBA Imaging and Polarimetry Survey (VIPS; Helmboldt et al. 2007) and new 5 GHz observations...Array (VLBA). In total, 232 sources were observed with the VLBA. Ninety sources that were previously observed as part of the VLBA Imaging and Polarimetry

Radioactivity evaluation for the KSTAR tokamak.

PubMed

Kim, Hyunduk; Lee, Hee-Seock; Hong, Sukmo; Kim, Minho; Chung, Chinwha; Kim, Changsuk

2005-01-01

The deuterium-deuterium (D-D) reaction in the KSTAR (Korea Superconducting Tokamak Advanced Research) tokamak generates neutrons with a peak yield of 2.5 x 10(16) s(-1) through a pulse operation of 300 s. Since the structure material of the tokamak is irradiated with neutrons, this environment will restrict work around and inside the tokamak from a radiation protection physics point of view after shutdown. Identification of neutron-produced radionuclides and evaluation of absorbed dose in the structure material are needed to develop a guiding principle for radiation protection. The activation level was evaluated by MCNP4C2 and an inventory code, FISPACT. The absorbed dose in the working area decreased by 4.26 x 10(-4) mrem h(-1) in the inner vessel 1.5 d after shutdown. Furthermore, tritium strongly contributes to the contamination in the graphite tile. The amount of tritium produced by neutrons was 3.03 x 10(6) Bq kg(-1) in the carbon graphite of a plasma-facing wall.

Steady state plasma operation in RF dominated regimes on EAST

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, X. J.; Zhao, Y. P.; Gong, X. Z.

Significant progress has recently been made on EAST in the 2014 campaign, including the enhanced CW H&CD system over 20MW heating power (LHCD, ICRH and NBI), more than 70 diagnostics, ITER-like W-monoblock on upper divertor, two inner cryo-pumps and RMP coils, enabling EAST to investigate long pulse H mode operation with dominant electron heating and low torque to address the critical issues for ITER. H-mode plasmas were achieved by new H&CD system or 4.6GHz LHCD alone for the first time. Long pulse high performance H mode has been obtained by LHCD alone up to 28s at H{sub 98}∼1.2 or bymore » combing of ICRH and LHCD, no or small ELM was found in RF plasmas, which is essential for steady state operation in the future Tokamak. Plasma operation in low collision regimes were implemented by new 4.6GHz LHCD with core Te∼4.5keV. The non-inductive scenarios with high performance at high bootstrap current fraction have been demonstrated in RF dominated regimes for long pulse operation. Near full non-inductive CD discharges have been achieved. In addition, effective heating and decoupling method under multi-transmitter for ICRF system were developed in this campaign, etc. EAST could be in operation with over 30MW CW heating and current drive power (LHCD ICRH NBI and ECRH), enhanced diagnostic capabilities and full actively-cooled metal wall from 2015. It will therefore allow to access new confinement regimes and to extend these regimes towards to steady state operation.« less

Reconfigurable antenna options for 2.45/5 GHz wireless body area networks in healthcare applications.

PubMed

Abbas, Syed Muzahir; Ranga, Yogesh; Esselle, Karu P

2015-01-01

This paper presents electronically reconfigurable antenna options in healthcare applications. They are suitable for wireless body area network devices operating in the industrial, scientific, and medical (ISM) band at 2.45 GHz and IEEE 802.11 Wireless Local Area Network (WLAN) band at 5 GHz (5.15-5.35 GHz, 5.25-5.35 GHz). Two types of antennas are investigated: Antenna-I has a full ground plane and Antenna-II has a partial ground plane. The proposed antennas provide ISM operation in one mode while in another mode they support 5 GHz WLAN band. Their performance is assessed for body centric wireless communication using a simplified human body model. Antenna sensitivity to the gap between the antenna and the human body is investigated for both modes of each antenna. The proposed antennas exhibit a wide radiation pattern along the body surface to provide wide coverage and their small width (14 mm) makes them suitable for on-body communication in healthcare applications.

47 CFR 25.250 - Sharing between NGSO MSS Feeder links Earth Stations in the 19.3-19.7 GHz and 29.1-29.5 GHz Bands.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 47 Telecommunication 2 2014-10-01 2014-10-01 false Sharing between NGSO MSS Feeder links Earth....250 Sharing between NGSO MSS Feeder links Earth Stations in the 19.3-19.7 GHz and 29.1-29.5 GHz Bands. (a) NGSO MSS applicants shall be licensed to operate in the 29.1-29.5 GHz band for Earth-to-space...

47 CFR 25.250 - Sharing between NGSO MSS Feeder links Earth Stations in the 19.3-19.7 GHz and 29.1-29.5 GHz Bands.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 47 Telecommunication 2 2013-10-01 2013-10-01 false Sharing between NGSO MSS Feeder links Earth....250 Sharing between NGSO MSS Feeder links Earth Stations in the 19.3-19.7 GHz and 29.1-29.5 GHz Bands. (a) NGSO MSS applicants shall be licensed to operate in the 29.1-29.5 GHz band for Earth-to-space...

47 CFR 25.250 - Sharing between NGSO MSS Feeder links Earth Stations in the 19.3-19.7 GHz and 29.1-29.5 GHz Bands.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 47 Telecommunication 2 2012-10-01 2012-10-01 false Sharing between NGSO MSS Feeder links Earth....250 Sharing between NGSO MSS Feeder links Earth Stations in the 19.3-19.7 GHz and 29.1-29.5 GHz Bands. (a) NGSO MSS applicants shall be licensed to operate in the 29.1-29.5 GHz band for Earth-to-space...

47 CFR 25.250 - Sharing between NGSO MSS Feeder links Earth Stations in the 19.3-19.7 GHz and 29.1-29.5 GHz Bands.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 2 2010-10-01 2010-10-01 false Sharing between NGSO MSS Feeder links Earth....250 Sharing between NGSO MSS Feeder links Earth Stations in the 19.3-19.7 GHz and 29.1-29.5 GHz Bands. (a) NGSO MSS applicants shall be licensed to operate in the 29.1-29.5 GHz band for Earth-to-space...

47 CFR 25.250 - Sharing between NGSO MSS Feeder links Earth Stations in the 19.3-19.7 GHz and 29.1-29.5 GHz Bands.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 2 2011-10-01 2011-10-01 false Sharing between NGSO MSS Feeder links Earth....250 Sharing between NGSO MSS Feeder links Earth Stations in the 19.3-19.7 GHz and 29.1-29.5 GHz Bands. (a) NGSO MSS applicants shall be licensed to operate in the 29.1-29.5 GHz band for Earth-to-space...

Versatile controllability of non-axisymmetric magnetic perturbations in KSTAR experiments

NASA Astrophysics Data System (ADS)

Han, Hyunsun; Jeon, Y. M.; in, Y.; Kim, J.; Yoon, S. W.; Hahn, S. H.; Ahn, H. S.; Woo, M. H.; Park, B. H.; Bak, J. G.; Kstar Team

2015-11-01

A newly upgraded IVCC (In-Vessel Control Coil) system equipped with four broadband power supplies, along with current connection patch panel, will be presented and discussed in terms of its capability on various KSTAR experiments. Until the last run-campaign, there were impressive experimental results on ELM(Edge Localized Mode) control experiments using the 3D magnetic field, but the non-axisymmetric field configuration could not be changed in a shot, let alone the limited number of accessible configurations. Introducing the new power supplies, such restrictions have been greatly reduced. Based on the preliminary commissioning results for 2015 KSTAR run-campaign, this new system has been confirmed to easily cope with various dynamic demands for toroidal and poloidal phases of 3D magnetic field in a shot. This enables us to diagnose the plasma response in more detail and to address the 3-D field impacts on the ELM behaviors better than ever.

Modelling ion cyclotron emission from KSTAR tokamak and LHD helical device plasmas

NASA Astrophysics Data System (ADS)

Dendy, Richard; Chapman, Ben; Reman, Bernard; Chapman, Sandra; Akiyama, Tsuyoshi; Yun, Gunsu

2017-10-01

New high quality measurements of ion cyclotron emission (ICE) from KSTAR and LHD greatly extend the scope and diversity of plasma conditions under which ICE is observed. Variables include the origin (fusion reactions or neutral beam injection) and energy (sub- or super-Alfvénic) of the minority energetic ions that drive ICE; the composition of the bulk plasma (hydrogen or deuterium) which supports the modes excited; plasma density in the emitting region, and the timescale on which it changes; and toroidal magnetic field geometry (tokamak or helical device). Future exploitation of ICE as a diagnostic for energetic ion populations in JET D-T plasmas and in ITER rests on quantitative understanding of the physics of the emission. This is tested and extended by current KSTAR and LHD measurements of ICE. We report progress on direct numerical simulation using full orbit ion kinetic codes that solve the Maxwell-Lorentz equations for hundreds of millions of particles. In the saturated regime, these simulations yield excited field spectra that correspond directly to the measured ICE spectra under diverse KSTAR and LHD regimes. At early times, comparison of simulation outputs with linear analytical theory confirms the magnetoacoustic cyclotron instability as the basic driver of ICE. Supported by RCUK Energy Programme Grant EP/P012450/1, NRF Korea Grant 2014M1A7A1A03029881, NIFS budget ULHH029 and Euratom.

Progress in development of neutron energy spectrometer for deuterium plasma operation in KSTAR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tomita, H., E-mail: tomita@nagoya-u.jp; Yamashita, F.; Nakayama, Y.

2014-11-15

Two types of DD neutron energy spectrometer (NES) are under development for deuterium plasma operation in KSTAR to understand behavior of beam ions in the plasma. One is based on the state-of-the-art nuclear emulsion technique. The other is based on a coincidence detection of a recoiled proton and a scattered neutron caused by an elastic scattering of an incident DD neutron, which is called an associated particle coincidence counting-NES. The prototype NES systems were installed at J-port in KSTAR in 2012. During the 2012 and 2013 experimental campaigns, multiple shots-integrated neutron spectra were preliminarily obtained by the nuclear emulsion-based NESmore » system.« less

A compact 5.5 GHz band-rejected UWB antenna using complementary split ring resonators.

PubMed

Islam, M M; Faruque, M R I; Islam, M T

2014-01-01

A band-removal property employing microwave frequencies using complementary split ring resonators (CSRRs) is applied to design a compact UWB antenna wishing for the rejection of some frequency band, which is meanwhile exercised by the existing wireless applications. The reported antenna comprises optimization of a circular radiating patch, in which slotted complementary SRRs are implanted. It is printed on low dielectric FR4 substrate material fed by a partial ground plane and a microstrip line. Validated results exhibit that the reported antenna shows a wide bandwidth covering from 3.45 to more than 12 GHz, with a compact dimension of 22 × 26 mm(2), and VSWR < 2, observing band elimination of 5.5 GHz WLAN band.

Compact Planar Ultrawideband Antennas with 3.5/5.2/5.8 GHz Triple Band-Notched Characteristics for Internet of Things Applications.

PubMed

Dong, Jian; Li, Qianqian; Deng, Lianwen

2017-02-10

Ultrawideband (UWB) antennas, as core devices in high-speed wireless communication, are widely applied to mobile handsets, wireless sensor networks, and Internet of Things (IoT). A compact printed monopole antenna for UWB applications with triple band-notched characteristics is proposed in this paper. The antenna has a very compact size of 10 x 16 mm2 and is composed of a square slotted radiation patch and a narrow rectangular ground plane on the back of the substrate. First, by etching a pair of inverted T-shaped slots at the bottom of the radiation patch, one notched band at 5-6 GHz for rejecting the Wireless Local Area Network (WLAN) is generated. Then, by cutting a comb-shaped slot on the top of the radiation patch, a second notched band for rejecting 3.5 GHz Worldwide Interoperability for Microwave Access (WiMAX) is obtained. Further, by cutting a pair of rectangular slots and a C-shaped slot as well as adding a pair of small square parasitic patches at the center of the radiating patch, two separate notched bands for rejecting 5.2 GHz lower WLAN and 5.8 GHz upper WLAN are realized, respectively. Additionally, by integrating the slotted radiation patch with the narrow rectangular ground plane, an enhanced impedance bandwidth can be achieved, especially at the higher band. The antenna consists of linear symmetrical sections only and is easy for fabrication and fine-tuning. The measured results show that the designed antenna provides a wide impedance bandwidth of 150% from 2.12 to 14.80 GHz for VSWR < 2, except for three notched bands of 3.36-4.16, 4.92-5.36, and 5.68-6.0 GHz. Additionally, the antenna exhibits nearly omnidirectional radiation characteristics, low gain at the stopbands, and flat group delay over the whole UWB except at the stopbands. Simulated and experimental results show that the proposed antenna can provide good frequency-domain and time-domain performances at desired UWB frequencies and be an attractive candidate for portable Io

Relative performance of 8.5-GHz and 32-GHz telemetry links on the basis of total data return per pass

NASA Technical Reports Server (NTRS)

Koerner, M. A.

1986-01-01

The performance of X-band (8.5-GHz) and 32-GHz telemetry links is compared on the basis of the total data return per DSN station pass. Differences in spacecraft transmitter efficiency, transmit circuit loss, and transmitting antenna area efficiency and pointing loss are not considered in these calculations. Thus, the performance differentials calculated in this memo are those produced by a DSN 70-m station antenna gain and clear weather receiving system noise temperature and by weather. These calculations show that, assuming mechanical compensation of the DSN 70-m antenna for 32-GHz operation, a performance advantage for 32 GHz over X-band of 8.2 dB can be achieved for at least one DSN station location. Even if only Canberra and Madrid are used, a performance advantage of 7.7 dB can be obtained for at least one DSN station location. A system using a multiple beam feed (electronic compensation) should achieve similar results.

A Compact 5.5 GHz Band-Rejected UWB Antenna Using Complementary Split Ring Resonators

PubMed Central

Islam, M. M.; Faruque, M. R. I.; Islam, M. T.

2014-01-01

A band-removal property employing microwave frequencies using complementary split ring resonators (CSRRs) is applied to design a compact UWB antenna wishing for the rejection of some frequency band, which is meanwhile exercised by the existing wireless applications. The reported antenna comprises optimization of a circular radiating patch, in which slotted complementary SRRs are implanted. It is printed on low dielectric FR4 substrate material fed by a partial ground plane and a microstrip line. Validated results exhibit that the reported antenna shows a wide bandwidth covering from 3.45 to more than 12 GHz, with a compact dimension of 22 × 26 mm2, and VSWR < 2, observing band elimination of 5.5 GHz WLAN band. PMID:24971379

Assessment and modification of an ion source grid design in KSTAR neutral beam system.

PubMed

Lee, Dong Won; Shin, Kyu In; Jin, Hyung Gon; Choi, Bo Guen; Kim, Tae-Seong; Jeong, Seung Ho

2014-02-01

A new 2 MW NB (Neutral Beam) ion source for supplying 3.5 MW NB heating for the KSTAR campaign was developed in 2012 and its grid was made from OFHC (Oxygen Free High Conductivity) copper with rectangular cooling channels. However, the plastic deformation such as a bulging in the plasma grid of the ion source was found during the overhaul period after the 2012 campaign. A thermal-hydraulic and a thermo-mechanical analysis using the conventional code, ANSYS, were carried out and the thermal fatigue life assessment was evaluated. It was found that the thermal fatigue life of the OFHC copper grid was about 335 cycles in case of 0.165 MW/m(2) heat flux and it gave too short fatigue life to be used as a KSTAR NB ion source grid. To overcome the limited fatigue life of the current design, the following methods were proposed in the present study: (1) changing the OHFC copper to CuCrZr, copper-alloy or (2) adopting a new design with a pure Mo metal grid and CuCrZr tubes. It is confirmed that the proposed methods meet the requirements by performing the same assessment.

Design of WLAN microstrip antenna for 5.17 - 5.835 GHz

NASA Astrophysics Data System (ADS)

Bugaj, Jarosław; Bugaj, Marek; Wnuk, Marian

2017-04-01

This paper presents the project of miniaturized WLAN Antenna made in microstrip technique working at a frequency of 5.17 - 5.835 GHz in 802.11ac IEEE standard. This dual layer antenna is designed on RT/duroid 5870 ROGERS CORPORATION substrate with dielectric constant 2.33 and thickness of 3.175 mm. The antenna parameters such as return loss, VSWR, gain and directivity are simulated and optimized using commercial computer simulation technology microwave studio (CST MWS). The paper presents the results of discussed numerical analysis.

First Trial of Real-time Poloidal Beta Control in KSTAR

NASA Astrophysics Data System (ADS)

Han, Hyunsun; Hahn, S. H.; Bak, J. G.; Walker, M. L.; Woo, M. H.; Kim, J. S.; Kim, Y. J.; Bae, Y. S.; KSTAR Team

2014-10-01

Sustaining the plasma in a stable and a high performance condition is one of the important control issues for future steady state tokamaks. In the 2014 KSTAR campaign, we have developed a real-time poloidal beta (βp) control technique and carried out preliminary experiments to identify its feasibility. In the control system, the βp is calculated in real time using the measured diamagnetic loop signal (DLM03) with coil pickup corrections, and compared with the target value leading to the change of the neutral beam (NB) heating power using a feedback PID control algorithm. To match the required power of NB which is operated with constant voltage, the duty cycles of the modulation were adjusted as the ratio of the required power to the maximum achievable one. This paper will present the overall procedures of the βp control, the βp estimation process implemented in the plasma control system, and the analysis on the preliminary experimental results. This work is supported by the KSTAR research project funded by the Ministry of Science, ICT & Future Planning of Korea.

Compact Planar Ultrawideband Antennas with 3.5/5.2/5.8 GHz Triple Band-Notched Characteristics for Internet of Things Applications

PubMed Central

Dong, Jian; Li, Qianqian; Deng, Lianwen

2017-01-01

Ultrawideband (UWB) antennas, as core devices in high-speed wireless communication, are widely applied to mobile handsets, wireless sensor networks, and Internet of Things (IoT). A compact printed monopole antenna for UWB applications with triple band-notched characteristics is proposed in this paper. The antenna has a very compact size of 10 × 16 mm2 and is composed of a square slotted radiation patch and a narrow rectangular ground plane on the back of the substrate. First, by etching a pair of inverted T-shaped slots at the bottom of the radiation patch, one notched band at 5–6 GHz for rejecting the Wireless Local Area Network (WLAN) is generated. Then, by cutting a comb-shaped slot on the top of the radiation patch, a second notched band for rejecting 3.5 GHz Worldwide Interoperability for Microwave Access (WiMAX) is obtained. Further, by cutting a pair of rectangular slots and a C-shaped slot as well as adding a pair of small square parasitic patches at the center of the radiating patch, two separate notched bands for rejecting 5.2 GHz lower WLAN and 5.8 GHz upper WLAN are realized, respectively. Additionally, by integrating the slotted radiation patch with the narrow rectangular ground plane, an enhanced impedance bandwidth can be achieved, especially at the higher band. The antenna consists of linear symmetrical sections only and is easy for fabrication and fine-tuning. The measured results show that the designed antenna provides a wide impedance bandwidth of 150% from 2.12 to 14.80 GHz for VSWR < 2, except for three notched bands of 3.36–4.16, 4.92–5.36, and 5.68–6.0 GHz. Additionally, the antenna exhibits nearly omnidirectional radiation characteristics, low gain at the stopbands, and flat group delay over the whole UWB except at the stopbands. Simulated and experimental results show that the proposed antenna can provide good frequency-domain and time-domain performances at desired UWB frequencies and be an attractive candidate for portable Io

Lesson from Tungsten Leading Edge Heat Load Analysis in KSTAR Divertor

NASA Astrophysics Data System (ADS)

Hong, Suk-Ho; Pitts, Richard Anthony; Lee, Hyeong-Ho; Bang, Eunnam; Kang, Chan-Soo; Kim, Kyung-Min; Kim, Hong-Tack; ITER Organization Collaboration; Kstar Team Team

2016-10-01

An important design issue for the ITER tungsten (W) divertor and in fact for all such components using metallic plasma-facing elements and which are exposed to high parallel power fluxes, is the question of surface shaping to avoid melting of leading edges. We have fabricated a series of tungsten blocks with a variety of leading edge heights (0.3, 0.6, 1.0, and 2.0 mm), from the ITER worst case to heights even beyond the extreme value tested on JET. They are mounted into adjacent, inertially cooled graphite tile installed in the central divertor region of KSTAR, within the field of view of an infra-red (IR) thermography system with a spatial resolution to 0.4 mm/pixel. Adjustment of the outer divertor strike point position is used to deposit power on the different blocks in different discharges. The measured power flux density on flat regions of the surrounding graphite tiles is used to obtain the parallel power flux, q|| impinging on the various W blocks. Experiments have been performed in Type I ELMing H-mode with Ip = 600 kA, BT = 2 T, PNBI = 3.5 MW, leading to a hot attached divertor with typical pulse lengths of 10 s. Three dimensional ANSYS simulations using q|| and assuming geometric projection of the heat flux are found to be consistent with the observed edge loading. This research was partially supported by Ministry of Science, ICT, and Future Planning under KSTAR project.

Simple 2.5 GHz time-bin quantum key distribution

NASA Astrophysics Data System (ADS)

Boaron, Alberto; Korzh, Boris; Houlmann, Raphael; Boso, Gianluca; Rusca, Davide; Gray, Stuart; Li, Ming-Jun; Nolan, Daniel; Martin, Anthony; Zbinden, Hugo

2018-04-01

We present a 2.5 GHz quantum key distribution setup with the emphasis on a simple experimental realization. It features a three-state time-bin protocol based on a pulsed diode laser and a single intensity modulator. Implementing an efficient one-decoy scheme and finite-key analysis, we achieve record breaking secret key rates of 1.5 kbps over 200 km of standard optical fibers.

Design of 4x1 microstrip patch antenna array for 5.8 GHz ISM band applications

NASA Astrophysics Data System (ADS)

Valjibhai, Gohil Jayesh; Bhatia, Deepak

2013-01-01

This paper describes the new design of four element antenna array using corporate feed technique. The proposed antenna array is developed on the Rogers 5880 dielectric material. The antenna array works on 5.8 GHz ISM band. The industrial, scientific and medical (ISM) radio bands are radio bands (portions of the radio spectrum) reserved internationally for the use of radio frequency (RF) energy for industrial, scientific and medical purposes other than communications. The array antennas have VSWR < 1.6 from 5.725 - 5.875 GHz. The simulated return loss characteristic of the antenna array is - 39.3 dB at 5.8 GHz. The gain of the antenna array is 12.3 dB achieved. The directivity of the broadside radiation pattern is 12.7 dBi at the 5.8 GHz operating frequency. The antenna array is simulated using High frequency structure simulation software.

24-71 GHz PCB Array for 5G ISM

NASA Technical Reports Server (NTRS)

Novak, Markus H.; Volakis, John L.; Miranda, Felix A.

2017-01-01

Millimeter-wave 5G mobile architectures need to consolidate disparate frequency bands into a single, multifunctional array. Existing arrays are either narrow-band, prohibitively expensive or cannot be scaled to these frequencies. In this paper, we present the first ultra-wideband millimeter wave array to operate across six 5G and ISM bands spanning 24-71 GHz. Importantly, the array is realized using low-cost PCB. The paper presents the design and optimized layout, and discusses fabrication and measurements.

Simple and Low-Cost Dual-Band Printed Microwave Absorber for 2.4- and 5-GHz-Band Applications

NASA Astrophysics Data System (ADS)

Khoomwong, Ekajit; Phongcharoenpanich, Chuwong

2017-10-01

In this research, a dual-band thin printed-circuit-board (PCB) microwave absorber has been proposed for applications in 2.4 and 5 GHz frequency bands. Each unit cell of the absorber consists of a square ring and a thick cross-dipole, augmented with the tuning elements. In the design process, numerical simulations were performed for the optimal characteristics of the absorber and an absorber prototype was fabricated using the simple print-transferring and etching process. The measured absorption bandwidths (50 %) of 170 MHz (2.36-2.53 GHz) and 830 MHz (5.09-5.92 GHz) were achieved for the first and second bands, respectively, with the wideband characteristic at the second operating band. The absorption rates near the center frequencies (2.45 and 5.5 GHz) were respectively 97.85 % and 97.76 %. The simulation and measured results are in good agreement. Furthermore, the incidence-angle dependencies of the absorber were of moderately wide angles with the absorption capacity of at least 50 % for both operating bands. The proposed absorber is suitable for a variety of applications requiring absorption in the 2.4/5 GHz bands.

Measurements of the radar cross section and Inverse Synthetic Aperture Radar (ISAR) images of a Piper Navajo at 9.5 GHz and 49 GHz

NASA Astrophysics Data System (ADS)

Dinger, R.; Kinzel, G.; Lam, W.; Jones, S.

1993-01-01

Studies were conducted of the enhanced radar cross section (RCS) and improved inverse synthetic aperture radar (ISAR) image quality that may result at millimeter-wave (mmw) frequencies. To study the potential for mmw radar in these areas, a program was initiated in FY-90 to design and fabricate a 49.0- to 49.5-GHz stepped-frequency radar. After conducting simultaneous measurements of the RCS of an airborne Piper Navajo twin-engine aircraft at 9.0 and 49.0 GHz, the RCS at 49.0 GHz was always found to be higher than at 9.0 GHz by an amount that depended on the target aspect angle. The largest increase was 19 dB and was measured at nose-on incidence; at other angles of incidence, the increase ranged from 3 to 10 dB. The increase averaged over a 360-degree aspect-angle change was 7.2 dB. The 49.0-GHz radar has demonstrated a capability to gather well-calibrated millimeter-wave RCS data of flying targets. In addition, the successful ISAR images obtainable with short aperture time suggest that 49.0-GHz radar may have a role to play in noncooperative target identification (NCTI).

Synchronized operation by field programmable gate array based signal controller for the Thomson scattering diagnostic system in KSTAR.

PubMed

Lee, W R; Kim, H S; Park, M K; Lee, J H; Kim, K H

2012-09-01

The Thomson scattering diagnostic system is successfully installed in the Korea Superconducting Tokamak Advanced Research (KSTAR) facility. We got the electron temperature and electron density data for the first time in 2011, 4th campaign using a field programmable gate array (FPGA) based signal control board. It operates as a signal generator, a detector, a controller, and a time measuring device. This board produces two configurable trigger pulses to operate Nd:YAG laser system and receives a laser beam detection signal from a photodiode detector. It allows a trigger pulse to be delivered to a time delay module to make a scattered signal measurement, measuring an asynchronous time value between the KSTAR timing board and the laser system injection signal. All functions are controlled by the embedded processor running on operating system within a single FPGA. It provides Ethernet communication interface and is configured with standard middleware to integrate with KSTAR. This controller has operated for two experimental campaigns including commissioning and performed the reconfiguration of logic designs to accommodate varying experimental situation without hardware rebuilding.

Gyrokinetic simulation study of magnetic island effects on neoclassical physics and micro-instabilities in a realistic KSTAR plasma

NASA Astrophysics Data System (ADS)

Kwon, Jae-Min; Ku, S.; Choi, M. J.; Chang, C. S.; Hager, R.; Yoon, E. S.; Lee, H. H.; Kim, H. S.

2018-05-01

We perform gyrokinetic simulations to study the effects of a stationary magnetic island on neoclassical flow and micro-instability in a realistic KSTAR plasma condition. Through the simulations, we aim to analyze a recent KSTAR experiment, which was to measure the details of poloidal flow and fluctuation around a stationary (2, 1) magnetic island [M. J. Choi et al., Nucl. Fusion 57, 126058 (2017)]. From the simulations, it is found that the magnetic island can significantly enhance the equilibrium E × B flow. The corresponding flow shearing is strong enough to suppress a substantial portion of ambient micro-instabilities, particularly ∇Te -driven trapped electron modes. This implies that the enhanced E × B flow can sustain a quasi-internal transport barrier for Te in an inner region neighboring the magnetic island. The enhanced E × B flow has a (2, 1) mode structure with a finite phase shift from the mode structure of the magnetic island. It is shown that the flow shear and the fluctuation suppression patterns implied from the simulations are consistent with the observations on the KSTAR experiment.

Field orientation effects during 5. 6-GHz radiofrequency irradiation of rats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frei, M.R.; Jauchem, J.R.; Price, D.L.

1990-12-01

Ketamine-anesthetized Sprague-Dawley rats were exposed in E and H orientations (long axis parallel to electric and magnetic fields, respectively) to far-field 5.6-GHz continuous-wave radio-frequency radiation (RFR). Power densities were used that resulted in equivalent whole-body average specific absorption rates of 14 W/kg in both orientations (90 mW/cm2 for E and 66 mW/cm2 for H). Irradiation was conducted to increase colonic temperature by 1 degree C (from 38.5 to 39.5 degrees C). During experimentation, arterial blood pressure and respiratory rate and colonic, tympanic, left and right subcutaneous (sides toward and away from RFR source), and tail temperatures were continuously recorded. Resultsmore » showed no significant difference in the times required to cause a 1 degree C increase or to recover to the initial temperature when irradiation was stopped. Significant differences between E- and H-orientation exposure were seen in the patterns of localized heating. The tail and left subcutaneous temperature increases were significantly greater during E-orientation exposure, the tympanic site showed no difference, and the right subcutaneous temperature increase was significantly greater during H-orientation exposure. Under both exposure conditions, heart rate and mean arterial blood pressure significantly increased during irradiation; however, there were no significant differences between E and H orientation responses. These findings at 5.6 GHz are in contrast to the significant cardiovascular response differences between E- and H-orientation exposure noted during a previous study of irradiation at 2.45 GHz.« less

Impurity Radiation From The LHCD Launcher During Operation In JET And Investigation Of Launcher Damage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kirov, K.K.; Mailloux, J.; Ekedahl, A.

2005-09-26

In this study, the most likely causes of the enhanced radiation in front of the LHCD launcher are investigated: fast ions from the warm plasma, fast electrons parasitically accelerated in front of the grill and arcs. Evidence for the presence of each of these mechanisms is discussed. The experimental conditions favouring the appearance of these phenomena and their impact on the launcher have also been highlighted.

Analysis of edge density fluctuation measured by trial KSTAR beam emission spectroscopy systema)

NASA Astrophysics Data System (ADS)

Nam, Y. U.; Zoletnik, S.; Lampert, M.; Kovácsik, Á.

2012-10-01

A beam emission spectroscopy (BES) system based on direct imaging avalanche photodiode (APD) camera has been designed for Korea Superconducting Tokamak Advanced Research (KSTAR) and a trial system has been constructed and installed for evaluating feasibility of the design. The system contains two cameras, one is an APD camera for BES measurement and another is a fast visible camera for position calibration. Two pneumatically actuated mirrors were positioned at front and rear of lens optics. The front mirror can switch the measurement between edge and core region of plasma and the rear mirror can switch between the APD and the visible camera. All systems worked properly and the measured photon flux was reasonable as expected from the simulation. While the measurement data from the trial system were limited, it revealed some interesting characteristics of KSTAR plasma suggesting future research works with fully installed BES system. The analysis result and the development plan will be presented in this paper.

Evolution of the central safety factor during stabilized sawtooth instabilities at KSTAR

NASA Astrophysics Data System (ADS)

Messmer, M. C. C.; Ko, J.; Chung, J.; Woo, M. H.; Lee, K.-D.; Jaspers, R. J. E.

2018-01-01

A motional Stark effect (MSE) diagnostic has recently been installed in the KSTAR tokamak. A difficulty faced at KSTAR and common to other MSE diagnostics is calibration of the system for absolute measurements. In this report we present our novel calibration routine and discuss first results, evaluating the evolution of the the central safety factor during sawtooth instabilities. The calibration scheme ensures that the bandpass filters typically used in MSE systems are aligned correctly and identifies and removes systematic offsets present in the measurement. This is verified by comparing the reconstructed safety factor profile against various discharges where the locations of rational q surfaces have been obtained from MHD markers. The calibration is applied to analyse the evolution of q 0 in a shot where the sawteeth are stabilized by neutral beam injection. Within the analysed sawtooth periods q 0 drops below unity during the quiescent phase and relaxes close to or slightly above unity at the sawtooth crash. This finding is in line with the classical Kadomtsev model of full magnetic reconnection and earlier findings at JET.

Improvement of a plasma uniformity of the 2nd ion source of KSTAR neutral beam injector.

PubMed

Jeong, S H; Kim, T S; Lee, K W; Chang, D H; In, S R; Bae, Y S

2014-02-01

The 2nd ion source of KSTAR (Korea Superconducting Tokamak Advanced Research) NBI (Neutral Beam Injector) had been developed and operated since last year. A calorimetric analysis revealed that the heat load of the back plate of the ion source is relatively higher than that of the 1st ion source of KSTAR NBI. The spatial plasma uniformity of the ion source is not good. Therefore, we intended to identify factors affecting the uniformity of a plasma density and improve it. We estimated the effects of a direction of filament current and a magnetic field configuration of the plasma generator on the plasma uniformity. We also verified that the operation conditions of an ion source could change a uniformity of the plasma density of an ion source.

Conceptual communications system design in the 25.25-27.5 and 37.0-40.5 GHz frequency bands

NASA Technical Reports Server (NTRS)

Thompson, Michael W.

1993-01-01

Future space applications are likely to rely heavily on Ka-band frequencies (20-40 GHz) for communications traffic. Many space research activities are now conducted using S-band and X-band frequencies, which are becoming congested and require a degree of pre-coordination. In addition to providing relief from frequency congestion, Ka-band technologies offer potential size, weight, and power savings when compared to lower frequency bands. The use of the 37.0-37.5 and 40.0-40.5 GHz bands for future planetary missions was recently approved at the 1992 World Administrative Radio Conference (WARC-92). WARC-92 also allocated the band 25.25-27.5 GHz to the Intersatellite Service on a primary basis to accommodate Data Relay Satellite return link requirements. Intersatellite links are defined to be between artificial satellites and thus a communication link with the surface of a planetary body, such as the moon, and a relay satellite orbiting that body are not permitted in this frequency band. This report provides information about preliminary communications system concepts for forward and return links for earth-Mars and earth-lunar links using the 37.0-37.5 (return link) and 40.0-40.5 (forward link) GHz frequency bands. In this study we concentrate primarily on a conceptual system for communications between earth and a single lunar surface terminal (LST), and between earth and a single Mars surface terminal (MST). Due to large space losses, these links have the most stringent link requirements for an overall interplanetary system. The earth ground station is assumed to be the Deep Space Network (DSN) using either 34 meter or 70 meter antennas. We also develop preliminary communications concepts for a space-to-space system operating at near 26 GHz. Space-to-space applications can encompass a variety of operating conditions, and we consider several 'typical' scenarios described in more detail later in this report. Among these scenarios are vehicle-to-vehicle communications

Gyrokinetic simulation study of magnetic island effects on neoclassical physics and micro-instabilities in a realistic KSTAR plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kwon, Jae-Min; Ku, S.; Choi, M. J.

Here, we perform gyrokinetic simulations to study the effects of a stationary magnetic island on neoclassical flow and micro-instability in a realistic KSTAR plasma condition. Through the simulations, we aim to analyze a recent KSTAR experiment, which was to measure the details of poloidal flow and fluctuation around a stationary (2, 1) magnetic island [M. J. Choi et al., Nucl. Fusion 57, 126058 (2017)]. From the simulations, it is found that the magnetic island can significantly enhance the equilibrium E x B flow. The corresponding flow shearing is strong enough to suppress a substantial portion of ambient micro-instabilities, particularly ∇Tmore » e-driven trapped electron modes. This implies that the enhanced E x B flow can sustain a quasi-internal transport barrier for T e in an inner region neighboring the magnetic island. The enhanced E x B flow has a (2, 1) mode structure with a finite phase shift from the mode structure of the magnetic island. It is shown that the flow shear and the fluctuation suppression patterns implied from the simulations are consistent with the observations on the KSTAR experiment.« less

Gyrokinetic simulation study of magnetic island effects on neoclassical physics and micro-instabilities in a realistic KSTAR plasma

DOE PAGES

Kwon, Jae-Min; Ku, S.; Choi, M. J.; ...

2018-05-01

Here, we perform gyrokinetic simulations to study the effects of a stationary magnetic island on neoclassical flow and micro-instability in a realistic KSTAR plasma condition. Through the simulations, we aim to analyze a recent KSTAR experiment, which was to measure the details of poloidal flow and fluctuation around a stationary (2, 1) magnetic island [M. J. Choi et al., Nucl. Fusion 57, 126058 (2017)]. From the simulations, it is found that the magnetic island can significantly enhance the equilibrium E x B flow. The corresponding flow shearing is strong enough to suppress a substantial portion of ambient micro-instabilities, particularly ∇Tmore » e-driven trapped electron modes. This implies that the enhanced E x B flow can sustain a quasi-internal transport barrier for T e in an inner region neighboring the magnetic island. The enhanced E x B flow has a (2, 1) mode structure with a finite phase shift from the mode structure of the magnetic island. It is shown that the flow shear and the fluctuation suppression patterns implied from the simulations are consistent with the observations on the KSTAR experiment.« less

The second MIT-Green Bank 5 GHz survey

NASA Astrophysics Data System (ADS)

Langston, Glen I.; Heflin, Michael B.; Conner, Sam R.; Lehar, Joseph; Carilli, Chris L.; Burke, Bernard F.

1990-03-01

The MHT-Green Bank II (MG II) 5-GHz survey covers 1.51 sr of sky in the right ascension range 4-21 h between +17 and +39.15 deg declination (J2000.0). The final MG II catalog contains 6182 sources detected with a signal-to-noise ratio greater than 5. The MG II flux density limit is 41 mJy. The catalog was produced from two separate north and south surveys with the NRAO 91-m transit telescope. Spectral indices are computed for sources identified in the NRAO 1400-MHz Survey (Condon and Broderick, 1985). A comparison of the spectral-index distributions for sources above and below 10 deg Galactic latitude is presented.

Effect of the electric field pattern on the generation of fast electrons in front of lower hybrid launchers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Valade, Laurent, E-mail: laurent.valade@cea.fr; Ekedahl, Annika; Colas, Laurent

2015-12-10

The effect of the detailed waveguide spectrum on the electron acceleration has been studied for the 3.7 GHz LHCD launchers in Tore Supra, i.e. the ITER-like passive-active multijunction (PAM) launcher and the fully-active-multijunction (FAM) launcher, using test electron modelling technique. The detailed launched antenna wave spectrum is used as input to the code that computes the dynamics of the electrons in the electric field. Comparison with the LHCD launchers in EAST, operating at 2.45 GHz and 4.6 GHz, has also been made. The simulations show that the PAM-design generates lower flux of fast electrons than FAM-launchers, this could be themore » consequence of the wider waveguide of PAM-launcher (14.65 mm for Tore-Supra) than FAM-launcher (8 mm for Tore-Supra)« less

Millimeter wave absorption in the nonhuman primate eye at 35 GHz and 94 GHz.

PubMed

Chalfin, Steven; D'Andrea, John A; Comeau, Paul D; Belt, Michael E; Hatcher, Donald J

2002-07-01

The purpose of this study was to evaluate anterior segment bioeffects of pulsed 35 GHz and 94 GHz microwave exposure in the nonhuman primate eye. Five juvenile rhesus monkeys (Macaca mulatta) underwent baseline anterior segment ocular assessment consisting of slit lamp examination, corneal topography, specular microscopy, and pachymetry. These studies were repeated after exposure of one eye to pulsed 35 GHz or 94 GHz microwaves at varied fluences, with the other eye serving as a control. The mean fluence required to produce a threshold corneal lesion (faint epithelial edema and fluorescein staining) was 7.5 J cm(-2) at 35 GHz and 5 J cm(-2) at 94 GHz. Transient changes in corneal topography and pachymetry were noted at these fluences. Endothelial cell counts remained unchanged. Threshold corneal injury from 35 GHz and 94 GHz microwave exposure is produced at fluences below those previously reported for CO2 laser radiation. These data may help elucidate the mechanism of thermal injury to the cornea, and resolve discrepancies between IEEE C95.1 (1999), NCRP (1986), and ICNIRP (1998) safety standards for exposure to non-ionizing radiation at millimeter wavelengths.

2D scrape-off layer turbulence measurement using Deuterium beam emission spectroscopy on KSTAR

NASA Astrophysics Data System (ADS)

Lampert, M.; Zoletnik, S.; Bak, J. G.; Nam, Y. U.; Kstar Team

2018-04-01

Intermittent events in the scrape-off layer (SOL) of magnetically confined plasmas, often called blobs and holes, contribute significantly to the particle and heat loss across the magnetic field lines. In this article, the results of the scrape-off layer and edge turbulence measurements are presented with the two-dimensional Deuterium Beam Emission Spectroscopy system (DBES) at KSTAR (Korea Superconducting Tokamak Advanced Research). The properties of blobs and holes are determined in an L-mode and an H-mode shot with statistical tools and conditional averaging. These results show the capabilities and limitations of the SOL turbulence measurement of a 2D BES system. The results from the BES study were compared with the analysis of probe measurements. It was found that while probes offer a better signal-to-noise ratio and can measure blobs down to 3 mm size, BES can monitor the two-dimensional dynamics of larger events continuously during full discharges, and the measurement is not limited to the SOL on KSTAR.

47 CFR 25.136 - Licensing provisions for user transceivers in the 1.6/2.4 GHz, 1.5/1.6 GHz, and 2 GHz Mobile...

Code of Federal Regulations, 2010 CFR

2010-10-01

.../2.4 GHz Mobile-Satellite Service or 2 GHz Mobile-Satellite Service may not be operated on civil... rules and regulations in this Part and the applicable engineering standards. Prior to engaging in such...

Design of ITER divertor VUV spectrometer and prototype test at KSTAR tokamak

NASA Astrophysics Data System (ADS)

Seon, Changrae; Hong, Joohwan; Song, Inwoo; Jang, Juhyeok; Lee, Hyeonyong; An, Younghwa; Kim, Bosung; Jeon, Taemin; Park, Jaesun; Choe, Wonho; Lee, Hyeongon; Pak, Sunil; Cheon, MunSeong; Choi, Jihyeon; Kim, Hyeonseok; Biel, Wolfgang; Bernascolle, Philippe; Barnsley, Robin; O'Mullane, Martin

2017-12-01

Design and development of the ITER divertor VUV spectrometer have been performed from the year 1998, and it is planned to be installed in the year 2027. Currently, the design of the ITER divertor VUV spectrometer is in the phase of detail design. It is optimized for monitoring of chord-integrated VUV signals from divertor plasmas, chosen to contain representative lines emission from the tungsten as the divertor material, and other impurities. Impurity emission from overall divertor plasmas is collimated through the relay optics onto the entrance slit of a VUV spectrometer with working wavelength range of 14.6-32 nm. To validate the design of the ITER divertor VUV spectrometer, two sets of VUV spectrometers have been developed and tested at KSTAR tokamak. One set of spectrometer without the field mirror employs a survey spectrometer with the wavelength ranging from 14.6 nm to 32 nm, and it provides the same optical specification as the spectrometer part of the ITER divertor VUV spectrometer system. The other spectrometer with the wavelength range of 5-25 nm consists of a commercial spectrometer with a concave grating, and the relay mirrors with the same geometry as the relay mirrors of the ITER divertor VUV spectrometer. From test of these prototypes, alignment method using backward laser illumination could be verified. To validate the feasibility of tungsten emission measurement, furthermore, the tungsten powder was injected in KSTAR plasmas, and the preliminary result could be obtained successfully with regard to the evaluation of photon throughput. Contribution to the Topical Issue "Atomic and Molecular Data and their Applications", edited by Gordon W.F. Drake, Jung-Sik Yoon, Daiji Kato, Grzegorz Karwasz.

A 5.2/5.8 GHz Dual Band On-Off Keying Transmitter Design for Bio-Signal Transmission

NASA Astrophysics Data System (ADS)

Wu, Chang-Hsi; You, Hong-Cheng; Huang, Shun-Zhao

2018-02-01

An architecture of 5.2/5.8-GHz dual-band on-off keying (DBOOK) modulated transmitter is designed in a 0.18-μm CMOS technology. The proposed DBOOK transmitter is used in the biosignal transmission system with high power efficiency and small area. To reduce power consumption and enhance output swing, two pairs of center-tapped transformers are used as both LC tank and source grounding choke for the designed voltage controlled oscillator (VCO). Switching capacitances are used to achieve dual band operations, and a complemented power combiner is used to merge the differential output power of VCO to a single-ended output. Besides, the linearizer circuits are used in the proposed power amplifier with wideband output matching to improve the linearity both at 5.2/5.8-GHz bands. The designed DBOOK transmitter is implemented by dividing it into two chips. One chip implements the dual-band switching VCO and power combiner, and the other chip implements a linear power amplifier including dual-band operation. The first chip drives an output power of 2.2mW with consuming power of 5.13 mW from 1.1 V supply voltage. With the chip size including pad of 0.61 × 0.91 m2, the measured data rate and transmission efficiency attained are 100 Mb/s and 51 pJ/bit, respectively. The second chip, for power enhanced mode, exhibits P1 dB of -9 dBm, IIP3 of 1 dBm, the output power 1 dB compression point of 12.42 dBm, OIP3 of about 21 dBm, maximum output power of 17.02/16.18 dBm, and power added efficiency of 17.13/16.95% for 5.2/ 5.8 GHz. The chip size including pads is 0:693 × 1:084mm2.

Design and Realization of a Planar Ultrawideband Antenna with Notch Band at 3.5 GHz

PubMed Central

2014-01-01

A small antenna with single notch band at 3.5 GHz is designed for ultrawideband (UWB) communication applications. The fabricated antenna comprises a radiating monopole element and a perfectly conducting ground plane with a wide slot. To achieve a notch band at 3.5 GHz, a parasitic element has been inserted in the same plane of the substrate along with the radiating patch. Experimental results shows that, by properly adjusting the position of the parasitic element, the designed antenna can achieve an ultrawide operating band of 3.04 to 11 GHz with a notched band operating at 3.31–3.84 GHz. Moreover, the proposed antenna achieved a good gain except at the notched band and exhibits symmetric radiation patterns throughout the operating band. The prototype of the proposed antenna possesses a very compact size and uses simple structures to attain the stop band characteristic with an aim to lessen the interference between UWB and worldwide interoperability for microwave access (WiMAX) band. PMID:25133245

Maps based on 53 GHz (5.7 mm wavelength)

NASA Technical Reports Server (NTRS)

2002-01-01

Maps based on 53 GHz (5.7 mm wavelength) observations made with the DMR over the entire 4-year mission (top) on a scale from 0 - 4 K, showing the near-uniformity of the CMB brightness, (middle) on a scale intended to enhance the contrast due to the dipole described in the slide 19 caption, and (bottom) following subtraction of the dipole component. Emission from the Milky Way Galaxy is evident in the bottom image. See slide 19 caption for information about map smoothing and projection.

Precise Absolute Astrometry from the VLBA Imaging and Polarimetry Survey at 5 GHz

NASA Technical Reports Server (NTRS)

Petrov, L.; Taylor, G. B.

2011-01-01

We present accurate positions for 857 sources derived from the astrometric analysis of 16 eleven-hour experiments from the Very Long Baseline Array imaging and polarimetry survey at 5 GHz (VIPS). Among the observed sources, positions of 430 objects were not previously determined at milliarcsecond-level accuracy. For 95% of the sources the uncertainty of their positions ranges from 0.3 to 0.9 mas, with a median value of 0.5 mas. This estimate of accuracy is substantiated by the comparison of positions of 386 sources that were previously observed in astrometric programs simultaneously at 2.3/8.6 GHz. Surprisingly, the ionosphere contribution to group delay was adequately modeled with the use of the total electron content maps derived from GPS observations and only marginally affected estimates of source coordinates.

Measurement of the ratio of hydrogen to deuterium at the KSTAR 2009 experimental campaign

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kwak, Jong-Gu; Wang, Son Jong; Kim, Sun Ho

The control of the ratio of hydrogen to the deuterium is one of the very important issues for ion cyclotron range of frequency (ICRF) minority heating as well as the plasma wall interaction in the tokamak. The ratio of hydrogen to deuterium during the tokamak shot was deduced from the emission spectroscopy measurements during the KSTAR 2009 experimental campaign. Graphite tiles were used for the plasma facing components (PFCs) at KSTAR and its surface area exposed to the plasma was about 11 m{sup 2}. The data showed that it remained as high as around 50% during the campaign period becausemore » graphite tiles were exposed to the air for about two months and the hydrogen contents at the tiles are not fully pumped out due to the lack of baking on the PFC in the 2009 campaign. The validation of the spectroscopy method was checked by using the Zeeman effects and the ratio of hydrogen to the deuterium is compared with results from the residual gas analysis. During the tokamak shot, the ratio is low below 10% initially and saturated after around 1 s. When there is a hydrogen injection to the vessel via ion cyclotron wall conditioning and the boronization process where the carbone is used, the ratio of the hydrogen to the deuterium is increased by up to 100% and it recovers to around 50% after one day of operation. However it does not decrease below 50% at the end of the experimental campaign. It was found that the full baking on the PFC (with a high temperature and sufficient vacuum pumping) is required for the ratio control which guarantees the efficient ICRF heating at the KSTAR 2010 experimental campaign.« less

Propagation Characteristics in an Underground Shopping Area for 5GHz-band Wireless Access Systems

NASA Astrophysics Data System (ADS)

Itokawa, Kiyohiko; Kita, Naoki; Sato, Akio; Matsue, Hideaki; Mori, Daisuke; Watanabe, Hironobu

5-GHz band wireless access systems, such as the RLAN (Radio Local Area Network) system of IEEE802.11a, HiperLAN/2, HiSWANa and AWA, are developed and provide transmission rates over 20 Mbps for indoor use. Those 5-GHz access systems are expected to extend service areas from the office to the so-called “hot-spot" in public areas. Underground shopping malls are one of the anticipated service areas for such a nomadic wireless access service. Broadband propagation characteristics are required for radio zone design in an underground mall environment despite previous results obtained by narrow band measurements. This paper presents results of an experimental study on the propagation characteristics for broadband wireless access systems in an underground mall environment. First, broadband propagation path loss is measured and formulated considering human body shadowing. A ray trace simulation is used to clarify the basic propagation mechanism in such a closed environment. Next, a distance dependency of the delay spread during a crowded time period, rush hour, is found to be at most 65 nsec, which is under the permitted maximum value of the present 5-GHz systems. Finally, above propagation characteristics support the result of transmission test carried out by using AWA equipment.

Progress in the RAMI analysis of a conceptual LHCD system for DEMO

NASA Astrophysics Data System (ADS)

Mirizzi, F.

2014-02-01

Reliability, Availability, Maintainability and Inspectability (RAMI) concepts and techniques, that acquired great importance during the first manned space missions, have been progressively extended to industrial, scientific and consumer equipments to assure them satisfactory performances and lifetimes. In the design of experimental facilities, like tokamaks, mainly aimed at demonstrating validity and feasibility of scientific theories, RAMI analysis has been often left aside. DEMO, the future prototype fusion reactors, will be instead designed for steadily delivering electrical energy to commercial grids, so that the RAMI aspects will assume an absolute relevance since their initial design phases. A preliminary RAMI analysis of the LHCD system for the conceptual EU DEMO reactor is given in the paper.

Superconducting ECR ion source: From 24-28 GHz SECRAL to 45 GHz fourth generation ECR

NASA Astrophysics Data System (ADS)

Zhao, H. W.; Sun, L. T.; Guo, J. W.; Zhang, W. H.; Lu, W.; Wu, W.; Wu, B. M.; Sabbi, G.; Juchno, M.; Hafalia, A.; Ravaioli, E.; Xie, D. Z.

2018-05-01

The development of superconducting ECR source with higher magnetic fields and higher microwave frequency is the most straight forward path to achieve higher beam intensity and higher charge state performance. SECRAL, a superconducting third generation ECR ion source, is designed for 24-28 GHz microwave frequency operation with an innovative magnet configuration of sextupole coils located outside the three solenoids. SECRAL at 24 GHz has already produced a number of record beam intensities, such as 40Ar12+ 1.4 emA, 129Xe26+ 1.1 emA, 129Xe30+ 0.36 emA, and 209Bi31+ 0.68 emA. SECRAL-II, an upgraded version of SECRAL, was built successfully in less than 3 years and has recently been commissioned at full power of a 28 GHz gyrotron and three-frequency heating (28 + 45 + 18 GHz). New record beam intensities for highly charged ion production have been achieved, such as 620 eμA 40Ar16+, 15 eμA 40Ar18+, 146 eμA 86Kr28+, 0.5 eμA 86Kr33+, 53 eμA 129Xe38+, and 17 eμA 129Xe42+. Recent beam test results at SECRAL and SECRAL II have demonstrated that the production of more intense highly charged heavy ion beams needs higher microwave power and higher frequency, as the scaling law predicted. A 45 GHz superconducting ECR ion source FECR (a first fourth generation ECR ion source) is being built at IMP. FECR will be the world's first Nb3Sn superconducting-magnet-based ECR ion source with 6.5 T axial mirror field, 3.5 T sextupole field on the plasma chamber inner wall, and 20 kW at a 45 GHz microwave coupling system. This paper will focus on SECRAL performance studies at 24-28 GHz and technical design of 45 GHz FECR, which demonstrates a technical path for highly charged ion beam production from 24 to 28 GHz SECRAL to 45 GHz FECR.

The 30 GHz communications satellite low noise receiver

NASA Technical Reports Server (NTRS)

Steffek, L. J.; Smith, D. W.

1983-01-01

A Ka-band low noise front end in proof of concept (POC) model form for ultimate spaceborne communications receiver deployment was developed. The low noise receiver consists of a 27.5 to 30.0 GHz image enhanced mixer integrated with a 3.7 to 6.2 GHz FET low noise IF amplifier and driven by a self contained 23.8 GHz phase locked local oscillator source. The measured level of receiver performance over the 27.3 to 30.0 GHz RF/3.7 to 6.2 GHz IF band includes 5.5 to 6.5 dB (typ) SSB noise figure, 20.5 + or - 1.5 dB conversion gain and +23 dBm minimum third order two tone intermodulation output intercept point.

VUV spectroscopy in impurity injection experiments at KSTAR using prototype ITER VUV spectrometer.

PubMed

Seon, C R; Hong, J H; Song, I; Jang, J; Lee, H Y; An, Y H; Kim, B S; Jeon, T M; Park, J S; Choe, W; Lee, H G; Pak, S; Cheon, M S; Choi, J H; Kim, H S; Biel, W; Bernascolle, P; Barnsley, R

2017-08-01

The ITER vacuum ultra-violet (VUV) core survey spectrometer has been designed as a 5-channel spectral system so that the high spectral resolving power of 200-500 could be achieved in the wavelength range of 2.4-160 nm. To verify the design of the ITER VUV core survey spectrometer, a two-channel prototype spectrometer was developed. As a subsequent step of the prototype test, the prototype VUV spectrometer has been operated at KSTAR since the 2012 experimental campaign. From impurity injection experiments in the years 2015 and 2016, strong emission lines, such as Kr xxv 15.8 nm, Kr xxvi 17.9 nm, Ne vii 46.5 nm, Ne vi 40.2 nm, and an array of largely unresolved tungsten lines (14-32 nm) could be measured successfully, showing the typical photon number of 10 13 -10 15 photons/cm 2 s.

Imaging of SNR IC443 and W44 with the Sardinia Radio Telescope at 1.5 and 7 GHz

NASA Astrophysics Data System (ADS)

Egron, E.; Pellizzoni, A.; Iacolina, M. N.; Loru, S.; Marongiu, M.; Righini, S.; Cardillo, M.; Giuliani, A.; Mulas, S.; Murtas, G.; Simeone, D.; Concu, R.; Melis, A.; Trois, A.; Pilia, M.; Navarrini, A.; Vacca, V.; Ricci, R.; Serra, G.; Bachetti, M.; Buttu, M.; Perrodin, D.; Buffa, F.; Deiana, G. L.; Gaudiomonte, F.; Fara, A.; Ladu, A.; Loi, F.; Marongiu, P.; Migoni, C.; Pisanu, T.; Poppi, S.; Saba, A.; Urru, E.; Valente, G.; Vargiu, G. P.

2017-09-01

Observations of supernova remnants (SNRs) are a powerful tool for investigating the later stages of stellar evolution, the properties of the ambient interstellar medium and the physics of particle acceleration and shocks. For a fraction of SNRs, multiwavelength coverage from radio to ultra-high energies has been provided, constraining their contributions to the production of Galactic cosmic rays. Although radio emission is the most common identifier of SNRs and a prime probe for refining models, high-resolution images at frequencies above 5 GHz are surprisingly lacking, even for bright and well-known SNRs such as IC443 and W44. In the frameworks of the Astronomical Validation and Early Science Program with the 64-m single-dish Sardinia Radio Telescope, we provided, for the first time, single-dish deep imaging at 7 GHz of the IC443 and W44 complexes coupled with spatially resolved spectra in the 1.5-7 GHz frequency range. Our images were obtained through on-the-fly mapping techniques, providing antenna beam oversampling and resulting in accurate continuum flux density measurements. The integrated flux densities associated with IC443 are S1.5 GHz = 134 ± 4 Jy and S7 GHz = 67 ± 3 Jy. For W44, we measured total flux densities of S1.5 GHz = 214 ± 6 Jy and S7 GHz = 94 ± 4 Jy. Spectral index maps provide evidence of a wide physical parameter scatter among different SNR regions: a flat spectrum is observed from the brightest SNR regions at the shock, while steeper spectral indices (up to ˜ 0.7) are observed in fainter cooling regions, disentangling in this way different populations and spectra of radio/gamma-ray-emitting electrons in these SNRs.

Comparative study between the reflective optics and lens based system for microwave imaging system on KSTAR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, W.; Yun, G. S.; Nam, Y.

2010-10-15

Recently, two-dimensional microwave imaging diagnostics such as the electron cyclotron emission imaging (ECEI) system and microwave imaging reflectometry (MIR) have been developed to study magnetohydrodynamics instabilities and turbulence in magnetically confined plasmas. These imaging systems utilize large optics to collect passive emission or reflected radiation. The design of this optics can be classified into two different types: reflective or refractive optical systems. For instance, an ECEI/MIR system on the TEXTOR tokamak [Park et al., Rev. Sci. Instrum. 75, 3787 (2004)] employed the reflective optics which consisted of two large mirrors, while the TEXTOR ECEI upgrade [B. Tobias et al., Rev.more » Sci. Instrum. 80, 093502 (2009)] and systems on DIII-D, ASDEX-U, and KSTAR adopted refractive systems. Each system has advantages and disadvantages in the standing wave problem and optical aberrations. In this paper, a comparative study between the two optical systems has been performed in order to design a MIR system for KSTAR.« less

Recent progress of RF-dominated experiments on EAST

NASA Astrophysics Data System (ADS)

Liu, F. K.; Zhao, Y. P.; Shan, J. F.; Zhang, X. J.; Ding, B. J.; Wang, X. J.; Wang, M.; Xu, H. D.; Qin, C. M.; Li, M. H.; Gong, X. Z.; Hu, L. Q.; Wan, B. N.; Song, Y. T.; Li, J. G.

2017-10-01

The research of EAST program is mostly focused on the development of high performance steady state scenario with ITER-like poloidal configuration and RF-dominated heating schemes. With the enhanced ITER-relevant auxiliary heating and current drive systems, the plasma profile control by coupling/integration of various combinations has been investigated, including lower hybrid current drive (LHCD), electron cyclotron resonance heating (ECRH) and ion cyclotron resonance heating (ICRH). The 12 MW ICRH system has been installed on EAST. Heating and confinement studies using the Hydrogen Minority Heating scheme have been investigated. One of the importance challenges for EAST is coupling higher power into the core plasma, experiments including changing plasma position, electron density, local gas puffing and antenna phasing scanning were performed to improve ICRF coupling efficiency on EAST. Results show that local gas injection and reducing the k|| can improve the coupling efficiency directly. By means of the 4.6 GHz and 2.45 GHz LHCD systems, H-mode can be obtained and sustained at relatively high density, even up to ne ˜ 4.5 × 1019 m-3, where a current drive effect is still observed. Meanwhile, effect of source frequency (2.45GHz and 4.6GHz) on LHCD characteristic has been studied on EAST, showing that higher frequency improves penetration of the coupled LH (lower hybrid) power into the plasma core and leads to a better effect on plasma characteristics. Studies demonstrate the role of parasitic effects of edge plasma in LHCD and the mitigation by increasing source frequency. Experiments of effect of LH spectrum and plasma density on plasma characteristics are performed, suggesting the possibility of plasma control for high performance. The development of a 4MW ECRH system is in progress for the purpose of plasma heating and MHD control. The built ECRH system with 1MW source power has been successfully put into use on EAST in 2015. H-mode discharges with L

Polarization structure of six gamma-ray quasars at 5 and 15 GHz

NASA Astrophysics Data System (ADS)

Vetukhnovskaya, Yu. N.; Gabuzda, D. C.; Yakimov, V. E.

2011-05-01

The results of 5 and 15 GHz polarization observations of the six blazars 1222+216, 1406-076, 1606+106, 1611+343, 17415-038, and 2022-077 obtained on the American Very Long Baseline Array are presented. The degrees of polarization in the cores and jets of these six gamma-ray quasars do not differ from those for other blazars.

Parametric Instabilities During High Power Helicon Wave Injection on DIII-D

NASA Astrophysics Data System (ADS)

Porkolab, M.; Pinsker, R. I.

2017-10-01

High power helicon (whistler) waves at a frequency of 0.47 GHz are being considered for efficient off-axis current generation in high performance DIII-D plasmas and in K-Star [3]. The need for deploying helicon waves for current profile control has been noted in previous publications since penetration to the core of reactor grade plasmas is easier than with lower hybrid slow waves (LHCD) which suffer from accessibility limitations and strong electron Landau absorption in fusion grade high temperature plasmas. In this work we show that under typical experimental conditions in present day tokamaks with 1 MW of RF power coupled per antenna, the associated perpendicular electric fields of the order of 40 kV/m can drive strong parametric decay instabilities near the lower hybrid layer. The EXB and polarization drift velocities which are the dominant driver of the PDI can be comparable to the speed of sound in the outer plasma layers, a key measure of driving PDI instabilities. Here we calculate growth rates and convective thresholds for PDIs, and we find that decay waves into hot ion lower hybrid waves and ion cyclotron quasi modes dominate in the vicinity of the lower hybrid layer, possibly leading to pump depletion. Such instabilities in future reactor grade high temperature plasmas are less likely.

A 5GHz Band Low Noise and Wide Tuning Range Si-CMOS VCO with a Novel Varactors Pair Circuit

NASA Astrophysics Data System (ADS)

Ta, Tuan Thanh; Kameda, Suguru; Takagi, Tadashi; Tsubouchi, Kazuo

In this paper, a fully integrated 5GHz voltage controlled oscillator (VCO) is presented. The VCO is designed with 0.18µm silicon complementary metal oxide semiconductor (Si-CMOS) process. To achieve low phase noise, a novel varactors pair circuit is proposed to cancel effects of capacitance fluctuation that makes harmonic currents which increase phase noise of VCO. The VCO with the proposed varactor circuit has tuning range from 5.1GHz to 6.1GHz (relative value of 17.9%) and phase noise of lower than -110.8dBc/Hz at 1MHz offset over the full tuning range. Figure-of-merit-with-tuning-range (FOMT) of the proposed VCO is -182dBc/Hz.

Physical Models of Layered Polar Firn Brightness Temperatures from 0.5 to 2 GHz

NASA Technical Reports Server (NTRS)

Tan, Shurun; Aksoy, Mustafa; Brogioni, Marco; Macelloni, Giovanni; Durand, Michael; Jezek, Kenneth C.; Wang, Tian-Lin; Tsang, Leung; Johnson, Joel T.; Drinkwater, Mark R.;

Observations of tropospheric phase scintillations at 5 GHz on vertical paths

NASA Technical Reports Server (NTRS)

Armstrong, J. W.; Sramek, R. A.

1982-01-01

The article presents observations of turbulence-induced tropospheric phase fluctuations measured at 5 GHz on the near-vertical paths relevant to many astronomical and geophysical measurements. The data are summarized as phase power spectra, structure functions, and Allan variances. Comparisons to other microwave observations indicate relatively good agreement in both the level and shape of the power spectrum of these tropospheric phase fluctuations. Implications for precision Doppler tracking of spacecraft and geodesy/radio interferometry are discussed.

Wideband Circularly Polarized Printed Ring Slot Antenna for 5 GHz – 6 GHz

NASA Astrophysics Data System (ADS)

Nasrun Osman, Mohamed; Rahim, Mohamad Helmi A.; Jusoh, Muzammil; Sabapathy, Thennarasan; Rahim, Mohamad Kamal A.; Norlyana Azemi, Saidatul

2018-03-01

This paper presents the design of circularly polarized printed slot antenna operating at 5 – 6 GHz. The proposed antenna consists of L-shaped feedline on the top of structure and circular ring slot positioned at the ground plane underneath the substrate as a radiator. A radial and narrow slot in the ground plane provides coupling between the L-shaped feedline and circular ring slot. The circular polarization is realized by implementing the slits perturbation located diagonally to perturb the current flow on the slot structure. The antenna prototype is fabricated on FR4 substrate. The simulated and measured results are compared and analyzed to demonstrate the performance of the antenna. Good measured of simulated results are obtained at the targeted operating frequency. The simulated -10dB reflection coefficient bandwidths and axial ratio are 750 MHz and 165 MHz, respectively. The investigation on the affect of the important parameters towards the reflection coefficient and axial are also presented. The proposed antenna is highly potential to be used for wireless local area network (WLAN) and wireless power transfer (WPT).

Key comparison SIM.EM.RF-K5b.CL: scattering coefficients by broad-band methods, 2 GHz-18 GHz — type N connector

NASA Astrophysics Data System (ADS)

Silva, H.; Monasterios, G.

2016-01-01

The first key comparison in microwave frequencies within the SIM (Sistema Interamericano de Metrología) region has been carried out. The measurands were the S-parameters of 50 ohm coaxial devices with Type-N connectors and were measured at 2 GHz, 9 GHz and 18 GHz. SIM.EM.RF-K5b.CL was the identification assigned and it was based on a parent CCEM key comparison named CCEM.RF-K5b.CL. For this reason, the measurements standards and their nominal values were selected accordingly, i.e. two one-port devices (a matched and a mismatched load) to cover low and high reflection coefficients and two attenuators (3dB and 20 dB) to cover low and high transmission coefficients. This key comparison has met the need for ensuring traceability in high-frequency measurements across America by linking SIM's results to CCEM. Six NMIs have participated in this comparison which was piloted by the Instituto Nacional de Tecnología Industrial (Argentina). A linking method of multivariate values was proposed and implemented in order to allow the linking of 2-dimensional results. KEY WORDS FOR SEARCH Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

183-GHz Radiometer Handbook - November 2006

DOE Office of Scientific and Technical Information (OSTI.GOV)

MP Cadeddu

2006-11-30

The G-Band Vapor Radiometer (GVR) provides time-series measurements of brightness temperatures from four double sideband channels centered at ± 1, ± 3, ± 7, and ± 14 GHz around the 183.31-GHz water vapor line. Atmospheric emission in this spectral region is primarily due to water vapor, with some influence from liquid water. The 183.31 ± 14-GHz channel is particularly sensitive to the presence of liquid water. The sensitivity to water vapor of the 183.31-GHz line is approximately 30 times higher than at the frequencies of the two-channel microwave radiometer (MWR) for a precipitable water vapor (PWV) amount of less thanmore » 2.5 mm. Measurements from this nstrument are therefore especially useful during low-humidity conditions (PWV < 5 mm).« less

ASTEROID SIZING BY RADIOGALAXY OCCULTATION AT 5 GHZ

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lehtinen, K.; Muinonen, K.; Poutanen, M.

Stellar occultations by asteroids observed at visual wavelengths have been an important tool for studying the size and shape of asteroids and for revising the orbital parameters of asteroids. At radio frequencies, a shadow of an asteroid on the Earth is dominated by diffraction effects. Here, we show, for the first time, that a single observation of an occultation of a compact radio source at a frequency of 5 GHz can be used to derive the effective size of the occulting object and to derive the distance between the observer and the center of the occultation path on the Earth.more » The derived diameter of the occulting object, asteroid (115) Thyra, is 75 ± 6 km. The observed occultation profile shows features that cannot be explained by diffraction of a single asteroid.« less

RFI in the 0.5 to 10.8 GHz Band at the Allen Telescope Array

NASA Astrophysics Data System (ADS)

Backus, Peter R.; Kilsdonk, T. N.; Allen Telescope Array Team

2007-05-01

Thanks to funding from the Paul G. Allen Foundation (and other philanthropic supporters) for the technology development and first phase of construction, the first 42 elements of the Allen Telescope Array (ATA-42) are being commissioned for rapid surveys of the astrophysical and technological sky. Because of the innovative design of this array that will eventually include 350 elements, traditional radio astronomy and SETI are enabled simultaneously 24x7. The array has been designed to provide an optimal snapshot image of a very large field of view and simultaneously, 16 (dual polarization) phased beams within the field of view to be analyzed by a suite of backend processors. Four independent 100 MHz bands may be tuned anywhere within the instantaneous receiver bandwidth from 0.5 to 11.2 GHz. One key to the success of rapid surveys for astrophysical or technological signals is a quiet background. This poster presents the results of initial surveys with 6.1 meter dishes at high-spectral-resolution of the background spectrum from 0.5 to 10.8 GHz at the Hat Creek Radio Observatory, where the ATA is being constructed, and compares it with the background spectrum from 1.2-3 GHz at other observatories where SETI observations have been conducted within the past 11 years.

Validation of the 'full reconnection model' of the sawtooth instability in KSTAR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nam, Y. B.; Ko, J. S.; Choe, G. H.

In this paper, the central safety factor (q 0) during sawtooth oscillation has been measured with a great accuracy with the motional Stark effect (MSE) system on KSTAR and the measured value was However, this measurement alone cannot validate the disputed full and partial reconnection models definitively due to non-trivial off-set error (~0.05). Supplemental experiment of the excited m = 2, m = 3 modes that are extremely sensitive to the background q 0 and core magnetic shear definitively validates the 'full reconnection model'. The radial position of the excited modes right after the crash and time evolution into themore » 1/1 kink mode before the crash in a sawtoothing plasma suggests that in the MHD quiescent period after the crash and before the crash. Finally, additional measurement of the long lived m = 3, m = 5 modes in a non-sawtoothing discharge (presumably ) further validates the 'full reconnection model'.« less

Validation of the 'full reconnection model' of the sawtooth instability in KSTAR

DOE PAGES

Nam, Y. B.; Ko, J. S.; Choe, G. H.; ...

2018-03-26

In this paper, the central safety factor (q 0) during sawtooth oscillation has been measured with a great accuracy with the motional Stark effect (MSE) system on KSTAR and the measured value was However, this measurement alone cannot validate the disputed full and partial reconnection models definitively due to non-trivial off-set error (~0.05). Supplemental experiment of the excited m = 2, m = 3 modes that are extremely sensitive to the background q 0 and core magnetic shear definitively validates the 'full reconnection model'. The radial position of the excited modes right after the crash and time evolution into themore » 1/1 kink mode before the crash in a sawtoothing plasma suggests that in the MHD quiescent period after the crash and before the crash. Finally, additional measurement of the long lived m = 3, m = 5 modes in a non-sawtoothing discharge (presumably ) further validates the 'full reconnection model'.« less

The Future RFI Environment Above 30 GHz

NASA Astrophysics Data System (ADS)

Clegg, Andrew W.

1995-12-01

Encompassing 30 - 300 GHz, the millimeter wave (mmW) band offers relief from spectrum crowding at lower frequencies, large available bandwidth, favorable propagation characteristics for certain applications, and relatively high directivity with small antennas. The FCC has recently proposed regulatory changes to foster commercial development of the mmW band. Impending actions include: Designating the 46.7-46.9 GHz and 76-77 GHz bands for unlicensed vehicular radar systems. Potentially tens of millions of vehicles will be equipped with radars to provide ``intelligent cruise control" capability and driver blind-spot warnings. Unwanted emissions from vehicular radar systems may produce harmful interference to passive systems operating in protected bands. Opening the 59-64 GHz band, in which propagation is limited to short distances due to high atmospheric attenuation, to general unlicensed devices. A likely application for this band is wireless local area computer networks. The neighboring bands of 58.2 - 59 and 64 - 65 GHz are allocated to the passive services. Changes still under consideration include: Opening the 116 - 117 GHz band, co-located with an existing passive allocation, for licensed (116 - 116.5 GHz) and general unlicensed (116.5 - 117 GHz) devices. The opening (for licensed and unlicensed services) of nearly 5 GHz of additional spectrum space which neighbors passive allocations and poses a potential interference problem from out-of-band emissions. The status of the FCC's actions concerning the mmW band will be updated. An attempt will be made to predict the RFI environment in the mmW band assuming the likely applications for each of the reallocated bands. Particular emphasis will be placed on the impact of the FCC's actions on current and planned remote sensing and radio astronomy operations.

Widely tunable laser frequency offset lock with 30 GHz range and 5 THz offset.

PubMed

Biesheuvel, J; Noom, D W E; Salumbides, E J; Sheridan, K T; Ubachs, W; Koelemeij, J C J

2013-06-17

We demonstrate a simple and versatile method to greatly extend the tuning range of optical frequency shifting devices, such as acousto-optic modulators (AOMs). We use this method to stabilize the frequency of a tunable narrow-band continuous-wave (CW) laser to a transmission maximum of an external Fabry-Perot interferometer (FPI) with a tunable frequency offset. This is achieved through a servo loop which contains an in-loop AOM for simple radiofrequency (RF) tuning of the optical frequency over the full 30 GHz mode-hop-free tuning range of the CW laser. By stabilizing the length of the FPI to a stabilized helium-neon (HeNe) laser (at 5 THz offset from the tunable laser) we simultaneously transfer the ~ 1 MHz absolute frequency stability of the HeNe laser to the entire 30 GHz range of the tunable laser. Thus, our method allows simple, wide-range, fast and reproducible optical frequency tuning and absolute optical frequency measurements through RF electronics, which is here demonstrated by repeatedly recording a 27-GHz-wide molecular iodine spectrum at scan rates up to 500 MHz/s. General technical aspects that determine the performance of the method are discussed in detail.

Comparative ELM study between the observation by ECEI and linear/nonlinear simulation in the KSTAR plasmas

NASA Astrophysics Data System (ADS)

Kim, Minwoo; Park, Hyeon K.; Yun, Gunsu; Lee, Jaehyun; Lee, Jieun; Lee, Woochang; Jardin, Stephen; Xu, X. Q.; Kstar Team

2015-11-01

The modeling of the Edge-localized-mode (ELM) should be rigorously pursued for reliable and robust ELM control for steady-state long-pulse H-mode operation in ITER as well as DEMO. In the KSTAR discharge #7328, a linear stability of the ELMs is investigated using M3D-C1 and BOUT + + codes. This is achieved by linear simulation for the n = 8 mode structure of the ELM observed by the KSTAR electron cyclotron emission imaging (ECEI) systems. In the process of analysis, variations due to the plasma equilibrium profiles and transport coefficients on the ELM growth rate are investigated and simulation results with the two codes are compared. The numerical simulations are extended to nonlinear phase of the ELM dynamics, which includes saturation and crash of the modes. Preliminary results of the nonlinear simulations are compared with the measured images especially from the saturation to the crash. This work is supported by NRF of Korea under contract no. NRF-2014M1A7A1A03029865, US DoE by LLNL under contract DE-AC52-07NA27344 and US DoE by PPPL under contract DE-AC02-09CH11466.

47 CFR 101.525 - 24 GHz system operations.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 5 2010-10-01 2010-10-01 false 24 GHz system operations. 101.525 Section 101.525 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES 24 GHz Service and Digital Electronic Message Service § 101.525 24 GHz system...

80-GHz MMIC HEMT Voltage-Controlled Oscillator

NASA Technical Reports Server (NTRS)

Samoska, Lorene; Radisic, Vesna; Micovic, Miro; Hu, Ming; Janke, Paul; Ngo, Catherine; Nguyen, Loi

2003-01-01

A voltage-controlled oscillator (VCO) that operates in the frequency range from 77.5 to 83.5 GHz has been constructed in the form of a monolithic microwave integrated circuit (MMIC) that includes high-electron-mobility transistors (HEMTs). This circuit is a prototype of electronically tunable signal sources in the 75-to-110-GHz range, needed for communication, imaging, and automotive radar applications, among others. This oscillator (see Figure 1) includes two AlInAs/GaInAs/InP HEMTs. One HEMT serves mainly as an oscillator gain element. The other HEMT serves mainly as a varactor for controlling the frequency: the frequency-control element is its gate-to-source capacitance, which is varied by changing its gate supply voltage. The gain HEMT is biased for class-A operation (meaning that current is conducted throughout the oscillation cycle). Grounded coplanar waveguides are used as impedance-matching transmission lines, the input and output matching being chosen to sustain oscillation and maximize output power. Air bridges are placed at discontinuities to suppress undesired slot electromagnetic modes. A high density of vias is necessary for suppressing a parallel-plate electromagnetic mode that is undesired because it can propagate energy into the MMIC substrate. Previous attempts at constructing HEMT-based oscillators yielded circuits with relatively low levels of output power and narrow tuning ranges. For example, one HEMT VCO reported in the literature had an output power of 7 dBm (.5 mW) and a tuning range 2-GHz wide centered approximately at a nominal frequency of 77 GHz. In contrast, as shown in Figure 2, the present MMIC HEMT VCO puts out a power of 12.5 dBm (.18 mW) or more over the 6-GHz-wide frequency range from 77.5 to 83.5 GHz

Electrodynamics and radiofrequency antenna concepts for human magnetic resonance at 23.5 T (1 GHz) and beyond.

PubMed

Winter, Lukas; Niendorf, Thoralf

2016-06-01

This work investigates electrodynamic constraints, explores RF antenna concepts and examines the transmission fields (B 1 (+) ) and RF power deposition of dipole antenna arrays for (1)H magnetic resonance of the human brain at 1 GHz (23.5 T). Electromagnetic field (EMF) simulations are performed in phantoms with average tissue simulants for dipole antennae using discrete frequencies [300 MHz (7.0 T) to 3 GHz (70.0 T)]. To advance to a human setup EMF simulations are conducted in anatomical human voxel models of the human head using a 20-element dipole array operating at 1 GHz. Our results demonstrate that transmission fields suitable for (1)H MR of the human brain can be achieved at 1 GHz. An increase in transmit channel density around the human head helps to enhance B 1 (+) in the center of the brain. The calculated relative increase in specific absorption rate at 23.5 versus 7.0 T was below 1.4 (in-phase phase setting) and 2.7 (circular polarized phase setting) for the dipole antennae array. The benefits of multi-channel dipole antennae at higher frequencies render MR at 23.5 T feasible from an electrodynamic standpoint. This very preliminary finding opens the door on further explorations that might be catalyzed into a 20-T class human MR system.

Validation of the ‘full reconnection model’ of the sawtooth instability in KSTAR

NASA Astrophysics Data System (ADS)

Nam, Y. B.; Ko, J. S.; Choe, G. H.; Bae, Y.; Choi, M. J.; Lee, W.; Yun, G. S.; Jardin, S.; Park, H. K.

2018-06-01

The central safety factor (q 0) during sawtooth oscillation has been measured with a great accuracy with the motional Stark effect (MSE) system on KSTAR and the measured value was However, this measurement alone cannot validate the disputed full and partial reconnection models definitively due to non-trivial off-set error (~0.05). Supplemental experiment of the excited m  =  2, m  =  3 modes that are extremely sensitive to the background q 0 and core magnetic shear definitively validates the ‘full reconnection model’. The radial position of the excited modes right after the crash and time evolution into the 1/1 kink mode before the crash in a sawtoothing plasma suggests that in the MHD quiescent period after the crash and before the crash. Additional measurement of the long lived m  =  3, m  =  5 modes in a non-sawtoothing discharge (presumably ) further validates the ‘full reconnection model’.

78 FR 21320 - Unlicensed National Information Infrastructure (U-NII) Devices in the 5 GHz Band

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-10

... provide a wide array of high data rate mobile and fixed communications for individuals, businesses, and... FEDERAL COMMUNICATIONS COMMISSION 47 CFR Part 15 [ET Docket No. 13-49; FCC 13-22] Unlicensed National Information Infrastructure (U-NII) Devices in the 5 GHz Band AGENCY: Federal Communications...

5 GHz fundamental repetition rate, wavelength tunable, all-fiber passively mode-locked Yb-fiber laser.

PubMed

Cheng, Huihui; Wang, Wenlong; Zhou, Yi; Qiao, Tian; Lin, Wei; Xu, Shanhui; Yang, Zhongmin

2017-10-30

A passively mode-locked Yb 3+ -doped fiber laser with a fundamental repetition rate of 5 GHz and wavelength tunable performance is demonstrated. A piece of heavily Yb 3+ -doped phosphate fiber with a high net gain coefficient of 5.7 dB/cm, in conjunction with a fiber mirror by directly coating the SiO 2 /Ta 2 O 5 dielectric films on a fiber ferrule is exploited for shortening the laser cavity to 2 cm. The mode-locked oscillator has a peak wavelength of 1058.7 nm, pulse duration of 2.6 ps, and the repetition rate signal has a high signal-to-noise ratio of 90 dB. Moreover, the wavelength of the oscillator is found to be continuously tuned from 1056.7 to 1060.9 nm by increasing the temperature of the laser cavity. Simultaneously, the repetition rate correspondingly decreases from 4.945874 to 4.945496 GHz. Furthermore, the long-term stability of the mode-locked operation in the ultrashort laser cavity is realized by exploiting temperature controls. This is, to the best of our knowledge, the highest fundamental pulse repetition rate for 1-μm mode-locked fiber lasers.

Use of the 37-38 GHz and 40-40.5 GHz Ka-bands for Deep Space Communications

NASA Technical Reports Server (NTRS)

Morabito, David; Hastrup, Rolf

2004-01-01

This paper covers a wide variety of issues associated with the implementation and use of these frequency bands for deep space communications. Performance issues, such as ground station pointing stability, ground antenna gain, antenna pattern, and propagation effects such as due to atmospheric, charged-particle and space loss at 37 GHz, will be addressed in comparison to the 32 GHz Ka-band deep space allocation. Issues with the use of and competition for this spectrum also will be covered. The state of the hardware developed (or proposed) for operating in this frequency band will be covered from the standpoint of the prospects for achieving higher data rates that could be accommodated in the available bandwidth. Hardware areas to be explored include modulators, digital-to-analog converters, filters, power amplifiers, receivers, and antennas. The potential users of the frequency band will be explored as well as their anticipated methods to achieve the potential high data rates and the implications of the competition for bandwidth.

Distilling perfect GHZ states from two copies of non-GHZ-diagonal mixed states

NASA Astrophysics Data System (ADS)

Wang, Xin-Wen; Tang, Shi-Qing; Yuan, Ji-Bing; Zhang, Deng-Yu

2017-06-01

It has been shown that a nearly pure Greenberger-Horne-Zeilinger (GHZ) state could be distilled from a large (even infinite) number of GHZ-diagonal states that can be obtained by depolarizing general multipartite mixed states (non-GHZ-diagonal states) through sequences of (probabilistic) local operations and classical communications. We here demonstrate that perfect GHZ states can be extracted, with certain probabilities, from two copies of non-GHZ-diagonal mixed states when some conditions are satisfied. This result implies that it is not necessary to depolarize these entangled mixed states to the GHZ-diagonal type, and that they are better than GHZ-diagonal states for distillation of pure GHZ states. We find a wide class of multipartite entangled mixed states that fulfill the requirements. Moreover, we display that the obtained result can be applied to practical noisy environments, e.g., amplitude-damping channels. Our findings provide an important complementarity to conventional GHZ-state distillation protocols (designed for GHZ-diagonal states) in theory, as well as having practical applications.

A 12.5 GHz-spaced optical frequency comb spanning >400 nm for near-infrared astronomical spectrograph calibration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Quinlan, F.; Diddams, S. A.; Ycas, G.

2010-06-15

A 12.5 GHz-spaced optical frequency comb locked to a global positioning system disciplined oscillator for near-infrared (IR) spectrograph calibration is presented. The comb is generated via filtering a 250 MHz-spaced comb. Subsequent nonlinear broadening of the 12.5 GHz comb extends the wavelength range to cover 1380-1820 nm, providing complete coverage over the H-band transmission window of earth's atmosphere. Finite suppression of spurious sidemodes, optical linewidth, and instability of the comb has been examined to estimate potential wavelength biases in spectrograph calibration. Sidemode suppression varies between 20 and 45 dB, and the optical linewidth is {approx}350 kHz at 1550 nm. Themore » comb frequency uncertainty is bounded by {+-}30 kHz (corresponding to a radial velocity of {+-}5 cm/s), limited by the global positioning system disciplined oscillator reference. These results indicate that this comb can readily support radial velocity measurements below 1 m/s in the near IR.« less

Simultaneous 183 GHz H2O maser and SiO observations towards evolved stars using APEX SEPIA Band 5

NASA Astrophysics Data System (ADS)

Humphreys, E. M. L.; Immer, K.; Gray, M. D.; De Beck, E.; Vlemmings, W. H. T.; Baudry, A.; Richards, A. M. S.; Wittkowski, M.; Torstensson, K.; De Breuck, C.; Møller, P.; Etoka, S.; Olberg, M.

2017-07-01

Aims: The aim is to investigate the use of 183 GHz H2O masers for characterization of the physical conditions and mass loss process in the circumstellar envelopes of evolved stars. Methods: We used APEX SEPIA Band 5 (an ALMA Band 5 receiver on the APEX telescope) to observe the 183 GHz H2O line towards two red supergiant (RSG) and three asymptotic giant branch (AGB) stars. Simultaneously, we observed the J = 4-3 line for 28SiO v = 0, 1, 2 and 3, and for 29SiO v = 0 and 1. We compared the results with simulations and radiative transfer models for H2O and SiO, and examined data for the individual linear orthogonal polarizations. Results: We detected the 183 GHz H2O line towards all the stars with peak flux densities >100 Jy, including a new detection from VY CMa. Towards all five targets, the water line had indications of being caused by maser emission and had higher peak flux densities than for the SiO lines. The SiO lines appear to originate from both thermal and maser processes. Comparison with simulations and models indicate that 183 GHz maser emission is likely to extend to greater radii in the circumstellar envelopes than SiO maser emission and to similar or greater radii than water masers at 22, 321 and 325 GHz. We speculate that a prominent blue-shifted feature in the W Hya 183 GHz spectrum is amplifying the stellar continuum, and is located at a similar distance from the star as mainline OH maser emission. We note that the coupling of an SiO maser model to a hydrodynamical pulsating model of an AGB star yields qualitatively similar simulated results to the observations. From a comparison of the individual polarizations, we find that the SiO maser linear polarization fraction of several features exceeds the maximum fraction allowed under standard maser assumptions and requires strong anisotropic pumping of the maser transition and strongly saturated maser emission. The low polarization fraction of the H2O maser however, fits with the expectation for a non

One GHz digitizer for space based laser altimeter

NASA Technical Reports Server (NTRS)

Staples, Edward J.

1991-01-01

This is the final report for the research and development of the one GHz digitizer for space based laser altimeter. A feasibility model was designed, built, and tested. Only partial testing of essential functions of the digitizer was completed. Hybrid technology was incorporated which allows analog storage (memory) of the digitally sampled data. The actual sampling rate is 62.5 MHz, but executed in 16 parallel channels, to provide an effective sampling rate of one GHz. The average power consumption of the one GHz digitizer is not more than 1.5 Watts. A one GHz oscillator is incorporated for timing purposes. This signal is also made available externally for system timing. A software package was also developed for internal use (controls, commands, etc.) and for data communication with the host computer. The digitizer is equipped with an onboard microprocessor for this purpose.

Fuel retention under elevated wall temperature in KSTAR with a carbon wall

NASA Astrophysics Data System (ADS)

Cao, B.; Hong, S. H.

2018-03-01

The fuel retention during KSTAR discharges with elevated wall temperature (150 °C) has been studied by using the method of global particle balance. The results show that the elevated wall temperature could reduce the dynamic retention via implantation and absorption, especially for the short pulse shots with large injected fuel particles. There is no signature changing of long-term retention, which related to co-deposition, under elevated wall temperature. For soft-landing shots (normal shots), the exhausted fuel particles during discharges is larger with elevated wall temperature than without, but the exhausted particles after discharges within 90 s looks similar. The outgassing particles because of disruption could be exhausted within 15 s.

A 94/183 GHz multichannel radiometer for Convair flights

NASA Technical Reports Server (NTRS)

Gagliano, J. A.; Stratigos, J. A.; Forsythe, R. E.; Schuchardt, J. M.

1979-01-01

A multichannel 94/183 GHz radiometer was designed, built, and installed on the NASA Convair 990 research aircraft to take data for hurricane penetration flights, SEASAT-A underflights for measuring rain and water vapor, and Nimbus-G underflights for new sea ice signatures and sea surface temperature data (94 GHz only). The radiometer utilized IF frequencies of 1, 5, and 8.75 GHz about the peak of the atmospheric water vapor absorption line, centered at 183.3 GHz, to gather data needed to determine the shape of the water molecule line. Another portion of the radiometer operated at 94 GHz and obtained data on the sea brightness temperature, sea ice signatures, and on areas of rain near the ocean surface. The radiometer used a multiple lens antenna/temperature calibration technique using 3 lenses and corrugated feed horns at 94 GHz and 183 GHz. Alignment of the feed beams at 94 GHz and 183 GHz was accomplished using a 45 deg oriented reflecting surface which permitted simultaneous viewing of the feeds on alternate cycles of the chopping intervals.

Overview of EAST experiments on the development of high-performance steady-state scenario

NASA Astrophysics Data System (ADS)

Wan, B. N.; Liang, Y. F.; Gong, X. Z.; Li, J. G.; Xiang, N.; Xu, G. S.; Sun, Y. W.; Wang, L.; Qian, J. P.; Liu, H. Q.; Zhang, X. D.; Hu, L. Q.; Hu, J. S.; Liu, F. K.; Hu, C. D.; Zhao, Y. P.; Zeng, L.; Wang, M.; Xu, H. D.; Luo, G. N.; Garofalo, A. M.; Ekedahl, A.; Zhang, L.; Zhang, X. J.; Huang, J.; Ding, B. J.; Zang, Q.; Li, M. H.; Ding, F.; Ding, S. Y.; Lyu, B.; Yu, Y. W.; Zhang, T.; Zhang, Y.; Li, G. Q.; Xia, T. Y.; the EAST Team; Collaborators

2017-10-01

The EAST research program aims to demonstrate steady-state long-pulse advanced high-performance H-mode operations with ITER-like poloidal configuration and RF-dominated heating schemes. Since the 2014 IAEA FEC, EAST has been upgraded with all ITER-relevant auxiliary heating and current drive systems, enabling the investigation of plasma profile control by the coupling/integration of various auxiliary heating combinations. Fully non-inductive steady-state H-mode plasma (H 98,y2  >  1.1) was extended over 60 s for the first time with sole RF heating plus good power coupling and impurity and particle control. By means of the 4.6 GHz and 2.45 GHz LHCD systems, H-mode can be obtained and maintained at relatively high density, even up to n e ~ 4.5  ×  1019 m-3, where a current drive effect is still observed. Significant progress has been achieved on EAST, including: (i) demonstration of a steady-state scenario (fully non-inductive with V loop ~ 0.0 V at high β P ~ 1.8 and high-performance in upper single-null (ɛ ~ 1.6) configuration with the tungsten divertor; (ii) discovery of a stationary H-mode regime with no/small ELM using 4.6 GHz LHCD, and; (iii) achievement of ELM suppression in slowly rotating H-mode plasma with n  =  1 and 2 RMP compatible with long-pulse operations. The new advances in scenario development provide an integrated solution in achieving long-pulse steady-state operations on EAST.

Tearing modes induced by perpendicular electron cyclotron resonance heating in the KSTAR tokamak

NASA Astrophysics Data System (ADS)

Lee, H. H.; Lee, S. G.; Seol, J.; Aydemir, A. Y.; Bae, C.; Yoo, J. W.; Na, Y. S.; Kim, H. S.; Woo, M. H.; Kim, J.; Joung, M.; You, K. I.; Park, B. H.

2014-10-01

This paper reports on experimental evidence that shows perpendicular electron cyclotron resonance heating (ECRH) can trigger classical tearing modes when deposited near a rational flux surface. The complex evolution of an m = 2 island is followed during current ramp-up in KSTAR plasmas, from its initial onset as the rational surface enters the ECRH resonance layer to its eventual lock on the wall after the rational surface leaves the layer. Stability analysis coupled to a transport calculation of the current profile with ECRH shows that the perpendicular ECRH may play a significant role in triggering and destabilizing classical m = 2 tearing modes, in agreement with our experimental observation.

Earth-satellite propagation above GHz: Papers from the 1972 spring URSI session on experiments utilizing the ATS-5 satellite

NASA Technical Reports Server (NTRS)

Ippolito, L. J. (Compiler)

1972-01-01

Papers are reported from the Special Session on Earth-Satellite Propagation Above 10 GHz, presented at The 1972 Spring Meeting of the United States National Committee, International Union of Radio Science, April 1972, Washington, D. C. This session was devoted to propagation measurements associated with the Applications Technology Satellite (ATS-5), which provided the first operational earth-space links at frequencies above 15 GHz. A comprehensive summary is presented of the major results of the ATS-5 experiment measurements and related radiometric, radar and meteorological studies. The papers are organized around seven selected areas of interest, with the results of the various investigators combined into a single paper presented by a principal author for that area. A comprehensive report is provided on the results of the ATS-5 satellite to earth transmissions. A complete list of published reports and presentations related to the ATS-5 Millimeter Wave Experiment is included.

Propagation Dynamics Associated with Resonant Magnetic Perturbation Fields in High-Confinement Mode Plasmas inside the KSTAR Tokamak.

PubMed

Xiao, W W; Evans, T E; Tynan, G R; Yoon, S W; Jeon, Y M; Ko, W H; Nam, Y U; Oh, Y K

2017-11-17

The propagation dynamics of resonant magnetic perturbation fields in KSTAR H-mode plasmas with injection of small edge perturbations produced by a supersonic molecular beam injection is reported for the first time. The results show that the perturbation field first excites a plasma response on the q=3 magnetic surface and then propagates inward to the q=2 surface with a radially averaged propagation velocity of resonant magnetic perturbations field equal to 32.5  m/ s. As a result, the perturbation field brakes the toroidal rotation on the q=3 surface first causing a momentum transport perturbation that propagates both inward and outward. A higher density fluctuation level is observed. The propagation velocity of the resonant magnetic perturbations field is larger than the radial propagation velocity of the perturbation in the toroidal rotation.

Direct measurements of safety factor profiles with motional Stark effect for KSTAR tokamak discharges with internal transport barriers

NASA Astrophysics Data System (ADS)

Ko, J.; Chung, J.

2017-06-01

The safety factor profile evolutions have been measured from the plasma discharges with the external current drive mechanism such as the multi-ion-source neutral beam injection for the Korea Superconducting Tokamak Advanced Research (KSTAR) for the first time. This measurement has been possible by the newly installed motional Stark effect (MSE) diagnostic system that utilizes the polarized Balmer-alpha emission from the energetic neutral deuterium atoms induced by the Stark effect under the Lorentz electric field. The 25-channel KSTAR MSE diagnostic is based on the conventional photoelastic modulator approach with the spatial and temporal resolutions less than 2 cm (for the most of the channels except 2 to 3 channels inside the magnetic axis) and about 10 ms, respectively. The strong Faraday rotation imposed on the optical elements in the diagnostic system is calibrated out from a separate and well-designed polarization measurement procedure using an in-vessel reference polarizer during the toroidal-field ramp-up phase before the plasma experiment starts. The combination of the non-inductive current drive during the ramp-up and shape control enables the formation of the internal transport barrier where the pitch angle profiles indicate flat or slightly hollow profiles in the safety factor.

Microwave soft x-ray microscopy for nanoscale magnetization dynamics in the 5–10 GHz frequency range

DOE PAGES

Bonetti, Stefano; Kukreja, Roopali; Chen, Zhao; ...

2015-09-10

In this study, we present a scanning transmission x-ray microscopy setup combined with a novel microwave synchronization scheme in order to study high frequency magnetization dynamics at synchrotron light sources. The sensitivity necessary to detect small changes of the magnetization on short time scales and nanometer spatial dimensions is achieved by combination of the developed excitation mechanism with a single photon counting electronics that is locked to the synchrotron operation frequency. The required mechanical stability is achieved by a compact design of the microscope. Our instrument is capable of creating direct images of dynamical phenomena in the 5-10 GHz range,more » with 35 nm resolution. When used together with circularly polarized x-rays, the above capabilities can be combined to study magnetic phenomena at microwave frequencies, such as ferromagnetic resonance (FMR) and spin waves. We demonstrate the capabilities of our technique by presenting phase resolved images of a –6 GHz nanoscale spin wave generated by a spin torque oscillator, as well as the uniform ferromagnetic precession with ~0.1° amplitude at –9 GHz in a micrometer-sized cobalt strip.« less

The 30-GHz monolithic receive module

NASA Technical Reports Server (NTRS)

Sokolov, V.; Geddes, J.; Bauhahn, P.

1983-01-01

Key requirements for a 30 GHz GaAs monolithic receive module for spaceborne communication antenna feed array applications include an overall receive module noise figure of 5 dB, a 30 dB RF to IF gain with six levels of intermediate gain control, a five-bit phase shifter, and a maximum power consumption of 250 mW. The RF designs for each of the four submodules (low noise amplifier, some gain control, phase shifter, and RF to IF sub-module) are presented. Except for the phase shifter, high frequency, low noise FETs with sub-half micron gate lengths are employed in the submodules. For the gain control, a two stage dual gate FET amplifier is used. The phase shifter is of the passive switched line type and consists of 5-bits. It uses relatively large gate width FETs (with zero drain to source bias) as the switching elements. A 20 GHz local oscillator buffer amplifier, a FET compatible balanced mixer, and a 5-8 GHz IF amplifier constitute the RF/IF sub-module. Phase shifter fabrication using ion implantation and a self-aligned gate technique is described. Preliminary RF results obtained on such phase shifters are included.

Investigation of MHD instabilities and control in KSTAR preparing for high beta operation

NASA Astrophysics Data System (ADS)

Park, Y. S.; Sabbagh, S. A.; Bialek, J. M.; Berkery, J. W.; Lee, S. G.; Ko, W. H.; Bak, J. G.; Jeon, Y. M.; Park, J. K.; Kim, J.; Hahn, S. H.; Ahn, J.-W.; Yoon, S. W.; Lee, K. D.; Choi, M. J.; Yun, G. S.; Park, H. K.; You, K.-I.; Bae, Y. S.; Oh, Y. K.; Kim, W.-C.; Kwak, J. G.

2013-08-01

Initial H-mode operation of the Korea Superconducting Tokamak Advanced Research (KSTAR) is expanded to higher normalized beta and lower plasma internal inductance moving towards design target operation. As a key supporting device for ITER, an important goal for KSTAR is to produce physics understanding of MHD instabilities at long pulse with steady-state profiles, at high normalized beta, and over a wide range of plasma rotation profiles. An advance from initial plasma operation is a significant increase in plasma stored energy and normalized beta, with Wtot = 340 kJ, βN = 1.9, which is 75% of the level required to reach the computed ideal n = 1 no-wall stability limit. The internal inductance was lowered to 0.9 at sustained H-mode duration up to 5 s. In ohmically heated plasmas, the plasma current reached 1 MA with prolonged pulse length up to 12 s. Rotating MHD modes are observed in the device with perturbations having tearing rather than ideal parity. Modes with m/n = 3/2 are triggered during the H-mode phase but are relatively weak and do not substantially reduce Wtot. In contrast, 2/1 modes to date only appear when the plasma rotation profiles are lowered after H-L back-transition. Subsequent 2/1 mode locking creates a repetitive collapse of βN by more than 50%. Onset behaviour suggests the 3/2 mode is close to being neoclassically unstable. A correlation between the 2/1 mode amplitude and local rotation shear from an x-ray imaging crystal spectrometer suggests that the rotation shear at the mode rational surface is stabilizing. As a method to access the ITER-relevant low plasma rotation regime, plasma rotation alteration by n = 1, 2 applied fields and associated neoclassical toroidal viscosity (NTV) induced torque is presently investigated. The net rotation profile change measured by a charge exchange recombination diagnostic with proper compensation of plasma boundary movement shows initial evidence of non-resonant rotation damping by the n = 1, 2 applied

Wireless Channel Characterization in the 5 GHz Microwave Landing System Extension Band for Airport Surface Areas

NASA Technical Reports Server (NTRS)

Matolak, David W.

2007-01-01

In this project final report, entitled "Wireless Channel Characterization in the 5 GHz Microwave Landing System Extension Band for Airport Surface Areas," we provide a detailed description and model representation for the wireless channel in the airport surface environment in this band. In this executive summary, we review report contents, describe the achieved objectives and major findings, and highlight significant conclusions and recommendations.

Microwave ablation at 10.0 GHz achieves comparable ablation zones to 1.9 GHz in ex vivo bovine liver.

PubMed

Luyen, Hung; Gao, Fuqiang; Hagness, Susan C; Behdad, Nader

2014-06-01

We demonstrate the feasibility of using high-frequency microwaves for tissue ablation by comparing the performance of a 10 GHz microwave ablation system with that of a 1.9 GHz system. Two sets of floating sleeve dipole antennas operating at these frequencies were designed and fabricated for use in ex vivo experiments with bovine livers. Combined electromagnetic and transient thermal simulations were conducted to analyze the performance of these antennas. Subsequently, a total of 16 ablation experiments (eight at 1.9 GHz and eight at 10.0 GHz) were conducted at a power level of 42 W for either 5 or 10 min. In all cases, the 1.9 and 10 GHz experiments resulted in comparable ablation zone dimensions. Temperature monitoring probes revealed faster heating rates in the immediate vicinity of the 10.0 GHz antenna compared to the 1.9 GHz antenna, along with a slightly delayed onset of heating farther from the 10 GHz antenna, suggesting that heat conduction plays a greater role at higher microwave frequencies in achieving a comparably sized ablation zone. The results obtained from these experiments agree very well with the combined electromagnetic/thermal simulation results. These simulations and experiments show that using lower frequency microwaves does not offer any significant advantages, in terms of the achievable ablation zones, over using higher frequency microwaves. Indeed, it is demonstrated that high-frequency microwave antennas may be used to create reasonably large ablation zones. Higher frequencies offer the advantage of smaller antenna size, which is expected to lead to less invasive interstitial devices and may possibly lead to the development of more compact multielement arrays with heating properties not available from single-element antennas.

Detection of 183 GHz H2O megamaser emission towards NGC 4945

NASA Astrophysics Data System (ADS)

Humphreys, E. M. L.; Vlemmings, W. H. T.; Impellizzeri, C. M. V.; Galametz, M.; Olberg, M.; Conway, J. E.; Belitsky, V.; De Breuck, C.

2016-08-01

Aims: The aim of this work is to search Seyfert 2 galaxy NGC 4945, a well-known 22 GHz water megamaser galaxy, for H2O (mega)maser emission at 183 GHz. Methods: We used APEX SEPIA Band 5 (an ALMA Band 5 receiver on the APEX telescope) to perform the observations. Results: We detected 183 GHz H2O maser emission towards NGC 4945 with a peak flux density of ~3 Jy near the galactic systemic velocity. The emission spans a velocity range of several hundred km s-1. We estimate an isotropic luminosity of >1000 L⊙, classifying the emission as a megamaser. A comparison of the 183 GHz spectrum with that observed at 22 GHz suggests that 183 GHz emission also arises from the active galactic nucleus (AGN) central engine. If the 183 GHz emission originates from the circumnuclear disk, then we estimate that a redshifted feature at 1084 km s-1 in the spectrum should arise from a distance of 0.022 pc from the supermassive black hole (1.6 × 105 Schwarzschild radii), I.e. closer than the water maser emission previously detected at 22 GHz. This is only the second time 183 GHz maser emission has been detected towards an AGN central engine (the other galaxy being NGC 3079). It is also the strongest extragalactic millimetre/submillimetre water maser detected to date. Conclusions: Strong millimetre 183 GHz H2O maser emission has now been shown to occur in an external galaxy. For NGC 4945, we believe that the maser emission arises, or is dominated by, emission from the AGN central engine. Emission at higher velocity, I.e. for a Keplerian disk closer to the black hole, has been detected at 183 GHz compared with that for the 22 GHz megamaser. This indicates that millimetre/submillimetre H2O masers can indeed be useful for tracing out more of AGN central engine structures and dynamics than previously probed. Future observations using ALMA Band 5 should unequivocally determine the origin of the emission in this and other galaxies.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Joung, M.; Woo, M. H.; Jeong, J. H.

For a high-performance, advanced tokamak mode in KSTAR, we have been developing a real-time control system of MHD modes such as sawtooth and Neo-classical Tearing Mode (NTM) by ECH/ECCD. The active feedback control loop will be also added to the mirror position and the real-time detection of the mode position. In this year, for the stabilization of NTM that is crucial to plasma performance we have implemented open-loop ECH antenna control system in KSTAR Plasma Control System (PCS) for ECH mirror movement during a single plasma discharge. KSTAR 170 GHz ECH launcher which was designed and fabricated by collaboration withmore » PPPL and POSTECH has a final mirror of a poloidally and toroidally steerable mirror. The poloidal steering motion is only controlled in the real-time NTM control system and its maximum steering speed is 10 degree/sec by DC motor. However, the latency of the mirror control system and the return period of ECH antenna mirror angle are not fast because the existing launcher mirror control system is based on PLC which is connected to the KSTAR machine network through serial to LAN converter. In this paper, we present the design of real time NTM control system, ECH requirements, and the upgrade plan.« less

A measurement of the cosmic microwave background temperature at 7.5 GHz

NASA Technical Reports Server (NTRS)

Levin, S.; Bensadoun, M.; Bersanelli, M.; De Amici, G.; Kogut, A.; Limon, M.; Smoot, G.

1992-01-01

The temperature of the cosmic microwave background (CMB) radiation at a frequency of 7.5 GHz (4 cm wavelength) is measured, obtaining a brightness temperature of T(CMB) = 2.70 +/- 0.08 K (68 percent confidence level). The measurement was made from a site near the geographical South Pole during the austral spring of 1989 and was part of an international collaboration to measure the CMB spectrum at low frequencies with a variety of radiometers from several different sites. This recent result is in agreement with the 1988 measurement at the same frequency, which was made from a different site with significantly different systematic errors. The combined result of the 1988 and 1989 measurements is 2.64 +/- 0.06 K.

Feasibility study of direct spectra measurements for Thomson scattered signals for KSTAR fusion-grade plasmas

NASA Astrophysics Data System (ADS)

Park, K.-R.; Kim, K.-h.; Kwak, S.; Svensson, J.; Lee, J.; Ghim, Y.-c.

2017-11-01

Feasibility study of direct spectra measurements of Thomson scattered photons for fusion-grade plasmas is performed based on a forward model of the KSTAR Thomson scattering system. Expected spectra in the forward model are calculated based on Selden function including the relativistic polarization correction. Noise in the signal is modeled with photon noise and Gaussian electrical noise. Electron temperature and density are inferred using Bayesian probability theory. Based on bias error, full width at half maximum and entropy of posterior distributions, spectral measurements are found to be feasible. Comparisons between spectrometer-based and polychromator-based Thomson scattering systems are performed with varying quantum efficiency and electrical noise levels.

Test of prototype ITER vacuum ultraviolet spectrometer and its application to impurity study in KSTAR plasmas.

PubMed

Seon, C R; Hong, J H; Jang, J; Lee, S H; Choe, W; Lee, H H; Cheon, M S; Pak, S; Lee, H G; Biel, W; Barnsley, R

2014-11-01

To optimize the design of ITER vacuum ultraviolet (VUV) spectrometer, a prototype VUV spectrometer was developed. The sensitivity calibration curve of the spectrometer was calculated from the mirror reflectivity, the grating efficiency, and the detector efficiency. The calibration curve was consistent with the calibration points derived in the experiment using the calibrated hollow cathode lamp. For the application of the prototype ITER VUV spectrometer, the prototype spectrometer was installed at KSTAR, and various impurity emission lines could be measured. By analyzing about 100 shots, strong positive correlation between the O VI and the C IV emission intensities could be found.

Packaging of microwave integrated circuits operating beyond 100 GHz

NASA Technical Reports Server (NTRS)

Samoska, L.; Daniel, E.; Sokolov, V.; Sommerfeldt, S.; Bublitz, J.; Olson, K.; Gilbert, B.; Chow, D.

2002-01-01

Several methods of packaging high speed (75-330 GHz) InP HEMT MMIC devices are discussed. Coplanar wirebonding is presented with measured insertion loss of less than 0.5dB and return loss better than -17 dB from DC to 110 GHz. A motherboard/daughterboard packaging scheme is presented which supports minimum loss chains of MMICs using this coplanar wirebonding method. Split waveguide block packaging approaches are presented in G-band (140-220 GHz) with two types of MMIC-waveguide transitions: E-plane probe andantipodal finline.

Vibrationally excited water emission at 658 GHz from evolved stars

NASA Astrophysics Data System (ADS)

Baudry, A.; Humphreys, E. M. L.; Herpin, F.; Torstensson, K.; Vlemmings, W. H. T.; Richards, A. M. S.; Gray, M. D.; De Breuck, C.; Olberg, M.

2018-01-01

Context. Several rotational transitions of ortho- and para-water have been identified toward evolved stars in the ground vibrational state as well as in the first excited state of the bending mode (v2 = 1 in (0, 1, 0) state). In the latter vibrational state of water, the 658 GHz J = 11,0-10,1 rotational transition is often strong and seems to be widespread in late-type stars. Aims: Our main goals are to better characterize the nature of the 658 GHz emission, compare the velocity extent of the 658 GHz emission with SiO maser emission to help locate the water layers and, more generally, investigate the physical conditions prevailing in the excited water layers of evolved stars. Another goal is to identify new 658 GHz emission sources and contribute in showing that this emission is widespread in evolved stars. Methods: We have used the J = 11,0-10,1 rotational transition of water in the (0, 1, 0) vibrational state nearly 2400 K above the ground-state to trace some of the physical conditions of evolved stars. Eleven evolved stars were extracted from our mini-catalog of existing and potential 658 GHz sources for observations with the Atacama Pathfinder EXperiment (APEX) telescope equipped with the SEPIA Band 9 receiver. The 13CO J = 6-5 line at 661 GHz was placed in the same receiver sideband for simultaneous observation with the 658 GHz line of water. We have compared the ratio of these two lines to the same ratio derived from HIFI earlier observations to check for potential time variability in the 658 GHz line. We have compared the 658 GHz line properties with our H2O radiative transfer models in stars and we have compared the velocity ranges of the 658 GHz and SiO J = 2-1, v = 1 maser lines. Results: Eleven stars have been extracted from our catalog of known or potential 658 GHz evolved stars. All of them show 658 GHz emission with a peak flux density in the range ≈50-70 Jy (RU Hya and RT Eri) to ≈2000-3000 Jy (VY CMa and W Hya). Five Asymptotic Giant Branch (AGB

Detection of cardiac activity using a 5.8 GHz radio frequency sensor.

PubMed

Vasu, V; Fox, N; Brabetz, T; Wren, M; Heneghan, C; Sezer, S

2009-01-01

A 5.8-GHz ISM-Band radio-frequency sensor has been developed for non-contact measurement of respiration and heart rate from stationary and semi-stationary subjects at a distance of 0.5 to 1.5 meters. We report on the accuracy of the heart rate measurements obtained using two algorithmic approaches, as compared to a reference heart rate obtained using a pulse oximeter. Simultaneous Photoplethysmograph (PPG) and non-contact sensor recordings were recorded over fifteen minute periods for ten healthy subjects (8M/2F, ages 29.6 + or - 5.6 yrs) One algorithm is based on automated detection of individual peaks associated with each cardiac cycle; a second algorithm extracts a heart rate over a 60-second period using spectral analysis. Peaks were also extracted manually for comparison with the automated method. The peak-detection methods were less accurate than the spectral methods, but suggest the possibility of acquiring beat by beat data; the spectral algorithms measured heart rate to within + or -10% for the ten subjects chosen. Non-contact measurement of heart rate will be useful in chronic disease monitoring for conditions such as heart failure and cardiovascular disease.

Long reach DWDM-PON with 12.5 GHz channel spacing based on comb source seeding

NASA Astrophysics Data System (ADS)

Zhou, Zhao; Nie, Hai-tao; Wang, Yao-jun

2016-07-01

A long reach dense wavelength division multiplexing passive optical network (DWDM-PON) with 12.5 GHz channel spacing is proposed and experimentally demonstrated. An optical frequency comb source is used to provide the multiwavelength seeding light, while reflective semiconductor optical amplifiers (RSOAs) are installed in both optical line terminal (OLT) and optical network units (ONUs) as colorless transmitter. The experimental results show that the bidirectional transmission for 1.2 Gbit/s data rate is achieved over 80 km single mode fiber (SMF).

JVLA 1.5 GHz Continuum Observation of CLASH Clusters. I. Radio Properties of the BCGs

NASA Astrophysics Data System (ADS)

Yu, Heng; Tozzi, Paolo; van Weeren, Reinout; Liuzzo, Elisabetta; Giovannini, Gabriele; Donahue, Megan; Balestra, Italo; Rosati, Piero; Aravena, Manuel

2018-02-01

We present high-resolution (∼1″), 1.5 GHz continuum observations of the brightest cluster galaxies (BCGs) of 13 CLASH (Cluster Lensing And Supernova survey with Hubble) clusters at 0.18< z< 0.69 with the Karl G. Jansky Very Large Array (JVLA). Radio emission is clearly detected and characterized for 11 BCGs, while for two of them we obtain only upper limits to their radio flux (< 0.1 mJy at 5σ confidence level). We also consider five additional clusters whose BCG is detected in FIRST or NVSS. We find radio powers in the range from 2× {10}23 to ∼ {10}26 {{W}} {{Hz}}-1 and radio spectral indices {α }1.530 (defined as the slope between 1.5 and 30 GHz) distributed from ∼ -1 to ‑0.25 around the central value < α > =-0.68. The radio emission from the BCGs is resolved in three cases (Abell 383, MACS J1931, and RX J2129), and unresolved or marginally resolved in the remaining eight cases observed with JVLA. In all the cases the BCGs are consistent with being powered by active galactic nuclei. The radio power shows a positive correlation with the BCG star formation rate, and a negative correlation with the central entropy of the surrounding intracluster medium (ICM) except in two cases (MACS J1206 and CL J1226). Finally, over the restricted range in radio power sampled by the CLASH BCGs, we observe a significant scatter between the radio power and the average mechanical power stored in the ICM cavities.

0.5 V 5.8 GHz highly linear current-reuse voltage-controlled oscillator with back-gate tuning technique

NASA Astrophysics Data System (ADS)

Ikeda, Sho; Lee, Sang-Yeop; Ito, Hiroyuki; Ishihara, Noboru; Masu, Kazuya

2015-04-01

In this paper, we present a voltage-controlled oscillator (VCO), which achieves highly linear frequency tuning under a low supply voltage of 0.5 V. To obtain the linear frequency tuning of a VCO, the high linearity of the threshold voltage of a varactor versus its back-gate voltage is utilized. This enables the linear capacitance tuning of the varactor; thus, a highly linear VCO can be achieved. In addition, to decrease the power consumption of the VCO, a current-reuse structure is employed as a cross-coupled pair. The proposed VCO was fabricated using a 65 nm Si complementary metal oxide semiconductor (CMOS) process. It shows the ratio of the maximum VCO gain (KVCO) to the minimum one to be 1.28. The dc power consumption is 0.33 mW at a supply voltage of 0.5 V. The measured phase noise at 10 MHz offset is -123 dBc/Hz at an output frequency of 5.8 GHz.

A cooperative transponder system for improved traffic safety, localizing road users in the 5 GHz band

NASA Astrophysics Data System (ADS)

Schaffer, B.; Kalverkamp, G.; Chaabane, M.; Biebl, E. M.

2012-09-01

We present a multi-user cooperative mobile transponder system which enables cars to localize pedestrians, bicyclists and other road users in order to improve traffic safety. The system operates at a center frequency of 5.768 GHz, offering the ability to test precision localization technology at frequencies close to the newly designated automotive safety related bands around 5.9 GHz. By carrying out a roundtrip time of flight measurement, the sensor can determine the distance from the onboard localization unit of a car to a road user who is equipped with an active transponder, employing the idea of a secondary radar and pulse compression. The onboard unit sends out a pseudo noise coded interrogation pulse, which is answered by one or more transponders after a short waiting time. Each transponder uses a different waiting time in order to allow for time division multiple access. We present the system setup as well as range measurement results, achieving an accuracy up to centimeters for the distance measurement and a range in the order of hundred meters. We also discuss the effect of clock drift and offset on distance accuracy for different waiting times and show how the system can be improved to further increase precision in a multiuser environment.

Characteristics of ocular temperature elevations after exposure to quasi- and millimeter waves (18-40 GHz)

NASA Astrophysics Data System (ADS)

Kojima, Masami; Suzuki, Yukihisa; Tsai, Cheng-Yu; Sasaki, Kensuke; Wake, Kanako; Watanabe, Soichi; Taki, Masao; Kamimura, Yoshitsugu; Hirata, Akimasa; Sasaki, Kazuyuki; Sasaki, Hiroshi

2015-04-01

In order to investigate changes in ocular temperature in rabbit eyes exposed to different frequencies (18 to 40 GHz) of quasi-millimeter waves, and millimeter waves (MMW). Pigmented rabbits were anesthetized with both general and topical anesthesia, and thermometer probes (0.5 mm in diameter) were inserted into their cornea (stroma), lens (nucleus) and vitreous (center of vitreous). The eyes were exposed unilaterally to 200 mW/cm2 by horn antenna for 3 min at 18, 22 and 26.5 GHz using a K band exposure system or 26.5, 35 and 40 GHz using a Ka band exposure system. Changes in temperature of the cornea, lens and vitreous were measured with a fluoroptic thermometer. Since the ocular temperatures after exposure to 26.5 GHz generated by the K band and Ka band systems were similar, we assumed that experimental data from these 2 exposure systems were comparable. The highest ocular temperature was induced by 40 GHz MMW, followed by 35 GHz. The 26.5 and 22 GHz corneal temperatures were almost the same. The lowest temperature was recorded at 18 GHz. The elevation in ocular temperature in response to exposure to 200 mW/cm2 MMW is dependent on MMW frequency. MMW exposure induced heat is conveyed not only to the cornea but also the crystalline lens.

Predictive modeling of pedestal structure in KSTAR using EPED model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, Hyunsun; Kim, J. Y.; Kwon, Ohjin

2013-10-15

A predictive calculation is given for the structure of edge pedestal in the H-mode plasma of the KSTAR (Korea Superconducting Tokamak Advanced Research) device using the EPED model. Particularly, the dependence of pedestal width and height on various plasma parameters is studied in detail. The two codes, ELITE and HELENA, are utilized for the stability analysis of the peeling-ballooning and kinetic ballooning modes, respectively. Summarizing the main results, the pedestal slope and height have a strong dependence on plasma current, rapidly increasing with it, while the pedestal width is almost independent of it. The plasma density or collisionality gives initiallymore » a mild stabilization, increasing the pedestal slope and height, but above some threshold value its effect turns to a destabilization, reducing the pedestal width and height. Among several plasma shape parameters, the triangularity gives the most dominant effect, rapidly increasing the pedestal width and height, while the effect of elongation and squareness appears to be relatively weak. Implication of these edge results, particularly in relation to the global plasma performance, is discussed.« less

90 GHz and 150 GHz Observations of the Orion M42 Region. A Submillimeter to Radio Analysis

NASA Technical Reports Server (NTRS)

Dicker, S. R.; Mason, B. S.; Korngut, P. M.; Cotton, W. D.; Compiegne, M.; Devlin, M. J.; Martin, P. G.; Ade, P. A. R; Benford, D. J.; Irwin, K. D.;

Analysis of a Near Field MIMO Wireless Channel Using 5.6 GHz Dipole Antennas

NASA Astrophysics Data System (ADS)

Maricar, Mohamed Ismaeel; Gradoni, Gabriele; Greedy, Steve; Ivrlac, Michel T.; Nossek, Josef A.; Phang, Sendy; Creagh, Stephen C.; Tanner, Gregor; Thomas, David W. P.

2016-05-01

Understanding the impact of interference upon the performance of a multiple input multiple output (MIMO) based device is of paramount importance in ensuring a design is both resilient and robust. In this work the effect of element-element interference in the creation of multiple channels of a wireless link approaching the near-field regime is studied. The elements of the 2-antenna transmit- and receive-arrays are chosen to be identical folded dipole antennas operating at 5.6 GHz. We find that two equally strong channels can be created even if the antennas interact at sub-wavelength distances, thus confirming previous theoretical predictions.

GHz Modulation of GaAs-Based Bipolar Cascade VCSELs (Preprint)

DTIC Science & Technology

2006-11-01

VCSELs were grown on n+ GaAs substrates by molecular beam epitaxy . The laser cavities consist of 1-, 2-, or 3-stage 52λ microcavi- ties, each containing...AFRL-SN-WP-TP-2006-128 GHz MODULATION OF GaAs-BASED BIPOLAR CASCADE VCSELs (PREPRINT) W.J. Siskaninetz, R.G. Bedford, T.R. Nelson, Jr., J.E...TITLE AND SUBTITLE GHz MODULATION OF GaAs-BASED BIPOLAR CASCADE VCSELs (PREPRINT) 5c. PROGRAM ELEMENT NUMBER 69199F 5d. PROJECT NUMBER 2002 5e

A two-stage monolithic buffer amplifier for 20 GHz satellite communication

NASA Technical Reports Server (NTRS)

Petersen, W. C.; Gupta, A. K.

1983-01-01

Design, fabrication, and test results of a two-stage GaAs monolithic buffer amplifier for 20 GHz satellite communication are described in this paper. A gain of 13 + or - 0.75 dB from 17.7 to 20.2 GHz was obtained from the 1.5 x 1.5 millimeter chip, which includes all necessary bias and dc blocking circuitry.

Design of 5.8 GHz Integrated Antenna on 180nm Complementary Metal Oxide Semiconductor (CMOS) Technology

NASA Astrophysics Data System (ADS)

Razak, A. H. A.; Shamsuddin, M. I. A.; Idros, M. F. M.; Halim, A. K.; Ahmad, A.; Junid, S. A. M. Al

2018-03-01

This project discusses the design and simulation performances of integrated loop antenna. Antenna is one of the main parts in any wireless radio frequency integrated circuit (RFIC). Naturally, antenna is the bulk in any RFIC design. Thus, this project aims to implement an integrated antenna on a single chip making the end product more compact. This project targets 5.8 GHz as the operating frequency of the integrated antenna for a transceiver module based on Silterra CMOS 180nm technology. The simulation of the antenna was done by using High Frequency Structure Simulator (HFSS). This software is industrial standard software that been used to simulate all electromagnetic effect including antenna simulation. This software has ability to simulate frequency at range of 100 MHz to 4 THz. The simulation set up in 3 dimension structure with driven terminal. The designed antenna has 1400um of diameter and placed on top metal layer. Loop configuration of the antenna has been chosen as the antenna design. From the configuration, it is able to make the chip more compact. The simulation shows that the antenna has single frequency band at center frequency 5.8 GHz with -48.93dB. The antenna radiation patterns shows, the antenna radiate at omnidirectional. From the simulation result, it could be concluded that the antenna have a good radiation pattern and propagation for wireless communication.

78 FR 36684 - 4.9 GHz Band

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-19

... FEDERAL COMMUNICATIONS COMMISSION 47 CFR Part 90 [WP Docket No. 07-100; PS Docket No. 06-229; WT Docket No. 06-150; FCC 12-61] 4.9 GHz Band AGENCY: Federal Communications Commission. ACTION: Correcting... 4957.5 5 8 4962.5 5 9 4967.5 5 10 4972.5 5 11 4977.5 5 12 4982.5 5 13 4985.5 1 14 4986.5 1 15 4987.5 1...

The 20 GHz spacecraft IMPATT solid state transmitter

NASA Technical Reports Server (NTRS)

Best, T.; Ngan, Y. C.

1986-01-01

The engineering development of a solid-state transmitter amplifier operating in the 20-GHz frequency range is described. This effort involved a multitude of disciplines including IMPATT device development, circulator design, multiple-diode circuit design, and amplifier integration and test. The objective was to develop a transmitter amplifier demonstrating the feasibility of providing an efficient, reliable, lightweight solid-state transmitter to be flown on a 30 to 20 GHz communication demonstration satellite. The work was done under contract from NASA/Lewis Research Center for a period of three years. The result was the development of a GaAs IMPACT diode amplifier capable of an 11-W CW output power and a 2-dB bandwidth of 300 MHz. GaAs IMPATT diodes incorporating diamond heatsink and double-Read doping profile capable of 5.3-W CW oscillator output power and 15.5% efficiency were developed. Up to 19% efficiency was also observed for an output power level of 4.4 W. High performance circulators with a 0.2 dB inserting loss and bandwidth of 5 GHz have also been developed. These represent a significant advance in both device and power combiner circuit technologies in K-band frequencies.

FRB121102: First detection across 5 - 8 GHz and spectral properties from the Breakthrough Listen instrument

NASA Astrophysics Data System (ADS)

Gajjar, Vishal; Siemion, Andrew; MacMohan, David; Croft, Steve; Hellbourg, Greg; Isaacson, Howard; Enriquez, J. Emilio; Price, Daniel; Lebofsky, Matt; De Boer, David; Werthimer, Dan; Hickish, Jack; Brinkman, Casey; Chatterjee, Shami; Ransom, Scott M.; Law, Casey; Hessels, Jason W. T.; Cordes, Jim; Spitler, Laura; Lynch, Ryan; McLaughlin, Maura; Scholz, Paul; Marcote, Benito; Bower, Geoffrey C.; Tendulkar, Shriharsh

2018-01-01

Fast Radio Bursts (FRBs) are some of the most energetic and enigmatic events in the Universe. The origin of these sources is among the most challenging questions of modern-day astrophysics. Thus, it is imperative to understand the properties of these bursts across a range of radio frequencies. Among the known FRBs, FRB121102 is the only source known to show repeated bursts [Spitler et al., Nature, 531, 7593 202-205, 2016], which can allow a detailed investigation of various origin models. In August 2017, we initiated a campaign observing FRB 121102 using the Breakthrough Listen Digital Backend with the C-band receiver at the Robert C. Byrd Green Bank Telescope (GBT). We recorded baseband voltage data across 5.4 GHz of bandwidth, completely covering the C-band receiver's nominal 4-8 GHz band [MacMahon et al. arXiv:1707.06024v2]. The recorded data were searched for dispersed pulses consistent with the known dispersion measure of FRB 121102 (557 pc cm-3) using high-speed GPU software tools. We detected 21 bursts above our detection threshold of 6 sigmas in the first 60-minutes, out of which 18 occurred in the first 30-minutes only. To our knowledge, this is the highest event rate seen for FRB121102 at any observing frequency. These observations are the highest frequency and widest bandwidth detection of bursts from FRB 121102 (or any other FRB) obtained to-date. We note that individual bursts show marked changes in spectral extent ranging from hundreds of MHz to several GHz. We have used high frequency dynamic spectra of these bursts to estimate the characteristic scintillation bandwidth and correlation time-scale. We also found distinctive temporal structures, separated by a few milliseconds, in three of the strongest bursts, with each sub-structure exhibiting varied spectral features. We will discuss our findings and how these detections of FRB 121102 around 8 GHz opens up a new regime in scrutinizing various origin models. We will also highlight the unique

47 CFR 101.537 - 24 GHz band subject to competitive bidding.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 5 2010-10-01 2010-10-01 false 24 GHz band subject to competitive bidding. 101.537 Section 101.537 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES 24 GHz Service and Digital Electronic Message Service § 101.537...

5 MeV Proton irradiation effects on 200 GHz silicon-germanium heterojunction bipolar transistors

NASA Astrophysics Data System (ADS)

Gnana Prakash, A. P.; Hegde, Vinayakprasanna N.; Pradeep, T. M.; Pushpa, N.; Bajpai, P. K.; Patel, S. P.; Trivedi, Tarkeshwar; Cressler, J. D.

2017-12-01

The total dose effects of 5 MeV proton and Co-60 gamma irradiation in the dose range from 1 to 100 Mrad on advanced 200 GHz Silicon-Germanium heterojunction bipolar transistors (SiGe HBTs) are investigated. The SRIM simulation study was conducted to understand the energy loss of 5 MeV proton ions in SiGe HBT structure. Pre- and post-radiation DC figure of merits such as forward- and inverse-mode Gummel characteristics, excess base current, DC current gain and output characteristics were used to quantify the radiation tolerance of the devices. The results show that the proton creates a significant amount of damages in the surface and bulk of the transistor when compared with gamma irradiation. The SiGe HBTs shows robust ionizing radiation tolerance even up to a total dose of 100 Mrad for both radiations.

Spacecraft mass trade-offs versus radio-frequency power and antenna size at 8 GHz and 32 GHz

NASA Technical Reports Server (NTRS)

Gilchriest, C. E.

1987-01-01

The purpose of this analysis is to help determine the relative merits of 32 GHz over 8 GHz for future deep space communications. This analysis is only a piece of the overall analysis and only considers the downlink communication mass, power, and size comparisons for 8 and 32 GHz. Both parabolic antennas and flat-plate arrays are considered. The Mars Sample Return mission is considered in some detail as an example of the tradeoffs involved; for this mission the mass, power, and size show a definite advantage of roughly 2:1 in using the 32 GHz over 8 GHz.

Cool-Down and Current Test Results of the KSTAR Prototype TF Coil

NASA Astrophysics Data System (ADS)

Oh, Y. K.; Lee, S.; Chu, Y.; Park, K. R.; Yonekawa, H.; Baek, S. H.; Cho, K. W.; Park, Y. M.; Kim, M. K.; Chang, H. S.; Kim, Y. S.; Chang, Y. B.; Lee, Y. J.; Kim, W. C.; Kim, K.; Kwag, S. W.; Lee, S. H.; Yang, S. H.; Lee, S. J.; Bak, J. S.; Lee, G. S.

2004-06-01

A prototype toroidal field (TF) coil, TF00 coil, of the Korea Superconducting Tokamak Advanced Research (KSTAR) project has been assembled and tested at the coil test facility in Korea Basic Science Institute (KBSI). The TF00 coil is a real-sized TF coil made of Nb3Sn superconducting cable-in-conduit conductor (CICC). The coil test was conducted by several campaigns according to the objectives. The first campaign, which was carried out by Jan. 2003, has objectives of cooling the coil into operating temperature and finding any defect in the coil such as cold leaks. From the results of the first campaign experiment, any defect in the coil was not found. The second campaign, which was carried out by Aug. 2003, has objectives to get the operating characteristics according to the current ramp up and discharge operations. In this paper, the coil test results are introduced as well as the details of the coil test system setup.

The Nature of Radio Emission from Distant Galaxies: The 1.4 GHZ Observations

NASA Astrophysics Data System (ADS)

Richards, E. A.

2000-04-01

We have conducted a deep radio survey with the Very Large Array at 1.4 GHz of a region containing the Hubble Deep Field (HDF). This survey overlaps previous observations at 8.5 GHz allowing us to investigate the radio spectral properties of microjansky sources to flux densities greater than 40 μJy at 1.4 GHz and greater than 8 μJy at 8.5 GHz. A total of 371 sources have been cataloged at 1.4 GHz as part of a complete sample within 20' of the HDF. The differential source count for this region is only marginally sub-Euclidean and is given by n(S)=(8.3+/-0.4)S-2.4+/-0.1 sr-1 Jy-1. Above about 100 μJy the radio source count is systematically lower in the HDF as compared to other fields. We conclude that there is clustering in our radio sample on size scales of 1'-40'. The 1.4 GHz-selected sample shows that the radio spectral indices are preferentially steep (α1.4=0.85) and that the sources are moderately extended with average angular size θ=1.8". Optical identification with disk-type systems at z~0.1-1 suggests that synchrotron emission, produced by supernovae remnants, is powering the radio emission in the majority of sources. The 8.5 GHz sample contains primarily moderately flat spectrum sources (α8.5=0.35), with less than 15% inverted. We argue that we may be observing an increased fraction of optically thin bremsstrahlung over synchrotron radiation in these distant star-forming galaxies.

Limits on Arcminute-Scale Cosmic Microwave Background Anisotropy at 28.5 GHz

NASA Technical Reports Server (NTRS)

Holzapfel, W. L.; Carlstrom, J. E.; Grego, L.; Holder, G.; Joy, M.; Reese, E. D.

2000-01-01

We have used the Berkeley-Illinois-Maryland Association (BIMA) millimeter array outfitted with sensitive centimeter-wave receivers to search for cosmic microwave background (CMB) anisotropies on arcminute scales. The interferometer was placed in a compact configuration that produces high brightness sensitivity, while providing discrimination against point sources. Operating at a frequency of 28.5 GHz, the FWHM primary beam of the instrument is approximately 6'.6. We have made sensitive images of seven fields, four of which where chosen specifically to have low infrared dust contrast and to be free of bright radio sources. Additional observations with the Owens Valley Radio Observatory (OVRO) millimeter array were used to assist in the location and removal of radio point sources. Applying a Bayesian analysis to the raw visibility data, we place limits on CMB anisotropy flat-band power of Q(sub flat) = 5.6(sub -5.6)(exp 3.0) microK and Q(sub flat) < 14.1 microK at 68% and 95% confidence, respectively. The sensitivity of this experiment to flat-band power peaks at a multipole of I = 5470, which corresponds to an angular scale of approximately 2'. The most likely value of Q(sub flat) is similar to the level of the expected secondary anisotropies.

Left-handed compact MIMO antenna array based on wire spiral resonator for 5-GHz wireless applications

NASA Astrophysics Data System (ADS)

Alqadami, Abdulrahman Shueai Mohsen; Jamlos, Mohd Faizal; Soh, Ping Jack; Rahim, Sharul Kamal Abdul; Narbudowicz, Adam

2017-01-01

A compact coplanar waveguide-fed multiple-input multiple-output antenna array based on the left-handed wire loaded spiral resonators (SR) is presented. The proposed antenna consists of a 2 × 2 wire SR with two symmetrical microstrip feed lines, each line exciting a 1 × 2 wire SR. Left-handed metamaterial unit cells are placed on its reverse side and arranged in a 2 × 3 array. A reflection coefficient of less than -16 dB and mutual coupling of less than -28 dB are achieved at 5.15 GHz WLAN band.

The 20 GHz spacecraft FET solid state transmitter

NASA Technical Reports Server (NTRS)

1983-01-01

The engineering development of a solid state transmitter amplifier operating in the 20 GHz frequency band using GaAs field effect transistors (FETs) was detailed. The major efforts include GaAs FET device development, single-ended amplifier stage, balanced amplifier stage, cascaded stage and radial combiner designs, and amplifier integration and test. A multistage GaAs FET amplifier capable of 8.2 W CW output over the 17.9 to 19.1 GHz frequency band was developed. The GaAs FET devices developed represent state of the art FET power device technology. Further device improvements are necessary to increase the bandwidth to 2.5 GHz, improve dc-to-RF efficiency, and increase power capability at the device level. Higher power devices will simplify the amplifier combining scheme, reducing the size and weight of the overall amplifier.

InP MMIC Chip Set for Power Sources Covering 80-170 GHz

NASA Technical Reports Server (NTRS)

Ngo, Catherine

2001-01-01

We will present a Monolithic Millimeter-wave Integrated Circuit (MMIC) chip set which provides high output-power sources for driving diode frequency multipliers into the terahertz range. The chip set was fabricated at HRL Laboratories using a 0.1-micrometer gate-length InAlAs/InGaAs/InP high electron mobility transistor (HEMT) process, and features transistors with an f(sub max) above 600 GHz. The HRL InP HEMT process has already demonstrated amplifiers in the 60-200 GHz range. In this paper, these high frequency HEMTs form the basis for power sources up to 170 GHz. A number of state-of-the-art InP HEMT MMICs will be presented. These include voltage-controlled and fixed-tuned oscillators, power amplifiers, and an active doubler. We will first discuss an 80 GHz voltage-controlled oscillator with 5 GHz of tunability and at least 17 mW of output power, as well as a 120 GHz oscillator providing 7 mW of output power. In addition, we will present results of a power amplifier which covers the full WRIO waveguide band (75-110 GHz), and provides 40-50 mW of output power. Furthermore, we will present an active doubler at 164 GHz providing 8% bandwidth, 3 mW of output power, and an unprecedented 2 dB of conversion loss for an InP HEMT MMIC at this frequency. Finally, we will demonstrate a power amplifier to cover 140-170 GHz with 15-25 mW of output power and 8 dB gain. These components can form a power source in the 155-165 GHz range by cascading the 80 GHz oscillator, W-band power amplifier, 164 GHz active doubler and final 140-170 GHz power amplifier for a stable, compact local oscillator subsystem, which could be used for atmospheric science or astrophysics radiometers.

Multiwavelength optical source at 12.5-GHz optical spacing based on a coupled optoelectronic oscillator with a whispering gallery mode resonator

NASA Astrophysics Data System (ADS)

Kossakovski, Dmitri; Solomatine, Iouri V.; Morozov, Nikolai; Ilchenko, Vladimir S.

2004-06-01

The evolution of optical networks calls for denser channel grids and increased number of channels. Additionally, there is a system architecture benefit to eliminate the banks of DFB lasers that act as light sources for individual channels, and use instead a single multi-wavelength source. We have demonstrated a compact multi-wavelength optical source (MWS) for 12.5 GHz DWDM. At least 16 channels are observed within 3 dB optical power bandwidth with optical spectrum contrast ratio exceeding 28 dB. The source is based on a coupled opto-electronic oscillator (COEO) with an optical whispering gallery mode (WGM) microresonator. Free spectral range of the resonator determines the spacing of the optical channels in the MWS. The spacing can be scaled up or down depending on design requirements. The resonator is robustly packaged and fiber pigtailed. In the RF domain the MWS acts as oscillator with operational frequency of 12.5 GHz.

154 GHz collective Thomson scattering in LHD

NASA Astrophysics Data System (ADS)

Tanaka, K.; Nishiura, M.; Kubo, S.; Shimozuma, T.; Saito, T.; Moseev, D.; Abramovic, I.

2018-01-01

Collective Thomson scattering (CTS) was developed by using a 154 GHz gyrotron, and the first data has been obtained. Already, 77 GHz CTS has worked successfully. However, in order to access higher density region, 154 GHz option enhances the usability that reduces the refraction effect, which deteriorates in the local measurements. The system in the down converted frequency was almost identical to the system for 77 GHz. Probing beam, a notch filter, a mixer, and a local oscillator in the receiver system for 77 GHz option were replaced to those for the 154 GHz option. 154 GHz gyrotron was originally prepared for the second harmonic electron cyclotron heating (ECRH) at 2.75 T. However, scattering signal was masked by the second harmonic electron cyclotron emission (ECE) at 2.75 T. Therefore, 154 GHz CTS was operated at 1.375 T with fourth harmonic ECE, and an acceptable signal to noise ratio was obtained. There is a signature of fast ion components with neutral beam (NB) injection. In addition, the CTS spectrum became broader in hydrogen discharge than in deuterium discharge, as the theoretical CTS spectrum expects. This observation indicates a possibility to identify ion species ratio by the 154 GHz CTS diagnostic.

A 250 GHz Gyrotron with a 3 GHz Tuning Bandwidth for Dynamic Nuclear Polarization

PubMed Central

Barnes, Alexander B.; Nanni, Emilio A.; Herzfeld, Judith; Griffin, Robert G.; Temkin, Richard J.

2012-01-01

We describe the design and implementation of a novel tunable 250 GHz gyrotron oscillator with >10 W output power over most of a 3 GHz band and >35 W peak power. The tuning bandwidth and power are sufficient to generate a >1 MHz nutation frequency across the entire nitroxide EPR lineshape for cross effect DNP, as well as to excite solid effect transitions utilizing other radicals, without the need for sweeping the NMR magnetic field. Substantially improved tunability is achieved by implementing a long (23 mm) interaction cavity that can excite higher order axial modes by changing either the magnetic field of the gyrotron or the cathode potential. This interaction cavity excites the rotating TE5,2,q mode, and an internal mode converter outputs a high-quality microwave beam with >94% Gaussian content. The gyrotron was integrated into a DNP spectrometer, resulting in a measured DNP enhancement of 54 on the membrane protein bacteriorhodopsin. PMID:22743211

A spectral line survey of IRC +10216 between 13.3 and 18.5 GHz

NASA Astrophysics Data System (ADS)

Zhang, Xiao-Yan; Zhu, Qing-Feng; Li, Juan; Chen, Xi; Wang, Jun-Zhi; Zhang, Jiang-Shui

2017-10-01

A spectral line survey of IRC +10216 between 13.3 and 18.5 GHz was carried out using the Shanghai Tian Ma 65 m Radio Telescope (TMRT-65 m) with a sensitivity of <7 mK. Thirty-five spectral lines of 12 different molecules and radicals were detected in total. Except for SiS, the detected molecules are all carbon-chain molecules, including HC3N, HC5N, HC7N, HC9N, C6H, C6H-, C8H, SiC2, SiC4, c-C3H2, and l-C5H. The presence of rich carbon-bearing molecules is consistent with the identity of IRC +10216 as a carbon-rich asymptotic giant branch (AGB) star. The excitation temperatures and column densities of the observed species are derived by assuming a local thermodynamic equilibrium and homogeneous conditions. The reduced spectrum as a FITS file is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/606/A74

Modulation of electromagnetic and absorption properties in 18-26.5 GHz frequency range of strontium hexaferrites with doping of cobalt-zirconium

NASA Astrophysics Data System (ADS)

Pubby, Kunal; Narang, Sukhleen Bindra; Kaur, Prabhjyot; Chawla, S. K.

2017-05-01

Hexaferrite nano-particles of stoichiometric composition {{Sr}}{({{CoZr}})_x}{{F}}{{{e}}_{12 - 2x}}{{{O}}_{19}}, with x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0 were prepared using sol-gel auto-combustion route owing to its advantages such as low sintering temperature requirement, homogeneity and uniformity of grains. Tartaric acid as a fuel was utilized to complete the chemical reaction. The goal of this study is to analyse the effect of co-substitution of cobalt and zirconium on the electromagnetic and absorption properties of pure {{SrF}}{{{e}}_{12}}{{{O}}_{19}} hexaferrite. The properties were measured on the rectangular pellets of thickness 2.5 mm for K-frequency band using Vector Network Analyzer. The doping of Co-Zr has resulted in increase in real as well as imaginary parts of permittivity. The values of real permittivity lie in the range 3.6-7.0 for all the composition. The real part of permeability remains in range 0.7-1.6 in the studied frequency band for all the samples and shows slightly increasing trend with frequency. The maximum values of dielectric loss tangent peak (3.04) and magnetic loss tangent peak (2.34), among all the prepared compositions, have been observed for composition x = 0.2. Compositions with x = 0.6 and x = 0.0 also have high dielectric and magnetic loss peaks. Dielectric loss peaks are attributed to dielectric resonance and magnetic loss peaks are attributed to natural resonance. Experimentally determined reflection loss results show that all six compositions of prepared series have high values of absorption to propose them as single-layer absorbers in 18-26.5 GHz frequency range. The composition with x = 0.2 has maximum absorption capacity with reflection loss peak of -37.2 dB at 24.3 GHz frequency. The undoped composition also has high absorption peak (-25.46 dB), but -10 dB absorption bandwidth is minimum (2.2 GHz) out of the present series. Maximum absorption bandwidth is obtained for x = 1.0 (4.1 GHz). Other doped compositions also

Dual-polarization 8.45 GHz traveling-wave maser

NASA Technical Reports Server (NTRS)

Quinn, R. B.

1987-01-01

An 8.5 GHz dual-channel, dual-polarization traveling-wave maser (TWM) amplifier was installed in the XKR solar system radar cone at DSS 14. The TWM is based on the Blk IIA 8.45 GHz maser structure, with two of the four maser stages being used for each channel, and each maser half then followed by a high-performance GaAs FET amplifier to achieve the desired net gain. A shortened low-noise input waveguide and an orthogonal-mode junction which is cooled to 4.5 K feeds each amplifier chain. The rotation of an external polarizer permits the polarization of each channel to be defined as either linear or circular. A circular waveguide switch was also developed to provide for noise calibration and to protect the maser from incident transmitter power.

A 20 GHz bright sample for δ > 72° - II. Multifrequency follow-up

NASA Astrophysics Data System (ADS)

Ricci, R.; Righini, S.; Verma, R.; Prandoni, I.; Carretti, E.; Mack, K.-H.; Massardi, M.; Procopio, P.; Zanichelli, A.; Gregorini, L.; Mantovani, F.; Gawroński, M. P.; Peel, M. W.

2013-11-01

We present follow-up observations at 5, 8 and 30 GHz of the K-band Northern Wide Survey (KNoWS) 20 GHz Bright Sample, performed with the 32-m Medicina radio telescope and the 32-m Toruń radio telescope. The KNoWS sources were selected in the Northern Polar Cap (δ > 72°) and have a flux density limit S20 GHz = 115 mJy. We include NRAO-VLA Sky Survey 1.4 GHz measurements to derive the source radio spectra between 1.4 and 30 GHz. Based on optical identifications, 68 per cent of the sources are quasars and 27 per cent are radio galaxies. A redshift measurement is available for 58 per cent of the sources. The radio spectral properties of the different source populations are found to be in agreement with those of other high-frequency-selected samples.

The 20 GHz GaAs monolithic power amplifier module development

NASA Technical Reports Server (NTRS)

1984-01-01

The development of a 20 GHz GaAs FET monlithic power amplifier module for advanced communication applications is described. Four-way power combing of four 0.6 W amplifier modules is used as the baseline approach. For this purpose, a monolithic four-way traveling-wave power divider/combiner was developed. Over a 20 GHz bandwidth (10 to 30 GHz), an insertion loss of no more than 1.2 dB was measured for a pair of back-to-back connected divider/combiners. Isolation between output ports is better than 20 dB, and VSWRs are better than 21:1. A distributed amplifier with six 300 micron gate width FETs and gate and drain transmission line tapers has been designed, fabricated, and evaluated for use as an 0.6 W module. This amplifier has achieved state-of-the-art results of 0.5 W output power with at least 4 dB gain across the entire 2 to 21 GHz frequency range. An output power of 2 W was achieved at a measurement frequency of 18 GHz when four distributed amplifiers were power-combined using a pair of traveling-wave divider/combiners. Another approach is the direct common-source cascading of three power FET stages. An output power of up to 2W with 12 dB gain and 20% power-added efficiency has been achieved with this approach (at 17 GHz). The linear gain was 14 dB at 1 W output. The first two stages of the three-stage amplifier have achieved an output power of 1.6 W with 9 dB gain and 26% power-added efficiency at 16 GHz.

Helicon wave coupling in KSTAR plasmas for off-axis current drive in high electron pressure plasmas

NASA Astrophysics Data System (ADS)

Wang, S. J.; Wi, H. H.; Kim, H. J.; Kim, J.; Jeong, J. H.; Kwak, J. G.

2017-04-01

A helicon wave current drive is proposed as an efficient off-axis current drive in the high electron β plasmas that are expected in fusion reactors. A high frequency helicon wave coupling was analyzed using the surface impedance at a plasma boundary. A slow wave coupling, which may compete with the helicon wave coupling at a frequency of 500 MHz, is estimated to be lower than the fast wave coupling by an order of magnitude in the KSTAR edge plasma density and in practical Faraday shield misalignment with the magnetic pitch. A traveling wave antenna, which is a two port combline antenna, was analyzed using a simplified lumped element model. The results show that the traveling wave antenna provides load resiliency because of its insensitivity to loading resistance, provided that the loading resistance at a radiating element is limited within a practical range. The combline antenna is attractive because it does not require a matching system and exhibits a high selectivity of parallel refractive index. Based on the analysis, a seven element combline antenna was fabricated and installed at an off-mid-plane offset of 30 cm from the mid-plane in KSTAR. The low power RF characteristics measured during several plasma discharges showed no evidence of slow wave coupling. This is consistent with the expectation made through the surface impedance analysis which predicted low slow wave coupling. The wave coupling to the plasma is easily controlled by a radial outer-gap control and gas puffing. No plasma confinement degradation was observed during the radial outer-gap control of up to 3 cm in H-mode discharges. In a ELMy plasmas, only a small reflection peak was observed during a very short portion of the ELM bursting period. If the number of radiating elements is increased for high power operation, then complete load resiliency can be expected. A very large coupling can be problematic for maintaining a parallel refractive index, although this issue can be mitigated by

MMIC DHBT Common-Base Amplifier for 172 GHz

NASA Technical Reports Server (NTRS)

Paidi, Vamsi; Griffith, Zack; Wei, Yun; Dahlstrom, Mttias; Urteaga, Miguel; Rodwell, Mark; Samoska, Lorene; Fung, King Man; Schlecht, Erich

2006-01-01

Figure 1 shows a single-stage monolithic microwave integrated circuit (MMIC) power amplifier in which the gain element is a double-heterojunction bipolar transistor (DHBT) connected in common-base configuration. This amplifier, which has been demonstrated to function well at a frequency of 172 GHz, is part of a continuing effort to develop compact, efficient amplifiers for scientific instrumentation, wide-band communication systems, and radar systems that will operate at frequencies up to and beyond 180 GHz. The transistor is fabricated from a layered structure formed by molecular beam epitaxy in the InP/InGaAs material system. A highly doped InGaAs base layer and a collector layer are fabricated from the layered structure in a triple mesa process. The transistor includes two separate emitter fingers, each having dimensions of 0.8 by 12 m. The common-base configuration was chosen for its high maximum stable gain in the frequency band of interest. The input-matching network is designed for high bandwidth. The output of the transistor is matched to a load line for maximum saturated output power under large-signal conditions, rather than being matched for maximum gain under small-signal conditions. In a test at a frequency of 172 GHz, the amplifier was found to generate an output power of 7.5 mW, with approximately 5 dB of large-signal gain (see Figure 2). Moreover, the amplifier exhibited a peak small-signal gain of 7 dB at a frequency of 176 GHz. This performance of this MMIC single-stage amplifier containing only a single transistor represents a significant advance in the state of the art, in that it rivals the 170-GHz performance of a prior MMIC three-stage, four-transistor amplifier. [The prior amplifier was reported in "MMIC HEMT Power Amplifier for 140 to 170 GHz" (NPO-30127), NASA Tech Briefs, Vol. 27, No. 11 (November 2003), page 49.] This amplifier is the first heterojunction- bipolar-transistor (HBT) amplifier built for medium power operation in this

Studying Star Formation in the Central Molecular Zone using 22 GHz Water and 6.7 GHz Methanol Masers

NASA Astrophysics Data System (ADS)

Rickert, Matthew; Yusef-Zadeh, Farhad; Ott, Juergen; Meier, David S.; SWAG

2016-01-01

The inner 400 pc of our Galaxy, or the so-called the central molecular zone (CMZ), has a unique environment with a large mass of dense, warm molecular gas. One of the premier questions is how star formation (SF) differs in this unique environment from elsewhere in the Galaxy. We intend to address this issue by identifying improved numbers and locations of early sites of SF. We have conducted high resolution surveys of the CMZ, looking for early SF indicators such as 22 GHz water and 6.7 GHz methanol masers. We present the initial water maser results from the SWAG survey and methanol results from the first full VLA survey of 6.7 GHz methanol masers in the CMZ. These surveys span beyond the inner 1.2ο x 0.5ο of the Galaxy, including Sgr B through Sgr C. The improved spatial and spectral resolutions (~26" and 2 km s-1) and sensitivity (RMS ~10 mJy beam-1) of our ATCA observations have allowed us to identify over 140 water maser candidates in the SWAG survey. This is a factor of 3 more than detected from prior surveys of the CMZ. The preliminary distribution of these candidates appears to be uniform along Galactic longitude. Should this distribution persist for water masers associated with star formation (as opposed to those produced by evolved stars), then this result would imply a more uniform distribution of recent SF activity in the CMZ. Prior works have shown that 2/3 of the molecular gas mass is located at positive Galactic longitudes, and young stellar objects (YSOs) identified by IR SEDs are located predominantly at negative Galactic longitudes. A combination of these results can provide insight on the evolution of SF within the CMZ. We are currently comparing the water maser positions to other catalogs (ex. OH/IR stars) in order to distinguish between the mechanisms producing these masers. We are also currently working on determining the distribution of 6.7 GHz methanol masers. These masers do not contain the same ambiguity as water masers as to their source

Genotoxic Potential of 1.6 GHz Wireless Communication Signal: In vivo Two-Year Bioassay

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vijayalaxmi, Vijay; Sasser, Lyle B.; Morris, J E.

Timed-pregnant Fischer 344 rats (from nineteenth day of gestation) and their nursing offspring (until weaning) were exposed to a far-field 1.6 GHz Iridium wireless communication signal for 2 h/day, 5 days/week. Far-field whole-body exposures were conducted with a field intensity of 0.43 mW/cm 2 and whole-body average specific absorption rate (SAR) of 0.036 to 0.077 W/kg (0.10 to 0.22 W/kg in the brain). This was followed by chronic, head-only exposures of male and female offspring to a near-field 1.6 GHz signal for 2 h/day, 5 days/week, over 2 years. Near-field exposures were conducted at an SAR of 0.16 or 1.6more » W/kg in the brain. Concurrent sham-exposed and cage control rats were also included in the study. At the end of 2 years, all rats were necropsied. Bone marrow smears were examined for the extent of genotoxicity, assessed from the presence of micronuclei in polychromatic erythrocytes. The results indicated that the incidence of micronuclei/ 2000 polychromatic erythrocytes were not significantly different between 1.6 GHz-exposed, sham-exposed and cage control rats. The group mean frequencies were 5.6 6 1.8 (130 rats exposed to 1.6 GHz at 0.16 W/kg SAR), 5.4 6 1.5 (135 rats exposed to 1.6 GHz at 1.6 W/kg SAR), 5.6 6 1.7 (119 sham-exposed rats), and 5.8 6 1.8 (100 cage control rats). In contrast, positive control rats treated with mitomycin C exhibited significantly elevated incidence of micronuclei/2000 polychromatic erythrocytes in bone marrow cells; the mean frequency was 38.2 6 7.0 (five rats). Thus there was no evidence for excess genotoxicity in rats that were chronically exposed to 1.6 GHz compared to sham-exposed and cage controls.« less

Radio continuum of galaxies with H2O megamaser disks: 33 GHz VLA data

NASA Astrophysics Data System (ADS)

Kamali, F.; Henkel, C.; Brunthaler, A.; Impellizzeri, C. M. V.; Menten, K. M.; Braatz, J. A.; Greene, J. E.; Reid, M. J.; Condon, J. J.; Lo, K. Y.; Kuo, C. Y.; Litzinger, E.; Kadler, M.

2017-09-01

Context. Galaxies with H2O megamaser disks are active galaxies in whose edge-on accretion disks 22 GHz H2O maser emission has been detected. Because their geometry is known, they provide a unique view into the properties of active galactic nuclei. Aims: The goal of this work is to investigate the nuclear environment of galaxies with H2O maser disks and to relate the maser and host galaxy properties to those of the radio continuum emission of the galaxy. Methods: The 33 GHz (9 mm) radio continuum properties of 24 galaxies with reported 22 GHz H2O maser emission from their disks are studied in the context of the multiwavelength view of these sources. The 29-37 GHz Ka-band observations are made with the Karl Jansky Very Large Array in B, CnB, or BnA configurations, achieving a resolution of 0.2-0.5 arcsec. Hard X-ray data from the Swift/BAT survey and 22 μm infrared data from WISE, 22 GHz H2O maser data and 1.4 GHz data from NVSS and FIRST surveys are also included in the analysis. Results: Eighty-seven percent (21 out of 24) galaxies in our sample show 33 GHz radio continuum emission at levels of 4.5-240σ. Five sources show extended emission (deconvolved source size larger than 2.5 times the major axis of the beam), including one source with two main components and one with three main components. The remaining detected 16 sources (and also some of the above-mentioned targets) exhibit compact cores within the sensitivity limits. Little evidence is found for extended jets (>300 pc) in most sources. Either they do not exist, or our chosen frequency of 33 GHz is too high for a detection of these supposedly steep spectrum features. In NGC 4388, we find an extended jet-like feature that appears to be oriented perpendicular to the H2O megamaser disk. NGC 2273 is another candidate whose radio continuum source might be elongated perpendicular to the maser disk. Smaller 100-300 pc sized jets might also be present, as is suggested by the beam-deconvolved morphology of our

37 GHz Methanol Masers : Horsemen of the Apocalypse for the Class II Methanol Maser Phase?

NASA Astrophysics Data System (ADS)

Ellingsen, S. P.; Breen, S. L.; Sobolev, A. M.; Voronkov, M. A.; Caswell, J. L.; Lo, N.

2011-12-01

We report the results of a search for class II methanol masers at 37.7, 38.3, and 38.5 GHz toward a sample of 70 high-mass star formation regions. We primarily searched toward regions known to show emission either from the 107 GHz class II methanol maser transition, or from the 6.035 GHz excited OH transition. We detected maser emission from 13 sources in the 37.7 GHz transition, eight of these being new detections. We detected maser emission from three sources in the 38 GHz transitions, one of which is a new detection. We find that 37.7 GHz methanol masers are only associated with the most luminous 6.7 and 12.2 GHz methanol maser sources, which in turn are hypothesized to be the oldest class II methanol sources. We suggest that the 37.7 GHz methanol masers are associated with a brief evolutionary phase (of 1000-4000 years) prior to the cessation of class II methanol maser activity in the associated high-mass star formation region.

47 CFR 25.222 - Blanket Licensing provisions for Earth Stations on Vessels (ESVs) receiving in the 10.95-11.2 GHz...

Code of Federal Regulations, 2014 CFR

2014-10-01

... on Vessels (ESVs) receiving in the 10.95-11.2 GHz (space-to-Earth), 11.45-11.7 GHz (space-to-Earth), 11.7-12.2 GHz (space-to-Earth) bands and transmitting in the 14.0-14.5 GHz (Earth-to-space) band... the 10.95-11.2 GHz (space-to-Earth), 11.45-11.7 GHz (space-to-Earth), 11.7-12.2 GHz (space-to-Earth...

The 30-GHz monolithic receive module

NASA Technical Reports Server (NTRS)

Bauhahn, P.; Geddes, J.; Sokolov, V.; Contolatis, T.

1988-01-01

The fourth year progress is described on a program to develop a 27.5 to 30 GHz GaAs monolithic receive module for spaceborne-communication antenna feed array applications, and to deliver submodules for experimental evaluation. Program goals include an overall receive module noise figure of 5 dB, a 30 dB RF to IF gain with six levels of intermediate gain control, a five bit phase shifter, and a maximum power consumption of 250 mW. Submicron gate length single and dual gate FETs are described and applied in the development of monolithic gain control amplifiers and low noise amplifiers. A two-stage monolithic gain control amplifier based on ion implanted dual gate MESFETs was designed and fabricated. The gain control amplifier has a gain of 12 dB at 29 GHz with a gain control range of over 13 dB. A two-stage monolithic low noise amplifier based on ion implanted MESFETs which provides 7 dB gain with 6.2 dB noise figure at 29 GHz was also developed. An interconnected receive module containing LNA, gain control, and phase shifter submodules was built using the LNA and gain control ICs as well as a monolithic phase shifter developed previously under this program. The design, fabrication, and evaluation of this interconnected receiver is presented. Progress in the development of an RF/IF submodule containing a unique ion implanted diode mixer diode and a broadband balanced mixer monolithic IC with on-chip IF amplifier and the initial design of circuits for the RF portion of a two submodule receiver are also discussed.

Synchrotron Spectral Curvature from 22 MHZ to 23 GHZ

NASA Technical Reports Server (NTRS)

Kogut, Alan J.

2012-01-01

We combine surveys of the radio sky at frequencies 22 MHz to 1.4 GHz with data from the ARCADE-2 instrument at frequencies 3 GHz to 10 GHz to characterize the frequency spectrum of diffuse synchrotron emission in the Galaxy. The radio spectrum steepens with frequency from 22 MHz to 10 GHz. The projected spectral index at 23 GHz derived from the low-frequency data agrees well with independent measurements using only data at frequencies 23 GHz and above. Comparing the spectral index at 23 GHz to the value from previously published analyses allows extension of the model to higher frequencies. The combined data are consistent with a power-law index beta = -2.64 +/-= 0.03 at 0.31 GHz, steepening by an amount of Delta-beta = 0.07 every octave in frequency. Comparison of the radio data to models including the cosmic-ray energy spectrum suggests that any break in the synchrotron spectrum must occur at frequencies above 23 GHz.

30-100-GHz inductors and transformers for millimeter-wave (Bi)CMOS integrated circuits

NASA Astrophysics Data System (ADS)

Dickson, T. O.; Lacroix, M.-A.; Boret, S.; Gloria, D.; Beerkens, R.; Voinigescu, S. P.

2005-01-01

Silicon planar and three-dimensional inductors and transformers were designed and characterized on-wafer up to 100 GHz. Self-resonance frequencies (SRFs) beyond 100 GHz were obtained, demonstrating for the first time that spiral structures are suitable for applications such as 60-GHz wireless local area network and 77-GHz automotive RADAR. Minimizing area over substrate is critical to achieving high SRF. A stacked transformer is reported with S21 of -2.5 dB at 50 GHz, and which offers improved performance and less area (30 μm × 30 μm) than planar transformers or microstrip couplers. A compact inductor model is described, along with a methodology for extracting model parameters from simulated or measured y-parameters. Millimeter-wave SiGe BiCMOS mixer and voltage-controlled-oscillator circuits employing spiral inductors are presented with better or comparable performance to previously reported transmission-line-based circuits.

77 FR 45503 - 4.9 GHz Band

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-01

... Docket No. 06-150; FCC 12-61] 4.9 GHz Band AGENCY: Federal Communications Commission. ACTION: Final rule... that exempted 4940-4990 MHz (4.9 GHz) band applicants from certified frequency coordination. Next, the Commission corrects the bandwidth of Channel 14 in the 4.9 GHz band plan from five megahertz to one megahertz...

Laboratory Heterodyne Spectrometers Operating at 100 and 300 GHZ

NASA Astrophysics Data System (ADS)

Maßen, Jakob; Wehres, Nadine; Hermanns, Marius; Lewen, Frank; Heyne, Bettina; Endres, Christian; Graf, Urs; Honingh, Netty; Schlemmer, Stephan

2017-06-01

Two new laboratory heterodyne emission spectrometers are presented that are currently used for high-resolution rotational spectroscopy of complex organic molecules. The room temperature heterodyne receiver operating between 80-110 GHz, as well as the SIS heterodyne receiver operating between 270-370 GHz allow access to two very important frequency regimes, coinciding with Bands 3 and 7 of the ALMA (Atacama Large Millimeter Array) telescope. Taking advantage of recent progresses in the field of mm/submm technology, we build these two spectrometers using an XFFFTS (eXtended Fast Fourier Transform Spectrometer) for spectral acquisition. The instantaneous bandwidth is 2.5 GHz in a single sideband, spread over 32768 channels. Thus, the spectral resolution is about 76 kHz per channel and thus comparable to high resolution spectra from telescopes. Both receivers are operated in double sideband mode resulting in a total instantaneous bandwidth of 5 GHz. The system performances, in particular the noise temperatures and stabilities are presented. Proof-of-concept is demonstrated by showing spectra of methyl cyanide obtained with both spectrometers. While the transition frequencies for this molecule are very well known, intensities of those transitions can also be determined with high accuracy using our new instruments. This additional information shall be exploited in future measurements to improve spectral predictions for astronomical observations. Other future prospects concern the study of more complex organic species, such as ethyl cyanide. These aspects of the new instruments as well as limitations of the two distinct receivers will be discussed.

The 18 and 30 GHz fixed service communication satellite system study: Executive summary

NASA Technical Reports Server (NTRS)

Bronstein, L. M.

1979-01-01

The use of the 18 and 30 GHz bands for fixed service satellite communications is examined. Primary objectives were to determine if satellite communication systems using this allocation (27.5 to 30.0 GHz uplink; 17.7 to 20.2 GHz downlink) can be cost competitive with alternate means of communication, and to determine what technological developments would be required to make these systems competitive. To meet these objectives, the cost and performance to be expected of 18 and 30 GHz hardware in the 1985 to 1990 era was assessed, selected trunking and direct to user concepts were optimized, and the cost of these systems was estimated. Finally, the technology developments required to make the most promising of the concepts competitive were identified.

A spectral radiance comparison of a noise tube and a HgXe arc lamp between 60 GHz and 600 GHz

NASA Technical Reports Server (NTRS)

Heaney, J. B.; Stewart, K. P.; Boucarut, R. A.; Moller, K. D.; Zoeller, R.

1987-01-01

The relative spectral radiance of a noise tube, model TN-167, designed for the frequency range 90-140 GHz (3.3 mm to 2.1 mm) was compared to that from a 200-watt high pressure HgXe arc lamp over the wavelength region from 0.5 to about 5 mm. A Michelson Fourier transform spectrometer and a lamellar grating instrument were used in conjunction with liquid helium-cooled bolometers of NEP 10 to the -12th to 10 to the -14th watt/(Hz) exp 1/2 to measure relative spectral radiant power. With this instrumental arrangement, the noise tube exhibited a very sharp low frequency cutoff at about 2.2/cm. The HgXe arc lamp emitted more radiant power than the noise tube in the wavelength region below 3 mm (100 GHz) down to 0.5 mm. Above 3 mm, the noise tube had a stronger output. The noise tube spectral radiance shifted to lower frequencies when the input current was lowered from 125 mA to 50 mA.

3.5 GHz Environmental Sensing Capability Detection Thresholds and Deployment

PubMed Central

Nguyen, Thao T.; Souryal, Michael R.; Sahoo, Anirudha; Hall, Timothy A.

2017-01-01

Spectrum sharing in the 3.5 GHz band between commercial and government users along U.S. coastal areas depends on an environmental sensing capability (ESC)—that is, a network of radio frequency sensors and a decision system—to detect the presence of incumbent shipborne radar systems and trigger protective measures, as needed. It is well known that the sensitivity of these sensors depends on the aggregate interference generated by commercial systems to the incumbent radar receivers, but to date no comprehensive study has been made of the aggregate interference in realistic scenarios and its impact on the requirement for detection of the radar signal. This paper presents systematic methods for determining the placement of ESC sensors and their detection thresholds to adequately protect incumbent shipborne radar systems from harmful interference. Using terrain-based propagation models and a population-based deployment model, the analysis finds the offshore distances at which protection must be triggered and relates these to the detection levels of coastline sensors. We further show that sensor placement is a form of the well-known set cover problem, which has been shown to be NP-complete, and demonstrate practical solutions achieved with a greedy algorithm. Results show detection thresholds to be as much as 22 dB lower than required by current industry standards. The methodology and results presented in this paper can be used by ESC operators for planning and deployment of sensors and by regulators for testing sensor performance. PMID:29303162

The Atacama Cosmology Telescope: Extragalactic Sources at 148 GHz in the 2008 Survey

NASA Technical Reports Server (NTRS)

Marriage, T. A.; Juin, J. B.; Lin, Y. T.; Marsden, D.; Nolta, M. R.; Partridge, B.; Ade, P. A. R.; Aguirre, P.; Amiri, M.; Appel, J. W.;

Polarimetric measurements of natural surfaces at 95 GHz

NASA Astrophysics Data System (ADS)

Chang, Paul S.; McIntosh, Robert E.

1992-08-01

A high power 95 GHz radar system, developed at the University of Massachusetts, was used to make polarimetric measurements of natural surfaces. Over the two year period of this grant, the following items were accomplished: (1) The 95 GHz radar was configured into a unique system capable of simultaneously making coherent and incoherent Mueller matrix measurements; (2) The equivalence of the coherent and noncoherent measurement technique was demonstrated; (3) The polarimetric properties of various foliage targets were characterized. These included the weeping willow, the sugar maple, and the white pine tree species; (4) The polarimetric properties of various snowcover types were characterized; and (5) Mueller matrix models for wet and dry snow were developed.

Cryogenic 160-GHz MMIC Heterodyne Receiver Module

NASA Technical Reports Server (NTRS)

Samoska, Lorene A.; Soria, Mary M.; Owen, Heather R.; Dawson, Douglas E.; Kangaslahti, Pekka P.; Gaier, Todd C.; Voll, Patricia; Lau, Judy; Sieth, Matt; Church, Sarah

2011-01-01

A cryogenic 160-GHz MMIC heterodyne receiver module has demonstrated a system noise temperature of 100 K or less at 166 GHz. This module builds upon work previously described in Development of a 150-GHz MMIC Module Prototype for Large-Scale CMB Radiation (NPO-47664), NASA Tech Briefs, Vol. 35, No. 8 (August 2011), p. 27. In the original module, the local oscillator signal was saturating the MMIC low-noise amplifiers (LNAs) with power. In order to suppress the local oscillator signal from reaching the MMIC LNAs, the W-band (75 110 GHz) signal had to be filtered out before reaching 140 170 GHz. A bandpass filter was developed to cover 120 170 GHz, using microstrip parallel-coupled lines to achieve the desired filter bandwidth, and ensure that the unwanted W-band local oscillator signal would be sufficiently suppressed. With the new bandpass filter, the entire receiver can work over the 140 180-GHz band, with a minimum system noise temperature of 460 K at 166 GHz. The module was tested cryogenically at 20 K ambient temperature, and it was found that the receiver had a noise temperature of 100 K over an 8-GHz bandwidth. The receiver module now includes a microstrip bandpass filter, which was designed to have a 3-dB bandwidth of approximately 120-170 GHz. The filter was fabricated on a 3-mil-thick alumina substrate. The filter design was based on a W-band filter design made at JPL and used in the QUIET (Q/U Imaging ExperimenT) radiometer modules. The W-band filter was scaled for a new center frequency of 150 GHz, and the microstrip segments were changed accordingly. Also, to decrease the bandwidth of the resulting scaled design, the center gaps between the microstrip lines were increased (by four micrometers in length) compared to the gaps near the edges. The use of the 150-GHz bandpass filter has enabled the receiver module to function well at room temperature. The system noise temperature was measured to be less than 600 K (at room temperature) from 154 to 168 GHz

160-190 GHz Monolithic Low Noise Amplifiers

NASA Technical Reports Server (NTRS)

Kok, Y. L.; Wang, H.; Huang, T. W.; Lai, R.; Chen, Y. C.; Sholley, M.; Block, T.; Streit, D. C.; Liu, P. H.; Allen, B. R.;

Rectenna Technology Program: Ultra light 2.45 GHz rectenna 20 GHz rectenna

NASA Technical Reports Server (NTRS)

Brown, William C.

1987-01-01

The program had two general objectives. The first objective was to develop the two plane rectenna format for space application at 2.45 GHz. The resultant foreplane was a thin-film, etched-circuit format fabricated from a laminate composed of 2 mil Kapton F sandwiched between sheets of 1 oz copper. The thin-film foreplane contains half wave dipoles, filter circuits, rectifying Schottky diode, and dc bussing lead. It weighs 160 grams per square meter. Efficiency and dc power output density were measured at 85% and 1 kw/sq m, respectively. Special testing techniques to measure temperature of circuit and diode without perturbing microwave operation using the fluoroptic thermometer were developed. A second objective was to investigate rectenna technology for use at 20 GHz and higher frequencies. Several fabrication formats including the thin-film scaled from 2.45 GHz, ceramic substrate and silk-screening, and monolithic were investigated, with the conclusion that the monolithic approach was the best. A preliminary design of the monolithic rectenna structure and the integrated Schottky diode were made.

Improvements in Speed and Functionality of a 670-GHz Imaging Radar

NASA Technical Reports Server (NTRS)

Dengler, Robert J.; Cooper, Ken B.; Mehdi, Imran; Siegel, Peter H.; Tarsala, Jan A.; Bryllert, Thomas E.

2011-01-01

Significant improvements have been made in the instrument originally described in a prior NASA Tech Briefs article: Improved Speed and Functionality of a 580-GHz Imaging Radar (NPO-45156), Vol. 34, No. 7 (July 2010), p. 51. First, the wideband YIG oscillator has been replaced with a JPL-designed and built phase-locked, low-noise chirp source. Second, further refinements to the data acquisition and signal processing software have been performed by moving critical code sections to C code, and compiling those sections to Windows DLLs, which are then invoked from the main LabVIEW executive. This system is an active, single-pixel scanned imager operating at 670 GHz. The actual chirp signals for the RF and LO chains were generated by a pair of MITEQ 2.5 3.3 GHz chirp sources. Agilent benchtop synthesizers operating at fixed frequencies around 13 GHz were then used to up-convert the chirp sources to 15.5 16.3 GHz. The resulting signals were then multiplied 36 times by a combination of off-the-shelf millimeter- wave components, and JPL-built 200- GHz doublers and 300- and 600-GHz triplers. The power required to drive the submillimeter-wave multipliers was provided by JPL-built W-band amplifiers. The receive and transmit signal paths were combined using a thin, high-resistivity silicon wafer as a beam splitter. While the results at present are encouraging, the system still lacks sufficient speed to be usable for practical applications in a contraband detection. Ideally, an image acquisition speed of ten seconds, or a factor of 30 improvement, is desired. However, the system improvements to date have resulted in a factor of five increase in signal acquisition speed, as well as enhanced signal processing algorithms, permitting clearer imaging of contraband objects hidden underneath clothing. In particular, advances in three distinct areas have enabled these performance enhancements: base source phase noise reduction, chirp rate, and signal processing. Additionally, a second

10C survey of radio sources at 15.7 GHz - II. First results

NASA Astrophysics Data System (ADS)

AMI Consortium; Davies, Mathhew L.; Franzen, Thomas M. O.; Waldram, Elizabeth M.; Grainge, Keith J. B.; Hobson, Michael P.; Hurley-Walker, Natasha; Lasenby, Anthony; Olamaie, Malak; Pooley, Guy G.; Riley, Julia M.; Rodríguez-Gonzálvez, Carmen; Saunders, Richard D. E.; Scaife, Anna M. M.; Schammel, Michel P.; Scott, Paul F.; Shimwell, Timothy W.; Titterington, David J.; Zwart, Jonathan T. L.

2011-08-01

In a previous paper (Paper I), the observational, mapping and source-extraction techniques used for the Tenth Cambridge (10C) Survey of Radio Sources were described. Here, the first results from the survey, carried out using the Arcminute Microkelvin Imager Large Array (LA) at an observing frequency of 15.7 GHz, are presented. The survey fields cover an area of ≈27 deg2 to a flux-density completeness of 1 mJy. Results for some deeper areas, covering ≈12 deg2, wholly contained within the total areas and complete to 0.5 mJy, are also presented. The completeness for both areas is estimated to be at least 93 per cent. The 10C survey is the deepest radio survey of any significant extent (≳0.2 deg2) above 1.4 GHz. The 10C source catalogue contains 1897 entries and is available online. The source catalogue has been combined with that of the Ninth Cambridge Survey to calculate the 15.7-GHz source counts. A broken power law is found to provide a good parametrization of the differential count between 0.5 mJy and 1 Jy. The measured source count has been compared with that predicted by de Zotti et al. - the model is found to display good agreement with the data at the highest flux densities. However, over the entire flux-density range of the measured count (0.5 mJy to 1 Jy), the model is found to underpredict the integrated count by ≈30 per cent. Entries from the source catalogue have been matched with those contained in the catalogues of the NRAO VLA Sky Survey and the Faint Images of the Radio Sky at Twenty-cm survey (both of which have observing frequencies of 1.4 GHz). This matching provides evidence for a shift in the typical 1.4-GHz spectral index to 15.7-GHz spectral index of the 15.7-GHz-selected source population with decreasing flux density towards sub-mJy levels - the spectra tend to become less steep. Automated methods for detecting extended sources, developed in Paper I, have been applied to the data; ≈5 per cent of the sources are found to be extended

47 CFR 25.222 - Blanket Licensing provisions for Earth Stations on Vessels (ESVs) receiving in the 10.95-11.2 GHz...

Code of Federal Regulations, 2013 CFR

2013-10-01

... of communication. (c) Operations of ESVs in the 14.0-14.2 GHz (Earth-to-space) frequency band within... on Vessels (ESVs) receiving in the 10.95-11.2 GHz (space-to-Earth), 11.45-11.7 GHz (space-to-Earth), 11.7-12.2 GHz (space-to-Earth) bands and transmitting in the 14.0-14.5 GHz (Earth-to-space) band...

UGC Galaxies Stronger than 25 MJy at 4.85 GHz

NASA Astrophysics Data System (ADS)

Condon, J. J.; Frayer, D. T.; Broderick, J. J.

1995-11-01

UGC galaxies in the declination band +5 degrees < delta < +75 degrees were identified by position coincidence with radio sources stronger than 25 mJy on the Green Bank 4.85 GHz sky maps. Candidate identifications were confirmed or rejected with the aid of published aperture-synthesis maps (including those in the companion directory UGC20CM.DIR) and new 4.86 GHz VLA D-array maps having 15 or 18 arcsec FWHM resolution. The 4.86 GHz maps in this directory cover both confirmed identifications and candidates rejected because of confusion, low flux density, etc. For more information on this study, please see the following references: Condon, J. J., Frayer, D. T., and Broderick, J. J. 1991, AJ, 101, 362. The image(s) and related TeX file come from the NRAO CDROM "Images From the Radio Universe" (c. 1992 National Radio Astronomy Observatory, used with permission).

Rain rate and modeled fade distributions at 20 GHz and 30 GHz derived from five years of network rain gauge measurements

NASA Technical Reports Server (NTRS)

Goldhirsh, Julius; Krichevsky, Vladimir; Gebo, Norman

1992-01-01

Five years of rain rate and modeled slant path attenuation distributions at 20 GHz and 30 GHz derived from a network of 10 tipping bucket rain gages was examined. The rain gage network is located within a grid 70 km north-south and 47 km east-west in the Mid-Atlantic coast of the United States in the vicinity of Wallops Island, Virginia. Distributions were derived from the variable integration time data and from one minute averages. It was demonstrated that for realistic fade margins, the variable integration time results are adequate to estimate slant path attenuations at frequencies above 20 GHz using models which require one minute averages. An accurate empirical formula was developed to convert the variable integration time rain rates to one minute averages. Fade distributions at 20 GHz and 30 GHz were derived employing Crane's Global model because it was demonstrated to exhibit excellent accuracy with measured COMSTAR fades at 28.56 GHz.

A 20 GHz bright sample for δ > +72° - I. Catalogue

NASA Astrophysics Data System (ADS)

Righini, S.; Carretti, E.; Ricci, R.; Zanichelli, A.; Mack, K.-H.; Massardi, M.; Prandoni, I.; Procopio, P.; Verma, R.; López-Caniego, M.; Gregorini, L.; Mantovani, F.

2012-11-01

During 2010-11, the Medicina 32-m dish hosted the seven-feed 18-26.5 GHz receiver built for the Sardinia Radio Telescope, with the goal to perform its commissioning. This opportunity was exploited to carry out a pilot survey at 20 GHz over the area for δ > +72°.3. This paper describes all the phases of the observations, as they were performed using new hardware and software facilities. The map-making and source extraction procedures are illustrated. A customized data reduction tool was used during the follow-up phase, which produced a list of 73 confirmed sources down to a flux density of 115 mJy. The resulting catalogue, presented here, is complete above 200 mJy. Source counts are in agreement with those provided by the Australia Telescope 20 GHz (AT20G) survey. This pilot activity paves the way for a larger project, the K-band Northern Wide Survey (KNoWS), whose final aim is to survey the whole Northern hemisphere down to a flux limit of 50 mJy (5σ).

VizieR Online Data Catalog: LMC and Cen A 1.3-10GHz polarization behavior (Anderson+, 2016)

NASA Astrophysics Data System (ADS)

Anderson, C. S.; Gaensler, B. M.; Feain, I. J.

2016-08-01

The targets for our study were selected from among two archival polarization data sets, which were observed and processed by several independent groups. i.e. LMC observations spanning from 1994 Oct to 1996 Jan in 1.328-1.432GHz band; Cen A observations spanning from 2006 Dec to 2008 Feb in 1.296-1.480GHz band. We observed the 40 sample sources using the Australia Telescope Compact Array (ATCA) over 1.1-3.1GHz (16cm), 4.5-6.5GHz (6cm), and 8.0-10.0GHz (3cm) in full polarization with a nominal 1MHz channel resolution between 2012 Feb 10-12 and 2012 Aug 17-19. We imaged each source in Stokes I, Q, and U at 20MHz intervals through the 16 and 6cm bands, and at a substantially coarser resolution of 200MHz in the 3cm band. See sections 2 and 3 for further explanations. (2 data files).

Experimental results for a 1.5 MW, 110 GHz gyrotron oscillator with reduced mode competition

NASA Astrophysics Data System (ADS)

Choi, E. M.; Marchewka, C. D.; Mastovsky, I.; Sirigiri, J. R.; Shapiro, M. A.; Temkin, R. J.

2006-02-01

A new result from a 110GHz gyrotron at MIT is reported with an output power of 1.67MW and an efficiency of 42% when operated at 97kV and 41A for 3μs pulses in the TE22,6 mode. These results are a major improvement over results obtained with an earlier cavity design, which produced 1.43MW of power at 37% efficiency. These new results were obtained using a cavity with a reduced output taper angle and a lower ohmic loss when compared with the earlier cavity. The improved operation is shown experimentally to be the result of reduced mode competition from the nearby TE19,7 mode. The reduced mode competition agrees well with an analysis of the startup scenario based on starting current simulations. The present results should prove useful in planning long pulse and CW versions of the 110GHz gyrotron.

Tunable All-Solid-State Local Oscillators to 1900 GHz

NASA Technical Reports Server (NTRS)

Ward, John; Chattopadhyay, Goutam; Maestrini, Alain; Schlecht, Erich; Gill, John; Javadi, Hamid; Pukala, David; Maiwald, Frank; Mehdi, Imran

2004-01-01

We present a status report of an ongoing effort to develop robust tunable all-solid-state sources up to 1900 GHz for the Heterodyne Instrument for the Far Infrared (HIFI) on the Herschel Space Observatory. GaAs based multi-chip power amplifier modules at W-band are used to drive cascaded chains of multipliers. We have demonstrated performance from chains comprised of four doublers up to 1600 GHz as well as from a x2x3x3 chain to 1900 GHz. Measured peak output power of 23 (micro)W at 1782 GHz and 2.6 (micro)W at 1900 GHz has been achieved when the multipliers are cooled to 120K. The 1900 GHz tripler was pumped with a four anode tripler that produces a peak of 4 mW at 630 GHz when cooled to 120 K. We believe that these sources can now be used to pump hot electron bolometer (HEB) heterodyne mixers.ter (HEB) heterodyne mixers.

Numerical Simulation of Single-anode and Double-anode Magnetron Injection Guns for 127.5 GHz 1 MW Gyrotron

NASA Astrophysics Data System (ADS)

Singh, Udaybir; Kumar, Nitin; Kumar, Anil; Purohit, Laxmi Prasad; Sinha, Ashok Kumar

2011-07-01

This paper presents the design of two types of magnetron injection guns (MIG's) for 1 MW, 127.5 GHz gyrotron. TE24,8 mode has been chosen as the operating mode. In-house developed code MIGSYN has been used to estimate the initial gun parameters. The electron trajectory tracing program EGUN and in-house developed code MIGANS have been used to optimize the single-anode and the double-anode design for 80 kV, 40 A MIG. The parametric analysis of MIG has also been presented. The advantages and the disadvantages of each kind of configuration have been critically examined.

Photonic integrated circuit implementation of a sub-GHz-selectivity frequency comb filter for optical clock multiplication.

PubMed

Geng, Zihan; Xie, Yiwei; Zhuang, Leimeng; Burla, Maurizio; Hoekman, Marcel; Roeloffzen, Chris G H; Lowery, Arthur J

2017-10-30

We report a photonic integrated circuit implementation of an optical clock multiplier, or equivalently an optical frequency comb filter. The circuit comprises a novel topology of a ring-resonator-assisted asymmetrical Mach-Zehnder interferometer in a Sagnac loop, providing a reconfigurable comb filter with sub-GHz selectivity and low complexity. A proof-of-concept device is fabricated in a high-index-contrast stoichiometric silicon nitride (Si 3 N 4 /SiO 2 ) waveguide, featuring low loss, small size, and large bandwidth. In the experiment, we show a very narrow passband for filters of this kind, i.e. a -3-dB bandwidth of 0.6 GHz and a -20-dB passband of 1.2 GHz at a frequency interval of 12.5 GHz. As an application example, this particular filter shape enables successful demonstrations of five-fold repetition rate multiplication of optical clock signals, i.e. from 2.5 Gpulses/s to 12.5 Gpulses/s and from 10 Gpulses/s to 50 Gpulses/s. This work addresses comb spectrum processing on an integrated platform, pointing towards a device-compact solution for optical clock multipliers (frequency comb filters) which have diverse applications ranging from photonic-based RF spectrum scanners and photonic radars to GHz-granularity WDM switches and LIDARs.

The Zeeman Effect in the 44 GHz Class I Methanol Maser Line toward DR21(OH)

NASA Astrophysics Data System (ADS)

Momjian, E.; Sarma, A. P.

2017-01-01

We report detection of the Zeeman effect in the 44 GHz Class I methanol maser line, toward the star-forming region DR21(OH). In a 219 Jy beam-1 maser centered at an LSR velocity of 0.83 km s-1, we find a 20-σ detection of zBlos = 53.5 ± 2.7 Hz. If 44 GHz methanol masers are excited at n ˜ 107-8 cm-3, then the B versus n1/2 relation would imply, from comparison with Zeeman effect detections in the CN(1 - 0) line toward DR21(OH), that magnetic fields traced by 44 GHz methanol masers in DR21(OH) should be ˜10 mG. Combined with our detected zBlos = 53.5 Hz, this would imply that the value of the 44 GHz methanol Zeeman splitting factor z is ˜5 Hz mG-1. Such small values of z would not be a surprise, as the methanol molecule is non-paramagnetic, like H2O. Empirical attempts to determine z, as demonstrated, are important because there currently are no laboratory measurements or theoretically calculated values of z for the 44 GHz CH3OH transition. Data from observations of a larger number of sources are needed to make such empirical determinations robust.

Two-Stage, 90-GHz, Low-Noise Amplifier

NASA Technical Reports Server (NTRS)

Samoska, Lorene A.; Gaier, Todd C.; Xenos, Stephanie; Soria, Mary M.; Kangaslahti, Pekka P.; Cleary, Kieran A.; Ferreira, Linda; Lai, Richard; Mei, Xiaobing

2010-01-01

A device has been developed for coherent detection of the polarization of the cosmic microwave background (CMB). A two-stage amplifier has been designed that covers 75-110 GHz. The device uses the emerging 35-nm InP HEMT technology recently developed at Northrop Grumman Corporation primarily for use at higher frequencies. The amplifier has more than 18 dB gain and less than 35 K noise figure across the band. These devices have noise less than 30 K at 100 GHz. The development started with design activities at JPL, as well as characterization of multichip modules using existing InP. Following processing, a test campaign was carried out using single-chip modules at 100 GHz. Successful development of the chips will lead to development of multichip modules, with simultaneous Q and U Stokes parameter detection. This MMIC (monolithic microwave integrated circuit) amplifier takes advantage of performance improvements intended for higher frequencies, but in this innovation are applied at 90 GHz. The large amount of available gain ultimately leads to lower possible noise performance at 90 GHz.

Compact 1.5-GHz intra-burst repetition rate Yb-doped all-PM-fiber laser system for ablation-cooled material removal

NASA Astrophysics Data System (ADS)

Akcaalan, Onder; Kalaycioglu, Hamit; Ilday, F. Omer

Although fs fiber laser systems are powerful technologies for material and tissue processing, limited ablation rates and high energy are drawbacks. Recently, we identified a new regime of laser-material interaction, ablation-cooled laser material removal, where the repetition rate has to be high enough so that the targeted spot size cannot cool down substantially by heat conduction which scales down ablation threshold by several orders of magnitude and reduces thermal effects to the bulk of the target. This opens the door to simplified laser systems for processing. In order to exploit this regime in tissue processing, a compact all-PM-fiber laser amplifier system with an intra-burst repetition rate of 1.5 GHz is developed on a 40 x 65 cm platform. The system is able to produce bursts ranging from 20-ns to 65-ns duration with 20 uJ to 80 uJ total energy, respectively, and pulses with up to 2 uJ individual energy and burst repetition rate ranging from 25 kHz to 200 kHz. The seed signal is generated by a home-built all-normal dispersion oscillator with 385 MHz repetition rate and converted to approximately 1.5 GHz by a multiplier. Amplified pulses are compressed to approximately 250-fs, the shortest pulse width for burst-mode fiber laser systems known to date.

An economical state-dependent telecloning for a multiparticle GHZ state

NASA Astrophysics Data System (ADS)

Meng, Fan-Xu; Yu, Xu-Tao; Zhang, Zai-Chen

2018-03-01

The scheme for a 1-3 economical state-dependent telecloning of a multiparticle GHZ state is proposed. It shows that every one of spatially separated three receivers obtains one copy which is dependent on original state. Fidelity can hit to the optimal fidelity 5/6. Meantime, we also propose a 1-3 asymmetric economical telecloning of a particular multiparticle GHZ state by parameterizing coefficients of state in the channel. The three fidelities can reach the best match that is the same as the symmetric case. Furthermore, the above two schemes can be generalized into the case of 1-M(M=2k+1,k>0) telecloning of a multiparticle GHZ state. Satisfying some certain conditions, optimal fidelities with 1/2+(M+1)/4M can be obtained. As without ancilla in the channel, the number of entangled particles is less than one in current schemes and fidelities can be optimal if the original state is an equatorial state.

THE KCAL VERA 22 GHz CALIBRATOR SURVEY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Petrov, L.; Honma, M.; Shibata, S. M., E-mail: Leonid.Petrov@lpetrov.net

2012-02-15

We observed a sample of 1536 sources with correlated flux densities brighter than 200 mJy at 8 GHz with the very long baseline interferometry (VLBI) array VLBI Exploration of Radio Astrometry at 22 GHz. One half of the target sources has been detected. The detection limit was around 200 mJy. We derived the correlated flux densities of 877 detected sources in three ranges of projected baseline lengths. The objective of these observations was to determine the suitability of given sources as phase calibrators for dual-beam and phase-referencing observations at high frequencies. Preliminary results indicate that the number of compact extragalacticmore » sources at 22 GHz brighter than a given correlated flux density level is two times less than that at 8 GHz.« less

Design of a collective scattering system for small scale turbulence study in Korea Superconducting Tokamak Advanced Research

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, W., E-mail: woochanglee@unist.ac.kr; Lee, D. J.; Park, H. K.

The design characteristics of a multi-channel collective (or coherent) scattering system for small scale turbulence study in Korea Superconducting Tokamak Advanced Research (KSTAR), which is planned to be installed in 2017, are given in this paper. A few critical issues are discussed in depth such as the Faraday and Cotton-Mouton effects on the beam polarization, radial spatial resolution, probe beam frequency, polarization, and power. A proper and feasible optics with the 300 GHz probe beam, which was designed based on these issues, provides a simultaneous measurement of electron density fluctuations at four discrete poloidal wavenumbers up to 24 cm{sup −1}.more » The upper limit corresponds to the normalized wavenumber k{sub θ}ρ{sub e} of ∼0.15 in nominal KSTAR plasmas. To detect the scattered beam power and extract phase information, a quadrature detection system consisting of four-channel antenna/detector array and electronics will be employed.« less

47 CFR 25.222 - Blanket Licensing provisions for Earth Stations on Vessels (ESVs) receiving in the 10.95-11.2 GHz...

Code of Federal Regulations, 2012 CFR

2012-10-01

... on Vessels (ESVs) receiving in the 10.95-11.2 GHz (space-to-Earth), 11.45-11.7 GHz (space-to-Earth), 11.7-12.2 GHz (space-to-Earth) frequency bands and transmitting in the 14.0-14.5 GHz (Earth-to-space... SATELLITE COMMUNICATIONS Technical Standards § 25.222 Blanket Licensing provisions for Earth Stations on...

47 CFR 25.222 - Blanket Licensing provisions for Earth Stations on Vessels (ESVs) receiving in the 10.95-11.2 GHz...

Code of Federal Regulations, 2010 CFR

2010-10-01

... on Vessels (ESVs) receiving in the 10.95-11.2 GHz (space-to-Earth), 11.45-11.7 GHz (space-to-Earth), 11.7-12.2 GHz (space-to-Earth) frequency bands and transmitting in the 14.0-14.5 GHz (Earth-to-space... SATELLITE COMMUNICATIONS Technical Standards § 25.222 Blanket Licensing provisions for Earth Stations on...

47 CFR 25.222 - Blanket Licensing provisions for Earth Stations on Vessels (ESVs) receiving in the 10.95-11.2 GHz...

Code of Federal Regulations, 2011 CFR

2011-10-01

... on Vessels (ESVs) receiving in the 10.95-11.2 GHz (space-to-Earth), 11.45-11.7 GHz (space-to-Earth), 11.7-12.2 GHz (space-to-Earth) frequency bands and transmitting in the 14.0-14.5 GHz (Earth-to-space... SATELLITE COMMUNICATIONS Technical Standards § 25.222 Blanket Licensing provisions for Earth Stations on...

The 40 and 50 GHz propagation experiments at the Rutherford Appleton Laboratory, UK, using the ITALSAT beacons

NASA Technical Reports Server (NTRS)

Woodroffe, J. M.; Davies, P. G.; Ladd, D. N.; Norbury, John R.

1994-01-01

This paper describes the current experimental program and future plans for the reception of transmissions from the 18.7, 39.6, and 49.5 GHz beacons from the ITALSAT satellite by the Radio Communications Research Unit at Rutherford Appleton Laboratory, UK. The Radio Communications Research Unit, which has had considerable experience in developing experimental millimetric equipment for propagation studies, has initiated the development of a single-channel receiver and a triple-channel receiver to measure propagation effects at 49.5 GHz and 39.6 GHz respectively. The initial location of the receivers will be at Chilbolton, Hampshire, UK.

A 30-GHz monolithic receiver

NASA Technical Reports Server (NTRS)

Liu, Louis C. T.; Liu, Carol S.; Kessler, Joel R.; Wang, Shing-Kuo; Chang, Ching-Der

1986-01-01

Several monolithic integrated circuits have been developed to make a 30-GHz receiver. The receiver components include a low-noise amplifier (LNA), an IF amplifier, a mixer, and a phase shifter. The LNA has a 7-dB noise figure with over 17 dB of associated gain. The IF amplifier has a 13-dB gain with a 30-dB control range. The mixer has a conversion loss of 10.5 dB. The phase shifter has a 180-deg phase shift control and a minimum insertion loss of 1.6 dB.

14/12-GHz-band satellite communication services

NASA Astrophysics Data System (ADS)

Hayashi, Kunihiro; Nagaki, Kiyoaki; Mori, Yasuo

1990-01-01

Three new systems for integrated TV-relay services have been developed: Satellite Video Comunication Service (SVCS) and Satellite Digital Communication Service (SDCS), with Japan's 14/12-GHz-band commercial communication satellites. These systems have been in commercial use since May 1989. Usually SVCS and SDCS have been provided using Ka-band (30/20 GHz-band) of CS-2 and Cs-3. This paper provides an overview of the design, the performance, and the systems of the new 14/12-GHz-band satellite communication services.

30/20 GHz spacecraft GaAs FET solid state transmitter for trunking and customer-premise-service application

NASA Technical Reports Server (NTRS)

Saunier, P.; Nelson, S.

1983-01-01

Sixteen 30 dB 0.5 W amplifier modules were combined to satisfy the requirement for a graceful degradation. If one module fails, the output power drops by only 0.43 dB. Also, by incorporating all the gain stages within the combiner the overall combining efficiency is maximized. A 16 way waveguide divider combiner was developed to minimize the insertion loss associated with such a large corporate feed structure. Tests showed that the 16 way insertion loss was less than 0.5 dB. To minimize loss, a direct transition from waveguide to microstrip, using a finline on duroid substrate, was developed. The FETs fabricated on MBE grown material, demonstrated superior performances. For example, a 600 micrometer device was capable of 320 mW output power with 5 dB gain and 26.6% efficiency at 21 GHz. The 16 module amplifier gave 8.95 W saturated output power with 30 dB gain. The overall efficiency was 9%. The 3 dB bandwidth was 2.5 GHz. At 17.7 GHz the amplifier had 5 W output power and at 20.2 GHz it still had 4.4 W.

Bi-layer kinetic inductance detectors for space observations between 80-120 GHz

NASA Astrophysics Data System (ADS)

Catalano, A.; Goupy, J.; le Sueur, H.; Benoit, A.; Bourrion, O.; Calvo, M.; D'addabbo, A.; Dumoulin, L.; Levy-Bertrand, F.; Macías-Pérez, J.; Marnieros, S.; Ponthieu, N.; Monfardini, A.

2015-08-01

We have developed lumped element kinetic inductance detectors (LEKIDs) that are sensitive in the frequency band from 80 to 120 GHz. In this work, we take advantage of the so-called proximity effect to reduce the superconducting gap of aluminium (Al), otherwise strongly suppressing the LEKID response for frequencies smaller than 100 GHz. We designed, produced, and optically tested various fully multiplexed arrays based on multi-layer combinations of Al and titanium (Ti). Their sensitivities were measured using a dedicated closed-circle 100 mK dilution cryostat and a sky simulator, which allowed us to reproduce realistic observation conditions. The spectral response was characterised with a Martin-Puplett interferometer up to THz frequencies and had a resolution of 3 GHz. We demonstrate that Ti-Al LEKID can reach an optical sensitivity of about 1.4 × 10-17 W/Hz0.5 (best pixel), or 2.2 × 10-17 W/Hz0.5 when averaged over the whole array. The optical background was set to roughly 0.4 pW per pixel, which is typical for future space observatories in this particular band. The performance is close to a sensitivity of twice the CMB photon noise limit at 100 GHz, which drove the design of the Planck HFI instrument. This figure remains the baseline for the next generation of millimetre-wave space satellites.

Heterodyne detection of the 752.033-GHz H2O rotational absorption line

NASA Technical Reports Server (NTRS)

Dionne, G. F.; Fitzgerald, J. F.; Chang, T. S.; Litvak, M. M.; Fetterman, H. R.

1980-01-01

A tunable high resolution two stage heterodyne radiometer was developed for the purpose of investigating the intensity and lineshape of the 752.033 GHz rotational transition of water vapor. Single-sideband system noise temperatures of approximately 45,000 K were obtained using a sensitive GaAs Schottky diode as the first stage mixer. First local oscillator power was supplied by a CO2 laser pumped formic acid laser (761.61 GHz), generating an X-band IF signal with theoretical line center at 9.5744 GHz. Second local oscillator power was provided by means of a 3 GHz waveguide cavity filter with only 9 dB insertion loss. In absorption measurements of the H2O taken from a laboratory simulation of a high altitude rocket plume, the center frequency of the 752 GHz line was determined to within 1 MHz of the reported value. A rotational temperature 75 K, a linewidth 5 MHz and a Doppler shift 3 MHz were measured with the line-of-sight intersecting the simulated-plume axis at a distance downstream of 30 nozzle diameters. These absorption data were obtained against continuum background radiation sources at temperatures of 1175 and 300 K.

Deep 20-GHz survey of the Chandra Deep Field South and SDSS Stripe 82: source catalogue and spectral properties

NASA Astrophysics Data System (ADS)

Franzen, Thomas M. O.; Sadler, Elaine M.; Chhetri, Rajan; Ekers, Ronald D.; Mahony, Elizabeth K.; Murphy, Tara; Norris, Ray P.; Waldram, Elizabeth M.; Whittam, Imogen H.

2014-04-01

We present a source catalogue and first results from a deep, blind radio survey carried out at 20 GHz with the Australia Telescope Compact Array, with follow-up observations at 5.5, 9 and 18 GHz. The Australia Telescope 20 GHz (AT20G) deep pilot survey covers a total area of 5 deg2 in the Chandra Deep Field South and in Stripe 82 of the Sloan Digital Sky Survey. We estimate the survey to be 90 per cent complete above 2.5 mJy. Of the 85 sources detected, 55 per cent have steep spectra (α _{1.4}^{20} < -0.5) and 45 per cent have flat or inverted spectra (α _{1.4}^{20} ≥ -0.5). The steep-spectrum sources tend to have single power-law spectra between 1.4 and 18 GHz, while the spectral indices of the flat- or inverted-spectrum sources tend to steepen with frequency. Among the 18 inverted-spectrum (α _{1.4}^{20} ≥ 0.0) sources, 10 have clearly defined peaks in their spectra with α _{1.4}^{5.5} > 0.15 and α 9^{18} < -0.15. On a 3-yr time-scale, at least 10 sources varied by more than 15 per cent at 20 GHz, showing that variability is still common at the low flux densities probed by the AT20G-deep pilot survey. We find a strong and puzzling shift in the typical spectral index of the 15-20-GHz source population when combining data from the AT20G, Ninth Cambridge and Tenth Cambridge surveys: there is a shift towards a steeper-spectrum population when going from ˜1 Jy to ˜5 mJy, which is followed by a shift back towards a flatter-spectrum population below ˜5 mJy. The 5-GHz source-count model by Jackson & Wall, which only includes contributions from FRI and FRII sources, and star-forming galaxies, does not reproduce the observed flattening of the flat-spectrum counts below ˜5 mJy. It is therefore possible that another population of sources is contributing to this effect.

Experimental study of a 1 MW, 170 GHz gyrotron oscillator

NASA Astrophysics Data System (ADS)

Kimura, Takuji

A detailed experimental study is presented of a 1 MW, 170 GHz gyrotron oscillator whose design is consistent with the ECH requirements of the International Thermonuclear Experimental Reactor (ITER) for bulk heating and current drive. This work is the first to demonstrate that megawatt power level at 170 GHz can be achieved in a gyrotron with high efficiency for plasma heating applications. Maximum output power of 1.5 MW is obtained at 170.1 GHz in 85 kV, 50A operation for an efficiency of 35%. Although the experiment at MIT is conducted with short pulses (3 μs), the gyrotron is designed to be suitable for development by industry for continuous wave operation. The peak ohmic loss on the cavity wall for 1 MW of output power is calculated to be 2.3 kW/cm2, which can be handled using present cooling technology. Mode competition problems in a highly over-moded cavity are studied to maximize the efficiency. Various aspects of electron gun design are examined to obtain high quality electron beams with very low velocity spread. A triode magnetron injection gun is designed using the EGUN simulation code. A total perpendicular velocity spread of less than 8% is realized by designing a low- sensitivity, non-adiabatic gun. The RF power is generated in a short tapered cavity with an iris step. The operating mode is the TE28,8,1 mode. A mode converter is designed to convert the RF output to a Gaussian beam. Power and efficiency are measured in the design TE28,8,1 mode at 170.1 GHz as well as the TE27,8,1 mode at 166.6 GHz and TE29,8,1 mode at 173.5 GHz. Efficiencies between 34%-36% are consistently obtained over a wide range of operating parameters. These efficiencies agree with the highest values predicted by the multimode simulations. The startup scenario is investigated and observed to agree with the linear theory. The measured beam velocity ratio is consistent with EGUN simulation. Interception of reflected beam by the mod-anode is measured as a function of velocity ratio

Concepts for 18/30 GHz satellite communication system study. Executive summary

NASA Technical Reports Server (NTRS)

Baker, M.; Davies, R.; Cuccia, L.; Mitchell, C.

1979-01-01

An examination of a multiplicity of interconnected parameters ranging from specific technology details to total system economic costs for satellite communication systems at the 18/30 GHz transmission bands are presented. It was determined that K sub A band systems can incur a small communications outage during very heavy rainfall periods and that reducing the outage to zero would lead to prohibitive system costs. On the other hand, the economics of scale, ie, one spacecraft accommodating 2.5 GHz of bandwidth coupled with multiple beam frequency reuse, leads to very low costs for those users who can tolerate the 5 to 50 hours per year of downtime. A multiple frequency band satellite network can provide the ultimate optimized match to the consumer performance/economics demands.

Quantum teleportation through noisy channels with multi-qubit GHZ states

NASA Astrophysics Data System (ADS)

Espoukeh, Pakhshan; Pedram, Pouria

2014-08-01

We investigate two-party quantum teleportation through noisy channels for multi-qubit Greenberger-Horne-Zeilinger (GHZ) states and find which state loses less quantum information in the process. The dynamics of states is described by the master equation with the noisy channels that lead to the quantum channels to be mixed states. We analytically solve the Lindblad equation for -qubit GHZ states where Lindblad operators correspond to the Pauli matrices and describe the decoherence of states. Using the average fidelity, we show that 3GHZ state is more robust than GHZ state under most noisy channels. However, GHZ state preserves same quantum information with respect to Einstein-Podolsky-Rosen and 3GHZ states where the noise is in direction in which the fidelity remains unchanged. We explicitly show that Jung et al.'s conjecture (Phys Rev A 78:012312, 2008), namely "average fidelity with same-axis noisy channels is in general larger than average fidelity with different-axes noisy channels," is not valid for 3GHZ and 4GHZ states.

Sixty GHz IMPATT diode development

NASA Technical Reports Server (NTRS)

Ma, Y. E.; Chen, J.; Benko, E.; Barger, M. J.; Nghiem, H.; Trinh, T. Q.; Kung, J.

1985-01-01

The objective of this program is to develop 60 GHz GaAs IMPATT Diodes suitable for communications applications. The performance goal of the 60 GHz IMPATT is 1W CW output power with a conversion efficiency of 15 percent and 10 year life time. During the course of the program, double drift (DD) GaAs IMPATT Diodes have been developed resulting in the state of the art performance at V band frequencies. A CW output power of 1.12 W was demonstrated at 51.9 GHz with 9.7 percent efficiency. The best conversion efficiency achieved was 15.3 percent. V band DD GaAs IMPATTs were developed using both small signal and large signal analyses. GaAs wafers of DD flat, DD hybrid, and DD Read profiles using molecular beam epitaxy (MBE) were developed with excellent doping profile control. Wafer evaluation was routinely made by the capacitance versus voltage (C-V) measurement. Ion mass spectrometry (SIMS) analysis was also used for more detailed profile evaluation.

200-GHz and 50-GHz AWG channelized linewidth dependent transmission of weak-resonant-cavity FPLD injection-locked by spectrally sliced ASE.

PubMed

Lin, Gong-Ru; Cheng, Tzu-Kang; Chi, Yu-Chieh; Lin, Gong-Cheng; Wang, Hai-Lin; Lin, Yi-Hong

2009-09-28

In a weak-resonant-cavity Fabry-Perot laser diode (WRC-FPLD) based DWDM-PON system with an array-waveguide-grating (AWG) channelized amplified spontaneous emission (ASE) source located at remote node, we study the effect of AWG filter bandwidth on the transmission performances of the 1.25-Gbit/s directly modulated WRC-FPLD transmitter under the AWG channelized ASE injection-locking. With AWG filters of two different channel spacings at 50 and 200 GHz, several characteristic parameters such as interfered reflection, relatively intensity noise, crosstalk reduction, side-mode-suppressing ratio and power penalty of BER effect of the WRC-FPLD transmitted data are compared. The 200-GHz AWG filtered ASE injection minimizes the noises of WRC-FPLD based ONU transmitter, improving the power penalty of upstream data by -1.6 dB at BER of 10(-12). In contrast, the 50-GHz AWG channelized ASE injection fails to promote better BER but increases the power penalty by + 1.5 dB under back-to-back transmission. A theoretical modeling elucidates that the BER degradation up to 4 orders of magnitude between two injection cases is mainly attributed to the reduction on ASE injection linewidth, since which concurrently degrades the signal-to-noise and extinction ratios of the transmitted data stream.

Study of ion-gyroscale fluctuations in low-density L-mode plasmas heated by NBI on KSTAR

NASA Astrophysics Data System (ADS)

Lee, W.; Ko, S. H.; Leem, J.; Yun, G. S.; Park, H. K.; Wang, W. X.; Budny, R. V.; Kim, K. W.; Luhmann, N. C., Jr.; The KSTAR Team

2018-04-01

Broadband density fluctuations with peak frequency ranging from 150 to 400 kHz were measured using a multichannel microwave imaging reflectometer in core region of the low-density L-mode plasmas heated by neutral beam injection on KSTAR. These fluctuations have been studied by comparing the dominant mode scales estimated from the measurement with those predicted from linear gyrokinetic simulation. The measured poloidal wavenumbers are qualitatively comparable to those of the ‘fastest growing modes’ from simulations, whereas they are larger than those of the ‘transport-dominant modes’ by about a factor of three. The agreement on wavenumbers between the measurement and linear simulation (for the fastest growing modes) is probably due to sufficiently weak E × B flow shear compared to the maximum linear growth rate. Meanwhile, the transport-dominant modes seem to be related to the fluctuations in lower frequencies (˜80-150 kHz) observed in some of the measurement.

Teleportation of a 3-dimensional GHZ State

NASA Astrophysics Data System (ADS)

Cao, Hai-Jing; Wang, Huai-Sheng; Li, Peng-Fei; Song, He-Shan

2012-05-01

The process of teleportation of a completely unknown 3-dimensional GHZ state is considered. Three maximally entangled 3-dimensional Bell states function as quantum channel in the scheme. This teleportation scheme can be directly generalized to teleport an unknown d-dimensional GHZ state.

Large-Area Monolayer MoS2 for Flexible Low-Power RF Nanoelectronics in the GHz Regime.

PubMed

Chang, Hsiao-Yu; Yogeesh, Maruthi Nagavalli; Ghosh, Rudresh; Rai, Amritesh; Sanne, Atresh; Yang, Shixuan; Lu, Nanshu; Banerjee, Sanjay Kumar; Akinwande, Deji

2016-03-02

Flexible synthesized MoS2 transistors are advanced to perform at GHz speeds. An intrinsic cutoff frequency of 5.6 GHz is achieved and analog circuits are realized. Devices are mechanically robust for 10,000 bending cycles. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High sensitivity broadband 360GHz passive receiver for TeraSCREEN

NASA Astrophysics Data System (ADS)

Wang, Hui; Oldfield, Matthew; Maestrojuán, Itziar; Platt, Duncan; Brewster, Nick; Viegas, Colin; Alderman, Byron; Ellison, Brian N.

2016-05-01

TeraSCREEN is an EU FP7 Security project aimed at developing a combined active, with frequency channel centered at 360 GHz, and passive, with frequency channels centered at 94, 220 and 360 GHz, imaging system for border controls in airport and commercial ferry ports. The system will include automatic threat detection and classification and has been designed with a strong focus on the ethical, legal and practical aspects of operating in these environments and with the potential threats in mind. Furthermore, both the passive and active systems are based on array receivers with the active system consisting of a 16 element MIMO FMCW radar centered at 360 GHz with a bandwidth of 30 GHz utilizing a custom made direct digital synthesizer. The 16 element passive receiver system at 360 GHz uses commercial Gunn diode oscillators at 90 GHz followed by custom made 90 to 180 GHz frequency doublers supplying the local oscillator for 360 GHz sub-harmonic mixers. This paper describes the development of the passive antenna module, local oscillator chain, frequency mixers and detectors used in the passive receiver array of this system. The complete passive receiver chain is characterized in this paper.

THE ZEEMAN EFFECT IN THE 44 GHZ CLASS I METHANOL MASER LINE TOWARD DR21(OH)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Momjian, E.; Sarma, A. P., E-mail: emomjian@nrao.edu, E-mail: asarma@depaul.edu

2017-01-10

We report detection of the Zeeman effect in the 44 GHz Class I methanol maser line, toward the star-forming region DR21(OH). In a 219 Jy beam{sup −1} maser centered at an LSR velocity of 0.83 km s{sup −1}, we find a 20- σ detection of zB {sub los} = 53.5 ± 2.7 Hz. If 44 GHz methanol masers are excited at n ∼ 10{sup 7–8} cm{sup −3}, then the B versus n {sup 1/2} relation would imply, from comparison with Zeeman effect detections in the CN(1 − 0) line toward DR21(OH), that magnetic fields traced by 44 GHz methanol masersmore » in DR21(OH) should be ∼10 mG. Combined with our detected zB {sub los} = 53.5 Hz, this would imply that the value of the 44 GHz methanol Zeeman splitting factor z is ∼5 Hz mG{sup −1}. Such small values of z would not be a surprise, as the methanol molecule is non-paramagnetic, like H{sub 2}O. Empirical attempts to determine z , as demonstrated, are important because there currently are no laboratory measurements or theoretically calculated values of z for the 44 GHz CH{sub 3}OH transition. Data from observations of a larger number of sources are needed to make such empirical determinations robust.« less

Results of a new OCTOPUS'' ECR ion source at 6. 4 GHz

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dupont, C.; Jongen, Y.; Arakawa, K.

1990-01-01

The first OCTOPUS electron cyclstron resonance (ECR) multicharged heavy ion source was built in 1985 at the Centre de Recherches du Cyclotron of the University of Louvain (Belgium). This first source used an ECR frequency of 14.3 GHz in the injector stage and 8.5 GHz in the main confinement stage. A new OCTOPUS source has now been built for a new cyclotron to be installed at the Japan Atomic Energy Research Institute (JAERI). The design of this new OCTOPUS source is identical to the first OCTOPUS source, but uses an ECR frequency of 6.4 GHz in the main confinement stage.more » The experimental results are described, and a comparison is made between the two sources. However, the available data does not allow any clear conclusion to be drawn on frequency scaling.« less

60-GHz integrated-circuit high data rate quadriphase shift keying exciter and modulator

NASA Technical Reports Server (NTRS)

Grote, A.; Chang, K.

1984-01-01

An integrated-circuit quadriphase shift keying (QPSK) exciter and modulator have demonstrated excellent performance directly modulating a carrier frequency of 60 GHz with an output phase error of less than 3 degrees and maximum amplitude error of 0.5 dB. The circuit consists of a 60-GHz Gunn VCO phase-locked to a low-frequency reference source, a 4th subharmonic mixer, and a QPSK modlator packaged into a small volume of 1.8 x 2.5 x 0.35 in. The use of microstrip has the advantages of small size, light-weight, and low-cost fabrication. The unit has the potential for multigigabit data rate applications.

Numerical analysis for infant's unintentional exposure to 3.5 GHz plane wave radiofrequency electromagnetic fields by field test of fifth generation wireless technologies

NASA Astrophysics Data System (ADS)

Liu, Dan; Li, Congsheng; Kang, Yangyang; Zhou, Zhou; Xie, Yi; Wu, Tongning

2017-09-01

In this study, the plane wave exposure of an infant to radiofrequency electromagnetic fields of 3.5 GHz was numerically analyzed to investigate the unintentional electromagnetic field (EMF) exposure of fifth generation (5G) signals during field test. The dosimetric influence of age-dependent dielectric properties and the influence of an adult body were evaluated using an infant model of 12 month old and an adult female model. The results demonstrated that the whole body-averaged specific absorption rate (WBASAR) was not significantly affected by age-dependent dielectric properties and the influence of the adult body did not enhance WBASAR. Taking the magnitude of the in situ E field strength into consideration, realistic WBASAR was far below the basic restriction. Age-dependent dielectric properties could significantly change the tissue specified specific absorption rate (TSSAR) of internal organs. However, the variation was not significant because the absolute values were marginal. Among the factors that influenced TSSAR variation, change in dielectric properties demonstrated a close correlation. In general, at 3.5 GHz, the infant did not absorb more power than the case of EMF exposure to third generation (3G) and fourth generation (4G) signals. The work was helpful for network operators and device manufactures to estimate the potential exposure risk during the field test, especially for the infant.

The influence of the reflective environment on the absorption of a human male exposed to representative base station antennas from 300 MHz to 5 GHz.

PubMed

Vermeeren, G; Gosselin, M C; Kühn, S; Kellerman, V; Hadjem, A; Gati, A; Joseph, W; Wiart, J; Meyer, F; Kuster, N; Martens, L

2010-09-21

The environment is an important parameter when evaluating the exposure to radio-frequency electromagnetic fields. This study investigates numerically the variation on the whole-body and peak spatially averaged-specific absorption rate (SAR) in the heterogeneous virtual family male placed in front of a base station antenna in a reflective environment. The SAR values in a reflective environment are also compared to the values obtained when no environment is present (free space). The virtual family male has been placed at four distances (30 cm, 1 m, 3 m and 10 m) in front of six base station antennas (operating at 300 MHz, 450 MHz, 900 MHz, 2.1 GHz, 3.5 GHz and 5.0 GHz, respectively) and in three reflective environments (a perfectly conducting wall, a perfectly conducting ground and a perfectly conducting ground + wall). A total of 72 configurations are examined. The absorption in the heterogeneous body model is determined using the 3D electromagnetic (EM) finite-difference time-domain (FDTD) solver Semcad-X. For the larger simulations, requirements in terms of computer resources are reduced by using a generalized Huygens' box approach. It has been observed that the ratio of the SAR in the virtual family male in a reflective environment and the SAR in the virtual family male in the free-space environment ranged from -8.7 dB up to 8.0 dB. A worst-case reflective environment could not be determined. ICNIRP reference levels not always showed to be compliant with the basic restrictions.

Results of Outdoor to Indoor Propagation Measurements from 5-32GHz

NASA Technical Reports Server (NTRS)

Houts, Jacquelynne R.; McDonough, Ryan S.

2016-01-01

The demand for wireless services has increased exponentially in the last few years and shows no signs of slowing in the near future. In order for the next generation wireless to provide seamless access, whether the user is indoors or out, a thorough understanding and validation of models describing the impact of building entry loss (BEL) is required. This information is currently lacking and presents a challenge for most system designers. For this reason empirical data is needed to assess the impact of BEL at frequencies that are being explored for future mobile broadband applications This paper present the results of measurements of outdoor-to-indoor propagation from 5-32 GHz in three different buildings. The first is a newer building that is similar in construction to modern residential home. The second is an older commercial office building. The last building is a very new commercial office building built using modern green building techniques. These three buildings allow for the measurement of propagation losses through both modern and older materials; such as glass windows and exterior block and siding. Initial results found that at particular spatial locations the BEL could be less than 1dB or more than 70dB with free space losses discounted (this is likely influenced by multipath). Additionally, it was observed that the PDF distributions of a majority of the measurements trended toward log-normal with means and standard deviations ranging from 8-38dB and 6-14dB, respectively.

Miniature MMIC Low Mass/Power Radiometer Modules for the 180 GHz GeoSTAR Array

NASA Technical Reports Server (NTRS)

Kangaslahti, Pekka; Tanner, Alan; Pukala, David; Lambrigtsen, Bjorn; Lim, Boon; Mei, Xiaobing; Lai, Richard

2010-01-01

We have developed and demonstrated miniature 180 GHz Monolithic Microwave Integrated Circuit (MMIC) radiometer modules that have low noise temperature, low mass and low power consumption. These modules will enable the Geostationary Synthetic Thinned Aperture Radiometer (GeoSTAR) of the Precipitation and All-weather Temperature and Humidity (PATH) Mission for atmospheric temperature and humidity profiling. The GeoSTAR instrument has an array of hundreds of receivers. Technology that was developed included Indium Phosphide (InP) MMIC Low Noise Amplifiers (LNAs) and second harmonic MMIC mixers and I-Q mixers, surface mount Multi-Chip Module (MCM) packages at 180 GHz, and interferometric array at 180 GHz. A complete MMIC chip set for the 180 GHz receiver modules (LNAs and I-Q Second harmonic mixer) was developed. The MMIC LNAs had more than 50% lower noise temperature (NT=300K) than previous state-of-art and MMIC I-Q mixers demonstrated low LO power (3 dBm). Two lots of MMIC wafers were processed with very high DC transconductance of up to 2800 mS/mm for the 35 nm gate length devices. Based on these MMICs a 180 GHz Multichip Module was developed that had a factor of 100 lower mass/volume (16x18x4.5 mm3, 3g) than previous generation 180 GHz receivers.

Broadband Characterization of a 100 to 180 GHz Amplifier

NASA Technical Reports Server (NTRS)

Kangaslahti, Pekka; Deal, W. R.; Mei, X. B.; Lai, R.

2007-01-01

Atmospheric science and weather forecasting require measurements of the temperature and humidity vs. altitude. These sounding measurements are obtained at frequencies close to the resonance frequencies of oxygen (118 GHz) and water (183 GHz) molecules. We have characterized a broadband amplifier that will increase the sensitivity of sounding and other instruments at these frequencies. This study demonstrated for the first t1me continuous low noise amplification from 100 to 180 GHz. The measured InP monolithic millimeter-wave Integrated circuit (MMIC) amplifier had more than 18 dB of gain from 100 to 180 GHz and 15 dB of gain up to 220 GHz. This is the widest bandwidth low noise amplifier result at these frequencies to date. The circuit was fabricated in Northrop Grumman Corporation 35 nm InP high electron mobility transistor (HEMT).

47 CFR 15.253 - Operation within the bands 46.7-46.9 GHz and 76.0-77.0 GHz.

Code of Federal Regulations, 2010 CFR

2010-10-01

...-77.0 GHz is restricted to vehicle-mounted field disturbance sensors used as vehicle radar systems... the radiating structure. (c) The power density of any emissions outside the operating band shall... GHz shall not exceed the general limits in § 15.209. (2) Radiated emissions outside the operating band...

VizieR Online Data Catalog: MGIV (Fourth MIT-Green Bank) 5GHz Survey (Griffith+ 1991)

NASA Astrophysics Data System (ADS)

Griffith, M.; Langston, G.; Heflin, M.; Conner, S.; Burke, B.

1998-10-01

The MIT-Green Bank IV (MG IV) 5 GHz survey covers 0.504 sr of sky in the right ascension range 15.5 to 2.5 hours, between +37.00 and +50.98 degrees declination (B1950). The final MG IV catalog contains 3427 sources detected with a signal-to-noise ratio greater than 5. The catalog was produced from two separate north and south surveys with the National Radio Astronomy Observatory (NRAO) 91m transit telescope. The north survey was produced from data collected while scanning the telescope north from +39.0 to +50.98 degrees declination and the south survey from data collected from scans from +48.98 to +37.00 degrees declination. The completeness and reliability of the final source list is checked by examination of north and south source lists in a twice observed comparison region, lying between +39.15 and +48.83 degrees declination and excluding the area between +/-10 degrees Galactic latitude. The comparison region covers 0.270 sr of sky and contains 1094 sources. In this region, the MG IV catalog contains 423 sources brighter than 90 mJy and is shown to be 99.1 +/- 1.2% complete at this flux density level. Spectral indices are computed for sources identified in the NRAO 1400 MHz Survey (published by Condon and Broderick in 1985). A comparison of the spectral index distributions between +/- 10 and outside of +/- 10 degrees Galactic latitude is presented. (1 data file).

Development of a 670 GHz Extended Interaction Klystron Power Amplifier

DTIC Science & Technology

2011-03-01

Klystron Power Amplifier 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR( S ) 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT...avelengths,” /40/EIK%20Tec W%20Wavelen oyski, R. Dobbs, act, High Power ction Klystron ,” Conf., Montere opments to the M or Modeling Cod 2005). ic...Research Projects Agency or the Department of Defense. Development of a 670 GHz Extended Interaction Klystron Power Amplifier David Chernin Science

93-133 GHz Band InP High-Electron-Mobility Transistor Amplifier with Gain-Enhanced Topology

NASA Astrophysics Data System (ADS)

Sato, Masaru; Shiba, Shoichi; Matsumura, Hiroshi; Takahashi, Tsuyoshi; Nakasha, Yasuhiro; Suzuki, Toshihide; Hara, Naoki

2013-04-01

In this study, we developed a new type of high-frequency amplifier topology using 75-nm-gate-length InP-based high-electron-mobility transistors (InP HEMTs). To enhance the gain for a wide frequency range, a common-source common-gate hybrid amplifier topology was proposed. A transformer-based balun placed at the input of the amplifier generates differential signals, which are fed to the gate and source terminals of the transistor. The amplified signal is outputted at the drain node. The simulation results show that the hybrid topology exhibits a higher gain from 90 to 140 GHz than that of the conventional common-source or common-gate amplifier. The two-stage amplifier fabricated using the topology exhibits a small signal gain of 12 dB and a 3-dB bandwidth of 40 GHz (93-133 GHz), which is the largest bandwidth and the second highest gain reported among those of published 120-GHz-band amplifiers. In addition, the measured noise figure was 5 dB from 90 to 100 GHz.

a 33GHZ and 95GHZ Cloud Profiling Radar System (cprs): Preliminary Estimates of Particle Size in Precipitation and Clouds.

NASA Astrophysics Data System (ADS)

Sekelsky, Stephen Michael

1995-11-01

The Microwave Remote Sensing Laboratory (MIRSL) st the University of Massachusetts has developed a unique single antenna, dual-frequency polarimetric Cloud Profiling Radar System (CPRS). This project was funded by the Department of Energy's Atmospheric Radiation Measurement (ARM) program, and was intended to help fill the void of ground-based remote sensors capable of characterizing cloud microphysical properties. CPRS is unique in that it can simultaneously measure the complex power backscattered from clouds at 33 GHz and 95 GHz through the same aperture. Both the 33 GHz and 95 GHz channels can transmit pulse-to-pulse selectable vertical or horizontal polarization, and simultaneously record both the copolarized and crosspolarized backscatter. CPRS Doppler, polarimetric and dual-wavelength reflectivity measurements combined with in situ cloud measurements should lead to the development of empirical models that can more accurately classify cloud-particle phase and habit, and make better quantitative estimates of particle size distribution parameters. This dissertation describes the CPRS hardware, and presents colocated 33 GHz and 95 GHz measurements that illustrate the use of dual-frequency measurements to estimate particle size when Mie scattering, is observed in backscatter from rain and ice-phase clouds. Polarimetric measurements are presented as a means of discriminating cloud phase (ice-water) and estimating crystal shape in cirrus clouds. Polarimetric and dual-wavelength observations of insects are also presented with a brief discussion of their impact on the interpretation of precipitation and liquid cloud measurements. In precipitation, Diermendjian's equations for Mie backscatter (1) and the Marshal-Palmer drop-size distribution are used to develop models relating differences in the reflectivity and mean velocity at 33 GHz and 95 GHz to the microphysical parameters of rain. These models are then used to estimate mean droplet size from CPRS measurements of

A 0.8-4.2 GHz monolithic all-digital PLL based frequency synthesizer for wireless communications

NASA Astrophysics Data System (ADS)

Yuanxin, Zhao; Yuanpei, Gao; Wei, Li; Ning, Li; Junyan, Ren

2015-01-01

A 0.8-4.2 GHz monolithic all-digital PLL based frequency synthesizer for wireless communications is successfully realized by the 130 nm CMOS process. A series of novel methods are proposed in this paper. Two band DCOs with high frequency resolution are utilized to cover the frequency band of interest, which is as wide as 2.5 to 5 GHz. An overflow counter is proposed to prevent the “pulse-swallowing” phenomenon so as to significantly reduce the locking time. A NTW-clamp digital module is also proposed to prevent the overflow of the loop control word. A modified programmable divider is presented to prevent the failure operation at the boundary. The measurement results show that the output frequency range of this frequency synthesizer is 0.8-4.2 GHz. The locking time achieves a reduction of 84% at 2.68 GHz. The best in-band and out-band phase noise performances have reached -100 dBc/Hz, and -125 dBc/Hz respectively. The lowest reference spur is -58 dBc.

VizieR Online Data Catalog: 22GHz image of 3C 273 (Bruni+, 2017)

NASA Astrophysics Data System (ADS)

Bruni, G.; Gomez, J. L.; Casadio, C.; Lobanov, A.; Kovalev, Y. Y.; Sokolovsky, K. V.; Lisakov, M. M.; Bach, U.; Marscher, A.; Jorstad, S.; Anderson, J. M.; Krichbaum, T. P.; Savolainen, T.; Vega-Garcia, L.; Fuentes, A.; Zensus, J. A.; Alberdi, A.; Lee, S.-S.; Lu, R.-S.; Perez-Torres, M.; Ros, E.

2017-07-01

A global ground array of 22 antennas was used to perform observations, including VLBA (Sc, Hn, Nl, Fd, La, Kp, Pt, Ov, Br, Mk), EVN (Hh, Mc, Nt, Tr, Jb, Ef, Ys), Long Baseline Array (-LBA- At, Mp, Ho, Cd), and two Kvazar antennas (Sv, Zc), plus Kalyazin (managed by ASC, Russia), and Green Bank (NRAO, USA). The observations took place on January 18-19, 2014, for a total of 16.8 hours, and at three different frequencies: 15GHz, 22GHz, and 43GHz. RA was involved only for the 22GHz part, while for the other bands only the VLBA was used. Both the Green Bank and Pushchino tracking station took part in the experiment. A RA-compatible total bandwidth of 32MHz, split into two 16-MHz IFs, was used. RA was scheduled to observe three consecutive 9.5 minute scans every 1.25 hours, to allow for antenna cooling. (2 data files).

A VLA (Very Large Array) Search for 5 GHz Radio Transients and Variables at Low Galactic Latitudes

NASA Technical Reports Server (NTRS)

Ofek, E. O.; Frail, D. A.; Breslauer, B.; Kulkarni, S. R.; Chandra, P.; Gal-Yam, A.; Kasliwal, M. M.; Gehrels, N.

2012-01-01

We present the results of a 5GHz survey with the Very Large Array (VLA) and the expanded VLA, designed to search for short-lived (approx < 1 day) transients and to characterize the variability of radio sources at milli-Jansky levels. A total sky area of 2.66 sq. deg, spread over 141 fields at low Galactic latitudes (b approx equals 6 - 8 deg) was observed 16 times with a cadence that was chosen to sample timescales of days, months and years. Most of the data were reduced, analyzed and searched for transients in near real time. Interesting candidates were followed up using visible light telescopes (typical delays of 1 - 2 hr) and the X-Ray Telescope on board the Swift satellite. The final processing of the data revealed a single possible transient with a flux density of f(sub v) approx equals 2.4mJy. This implies a transients sky surface density of kappa(f(sub v) > 1.8mJy) = 0.039(exp +0.13,+0.18) (sub .0.032,.0.038) / sq. deg (1, 2 sigma confidence errors). This areal density is consistent with the sky surface density of transients from the Bower et al. survey extrapolated to 1.8mJy. Our observed transient areal density is consistent with a Neutron Stars (NSs) origin for these events. Furthermore, we use the data to measure the sources variability on days to years time scales, and we present the variability structure function of 5GHz sources. The mean structure function shows a fast increase on approximately 1 day time scale, followed by a slower increase on time scales of up to 10 days. On time scales between 10 - 60 days the structure function is roughly constant. We find that approx > 30% of the unresolved sources brighter than 1.8mJy are variable at the > 4-sigma confidence level, presumably due mainly to refractive scintillation.

Experimental results of superimposing 9.9 GHz extraordinary mode microwaves on 2.45 GHz ECRIS plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nishiokada, Takuya, E-mail: nishiokada@nf.eie.eng.osaka-u.ac.jp; Nagaya, Tomoki; Hagino, Shogo

2016-02-15

Efficient production of multicharged ions has been investigated on the tandem-type ECRIS in Osaka University. According to the consideration of the accessibility conditions of microwaves to resonance and cutoff regions, it was suggested that the upper hybrid resonance (UHR) heating contributed to enhancement of ion beam intensity. In order to enhance multicharged ion beams efficiently, injecting higher frequency microwave with extraordinary (X-mode) toward UHR region has been tried. In this study, 2.45 GHz frequency microwaves are used for conventional ECR discharge, and 9.9 GHz frequency microwaves with X-mode are superimposed for UHR heating. The effects of additive microwave injection aremore » investigated experimentally in terms of plasma parameters and electron energy distribution function (EEDF) measured by Langmuir probe and ion beam current. As the results show, it is confirmed that the electrons in the high energy region are affected by 9.9 GHz X-mode microwave injection from the detailed analysis of EEDF.« less

Experimental results of superimposing 9.9 GHz extraordinary mode microwaves on 2.45 GHz ECRIS plasma.

PubMed

Nishiokada, Takuya; Nagaya, Tomoki; Hagino, Shogo; Otsuka, Takuro; Muramatsu, Masayuki; Sato, Fuminobu; Kitagawa, Atsushi; Kato, Yushi

2016-02-01

Efficient production of multicharged ions has been investigated on the tandem-type ECRIS in Osaka University. According to the consideration of the accessibility conditions of microwaves to resonance and cutoff regions, it was suggested that the upper hybrid resonance (UHR) heating contributed to enhancement of ion beam intensity. In order to enhance multicharged ion beams efficiently, injecting higher frequency microwave with extraordinary (X-mode) toward UHR region has been tried. In this study, 2.45 GHz frequency microwaves are used for conventional ECR discharge, and 9.9 GHz frequency microwaves with X-mode are superimposed for UHR heating. The effects of additive microwave injection are investigated experimentally in terms of plasma parameters and electron energy distribution function (EEDF) measured by Langmuir probe and ion beam current. As the results show, it is confirmed that the electrons in the high energy region are affected by 9.9 GHz X-mode microwave injection from the detailed analysis of EEDF.

Design of a high speed, high resolution thermometry system for 1.5 GHz superconducting radio frequency cavities

NASA Astrophysics Data System (ADS)

Knobloch, Jens; Muller, Henry; Padamsee, Hasan

1994-11-01

Presented in this paper are the description and the test results of a new stationary thermometry system used to map the temperature of the outer surface of 1.5 GHz superconducting single-cell cavities during operation at 1.6 K. The system comprises 764 removable carbon thermometers whose signals are multiplexed and scanned by a Macintosh computer. A complete temperature map can be obtained in as little as 0.1 s at a temperature resolution of about 0.2 mK. Alternatively, it has been demonstrated that if the acquisition time is increased to several seconds, then a temperature resolution on the order of 30 μK is possible. To our knowledge, these are the fastest acquisition times so far achieved with L-band cavities at these resolutions.

Elastic properties of transparent nano-polycrystalline diamond measured by GHz-ultrasonic interferometry and resonant sphere methods

NASA Astrophysics Data System (ADS)

Chang, Yun-Yuan; Jacobsen, Steven D.; Kimura, Masaki; Irifune, Tetsuo; Ohno, Ichiro

2014-03-01

The sound velocities and elastic moduli of transparent nano-polycrystalline diamond (NPD) have been determined by GHz-ultrasonic interferometry on three different bulk samples, and by resonant spectroscopy on a spherically fabricated NPD sample. We employ a newly-developed optical contact micrometer to measure the thickness of ultrasonic samples to ±0.05 μm with a spatial resolution of ∼50 μm in the same position of the GHz-ultrasonic measurements, resulting in acoustic-wave sound velocity measurements with uncertainties of 0.005-0.02%. The isotropic and adiabatic bulk and shear moduli of NPD measured by GHz-ultrasonic interferometry are KS0 = 442.5 (±0.5) GPa and G0 = 532.4 (±0.5) GPa. By rotating the shear-wave polarization direction, we observe no transverse anisotropy in this NPD. Using resonant sphere spectroscopy, we obtain KS0 = 440.3 (±0.5) GPa and G0 = 532.7 (±0.4) GPa. For comparison, we also measured by GHz-ultrasonic interferometry the elastic constants of a natural single-crystal type-IA diamond with about one-half the experimental uncertainty of previous measurements. The resulting Voigt-Reuss-Hill averaged bulk and shear moduli of natural diamond are KS0 = 441.8 (±0.8) GPa and G0 = 532.6 (±0.5) GPa, demonstrating that the bulk-elastic properties of transparent NPD are equivalent to natural single-crystal diamond as calculated from polycrystalline averaging of its elastic constants.

Power-Amplifier Module for 145 to 165 GHz

NASA Technical Reports Server (NTRS)

Samoska, Lorene; Peralta, Alejandro

2007-01-01

A power-amplifier module that operates in the frequency range of 145 to 165 GHz has been designed and constructed as a combination of (1) a previously developed monolithic microwave integrated circuit (MMIC) power amplifier and (2) a waveguide module. The amplifier chip was needed for driving a high-electron-mobility-transistor (HEMT) frequency doubler. While it was feasible to connect the amplifier and frequency-doubler chips by use of wire bonds, it was found to be much more convenient to test the amplifier and doubler chips separately. To facilitate separate testing, it was decided to package the amplifier and doubler chips in separate waveguide modules. Figure 1 shows the resulting amplifier module. The amplifier chip was described in "MMIC HEMT Power Amplifier for 140 to 170 GHz" (NPO-30127), NASA Tech Briefs, Vol. 27, No. 11, (November 2003), page 49. To recapitulate: This is a three-stage MMIC power amplifier that utilizes HEMTs as gain elements. The amplifier was originally designed to operate in the frequency range of 140 to 170 GHz. The waveguide module is based on a previously developed lower frequency module, redesigned to support operation in the frequency range of 140 to 220 GHz. Figure 2 presents results of one of several tests of the amplifier module - measurements of output power and gain as functions of input power at an output frequency of 150 GHz. Such an amplifier module has many applications to test equipment for power sources above 100 GHz.

Arbitrary waveform modulated pulse EPR at 200 GHz

NASA Astrophysics Data System (ADS)

Kaminker, Ilia; Barnes, Ryan; Han, Songi

2017-06-01

We report here on the implementation of arbitrary waveform generation (AWG) capabilities at ∼200 GHz into an Electron Paramagnetic Resonance (EPR) and Dynamic Nuclear Polarization (DNP) instrument platform operating at 7 T. This is achieved with the integration of a 1 GHz, 2 channel, digital to analog converter (DAC) board that enables the generation of coherent arbitrary waveforms at Ku-band frequencies with 1 ns resolution into an existing architecture of a solid state amplifier multiplier chain (AMC). This allows for the generation of arbitrary phase- and amplitude-modulated waveforms at 200 GHz with >150 mW power. We find that the non-linearity of the AMC poses significant difficulties in generating amplitude-modulated pulses at 200 GHz. We demonstrate that in the power-limited regime of ω1 < 1 MHz phase-modulated pulses were sufficient to achieve significant improvements in broadband (>10 MHz) spin manipulation in incoherent (inversion), as well as coherent (echo formation) experiments. Highlights include the improvement by one order of magnitude in inversion bandwidth compared to that of conventional rectangular pulses, as well as a factor of two in improvement in the refocused echo intensity at 200 GHz.

A 1.8 GHz Voltage-Controlled Oscillator using CMOS Technology

NASA Astrophysics Data System (ADS)

Maisurah, M. H. Siti; Emran, F. Nazif; Norman Fadhil, Idham M.; Rahim, A. I. Abdul; Razman, Y. Mohamed

2011-05-01

A Voltage-Controlled Oscillator (VCO) for 1.8 GHz application has been designed using a combination of both 0.13 μm and 0.35 μm CMOS technology. The VCO has a large tuning range, which is from 1.39 GHz to 1.91 GHz, using a control voltage from 0 to 3V. The VCO exhibits a low phase-noise at 1.8 GHz which is around -119.8dBc/Hz at a frequency offset of 1 MHz.

Design and assessment of a robust voltage amplifier with 2.5 GHz GBW and >100 kGy total dose tolerance

NASA Astrophysics Data System (ADS)

Verbeeck, J.; Leroux, P.; Steyaert, M.

2011-01-01

A differential voltage amplifier with a gain-bandwidth product of 2.5Ghz and using adaptive biasing has been designed in a standard CMOS technology and assessed under radiation and temperature variations. The principle used in this ASIC will be employed in the design of a Gbps TIA with improved tolerance for γ-irradiation and temperature for an optical instrumentation (LIDAR) receiver aiming at operation in harsh environments. The voltage amplifier was tested under gamma radiation and features a gain degradation of merely 4.5% up to a total dose of 100kGy. In order to verify the radiation effects on the IC, the threshold voltage shift of the separate transistors has been investigated. Temperature characterization has shown that the amplifier features a reduction of the voltage gain by only 5.6% for a temperature range of -40 till 130 °C.

Optimum concentric circular array antenna with high gain and side lobe reduction at 5.8 GHz

NASA Astrophysics Data System (ADS)

Zaid, Mohammed; Rafiqul Islam, Md; Habaebi, Mohamed H.; Zahirul Alam, AHM; Abdullah, Khaizuran

2017-11-01

The significance of high gain directional antennas stems from the need to cope up with the everyday progressing wireless communication systems. Due to low gain of the widely used microstrip antenna, combining multiple antennas in proper geometry increases the gain with good directive property. Over other array forms, this paper uses concentric circular array configuration for its compact structure and inherent symmetry in azimuth. This proposed array is composed of 9 elements on FR-4 substrate, which is designed for WLAN applications at 5.8GHz. Antenna Magus software is used for synthesis, while CST software is used for optimization. The proposed array is designed with optimum inter-element spacing and number of elements achieving a high directional gain of 15.7 dB compared to 14.2 dB of available literature, with a high reduction in side lobe level of -17.6 dB.

A low noise 665 GHz SIS quasi-particle waveguide receiver

NASA Technical Reports Server (NTRS)

Kooi, J. W.; Walker, C. K.; Leduc, H. G.; Hunter, T. R.; Benford, D. J.; Phillips, T. G.

1993-01-01

Recent results on a 565-690 GHz SIS heterodyne receiver employing a 0.36 micron(sup 2) Nb/AlOx/Nb SIS tunnel junction with high quality circular non-contacting back short and E-plane tuners in a full height wave guide mount are reported. No resonant tuning structures were incorporated in the junction design at this time, even though such structures are expected to help the performance of the receiver. The receiver operates to at least the gap frequency of Niobium, approximately 680 GHz. Typical receiver noise temperatures from 565-690 GHz range from 160K to 230K with a best value of 185K DSB at 648 GHz. With the mixer cooled from 4.3K to 2K the measured receiver noise temperatures decreased by approximately 15 percent, giving roughly 180K DSB from 660 to 680 GHz. The receiver has a full 1 GHz IF pass band and was successfully installed at the Caltech Submillimeter Observatory in Hawaii.

A spectroscopic survey of Orion KL between 41.5 and 50 GHz.

PubMed

Rizzo, J R; Tercero, B; Cernicharo, J

2017-09-01

The nearby massive star-forming region Orion KL is one of the richest molecular reservoirs known in our Galaxy. The region hosts newly formed protostars, and the strong interaction between their radiation and their outflows with the environment results in a series of complex chemical processes leading to a high diversity of interstellar tracers. The region is therefore one of the most frequently observed sources, and the site where many molecular species have been discovered for the first time. With the availability of powerful wideband backends, it is nowadays possible to complete spectral surveys in the entire mm-range to obtain a spectroscopically unbiased chemical picture of the region. In this paper we present a sensitive spectral survey of Orion KL, made with one of the 34 m antennas of the Madrid Deep Space Communications Complex in Robledo de Chavela, Spain. The spectral range surveyed is from 41.5 to 50 GHz, with a frequency spacing of 180 kHz (equivalent to ≈ 1.2 km s -1 , depending on the exact frequency). The rms achieved ranges from 8 to 12 mK. The spectrum is dominated by the J = 1 → 0 SiO maser lines and by radio recombination lines (RRLs), which were detected up to Δ n = 11. Above a 3 σ level, we identified 66 RRLs and 161 molecular lines corresponding to 39 isotopologues from 20 molecules; a total of 18 lines remain unidentified, two of them above a 5 σ level. Results of radiative modelling of the detected molecular lines (excluding masers) are presented. At this frequency range, this is the most sensitive survey and also the one with the widest band. Although some complex molecules like CH 3 CH 2 CN and CH 2 CHCN arise from the hot core, most of the detected molecules originate from the low temperature components in Orion KL.

A New 95 GHz Methanol Maser Catalog. I. Data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Wenjin; Xu, Ye; Lu, Dengrong

The Purple Mountain Observatory 13.7 m radio telescope has been used to search for 95 GHz (8{sub 0}–7{sub 1}A{sup +}) class I methanol masers toward 1020 Bolocam Galactic Plane Survey (BGPS) sources, leading to 213 detections. We have compared the line width of the methanol and HCO{sup +} thermal emission in all of the methanol detections, and on that basis, we find that 205 of the 213 detections are very likely to be masers. This corresponds to an overall detection rate of 95 GHz methanol masers toward our BGPS sample of 20%. Of the 205 detected masers, 144 (70%) aremore » new discoveries. Combining our results with those of previous 95 GHz methanol maser searches, a total of 481 95 GHz methanol masers are now known. We have compiled a catalog listing the locations and properties of all known 95 GHz methanol masers.« less

THE CELESTIAL REFERENCE FRAME AT 24 AND 43 GHz. II. IMAGING

DOE Office of Scientific and Technical Information (OSTI.GOV)

Charlot, P.; Boboltz, D. A.; Fey, A. L.

2010-05-15

We have measured the submilliarcsecond structure of 274 extragalactic sources at 24 and 43 GHz in order to assess their astrometric suitability for use in a high-frequency celestial reference frame (CRF). Ten sessions of observations with the Very Long Baseline Array have been conducted over the course of {approx}5 years, with a total of 1339 images produced for the 274 sources. There are several quantities that can be used to characterize the impact of intrinsic source structure on astrometric observations including the source flux density, the flux density variability, the source structure index, the source compactness, and the compactness variability.more » A detailed analysis of these imaging quantities shows that (1) our selection of compact sources from 8.4 GHz catalogs yielded sources with flux densities, averaged over the sessions in which each source was observed, of about 1 Jy at both 24 and 43 GHz, (2) on average the source flux densities at 24 GHz varied by 20%-25% relative to their mean values, with variations in the session-to-session flux density scale being less than 10%, (3) sources were found to be more compact with less intrinsic structure at higher frequencies, and (4) variations of the core radio emission relative to the total flux density of the source are less than 8% on average at 24 GHz. We conclude that the reduction in the effects due to source structure gained by observing at higher frequencies will result in an improved CRF and a pool of high-quality fiducial reference points for use in spacecraft navigation over the next decade.« less

VizieR Online Data Catalog: 22GHz observations of VX Sgr (Murakawa+, 2003)

NASA Astrophysics Data System (ADS)

Murakawa, K.; Yates, J. A.; Richards, A. M. S.; Cohen, R. J.

2012-07-01

The 22-GHz H2O maser emission from VX Sgr was observed on 1994 26 and 1999 January 16 for 5 and 7hr, respectively, in both left and right circular polarization, using 5 antennas of MERLIN. (3 data files).

47 CFR 15.252 - Operation of wideband vehicular radar systems within the bands 16.2-17.7 GHz and 23.12-29.0 GHz.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 1 2011-10-01 2011-10-01 false Operation of wideband vehicular radar systems within the bands 16.2-17.7 GHz and 23.12-29.0 GHz. 15.252 Section 15.252 Telecommunication FEDERAL..., Additional Provisions § 15.252 Operation of wideband vehicular radar systems within the bands 16.2-17.7 GHz...

47 CFR 15.252 - Operation of wideband vehicular radar systems within the bands 16.2-17.7 GHz and 23.12-29.0 GHz.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 47 Telecommunication 1 2013-10-01 2013-10-01 false Operation of wideband vehicular radar systems within the bands 16.2-17.7 GHz and 23.12-29.0 GHz. 15.252 Section 15.252 Telecommunication FEDERAL..., Additional Provisions § 15.252 Operation of wideband vehicular radar systems within the bands 16.2-17.7 GHz...

47 CFR 15.252 - Operation of wideband vehicular radar systems within the bands 16.2-17.7 GHz and 23.12-29.0 GHz.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 47 Telecommunication 1 2014-10-01 2014-10-01 false Operation of wideband vehicular radar systems within the bands 16.2-17.7 GHz and 23.12-29.0 GHz. 15.252 Section 15.252 Telecommunication FEDERAL..., Additional Provisions § 15.252 Operation of wideband vehicular radar systems within the bands 16.2-17.7 GHz...

47 CFR 15.252 - Operation of wideband vehicular radar systems within the bands 16.2-17.7 GHz and 23.12-29.0 GHz.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 47 Telecommunication 1 2012-10-01 2012-10-01 false Operation of wideband vehicular radar systems within the bands 16.2-17.7 GHz and 23.12-29.0 GHz. 15.252 Section 15.252 Telecommunication FEDERAL..., Additional Provisions § 15.252 Operation of wideband vehicular radar systems within the bands 16.2-17.7 GHz...

Detection of 17 GHz radio emission from X-ray-bright points

NASA Technical Reports Server (NTRS)

Kundu, M. R.; Shibasaki, K.; Enome, S.; Nitta, N.

1994-01-01

Using observations made with the Nobeyama radio heliograph (NRH) at 17 GHz and the Yohkoh/SXT experiment, we report the first detection of 17 GHz signatures of coronal X-ray-bright points (XBPs). This is also the first reported detection of flaring bright points in microwaves. We have detected four BPs at 17 GHz out of eight identified in SXT data on 1992 July 31, for which we looked for 17 GHz emission. For one XBP located in a quiet mixed-polarity region, the peak times at 17 GHz and X-rays are very similar, and both are long-lasting-about 2 hr in duration. There is a second BP (located near an active region) which is most likely flaring also, but the time profiles in the two spectral domains are not similar. The other two 17 GHz BPs are quiescent with fluctuations superposed upon them. For the quiet region XBP, the gradual, long-lasting, and unpolarized emission suggests that the 17 GHz emission is thermal.

MMIC HEMT Power Amplifier for 140 to 170 GHz

NASA Technical Reports Server (NTRS)

Samoska, Lorene; Radisic, Vesna; Ngo, Catherine; Janke, Paul; Hu, Ming; Micovic, Miro

2003-01-01

A three-stage monolithic microwave integrated circuit (MMIC) power amplifier that features high-electron-mobility transistors (HEMTs) as gain elements is reviewed. This amplifier is designed to operate in the frequency range of 140 to 170 GHz, which contains spectral lines of several atmospheric molecular species plus subharmonics of other such spectral lines. Hence, this amplifier could serve as a prototype of amplifiers to be incorporated into heterodyne radiometers used in atmospheric science. The original intended purpose served by this amplifier is to boost the signal generated by a previously developed 164-GHz MMIC HEMT doubler and drive a 164-to-328-GHz doubler to provide a few milliwatts of power at 328 GHz.

Future mobile satellite communication concepts at 20/30 GHz

NASA Technical Reports Server (NTRS)

Barton, S. K.; Norbury, J. R.

1990-01-01

The outline of a design of a system using ultra small earth stations (picoterminals) for data traffic at 20/30 GHz is discussed. The picoterminals would be battery powered, have an RF transmitter power of 0.5 W, use a 10 cm square patch antenna, and have a receiver G/T of about -8 dB/K. Spread spectrum modulation would be required (due to interference consideration) to allow a telex type data link (less than 200 bit/s data rate) from the picoterminal to the hub station of the network and about 40 kbit/s on the outbound patch. An Olympus type transponder at 20/30 GHz could maintain several thousand simultaneous picoterminal circuits. The possibility of demonstrating a picoterminal network with voice traffic using Olympus is discussed together with fully mobile systems based on this concept.

Robust Sub-harmonic Mixer at 340 GHz Using Intrinsic Resonances of Hammer-Head Filter and Improved Diode Model

NASA Astrophysics Data System (ADS)

Wang, Cheng; He, Yue; Lu, Bin; Jiang, Jun; Miao, Li; Deng, Xian-Jin; Xiong, Yong-zhong; Zhang, Jian

2017-11-01

This paper presents a sub-harmonic mixer at 340 GHz based on anti-parallel Schottky diodes (SBDs). Intrinsic resonances in low-pass hammer-head filter have been adopted to enhance the isolation for different harmonic components, while greatly minimizing the transmission loss. The application of new DC grounding structure, impedance matching structure, and suspended micro-strip mitigates the negative influences of fabrication errors from metal cavity, quartz substrate, and micro-assembly. An improved lumped element equivalent circuit model of SBDs guarantees the accuracy of simulation, which takes current-voltage (I/V) behavior, capacitance-voltage (C/V) behavior, carrier velocity saturation, DC series resistor, plasma resonance, skin effect, and four kinds of noise generation mechanisms into consideration thoroughly. The measurement indicates that with local oscillating signal of 2 mW, the lowest double sideband conversion loss is 5.5 dB at 339 GHz; the corresponding DSB noise temperature is 757 K. The 3 dB bandwidth of conversion loss is 50 GHz from 317 to 367 GHz.

Zeeman Effect observations toward 36 GHz methanol masers in the Galactic Center

NASA Astrophysics Data System (ADS)

Potvin, Justin A.; Momjian, Emmanuel; Pratim Sarma, Anuj

2017-01-01

We present observations of 36 GHz Class I methanol masers taken with the Karl G. Jansky Very Large Array (VLA) in the B configuration with the aim of detecting the Zeeman Effect. We targeted several 36 GHz Class I methanol masers associated with supernova remnants (SNRs) toward the Galactic Center. Each source was observed in dual circular polarizations for three hours. The observed spectral profiles of the masers are complex, with several components blended in velocity. In only one case was the Stokes V maser profile prominent enough to reveal a 2-sigma hint of a magnetic field of zBlos = 14.56 +/- 5.60 Hz; we have chosen to express our results in terms of zBlos since the Zeeman splitting factor (z) for 36 GHz methanol masers has not been measured. There are several hints that these spectra would reveal significant magnetic fields if they could be spatially and spectrally resolved.

Optimal GHZ Paradox for Three Qubits

NASA Astrophysics Data System (ADS)

Ren, Changliang; Su, Hong-Yi; Xu, Zhen-Peng; Wu, Chunfeng; Chen, Jing-Ling

2015-08-01

Quatum nonlocality as a valuable resource is of vital importance in quantum information processing. The characterization of the resource has been extensively investigated mainly for pure states, while relatively less is know for mixed states. Here we prove the existence of the optimal GHZ paradox by using a novel and simple method to extract an optimal state that can saturate the tradeoff relation between quantum nonlocality and the state purity. In this paradox, the logical inequality which is formulated by the GHZ-typed event probabilities can be violated maximally by the optimal state for any fixed amount of purity (or mixedness). Moreover, the optimal state can be described as a standard GHZ state suffering flipped color noise. The maximal amount of noise that the optimal state can resist is 50%. We suggest our result to be a step toward deeper understanding of the role played by the AVN proof of quantum nonlocality as a useful physical resource.

Coordinated Observations of Comet Hale-Bopp between 32 and 860 GHz

NASA Astrophysics Data System (ADS)

Wink, J. E.; Altenhoff, W. J.; Bieging, J.; Butler, B.; Butner, H.; Haslam, C. G. T.; Kreysa, E.; Martin, R.; Mauersberger, R.; McMullin, J.; Muders, D.; Peters, W.; Schmidt, J.; Schraml, J. B.; Sievers, A.; Stumpff, P.; von Kapp-Herr, A.; Thum, C.; Zylka, R.

1997-05-01

The concept of simultaneous multifrequency continuum observations, successfully tested on Comet Hyakutake, was applied to Comet Hale-Bopp, using the Heinrich Hertz Submillimeter Telescope (HHT) with the four color bolometer between 250 and 870 GHz, the IRAM 30m telescope at 240 Ghz, the MPIfR 100-m telescope at 32 GHz, and the IRAM interferometer near 90 and 240 GHz. Near-simultaneous measurements were done between February 15 and April 26, 1997, mainly concentrated in mid March shortly before perigee of the comet. The measurements gave the following preliminary results: Interferometer detection of the nuclear thermal emission. If the signal at the longest interferometer spacing of 170 m is due to thermal emission from the nucleus only, its equivalent diameter is ~49 km. If, however, this signal contains a contribution from a strongly centrally peaked halo distribution (e.g., r^-2 density variation) the diameter may be as low as 35 km. The emission found interferometrically was always 5arcsec north and 0.1 sec east from the position predicted by Yeoman's solution 55. The comparison of the interferometric continuum emission with the simultanously obtained molecular line observations (reported on this conference) shows the origin of the strongest line emission concentrated on the nucleus. The 30-m observations show a radio halo with a gaussian FWHP of ~11, corresponding to a diameter of 11000 km at geocentric distance of 1.2 a.u. A spectral index of ~3.0 for the total signal, which may indicate a smaller mean particle size than for Hyakutake. Assuming an average cometary density of 0.5 gcm^-3, the mass contained in the nucleus is ~1-3 10^19 g and 10^12 g in the particle halo.

The 30/20 GHz communications system functional requirements

NASA Technical Reports Server (NTRS)

Siperko, C. M.; Frankfort, M.; Markham, R.; Wall, M.

1981-01-01

The characteristics of 30/20 GHz usage in satellite systems to be used in support of projected communication requirements of the 1990's are defined. A requirements analysis which develops projected market demand for satellite services by general and specialized carriers and an analysis of the impact of propagation and system constraints on 30/20 GHz operation are included. A set of technical performance characteristics for the 30/20 GHz systems which can serve the resulting market demand and the experimental program necessary to verify technical and operational aspects of the proposed systems is also discussed.

A study of 60 GHz intersatellite link applications

NASA Technical Reports Server (NTRS)

Anzic, G.; Connolly, D. J.; Haugland, E. J.; Kosmahl, H. G.; Chitwood, J. S.

1983-01-01

Applications of intersatellite links operating at 60 GHz are reviewed. Likely scenarios, ranging from transmission of moderate and high data rates over long distances to low data rates over short distances are examined. A limited parametric tradeoff is performed with system variables such as radiofrequency power, receiver noise temperature, link distance, data rate, and antenna size. Present status is discussed and projections are given for both electron tube and solid state transmitter technologies. Monolithic transmit and receive module technology, already under development at 20 to 30 GHz, is reviewed and its extension to 60 GHz, and possible applicability is discussed.

A study of 60 GHz intersatellite link applications

NASA Astrophysics Data System (ADS)

Anzic, G.; Connolly, D. J.; Haugland, E. J.; Kosmahl, H. G.; Chitwood, J. S.

Applications of intersatellite links operating at 60 GHz are reviewed. Likely scenarios, ranging from transmission of moderate and high data rates over long distances to low data rates over short distances are examined. A limited parametric tradeoff is performed with system variables such as radiofrequency power, receiver noise temperature, link distance, data rate, and antenna size. Present status is discussed and projections are given for both electron tube and solid state transmitter technologies. Monolithic transmit and receive module technology, already under development at 20 to 30 GHz, is reviewed and its extension to 60 GHz, and possible applicability is discussed.

VizieR Online Data Catalog: The MIT-Green Bank 5GHz Survey (Bennett+, 1986-91)

NASA Astrophysics Data System (ADS)

Bennett, C. L.; Lawrence, C. R.; Burke, B. F.; Hewitt, J. N.; Mahoney, J.

2003-08-01

The MIT-Green Bank 5GHz survey catalog was produced from four separate surveys with the National Radio Astronomy Observatory (NRAO) 91m transit telescope (Bennett et al., 1986ApJS...61....1B (MG1); Langston et al., 1990ApJS...72..621L (MG2); Griffith et al., 1990ApJS...74..129G (MG3); Griffith et al. 1991ApJS...75..801G (MG4)). The sky coverage of the various surveys is: 00h < RAB < 24h, -00d30'13" < DECB < +19d29'47" for MG1; 04h < RAJ < 21h, +17.0d < DECJ < +39d09' for MG2; 16h30m < RAB < 05h, +17d < DECB < +39d09' for MG3; and 15h30m < RAB < 02h30m, +37.00d < DECB < +50d58'48" for MG4; where RAB and DECB refer to B1950 coordinates, and RAJ and DECJ refer to J2000 coordinates. The catalog contains 20344 sources detected with a signal-to-noise ratio greater than 5 and 3836 possible detections (MG1) with a signal-to-noise ratio less than 5. Spectral indices are computed for MG1 sources also identified in the Texas 365MHz survey (Douglas et al. 1980), and for MG1-MG4 sources also identified in the NRAO 1400MHz Survey (Condon and Broderick 1985). (1 data file).

VizieR Online Data Catalog: The MIT-Green Bank 5GHz Survey (Bennett+, 1986-91)

NASA Astrophysics Data System (ADS)

Bennett, C. L.; Lawrence, C. R.; Burke, B. F.; Hewitt, J. N.; Mahoney, J.

1999-04-01

The MIT-Green Bank 5 GHz survey catalog was produced from four separate surveys with the National Radio Astronomy Observatory (NRAO) 91m transit telescope (Bennett et al., 1986ApJS...61....1B (MG1); Langston et al., 1990ApJS...72..621L (MG2); Griffith et al., 1990ApJS...74..129G (MG3); Griffith et al. 1991ApJS...75..801G (MG4)). The sky coverage of the various surveys is: 00h < RAB < 24h, -00d30'13" < DECB < +19d29'47" for MG1; 04h < RAJ < 21h, +17.0d < DECJ < +39d09' for MG2; 16h30m < RAB < 05h, +17d < DECB < +39d09' for MG3; and 15h30m < RAB < 02h30m, +37.00d < DECB < +50d58'48" for MG4; where RAB and DECB refer to B1950 coordinates, and RAJ and DECJ refer to J2000 coordinates. The catalog contains 20344 sources detected with a signal-to-noise ratio greater than 5 and 3836 possible detections (MG1) with a signal-to-noise ratio less than 5. Spectral indices are computed for MG1 sources also identified in the Texas 365 MHz survey (Douglas et al. 1980), and for MG1-MG4 sources also identified in the NRAO 1400 MHz Survey (Condon and Broderick 1985). (1 data file).

Australia 31-GHz brightness temperature exceedance statistics

NASA Technical Reports Server (NTRS)

Gary, B. L.

1988-01-01

Water vapor radiometer measurements were made at DSS 43 during an 18 month period. Brightness temperatures at 31 GHz were subjected to a statistical analysis which included correction for the effects of occasional water on the radiometer radome. An exceedance plot was constructed, and the 1 percent exceedance statistics occurs at 120 K. The 5 percent exceedance statistics occurs at 70 K, compared with 75 K in Spain. These values are valid for all of the three month groupings that were studied.

Reliability of self-aligned, ledge passivated 7.5 GHz GaAs/AlGaAs HBT power amplifiers under RF bias stress at elevated temperatures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Henderson, T.S.; Ikalainen, P.K.

1995-12-31

The authors report a two-temperature RF bias stress test on nominal 1.2 W 7.5 GHz GaAs/AlGaAs HBT unit cell amplifiers. MTTF`s of 2020 and 1340 hours were obtained at Tj = 218{degrees}C and 245{degrees}C, respectively, under nominal input bias. An activation energy of 0.42 eV is estimated, consistent with published results for similar devices under DC bias stress.

The design and performance of a 2.5-GHz telecommand link for wireless biomedical monitoring.

PubMed

Crumley, G C; Evans, N E; Scanlon, W G; Burns, J B; Trouton, T G

2000-12-01

This paper details the implementation and operational performance of a minimum-power 2.45-GHz pulse receiver and a companion on-off keyed transmitter for use in a semi-active, duplex RF biomedical transponder. A 50-ohm microstrip stub-matched zero-bias diode detector forms the heart of a body-worn receiver that has a (CMOS baseband amplifier consuming 20 microA from +3 V and achieves a tangential sensitivity of -53 dBm. The base transmitter generates 0.5 W of peak RF output power into 50 ohms. Both linear and right-hand circularly polarized Tx-Rx antenna sets were employed in system reliability trials carried out in a hospital Coronary Care Unit. For transmitting antenna heights between 0.3 and 2.2 m above floor level, transponder interrogations were 95% reliable within the 67-m2 area of the ward, falling to an average of 46% in the surrounding rooms and corridors. Overall, the circular antenna set gave the higher reliability and lower propagation power decay index.

47 CFR 25.139 - NGSO FSS coordination and information sharing between MVDDS licensees in the 12.2 GHz to 12.7 GHz...

Code of Federal Regulations, 2010 CFR

2010-10-01

....2 GHz to 12.7 GHz band. (a) NGSO FSS licensees shall maintain a subscriber database in a format that... database to enable the MVDDS licensee to determine whether the proposed MVDDS transmitting site meets the...

THE CELESTIAL REFERENCE FRAME AT 24 AND 43 GHz. I. ASTROMETRY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lanyi, G. E.; Jacobs, C. S.; Naudet, C. J.

2010-05-15

We present astrometric results for compact extragalactic objects observed with the Very Long Baseline Array at radio frequencies of 24 and 43 GHz. Data were obtained from ten 24 hr observing sessions made over a five-year period. These observations were motivated by the need to extend the International Celestial Reference Frame (ICRF) to higher radio frequencies to enable improved deep space navigation after 2016 and to improve state-of-the-art astrometry. Source coordinates for 268 sources were estimated at 24 GHz and for 131 sources at 43 GHz. The median formal uncertainties of right ascension and declination at 24 GHz are 0.08more » and 0.15 mas, respectively. Median formal uncertainties at 43 GHz are 0.20 and 0.35 mas, respectively. Weighted root-mean-square differences between the 24 and 43 GHz positions and astrometric positions based on simultaneous 2.3 and 8.4 GHz Very Long Baseline Interferometry observations, such as the ICRF, are less than about 0.3 mas in both coordinates. With observations over five years we have achieved a precision at 24 GHz approaching that of the ICRF but unaccounted systematic errors limit the overall accuracy of the catalogs.« less

Double dipole antenna SIS receivers at 100 and 400 GHz

NASA Technical Reports Server (NTRS)

Skalare, A.; Vandestadt, H.; Degraauw, T.; Panhuyzen, R. A.; Dierichs, M. M. T. M.

1992-01-01

Antenna patterns were measured between 95 and 120 GHz for a double dipole antenna / ellipsoidal lens combination. The structure produces a non-astigmatic beam with low side lobe levels over that whole band. A heterodyne SIS receiver based on this concept gave a best noise temperature of 145 K DSB at 98 GHz. Measurements were also made with a 400 GHz heterodyne SIS receiver, using a double dipole antenna in conjunction with a hyperhemispherical lens. The best noise temperature was 220 K DSB at 402 GHz. On-chip stubs were used to tune out the SIS junction capacitance.

Traveling-Wave Maser for 32 GHz

NASA Technical Reports Server (NTRS)

Shell, James; Clauss, Robert

2009-01-01

The figure depicts a traveling-wave ruby maser that has been designed (though not yet implemented in hardware) to serve as a low-noise amplifier for reception of weak radio signals in the frequency band of 31.8 to 32.3 GHz. The design offers significant improvements over previous designs of 32-GHz traveling-wave masers. In addition, relative to prior designs of 32-GHz amplifiers based on high-electron-mobility transistors, this design affords higher immunity to radio-frequency interference and lower equivalent input noise temperature. In addition to the basic frequency-band and low-noise requirements, the initial design problem included a requirement for capability of operation in a closed-cycle helium refrigerator at a temperature .4 K and a requirement that the design be mechanically simplified, relative to prior designs, in order to minimize the cost of fabrication and assembly. Previous attempts to build 32- GHz traveling-wave masers involved the use of metallic slow-wave structures comprising coupled transverse electromagnetic (TEM)-mode resonators that were subject to very tight tolerances and, hence, were expensive to fabricate and assemble. Impedance matching for coupling signals into and out of these earlier masers was very difficult. A key feature of the design is a slow-wave structure, the metallic portions of which would be mechanically relatively simple in that, unlike in prior slow-wave structures, there would be no internal metal steps, irises, or posts. The metallic portions of the slow-wave structure would consist only of two rectangular metal waveguide arms. The arms would contain sections filled with the active material (ruby) alternating with evanescent-wave sections. This structure would be transparent in both the signal-frequency band (the aforementioned range of 31.8 to 32.3 GHz) and the pump-frequency band (65.75 to 66.75 GHz), and would impose large slowing factors in both frequency bands. Resonant ferrite isolators would be placed in the

ATS-6 ascending: Near horizon measurements over water at 30 GHz

NASA Technical Reports Server (NTRS)

Vogel, W. J.; Straiton, A. W.; Fannin, B. M.

1977-01-01

The return of the ATS 6 satellite to a western longitude during the fall of 1976 presented a unique opportunity to perform low angle of elevation measurements at 30 GHz. For this purpose a receiver using a 1.5 m antenna was set up at Port Aransas, Texas, resulting in a propagation path entirely over water. The 30 GHz beacon was monitored daily for at least one hour from 8 September 1976 to 21 September 1976. During the time the elevation angle changed from 1.5 deg to 17.3 deg, the mean attenuation decreased from 20 dB to 2 dB and the standard deviation from over 6 dB to less than .2 dB. The deep fades at angles below 4 deg show significantly sharper nulls than peaks on a log scale. Spectra of the log amplitude fluctuations vary as the (-8/3) power of the spectral frequency in the limit. A flattening is noticeable at the low frequencies. A precipitation event at 8.5 deg elevation produced a 16 dB fade and significantly increased the variance.

MHD stability analysis and global mode identification preparing for high beta operation in KSTAR

NASA Astrophysics Data System (ADS)

Park, Y. S.; Sabbagh, S. A.; Berkery, J. W.; Jiang, Y.; Ahn, J. H.; Han, H. S.; Bak, J. G.; Park, B. H.; Jeon, Y. M.; Kim, J.; Hahn, S. H.; Lee, J. H.; Ko, J. S.; in, Y. K.; Yoon, S. W.; Oh, Y. K.; Wang, Z.; Glasser, A. H.

2017-10-01

H-mode plasma operation in KSTAR has surpassed the computed n = 1 ideal no-wall stability limit in discharges exceeding several seconds in duration. The achieved high normalized beta plasmas are presently limited by resistive tearing instabilities rather than global kink/ballooning or RWMs. The ideal and resistive stability of these plasmas is examined by using different physics models. The observed m/ n = 2/1 tearing stability is computed by using the M3D-C1 code, and by the resistive DCON code. The global MHD stability modified by kinetic effects is examined using the MISK code. Results from the analysis explain the stabilization of the plasma above the ideal MHD no-wall limit. Equilibrium reconstructions used include the measured kinetic profiles and MSE data. In preparation for plasma operation at higher beta utilizing the planned second NBI system, three sets of 3D magnetic field sensors have been installed and will be used for RWM active feedback control. To accurately determine the dominant n-component produced by low frequency unstable RWMs, an algorithm has been developed that includes magnetic sensor compensation of the prompt applied field and the field from the induced current on the passive conductors. Supported by US DOE Contracts DE-FG02-99ER54524 and DE-SC0016614.

Estimation of reliable range of electron temperature measurements with sets of given optical bandpass filters for KSTAR Thomson scattering system based on synthetic Thomson data

NASA Astrophysics Data System (ADS)

Kim, K.-h.; Oh, T.-s.; Park, K.-r.; Lee, J. H.; Ghim, Y.-c.

2017-11-01

One factor determining the reliability of measurements of electron temperature using a Thomson scattering (TS) system is transmittance of the optical bandpass filters in polychromators. We investigate the system performance as a function of electron temperature to determine reliable range of measurements for a given set of the optical bandpass filters. We show that such a reliability, i.e., both bias and random errors, can be obtained by building a forward model of the KSTAR TS system to generate synthetic TS data with the prescribed electron temperature and density profiles. The prescribed profiles are compared with the estimated ones to quantify both bias and random errors.

VizieR Online Data Catalog: Jet kinematics of blazars at 43GHz with the VLBA (Jorstad+, 2017)

NASA Astrophysics Data System (ADS)

Jorstad, S. G.; Marscher, A. P.; Morozova, D. A.; Troitsky, I. S.; Agudo, I.; Casadio, C.; Foord, A.; Gomez, J. L.; MacDonald, N. R.; Molina, S. N.; Lahteenmaki, A.; Tammi, J.; Tornikoski, M.

2018-04-01

The VLBA-BU-BLAZAR monitoring program consists of approximately monthly observations with the VLBA at 43GHz of a sample of AGNs detected as γ-ray sources. In this paper, we present the results of observations from 2007 June to 2013 January. The sample consists of 21 FSRQs, 12 BLLacs, and 3 radio galaxies (RGs). It includes the blazars and radio galaxies detected at γ-ray energies by EGRET with average flux density at 43GHz exceeding 0.5Jy, declination north of -30°, and optical magnitude in the R band brighter than 18.5. (5 data files).

Radio Sources Toward Galaxy Clusters at 30 GHz

NASA Technical Reports Server (NTRS)

Coble, K.; Bonamente, M.; Carlstrom, J. E.; Dawson, K.; Hasler, N.; Holzapfel, W.; Joy, M.; LaRoque, S.; Marrone, D. P.; Reese, E. D.

2007-01-01

Extra-galactic radio sources are a significant contaminant in cosmic microwave background and Sunyaev-Zeldovich effect experiments. Deep interferometric observations with the BIMA and OVRO arrays are used to characterize the spatial, spectral, and flux distributions of radio sources toward massive galaxy clusters at 28.5 GHz. We compute counts of mJy source fluxes from 89 fields centered on known massive galaxy clusters and 8 non-cluster fields. We find that source counts in the inner regions of the cluster fields (within 0.5 arcmin of the cluster center) are a factor of 8.9 (+4.2 to -3.8) times higher than counts in the outer regions of the cluster fields (radius greater than 0.5 arcmin). Counts in the outer regions of the cluster fields are in turn a factor of 3.3 (+4.1 -1.8) greater than those in the noncluster fields. Counts in the non-cluster fields are consistent with extrapolations from the results of other surveys. We compute spectral indices of mJy sources in cluster fields between 1.4 and 28.5 GHz and find a mean spectral index of al[ja = 0.66 with an rms dispersion of 0.36, where flux S varies as upsilon(sup -alpha). The distribution is skewed, with a median spectral index of 0.72 and 25th and 75th percentiles of 0.51 and 0.92, respectively. This is steeper than the spectral indices of stronger field sources measured by other surveys.

Advances in long pulse operation at high radio frequency power in Tore Supra

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goniche, M.; Dumont, R.; Bourdelle, C.

2014-06-15

The lower hybrid current drive (LHCD) system of Tore Supra has been upgraded for long pulse operation at higher power (7–8 MW). The two launchers have coupled on plasma 3.8 MW and 2.7 MW separately. This new power capability allows extending the operational domain of Tore Supra for long pulses at higher current and density. 38 long (20 s –155 s) discharges with very low loop voltage (V{sub L} = 30-60 mV) were performed with combined LHCD (5-5.7 MW) and ICRH (1–3 MW) powers, with up to 1 GJ of injected energy. Higher LHCD efficiency, with respect to the previous long discharges, is reported. MHD stability of these discharges ismore » very sensitive to the LHCD power and parallel wave index, in particular in the preforming phase. For theses evanescent loop voltage plasmas, the ICRH power, in excess of 1 MW, is found to have a beneficial effect on the MHD stability.« less

A 94/183 GHz aircraft radiometer system for Project Storm Fury

NASA Technical Reports Server (NTRS)

Gagliano, J. A.; Stratigos, J. A.; Forsythe, R. E.; Schuchardt, J. M.; Welch, J. M.; Gallentine, D. O.

1980-01-01

A radiometer design suitable for use in NASA's WB-57F aircraft to collect data from severe storm regions was developed. The design recommended was a 94/183 GHz scanning radiometer with 3 IF channels on either side of the 183.3 GHz water vapor line and a single IF channel for a low loss atmospheric window channel at 94 GHz. The development and construction of the 94/183 GHz scanning radiometer known as the Advanced Microwave Moisture Sounder (AMMS) is presented. The radiometer scans the scene below the aircraft over an angle of + or - 45 degrees with the beamwidth of the scene viewed of approximately 2 degrees at 94 GHz and 1 degree at 183 GHz. The AMMS data collection system consists of a microcomputer used to store the radiometer data on the flight cartridge recorder, operate the stepper motor driven scanner, and collect housekeeping data such as thermistor temperature readings and aircraft time code.

A spectroscopic survey of Orion KL between 41.5 and 50 GHz

NASA Astrophysics Data System (ADS)

Rizzo, J. R.; Tercero, B.; Cernicharo, J.

2017-09-01

Context. The nearby massive star-forming region Orion KL is one of the richest molecular reservoirs known in our Galaxy. The region hosts newly formed protostars, and the strong interaction between their radiation and their outflows with the environment results in a series of complex chemical processes leading to a high diversity of interstellar tracers. The region is therefore one of the most frequently observed sources, and the site where many molecular species have been discovered for the first time. Aims: Current availability of wideband backends permits us to efficiently perform spectral surveys in the entire mm-range. We aim to study the almost unexplored 7 mm window in Orion KL to obtain an unbiased chemical picture of the region. Methods: In this paper we present a sensitive spectral survey of Orion KL, made with one of the 34 m antennas of the Madrid Deep Space Communications Complex in Robledo de Chavela, Spain. The spectral range surveyed is from 41.5 to 50 GHz, with a frequency spacing of 180 kHz (equivalent to ≈1.2 km s-1, depending on the exact frequency). The rms achieved ranges from 8 to 12 mK. Results: The spectrum is dominated by the J = 1 → 0 SiO maser lines and by radio recombination lines (RRLs), which were detected up to Δn = 11. Above a 3σ level, we identified 66 RRLs and 161 molecular lines corresponding to 39 isotopologues from 20 molecules; a total of 18 lines remain unidentified, two of them above a 5σ level. Results of radiative modelling of the detected molecular lines (excluding masers) are presented. Conclusions: At this frequency range, this is the most sensitive survey and also the one with the largest bandwidth. Although some complex molecules like CH3CH2CN and CH2CHCN arise from the hot core, most of the detected molecules originate from the low temperature components in Orion KL. The reduced spectrum is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http

A low power and low phase-noise 91 96 GHz VCO in 90 nm CMOS

NASA Astrophysics Data System (ADS)

Lin, Yo-Sheng; Lan, Kai-Siang; Chuang, Ming-Yuan; Lin, Yu-Ching

2018-06-01

This paper reports a 94 GHz CMOS voltage-controlled oscillator (VCO) using both the negative capacitance (NC) technique and series-peaking output power and phase noise (PN) enhancement technique. NC is achieved by adding two variable LC networks to the source nodes of the active circuit of the VCO. NMOSFET varicaps are adopted as the required capacitors of the LC networks. In comparison with the conventional one, the proposed active circuit substantially decreases the input capacitance (Cin) to zero or even a negative value. This leads to operation (or oscillation) frequency (OF) increase and tuning range (TR) enhancement of the VCO. The VCO dissipates 8.3 mW at 1 V supply. The measured TR of the VCO is 91 96 GHz, close to the simulated (92.1 96.7 GHz) and the calculated one (92.2 98.2 GHz). In addition, at 1 MHz offset from 95.16 GHz, the VCO attains an excellent PN of - 98.3 dBc/Hz. This leads to a figure-of-merit (FOM) of -188.5 dBc/Hz, a remarkable result for a V- or W-band CMOS VCO. The chip size of the VCO is 0.75 × 0.42 mm2, i.e. 0.315 mm2.

Wireless Channel Characterization: Modeling the 5 GHz Microwave Landing System Extension Band for Future Airport Surface Communications

NASA Technical Reports Server (NTRS)

Matolak, D. W.; Apaza, Rafael; Foore, Lawrence R.

2006-01-01

We describe a recently completed wideband wireless channel characterization project for the 5 GHz Microwave Landing System (MLS) extension band, for airport surface areas. This work included mobile measurements at large and small airports, and fixed point-to-point measurements. Mobile measurements were made via transmission from the air traffic control tower (ATCT), or from an airport field site (AFS), to a receiving ground vehicle on the airport surface. The point-to-point measurements were between ATCT and AFSs. Detailed statistical channel models were developed from all these measurements. Measured quantities include propagation path loss and power delay profiles, from which we obtain delay spreads, frequency domain correlation (coherence bandwidths), fading amplitude statistics, and channel parameter correlations. In this paper we review the project motivation, measurement coordination, and illustrate measurement results. Example channel modeling results for several propagation conditions are also provided, highlighting new findings.

47 CFR 25.143 - Licensing provisions for the 1.6/2.4 GHz mobile-satellite service and 2 GHz mobile-satellite...

Code of Federal Regulations, 2012 CFR

2012-10-01

... distress communications. (1) Stations operating in the 1.6/2.4 GHz Mobile-Satellite Service and 2 GHz... 321(b) and 359 of the Communications Act of 1934. Licensees are advised that these provisions give priority to radio communications or signals relating to ships in distress and prohibits a charge for the...

47 CFR 25.143 - Licensing provisions for the 1.6/2.4 GHz mobile-satellite service and 2 GHz mobile-satellite...

Code of Federal Regulations, 2011 CFR

2011-10-01

... distress communications. (1) Stations operating in the 1.6/2.4 GHz Mobile-Satellite Service and 2 GHz... 321(b) and 359 of the Communications Act of 1934. Licensees are advised that these provisions give priority to radio communications or signals relating to ships in distress and prohibits a charge for the...

47 CFR 25.143 - Licensing provisions for the 1.6/2.4 GHz mobile-satellite service and 2 GHz mobile-satellite...

Code of Federal Regulations, 2010 CFR

2010-10-01

... distress communications. (1) Stations operating in the 1.6/2.4 GHz Mobile-Satellite Service and 2 GHz... 321(b) and 359 of the Communications Act of 1934. Licensees are advised that these provisions give priority to radio communications or signals relating to ships in distress and prohibits a charge for the...

3.5 GHz longitudinal leaky surface acoustic wave resonator using a multilayered waveguide structure for high acoustic energy confinement

NASA Astrophysics Data System (ADS)

Kimura, Tetsuya; Kishimoto, Yutaka; Omura, Masashi; Hashimoto, Ken-ya

2018-07-01

In this paper, the use of a structure comprising a thin LiNbO3 plate and a multilayered acoustic mirror composed of SiO2 and Pt for high-performance longitudinal leaky surface acoustic wave (LLSAW) device is proposed. The mirror is expected to offer a much higher reflectivity than that composed of SiO2 and AlN, which the authors proposed previously. The field distribution of these structures is calculated by using a finite element method. It is shown that the acoustic wave energy of the proposed structure is well confined in the vicinity of the top surface, and that leakage to the substrate is reduced. A one-port resonator is fabricated on the structure and its performance characteristics are evaluated. Owing to a high phase velocity of 6,035 m/s, which is about 1.5 times higher than that of conventional SAWs, a large impedance ratio of 71 dB was achieved at 3.5 GHz in addition to a large fractional bandwidth of 9.5%.

47 CFR 15.251 - Operation within the bands 2.9-3.26 GHz, 3.267-3.332 GHz, 3.339-3.3458 GHz, and 3.358-3.6 GHz.

Code of Federal Regulations, 2011 CFR

2011-10-01

..., and 3.358-3.6 GHz. (a) Operation under the provisions of this section is limited to automatic vehicle identification systems (AVIS) which use swept frequency techniques for the purpose of automatically identifying transportation vehicles. (b) The field strength anywhere within the frequency range swept by the signal shall not...

47 CFR 15.251 - Operation within the bands 2.9-3.26 GHz, 3.267-3.332 GHz, 3.339-3.3458 GHz, and 3.358-3.6 GHz.

Code of Federal Regulations, 2012 CFR

2012-10-01

..., and 3.358-3.6 GHz. (a) Operation under the provisions of this section is limited to automatic vehicle identification systems (AVIS) which use swept frequency techniques for the purpose of automatically identifying transportation vehicles. (b) The field strength anywhere within the frequency range swept by the signal shall not...

47 CFR 15.251 - Operation within the bands 2.9-3.26 GHz, 3.267-3.332 GHz, 3.339-3.3458 GHz, and 3.358-3.6 GHz.

Code of Federal Regulations, 2014 CFR

2014-10-01

..., and 3.358-3.6 GHz. (a) Operation under the provisions of this section is limited to automatic vehicle identification systems (AVIS) which use swept frequency techniques for the purpose of automatically identifying transportation vehicles. (b) The field strength anywhere within the frequency range swept by the signal shall not...

47 CFR 15.251 - Operation within the bands 2.9-3.26 GHz, 3.267-3.332 GHz, 3.339-3.3458 GHz, and 3.358-3.6 GHz.

Code of Federal Regulations, 2013 CFR

2013-10-01

..., and 3.358-3.6 GHz. (a) Operation under the provisions of this section is limited to automatic vehicle identification systems (AVIS) which use swept frequency techniques for the purpose of automatically identifying transportation vehicles. (b) The field strength anywhere within the frequency range swept by the signal shall not...

Continuous-wave EPR at 275 GHz: Application to high-spin Fe 3+ systems

NASA Astrophysics Data System (ADS)

Mathies, G.; Blok, H.; Disselhorst, J. A. J. M.; Gast, P.; van der Meer, H.; Miedema, D. M.; Almeida, R. M.; Moura, J. J. G.; Hagen, W. R.; Groenen, E. J. J.

2011-05-01

The 275 GHz electron-paramagnetic-resonance spectrometer we reported on in 2004 has been equipped with a new probe head, which contains a cavity especially designed for operation in continuous-wave mode. The sensitivity and signal stability that is achieved with this new probe head is illustrated with 275 GHz continuous-wave spectra of a 1 mM frozen solution of the complex Fe(III)-ethylenediamine tetra-acetic acid and of 10 mM frozen solutions of the protein rubredoxin, which contains Fe 3+ in its active site, from three different organisms. The high quality of the spectra of the rubredoxins allows the determination of the zero-field-splitting parameters with an accuracy of 0.5 GHz. The success of our approach results partially from the enhanced absolute sensitivity, which can be reached using a single-mode cavity. At least as important is the signal stability that we were able to achieve with the new probe head.

90 GHz Observations of M87 and Hydra A

NASA Technical Reports Server (NTRS)

Cotton, W. D.; Mason, B. S.; Dicker, S. R.; Korngut, P. M.; Devlin, M. J.; Aquirre, J.; Benford, D. J.; Moseley, S. H.; Staguhn, J. G.; Irwin, K. D.;

Low noise 874 GHz receivers for the International Submillimetre Airborne Radiometer (ISMAR)

NASA Astrophysics Data System (ADS)

Hammar, A.; Sobis, P.; Drakinskiy, V.; Emrich, A.; Wadefalk, N.; Schleeh, J.; Stake, J.

2018-05-01

We report on the development of two 874 GHz receiver channels with orthogonal polarizations for the International Submillimetre Airborne Radiometer. A spline horn antenna and dielectric lens, a Schottky diode mixer circuit, and an intermediate frequency (IF) low noise amplifier circuit were integrated in the same metallic split block housing. This resulted in a receiver mean double sideband (DSB) noise temperature of 3300 K (minimum 2770 K, maximum 3400 K), achieved at an operation temperature of 40 °C and across a 10 GHz wide IF band. A minimum DSB noise temperature of 2260 K at 20 °C was measured without the lens. Three different dielectric lens materials were tested and compared with respect to the radiation pattern and noise temperature. All three lenses were compliant in terms of radiation pattern, but one of the materials led to a reduction in noise temperature of approximately 200 K compared to the others. The loss in this lens was estimated to be 0.42 dB. The local oscillator chains have a power consumption of 24 W and consist of custom-designed Schottky diode quadruplers (5% power efficiency in operation, 8%-9% peak), commercial heterostructure barrier varactor (HBV) triplers, and power amplifiers that are pumped by using a common dielectric resonator oscillator at 36.43 GHz. Measurements of the radiation pattern showed a symmetric main beam lobe with full width half maximum <5° and side lobe levels below -20 dB. Return loss of a prototype of the spline horn and lens was measured using a network analyzer and frequency extenders to 750-1100 GHz. Time-domain analysis of the reflection coefficients shows that the reflections are below -25 dB and are dominated by the external waveguide interface.

Monitoring middle-atmospheric water vapor over Seoul by using a 22 GHz ground-based radiometer SWARA

NASA Astrophysics Data System (ADS)

Ka, Soohyun; de Wachter, Evelyn; Kaempfer, Niklaus; Oh, Jung Jin

2010-10-01

Water vapor is the strongest natural greenhouse gas in the atmosphere. It is most abundant in the troposphere at low altitudes, due to evaporation at the ocean surface, with maximum values of around 6 g/kg. The amount of water vapor reaches a minimum at tropopause level and increases again in the middle atmosphere through oxidation of methane and vertical transport. Water vapor has both positive and negative effects on global warming, and we need to study how it works on climate change by monitoring water vapor concentration in the middle atmosphere. In this paper, we focus on the 22 GHz ground-based radiometer called SWARA (Seoul Water vapor Radiometer) which has been operated at Sookmyung women's university in Seoul, Korea since Oct. 2006. It is a joint project of the University of Bern, Switzerland, and the Sookmyung Women's University of Seoul, South Korea. The SWARA receives 22.235 GHz emitted from water vapor spontaneously and converts down to 1.5 GHz with +/- 0.5 GHz band width in 61 kHz resolution. To represent 22.235 GHz water vapor spectrum precisely, we need some calibration methods because the signal shows very weak intensity in ~0.1 K on the ground. For SWARA, we have used the balancing and the tipping curve methods for a calibration. To retrieve the water vapor profile, we have applied ARTS and Qpack software. In this paper, we will present the calibration methods and water vapor variation over Seoul for the last 4 years.

The Advanced ACTPol 27/39 GHz Array

NASA Astrophysics Data System (ADS)

Simon, S. M.; Beall, J. A.; Cothard, N. F.; Duff, S. M.; Gallardo, P. A.; Ho, S. P.; Hubmayr, J.; Koopman, B. J.; McMahon, J. J.; Nati, F.; Niemack, M. D.; Staggs, S. T.; Vavagiakis, E. M.; Wollack, E. J.

2018-05-01

Advanced ACTPol (AdvACT) will observe the temperature and polarization of the cosmic microwave background (CMB) at multiple frequencies and high resolution to place improved constraints on inflation, dark matter, and dark energy. Foregrounds from synchrotron and dust radiation are a source of contamination that must be characterized and removed across a wide range of frequencies. AdvACT will thus observe at five frequency bands from 27 to 230 GHz. We discuss the design of the pixels and feedhorns for the 27/39 GHz multichroic array for AdvACT, which will target the synchrotron radiation that dominates at these frequencies. To gain 35% in mapping speed in the 39 GHz band where the foreground signals are faintest, the pixel number was increased through reducing the pixel diameter to 1.08λ at the lowest frequency, which represents a 22% decrease in size compared to our previously most tightly packed pixels.

Microwave Dielectric Properties of Alfalfa Leaves From 0.3 to 18 GHz

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sokhansanj, Shahabaddine; Shrestha, Bijay; Wood, H.C.

2011-01-01

Dielectric properties (i.e., permittivity) are essential in designing, simulating, and modeling microwave applications. The permittivity of stacked leaves of alfalfa (Medicago sativa) were measured with a network analyzer and a coaxial probe, and the effect of moisture content (MC: 12% 73% wet basis), frequency (300 MHz to 18 GHz), bound water (Cole Cole dispersion equation), temperature ( 15 C and 30 C), leaf-orientation, and pressure (0 11 kPa) were investigated. The measured permittivity increased with MC. A critical moisture level (CML) of 23% was reported, below which the permittivity decreased with increasing frequency at 22 C. Above CML and upmore » to 5 GHz, the dielectric constants followed the Cole Cole dispersion, and the dielectric loss factors consisted of ionic and bound water losses. Above 5 GHz, the behavior of the dielectric constant was similar to that of free water, and the polar losses became dominant. Above 0 C, the measured permittivity followed a trend similar to that of free saline water and was characterized by the Debye equation. Below 0 C, it was dominated by nonfreezing bound and unfrozen supercooled moistures. The relaxation parameters and the optimum pressure (9 kPa) for the leaf measurements were determined. The effects of variations among the samples, and their orientations had negligible effects on the measured permittivity.« less

Sub-100 μm scale on-chip inductors with CoZrTa for GHz applications

NASA Astrophysics Data System (ADS)

Xu, Wei; Wu, Hao; Gardner, Donald S.; Sinha, Saurabh; Dastagir, Tawab; Bakkaloglu, Bertan; Cao, Yu; Yu, Hongbin

2011-04-01

On-chip inductors with magnetic material are fabricated with complementary metal-oxide semiconductor processes. The inductors use copper metallization and amorphous CoZrTa thinfilms. Enhancements of 3.5X in inductance and 3X for the quality factor at frequencies as highas 3 GHz have been successfully demonstrated by using a continuous CoZrTa-ring structure in spiral inductors at the 100 μm scale. Further improvement of the frequency response of inductance up to 6 GHz was achieved by micro-patterning the magnetic film. The effect ofincreasing the film thickness on the performance of strip line inductors was measured and modeled. This work demonstrates significantly larger increases in inductance and quality factor atabove 1 GHz as compared to prior efforts, thereby making the added processing cost worthwhile.

Calibration of a 35-GHz Airborne Cloud Radar: Lessons Learned and Intercomparison with a 94-GHz Airborne Cloud Radar

NASA Astrophysics Data System (ADS)

Ewald, Florian; Gross, Silke; Hagen, Martin; Hirsch, Lutz; Delanoë, Julien

2017-04-01

Clouds play an important role in the climate system since they have a profound influence on Earth's radiation budget and the water cycle. Uncertainties associated with their spatial characteristics as well as their microphysics still introduce large uncertainties in climate change predictions. In recent years, our understanding of the inner workings of clouds has been greatly advanced by the deployment of cloud profiling microwave radars from ground as well as from space like CloudSat or the upcoming EarthCARE satellite mission. In order to validate and assess the limitations of these spaceborne missions, a well-calibrated, airborne cloud radar with known sensitivity to clouds is indispensable. Within this context, the German research aircraft HALO was equipped with the high-power (30kW peak power) cloud radar operating at 35 GHz and a high spectral resolution lidar (HSRL) system at 532 nm. During a number of flight experiments over Europe and over the tropical and extra-tropical North-Atlantic, several radar calibration efforts have been made using the ocean surface backscatter. Moreover, CloudSat underflights have been conducted to compare the radar reflectivity and measurement sensitivity between the air- and spaceborne instruments. Additionally, the influence of different radar wavelengths was explored with joint flights of HALO and the French Falcon 20 aircraft, which was equipped with the RASTA cloud radar at 94 GHz and a HSRL at 355 nm. In this presentation, we will give an overview of lessons learned from different calibration strategies using the ocean surface backscatter. Additional measurements of signal linearity and signal saturation will complement this characterization. Furthermore, we will focus on the coordinated airborne measurements regarding the different sensitivity for clouds at 35 GHz and 94 GHz. By using the highly sensitive lidar signals, we show if the high-power cloud radar at 35 GHz can be used to validate spaceborne and airborne

A 205GHz Amplifier in 90nm CMOS Technology

DTIC Science & Technology

2017-03-01

San Jose State University San Jose, CA, USA       Abstract: This paper presents a 205GHz amplifier drawing 43.4mA from a 0.9V power supply with...10.5dB power gain, Psat of -1.6dBm, and P1dB ≈ -5.8dBm in a standard 90nm CMOS process. Moreover, the design employs internal (layout-based) /external...reported in [2]. In this paper, two neutralization techniques, internal and external approaches, have been implemented to achieve higher power

Coordinated Observations of Comet Hale-Bopp between 32 and 860 GHz

NASA Astrophysics Data System (ADS)

Bieging, J. H.; Mauersberger, R.; Altenhoff, W. J.; Haslam, C. G. T.; Kreysa, E.; Schmidt, J.; Schraml, J. B.; Stumpff, P.; von Kap-Herr, A.; Butler, B.; McMullin, J.; Butner, H. M.; Martin, R. N.; Muders, D.; Peters, W. L.; Sievers, A.; Thum, C.; Wink, J.; Zylka, R.

1997-12-01

The concept of simultaneous multifrequency continuum observations, successfully tested on Comet Hyakutake, was applied to Comet Hale-Bopp, using the Heinrich Hertz Submillimeter Telescope (HHT) with the four color bolometer between 250 and 870 GHz; the IRAM 30m telescope at 250 GHz; the IRAM Plateau de Bure Interferometer near 90 and 240 GHz; and the MPIfR 100m telescope at 32 GHz. Near-simultaneous measurements were done between 1997 February 15 and 1997 April 26, mainly concentrated in mid-March shortly before perigee of the comet. The measurements gave the following preliminary results: (a) interferometer detection of the nuclear continuum emission. The derived mean diameter is of the order of 50 km. (b) a radio halo with a gaussian HPW of ~ 11 arcsec , corresponding to a diameter of 11000 km at geocentric distance of 1.2 A.U. (c) a spectral index (SI) of ~ 3.0 of the total signal, indicating a particle size distribution in the radio halo between 0.1 and 3 mm. Assuming an average cometary density of 0.5 g cm(-3) , the mass contained in the nucleus is about 3x 10(19) g and 10(12) g in the particle halo, inferred from the SI. A more detailed analysis is under way, which includes corrections for the various calibration scales at the different telescopes and the possible contamination of the observed bolometer signal by molecular line emission. We will report on the results of this analysis and the implications for the mm -- submm wavelength radio spectrum of Comet Hale-Bopp.

Ka-band (32 GHz) allocations for deep space

NASA Technical Reports Server (NTRS)

Degroot, N. F.

1987-01-01

At the 1979 World Administrative Conference, two new bands were allocated for deep space telecommunications: 31.8 to 32.3 GHz, space-to-Earth, and 34.2 to 34.7 GHz, Earth-to-space. These bands provide opportunity for further development of the Deep Space Network and its support of deep space research. The history of the process by which JPL/NASA developed the rationale, technical background, and statement of requirement for the bands are discussed. Based on this work, United States proposals to the conference included the bands, and subsequent U.S. and NASA participation in the conference led to successful allocations for deep space telecommunications in the 30 GHz region of the spectrum. A detailed description of the allocations is included.

146-GHz millimeter-wave radio-over-fiber photonic wireless transmission system.

PubMed

Fice, M J; Rouvalis, E; van Dijk, F; Accard, A; Lelarge, F; Renaud, C C; Carpintero, G; Seeds, A J

2012-01-16

We report the experimental implementation of a wireless transmission system with a 146-GHz carrier frequency which is generated by optical heterodyning the two modes from a monolithically integrated quantum dash dual-DFB source. The monolithic structure of the device and the inherent low noise characteristics of quantum dash gain material allow us to demonstrate the transmission of a 1 Gbps ON-OFF keyed data signal with the two wavelengths in a free-running state at 146-GHz carrier wave frequency. The tuning range of the device fully covers the W-band (75 - 110 GHz) and the F-band (90 - 140 GHz).

Design of a 40-nm CMOS integrated on-chip oscilloscope for 5-50 GHz spin wave characterization

NASA Astrophysics Data System (ADS)

Egel, Eugen; Csaba, György; Dietz, Andreas; Breitkreutz-von Gamm, Stephan; Russer, Johannes; Russer, Peter; Kreupl, Franz; Becherer, Markus

2018-05-01

Spin wave (SW) devices are receiving growing attention in research as a strong candidate for low power applications in the beyond-CMOS era. All SW applications would require an efficient, low power, on-chip read-out circuitry. Thus, we provide a concept for an on-chip oscilloscope (OCO) allowing parallel detection of the SWs at different frequencies. The readout system is designed in 40-nm CMOS technology and is capable of SW device characterization. First, the SWs are picked up by near field loop antennas, placed below yttrium iron garnet (YIG) film, and amplified by a low noise amplifier (LNA). Second, a mixer down-converts the radio frequency (RF) signal of 5 - 50 GHz to lower intermediate frequencies (IF) around 10 - 50 MHz. Finally, the IF signal can be digitized and analyzed regarding the frequency, amplitude and phase variation of the SWs. The power consumption and chip area of the whole OCO are estimated to 166.4 mW and 1.31 mm2, respectively.

Demonstration of a 140-GHz 1-kW Confocal Gyro-Traveling-Wave Amplifier

PubMed Central

Joye, Colin D.; Shapiro, Michael A.; Sirigiri, Jagadishwar R.; Temkin, Richard J.

2009-01-01

The theory, design, and experimental results of a wideband 140-GHz 1-kW pulsed gyro-traveling-wave amplifier (gyro-TWA) are presented. The gyro-TWA operates in the HE06 mode of an overmoded quasi-optical waveguide using a gyrating electron beam. The electromagnetic theory, interaction theory, design processes, and experimental procedures are described in detail. At 37.7 kV and a 2.7-A beam current, the experiment has produced over 820 W of peak power with a –3-dB bandwidth of 0.8 GHz and a linear gain of 34 dB at 34.7 kV. In addition, the amplifier produced a –3-dB bandwidth of over 1.5 GHz (1.1%) with a peak power of 570 W from a 38.5-kV 2.5-A electron beam. The electron beam is estimated to have a pitch factor of 0.55–0.6, a radius of 1.9 mm, and a calculated perpendicular momentum spread of approximately 9%. The gyro-amplifier was nominally operated at a pulselength of 2 μs but was tested to amplify pulses as short as 4 ns with no noticeable pulse broadening. Internal reflections in the amplifier were identified using these short pulses by time-domain reflectometry. The demonstrated performance of this amplifier shows that it can be applied to dynamic nuclear polarization and electron paramagnetic resonance spectroscopy. PMID:20054451

47 CFR 15.251 - Operation within the bands 2.9-3.26 GHz, 3.267-3.332 GHz, 3.339-3.3458 GHz, and 3.358-3.6 GHz.

Code of Federal Regulations, 2010 CFR

2010-10-01

... exceed 3000 microvolts/meter/MHz at 3 meters in any direction. Further, an AVIS, when in its operating position, shall not produce a field strength greater than 400 microvolts/meter/MHz at 3 meters in any... maximum of 100 microvolts/meter/MHz at 3 meters, measured from 30 MHz to 20 GHz for the complete system...

Planning assistance for the 30/20 GHz program, volume 2

NASA Technical Reports Server (NTRS)

Al-Kinani, G.; Frankfort, M.; Kaushal, D.; Markham, R.; Siperko, C.; Wall, M.

1981-01-01

In the baseline concept development the communications payload on Flight 1 was specified to consist of on-board trunking and emergency communications systems (ECS). On Flight 2 the communications payloads consisted of trunking and CPS on-board systems, the CPS capability replacing the Flight 1 ECS. No restriction was placed on the launch vehicle size. Constraints placed on multiple concept development effort were that launch vehicle size for Concept 1 was restricted to SUSS-D and for Concept 2 a SUSS-A. The design concept development was based on satisfying the baseline requirements set forth in the SOW for a single demonstration flight system. Key constraints on contractors were cost and launch vehicle size. Five major areas of new technology development were reviewed: (1) 30 GHz low noise receivers; (2) 20 GHz Power Amplifiers; (3) SS-TDMA switch; (4) Baseband Processor; (5) Multibeam Antennas.

A low noise 230 GHz heterodyne receiver employing .25 sq micron area Nb/AlO(x)/Nb tunnel junctions

NASA Technical Reports Server (NTRS)

Kooi, Jacob W.; Chan, M.; Phillips, T. G.; Bumble, B.; Leduc, H. G.

1992-01-01

Recent results for a full height rectangular waveguide mixer with an integrated IF matching network are reported. Two 0.25 sq micron Nb/AlO(x)/Nb superconducting insulating superconducting (SIS) tunnel junctions with a current density of about 8500 A/sq cm and omega RC of about 2.5 at 230 GHz have been tested. Detailed measurements of the receiver noise have been made from 200-290 GHz for both junctions at 4.2 K. The lowest receiver noise temperatures were recorded at 239 GHz, measuring 48 K DSB at 4.2 K and 40 K DSB at 2.1 K. The 230 GHz receiver incorporates a one octave wide integrated low pass filter and matching network which transforms the pumped IF junction impedance to 50 ohms over a wide range of impedances.

A Study of Dielectric Properties of Proteinuria between 0.2 GHz and 50 GHz

PubMed Central

Mun, Peck Shen; Ting, Hua Nong; Ong, Teng Aik; Wong, Chew Ming; Ng, Kwan Hong; Chong, Yip Boon

2015-01-01

This paper investigates the dielectric properties of urine in normal subjects and subjects with chronic kidney disease (CKD) at microwave frequency of between 0.2 GHz and 50 GHz. The measurements were conducted using an open-ended coaxial probe at room temperature (25°C), at 30°C and at human body temperature (37°C). There were statistically significant differences in the dielectric properties of the CKD subjects compared to those of the normal subjects. Statistically significant differences in dielectric properties were observed across the temperatures for normal subjects and CKD subjects. Pearson correlation test showed the significant correlation between proteinuria and dielectric properties. The experimental data closely matched the single-pole Debye model. The relaxation dispersion and relaxation time increased with the proteinuria level, while decreasing with the temperature. As for static conductivity, it increased with proteinuria level and temperature. PMID:26066351

CAD of 0.1- to 10-GHz GaAs MMIC SPST switch

NASA Astrophysics Data System (ADS)

Yadav, Ramchandra; Kirty, V. S. R.

1998-04-01

The design of the SPST switch provides an insertion loss less than 2 dB, isolation more than 40 dB and return loss better than 17.5 dB in the frequency range of 0.1 GHz to 10 GHz. The insertion loss is improved by treating SPST switch as a 50 (Omega) artificial transmission line with incorporation of inductor in series arm and the capacitance of MESFET in the shunt arm. High isolation is ensured by the lower value of `ON' resistance of MESFET in shunt arm. Also good return loss is achieved by paralleling a 50 (Omega) resistor with capacitance of MESFET in series arm. The absence of DC blocking capacitors and replacement of large value bias chokes with 5 K(Omega) resistors effectively improved the performance of SPST switch at low frequency and also reduced the chip size. The overall chip dimension is 2.2 mm X 1.7 mm.

Polarisation observations of VY Canis Majoris H2O 532-441 620.701 GHz maser emission with HIFI

NASA Astrophysics Data System (ADS)

Harwit, M.; Houde, M.; Sonnentrucker, P.; Boogert, A. C. A.; Cernicharo, J.; De Beck, E.; Decin, L.; Henkel, C.; Higgins, R. D.; Jellema, W.; Kraus, A.; McCoey, C.; Melnick, G. J.; Menten, K. M.; Risacher, C.; Teyssier, D.; Vaillancourt, J. E.; Alcolea, J.; Bujarrabal, V.; Dominik, C.; Justtanont, K.; de Koter, A.; Marston, A. P.; Olofsson, H.; Planesas, P.; Schmidt, M.; Schöier, F. L.; Szczerba, R.; Waters, L. B. F. M.

2010-10-01

Context. Water vapour maser emission from evolved oxygen-rich stars remains poorly understood. Additional observations, including polarisation studies and simultaneous observation of different maser transitions may ultimately lead to greater insight. Aims: We have aimed to elucidate the nature and structure of the VY CMa water vapour masers in part by observationally testing a theoretical prediction of the relative strengths of the 620.701 GHz and the 22.235 GHz maser components of ortho H2O. Methods: In its high-resolution mode (HRS) the Herschel Heterodyne Instrument for the Far Infrared (HIFI) offers a frequency resolution of 0.125 MHz, corresponding to a line-of-sight velocity of 0.06 km s-1, which we employed to obtain the strength and linear polarisation of maser spikes in the spectrum of VY CMa at 620.701 GHz. Simultaneous ground based observations of the 22.235 GHz maser with the Max-Planck-Institut für Radioastronomie 100-m telescope at Effelsberg, provided a ratio of 620.701 GHz to 22.235 GHz emission. Results: We report the first astronomical detection to date of H2O maser emission at 620.701 GHz. In VY CMa both the 620.701 and the 22.235 GHz polarisation are weak. At 620.701 GHz the maser peaks are superposed on what appears to be a broad emission component, jointly ejected from the star. We observed the 620.701 GHz emission at two epochs 21 days apart, both to measure the potential direction of linearly polarised maser components and to obtain a measure of the longevity of these components. Although we do not detect significant polarisation levels in the core of the line, they rise up to approximately 6% in its wings. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Appendix (page 5) is only available in electronic form at http://www.aanda.org

Lower hybrid current drive in experiments for transport barriers at high βN of JET (Joint European Torus)

NASA Astrophysics Data System (ADS)

Cesario, R. C.; Castaldo, C.; Fonseca, A.; De Angelis, R.; Parail, V.; Smeulders, P.; Beurskens, M.; Brix, M.; Calabrò, G.; De Vries, P.; Mailloux, J.; Pericoli, V.; Ravera, G.; Zagorski, R.

2007-09-01

LHCD has been used in JET experiments aimed at producing internal transport barriers (ITBs) in highly triangular plasmas (δ≈0.4) at high βN (up to 3) for steady-state application. The LHCD is a potentially valuable tool for (i) modifying the target q-profile, which can help avoid deleterious MHD modes and favour the formation of ITBs, and (ii) contributing to the non-inductive current drive required to prolong such plasma regimes. The q-profile evolution has been simulated during the current ramp-up phase for such a discharge (B0 = 2.3 T, IP = 1.5 MA) where 2 MW of LHCD has been coupled. The JETTO code was used taking measured plasma profiles, and the LHCD profile modeled by the LHstar code. The results are in agreement with MSE measurements and indicate the importance of the elevated electron temperature due to LHCD, as well as the driven current. During main heating with 18 MW of NBI and 3 MW of ICRH the bootstrap current density at the edge also becomes large, consistently with the observed reduction of the local turbulence and of the MHD activity. JETTO modelling suggests that the bootstrap current can reduce the magnetic shear (sh) at large radius, potentially affecting the MHD stability and turbulence behaviour in this region. Keywords: lower hybrid current drive (LHCD), bootstrap current, q (safety factor) and shear (sh) profile evolutions.

Statistical results from the Virginia Tech propagation experiment using the Olympus 12, 20, and 30 GHz satellite beacons

NASA Technical Reports Server (NTRS)

Stutzman, Warren L.; Safaai-Jazi, A.; Pratt, Timothy; Nelson, B.; Laster, J.; Ajaz, H.

1993-01-01

Virginia Tech has performed a comprehensive propagation experiment using the Olympus satellite beacons at 12.5, 19.77, and 29.66 GHz (which we refer to as 12, 20, and 30 GHz). Four receive terminals were designed and constructed, one terminal at each frequency plus a portable one with 20 and 30 GHz receivers for microscale and scintillation studies. Total power radiometers were included in each terminal in order to set the clear air reference level for each beacon and also to predict path attenuation. More details on the equipment and the experiment design are found elsewhere. Statistical results for one year of data collection were analyzed. In addition, the following studies were performed: a microdiversity experiment in which two closely spaced 20 GHz receivers were used; a comparison of total power and Dicke switched radiometer measurements, frequency scaling of scintillations, and adaptive power control algorithm development. Statistical results are reported.

A 77-118 GHz RESONANCE-FREE SEPTUM POLARIZER

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Yen-Lin; Chiueh, Tzihong; Teng, Hsiao-Feng, E-mail: chiuehth@phys.ntu.edu.tw

2014-03-01

Measurements of polarized radiation often reveal specific physical properties of emission sources, such as the strengths and orientations of magnetic fields offered by synchrotron radiation and Zeeman line emission, and the electron density distribution caused by free-free emission. Polarization-capable, millimeter/sub-millimeter telescopes are normally equipped with either septum polarizers or ortho-mode transducers (OMT) to detect polarized radiation. Though the septum polarizer is limited to a significantly narrower bandwidth than the OMT, it possesses advantageous features unparalleled by the OMT when it comes to determining astronomical polarization measurements. We design an extremely wide-band circular waveguide septum polarizer, covering 42% bandwidth, from 77more » GHz to 118 GHz, without any undesired resonance, challenging the conventional bandwidth limit. Stokes parameters, constructed from the measured data between 77 GHz and 115 GHz, show that the leakage from I to Q and U is below ±2%, and the Q – U mutual leakage is below ±1%. Such a performance is comparable to other modern polarizers, but the bandwidth of this polarizer can be at least twice as wide. This extremely wide-band design removes the major weakness of the septum polarizer and opens up a new window for future astronomical polarization measurements.« less

A 32-GHz reflected-wave maser amplifier with wide instantaneous bandwidth

NASA Technical Reports Server (NTRS)

Shell, J.; Neff, D.

1988-01-01

An eight stage, 32 GHz reflected wave ruby maser was built. The maser operates in a 3 watt closed cycle refrigerator at 4.5 K and is capable of 21 dB of net gain with an instantaneous bandwidth of 400 MHz. The input noise temperature referred to the room temperature flange is approximately 21 K.

A 20-GHz IMPATT transmitter

NASA Technical Reports Server (NTRS)

Chan, J. L.; Sun, C.

1983-01-01

The engineering development of a solid state transmitter amplifier operating in the 20 GHz frequency band. The development effort involved a variety of disciplines including IMPATT device development, circulator design, simple and multiple diode circuits designs, and amplifier integration and test.

Low-cost 20-22 GHz MIC active receiver/radiometer

NASA Technical Reports Server (NTRS)

Mollenkopf, Steven; Katehi, Linda P. B.; Rebeiz, Gabriel M.

1995-01-01

A microwave integrated circuit active receiver is built and tested at 19-25 GHz. The receiver consists of a planar CPW-fed double folded-slot antenna coupled to a six-stage MESFET (metal semiconductor field effect transistors) amplifier and followed by a planar Schottky-diode detector. The folded-slot antenna on a GaAs half-space results in a wide frequency bandwidth suitable for MMIC amplifiers. The measured system performance show a video responsivity close to 1 GV/W at 20 GHz with a 3-dB bandwidth of 1500 MHz. A novel method which uses the planar video detector after the amplifier stages as an RF (radio frequency) mixer is used to measure the noise-figure of the direct detection radiometer. The system noise figure is 4.8 dB at 22 GHz. The radiometer sensitivity to a hot/cold load is 3.8 mu V/K. The measured antenna patterns show a 90% Gaussicity at 20-22 GHz. The active MIC receiver can be integrated monolithically for low-cost applications and is well suited for millimeter-wave linear imaging arrays.

Mermin inequalities for GHZ contradictions in many-qutrit systems

NASA Astrophysics Data System (ADS)

Lawrence, Walter

In view of recent experimental interest in multi-qutrit entanglement properties, we provide here new Mermin inequalities for use in experimental tests of many-qutrit GHZ contradictions, first predicted only recently (2013). Mermin inequalities refer here to Bell-like inequalities in which the quantum predictions are not probabilistic, thus elevating hidden variables to the status of EPR elements of reality. Earlier Bell inequalities for qutrits predate the discovery of GHZ contradictions, are based on non-concurrent observable sets, and hence cannot establish GHZ contradictions. The current Mermin inequalities are derived from those concurrent observable sets which produce GHZ contradictions, with the following results: (i) There is an operator M defined for every N >= 4 , built on two measurement bases, whose quantum eigenvalue grows as 2N, maximum classical value more slowly (1 .879N), with quantum to classical ratio being never less than 1.39, and (ii) For N = 3 , there is an M3, built on three local measurement bases, whose quantum to classical ratio is 3/2.

A quasioptical resonant-tunneling-diode oscillator operating above 200 GHz

NASA Technical Reports Server (NTRS)

Brown, E. R.; Parker, C. D.; Molvar, K. M.; Calawa, A. R.; Manfra, M. J.

1992-01-01

We have fabricated and characterized a quasioptically stabilized resonant-tunneling-diode (RTD) oscillator having attractive performance characteristics for application as a radiometric local oscillator. The fundamental frequency of the oscillator is tunable from about 200 to 215 GHz, the instantaneous linewidth is between 10 and 20 kHz, and the output power across the tuning band is about 50 micro-W. The narrow linewidth and fine tuning of the frequency are made possible by a scanning semiconfocal open cavity which acts as the high-Q resonator for the oscillator. The cavity is compact, portable, and insensitive to vibration and temperature variation. The total dc power consumption (RTD plus bias supply) is only 10 mW. The present oscillator provides the highest power obtained to date from an RTD above 200 GHz. We attribute this partly to the use of the quasioptical resonator, but primarily to the quality of the RTD. It is fabricated from the In(0.53)Ga(0.47)As/AlAs materials system, which historically has yielded the best overall resonant-tunneling characteristics of any material system. The RTD active area is 4 sq microns, and the room-temperature peak current density and peak-to-valley current ratio are 2.5x10(exp 5) A cm(exp -2) and 9, respectively. The RTD is mounted in a WR-3 standard-height rectangular waveguide and is contacted across the waveguide by a fine wire that protrudes through a via hole in a Si3N4 'honeycomb' overlayer. We estimate that the theoretical maximum frequency of oscillation of this RTD is approximately 1.1 THz, and that scaled-down versions of the same quasioptical oscillator design should operate in a fundamental mode up to frequencies of at least 500 GHz.

THz photonic wireless links with 16-QAM modulation in the 375-450 GHz band.

PubMed

Jia, Shi; Yu, Xianbin; Hu, Hao; Yu, Jinlong; Guan, Pengyu; Da Ros, Francesco; Galili, Michael; Morioka, Toshio; Oxenløwe, Leif K

2016-10-17

We propose and experimentally demonstrate THz photonic wireless communication systems with 16-QAM modulation in the 375-450 GHz band. The overall throughput reaches as high as 80 Gbit/s by exploiting four THz channels with 5 Gbaud 16-QAM baseband modulation per channel. We create a coherent optical frequency comb (OFC) for photonic generation of multiple THz carriers based on photo-mixing in a uni-travelling carrier photodiode (UTC-PD). The OFC configuration also allows us to generate reconfigurable THz carriers with low phase noise. The multiple-channel THz radiation is received by using a Schottky mixer based electrical receiver after 0.5 m free-space wireless propagation. 2-channel (40 Gbit/s) and 4-channel (80 Gbit/s) THz photonic wireless links with 16-QAM modulation are reported in this paper, and the bit error rate (BER) performance for all channels in both cases is below the hard decision forward error correction (HD-FEC) threshold of 3.8e-3 with 7% overhead. In addition, we also successfully demonstrate hybrid photonic wireless transmission of 40 Gbit/s 16-QAM signal at carrier frequencies of 400 GHz and 425 GHz over 30 km standard single mode fiber (SSMF) between the optical baseband signal transmitter and the THz wireless transmitter with negligible induced power penalty.

1.5-V-threshold-voltage Schottky barrier normally-off AlGaN/GaN high-electron-mobility transistors with f T/f max of 41/125 GHz

NASA Astrophysics Data System (ADS)

Hou, Bin; Ma, Xiaohua; Yang, Ling; Zhu, Jiejie; Zhu, Qing; Chen, Lixiang; Mi, Minhan; Zhang, Hengshuang; Zhang, Meng; Zhang, Peng; Zhou, Xiaowei; Hao, Yue

2017-07-01

In this paper, a normally-off AlGaN/GaN high-electron-mobility transistors (HEMT) fabricated using inductively coupled plasma (ICP) CF4 plasma recessing and an implantation technique is reported. A gate-to-channel distance of ˜10 nm and an equivalent negative fluorine sheet charge density of -1.21 × 1013 cm-2 extracted using a simple threshold voltage (V th) analytical model result in a high V th of 1.5 V, a peak transconductance of 356 mS/mm, and a subthreshold slope of 133 mV/decade. A small degradation of channel mobility leads to a high RF performance with f T/f max of 41/125 GHz, resulting in a record high f T × L g product of 10.66 GHz·µm among Schottky barrier AlGaN/GaN normally-off HEMTs with V th exceeding 1 V, to the best of our knowledge.

4 Kelvin Cryogenic Characterization of Commercial pHEMT Transistors at 9 kHz to 8.5 GHz Range

NASA Astrophysics Data System (ADS)

Ibarra-Medel, E.; Velázquez, M.; Ventura, S.; Ferrusca, D.; Gómez-Rivera, V.

2016-07-01

Nowadays, the technology innovations in large format array detectors at low temperature for millimetric observational astronomy demand the development of electronics capable to keep their functionality at cryogenic temperatures. In kinetic inductance detectors, the first stage of electronics readout requires high-bandwidth low-noise amplifiers (LNAs). These devices are commonly fabricated in monolithic microwave integrated circuit (MMIC) processes which commercially achieve a noise temperature level of 5 K. An alternative approach to the MMIC are the hybrid microwave circuit which mixes RF lumped elements and discrete electronic components. This paper describes the characterization of six commercial pHEMT transistors tested at cryogenic temperatures. DC properties such as I-V curves and transconductance (g_m) were measured for each transistor; these measurements allow us to calculate the best bias point versus gain, with the lowest noise figure and power consumption within the range of 9 kHz to 8.5 GHz at the operating temperature of 4 K. Experimental results suggest that the characterized pHEMTs have a noise figure that allow them to be used in hybrid LNAs arranges with a comparable MMIC performance.

42GHz ECRH assisted Plasma Breakdown in tokamak SST-1

NASA Astrophysics Data System (ADS)

Shukla, B. K.; Pradhan, S.; Patel, Paresh; Babu, Rajan; Patel, Jatin; Patel, Harshida; Dhorajia, Pragnesh; Tanna, V.; Atrey, P. K.; Manchanda, R.; Gupta, Manoj; Joisa, Shankar; Gupta, C. N.; Danial, Raju; Singh, Prashant; Jha, R.; Bora, D.

2015-03-01

In SST-1, 42GHz ECRH system has been commissioned to carry out breakdown and heating experiments at 0.75T and 1.5T operating toroidal magnetic fields. The 42GHz ECRH system consists of high power microwave source Gyrotron capable to deliver 500kW microwave power for 500ms duration, approximately 20 meter long transmission line and a mirror based launcher. The ECRH power in fundamental O-mode & second harmonic X-mode is launched from low field side (radial port) of the tokamak. At 0.75T operation, approximately 300 kW ECH power is launched in second harmonic X-mode and successful ECRH assisted breakdown is achieved at low loop_voltage ~ 3V. The ECRH power is launched around 45ms prior to loop voltage. The hydrogen pressure in tokamak is maintained ~ 1×10-5mbar and the pre-ionized density is ~ 4×1012/cc. At 1.5T operating toroidal magnetic field, the ECH power is launched in fundamental O-mode. The ECH power at fundamental harmonic is varied from 100 kW to 250 kW and successful breakdown is achieved in all ECRH shots. In fundamental harmonic there is no delay in breakdown while at second harmonic ~ 40ms delay is observed, which is normal in case of second harmonic ECRH assisted breakdown.

A 75 GHz regenerative dynamic frequency divider with active transformer using InGaAs/InP HBT technology

NASA Astrophysics Data System (ADS)

Wang, Xi; Zhang, Bichan; Zhao, Hua; Su, Yongbo; Muhammad, Asif; Guo, Dong; Jin, Zhi

2017-08-01

This letter presents a high speed 2:1 regenerative dynamic frequency divider with an active transformer fabricated in 0.7 μm InP DHBT technology with {f}{{T}} of 165 GHz and {f}\\max of 230 GHz. The circuit includes a two-stage active transformer, input buffer, divider core and output buffer. The core part of the frequency divider is composed of a double-balanced active mixer (widely known as the Gilbert cell) and a regenerative feedback loop. The active transformer with two stages can contribute to positive gain and greatly improve phase difference. Instead of the passive transformer, the active one occupies a much smaller chip area. The area of the chip is only 469× 414 μ {{{m}}}2 and it entirely consumes a total DC power of only 94.6 mW from a single -4.8 V DC supply. The measured results present that the divider achieves an operating frequency bandwidth from 75 to 80 GHz, and performs a -23 dBm maximum output power at 37.5 GHz with a 0 dBm input signal of 75 GHz.

47 CFR 25.225 - Geographic Service Requirements for 17/24 GHz Broadcasting Satellite Service.

Code of Federal Regulations, 2011 CFR

2011-10-01

... Requirements for 17/24 GHz Broadcasting Satellite Service. (a) Each operator of a 17/24 GHz BSS space station... GHz BSS space station subject to paragraph (a) of this section must design and configure its space... operator of a 17/24 GHz BSS space station that is used to provide video programming directly to consumers...

47 CFR 25.225 - Geographic Service Requirements for 17/24 GHz Broadcasting Satellite Service.

Code of Federal Regulations, 2014 CFR

2014-10-01

... Requirements for 17/24 GHz Broadcasting Satellite Service. (a) Each operator of a 17/24 GHz BSS space station... GHz BSS space station subject to paragraph (a) of this section must design and configure its space... operator of a 17/24 GHz BSS space station that is used to provide video programming directly to consumers...

47 CFR 25.225 - Geographic Service Requirements for 17/24 GHz Broadcasting Satellite Service.

Code of Federal Regulations, 2013 CFR

2013-10-01

... Requirements for 17/24 GHz Broadcasting Satellite Service. (a) Each operator of a 17/24 GHz BSS space station... GHz BSS space station subject to paragraph (a) of this section must design and configure its space... operator of a 17/24 GHz BSS space station that is used to provide video programming directly to consumers...

47 CFR 25.225 - Geographic Service Requirements for 17/24 GHz Broadcasting Satellite Service.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Requirements for 17/24 GHz Broadcasting Satellite Service. (a) Each operator of a 17/24 GHz BSS space station... GHz BSS space station subject to paragraph (a) of this section must design and configure its space... operator of a 17/24 GHz BSS space station that is used to provide video programming directly to consumers...

47 CFR 25.225 - Geographic Service Requirements for 17/24 GHz Broadcasting Satellite Service.

Code of Federal Regulations, 2012 CFR

2012-10-01

... Requirements for 17/24 GHz Broadcasting Satellite Service. (a) Each operator of a 17/24 GHz BSS space station... GHz BSS space station subject to paragraph (a) of this section must design and configure its space... operator of a 17/24 GHz BSS space station that is used to provide video programming directly to consumers...

Characterizing Daytime GHZ Scintillation at Equatorial Regions Using Gnss Radio Occultation Measurements

NASA Astrophysics Data System (ADS)

Seif, A.; Zhang, K.; Tsunoda, R. T.; Abdullah, M.; Carter, B. A.; Norman, R.; Wu, S.

2015-12-01

Ionospheric scintillation of radio waves can behave differently at different locations with a strong diurnal dependence; particularly in the equatorial regions. Ionospheric scintillations at gigahertz (GHz) frequencies have been observed during both daytime and nighttime. It is believed that daytime scintillation is associated with blanketing sporadic E (Esb), whereas nighttime scintillation is attributed to F layer irregularities. Scintillation events associated with Esbduring daytime are of our primary interest. Recent studies show that in the ionosphere, electron density profiles from Global Navigation Satellite System (GNSS) Radio Occultation (RO) provide valuable information to help better understand the physics of the ionosphere. In particular, GNSS RO observations of GHz scintillation in the proximity of the E-layer have been interpreted as being caused by sporadic E. In this paper the characteristics of daytime scintillations at 1.5 GHz recorded simultaneously from two stations (i) Universiti Kebangsaan Malaysia (UKM) (2.55°N, 101.461°E; dip latitude 5.78°S), and (ii) Langkawi (6.19°N, 99.51°E; dip latitude 1.90°S) during November and December 2010 are analyzed. The characteristics of daytime GHz scintillation and its relationship with E region irregularities at equatorial regions are investigated. Ground-based scintillation and Total Electron Content (TEC) data recorded by the GSV4004 receivers were utilized in combination with the amplitude scintillation measurements in terms of GPS C/A code SNR fluctuations during a ground-based GPS and space-borne GNSS RO experiment at the two equatorial stations. Scintillation activity was found to be more prominent at UKM. Moreover, strong scintillation with the S4 index exceeding 0.6 has only been observed at UKM, while at Langkawi the scintillation intensity (S4 index) did not exceed 0.3. Signal-to-noise measurements obtained from GNSS RO indicate that daytime scintillations are very likely caused by Esb. Our

A 20 Ghz Depolarization Experiment Using the ATS-6 Satellite

NASA Technical Reports Server (NTRS)

Bostian, C. W.; Manus, E. A.; Marshall, R. E.; Pendrak, H. N.; Stutzman, W. L.; Wiley, P. H.; Kauffman, S. R.

1975-01-01

A depolarization experiment using the 20 GHz downlink from the ATS-6 satellite was described. The following subjects were covered: (1) an operational summary of the experiment, (2) a description of the equipment used with emphasis on improvements made to the signal processing receiver used with the ATS-5 satellite, (3) data on depolarization and attenuation in one snow storm and two rain storms at 45 deg elevation, (4) data on low angle propagation, (5) conclusions about depolarization on satellite paths, and (6) recommendations for the depolarization portion of the CTS experiment.

Lower Hybrid Wave Induced SOL Emissivity Variation at High Density on the Alcator C-Mod Tokamak

DOE Office of Scientific and Technical Information (OSTI.GOV)

Faust, I.; Terry, J. L.; Reinke, M. L.

Lower Hybrid Current Drive (LHCD) in the Alcator C-Mod tokamak provides current profile control for the generation of Advanced Tokamak (AT) plasmas. Non-thermal electron bremsstrahlung emission decreases dramatically at n-bar{sub e}>1{center_dot}10{sup 20}[m{sup -3}] for diverted discharges, indicating low current drive efficiency. It is suggested that Scrape-Off-Layer (SOL) collisional absorption of LH waves is the cause for the absence of non-thermal electrons at high density. VUV and visible spectroscopy in the SOL provide direct information on collision excitation processes. Deuterium Balmer-, Lyman- and He-I transition emission measurements were used for initial characterization of SOL electron-neutral collisional absorption. Data from Helium andmore » Deuterium LHCD discharges were characterized by an overall increase in the emissivity as well as an outward radial shift in the emissivity profile with increasing plasma density and applied LHCD power. High-temperature, high-field (T{sub e} = 5keV,B{sub t} = 8T) helium discharges at high density display increased non-thermal signatures as well as reduced SOL emissivity. Variations in emissivity due to LHCD were seen in SOL regions not magnetically connected to the LH Launcher, indicating global SOL effects due to LHCD.« less

77 FR 45558 - 4.9 GHz Band

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-01

...The Commission allocated the 4940-4990 MHz (4.9 GHz) band in 2002 for fixed and mobile use and dedicated the band for public safety broadband communications. In the ten years since, the band has gone underutilized. The purpose of these proposed rules is to invigorate and maximize use of the 4.9 GHz band and attract more users while improving spectrum efficiency. The Commission seeks comment on formal coordination requirements, expanded eligibility, how the band can complement the 700 MHz public safety broadband network, technical rule changes, aeronautical mobile operations, interoperability standards, and deployment reporting.

324GHz CMOS VCO Using Linear Superimposition Technique

NASA Technical Reports Server (NTRS)

Daquan, Huang; LaRocca, Tim R.; Samoska, Lorene A; Fung, Andy; Chang, Frank

2007-01-01

Terahertz (frequencies ranged from 300GHz to 3THz) imaging and spectroscopic systems have drawn increasing attention recently due to their unique capabilities in detecting and possibly analyzing concealed objects. The generation of terahertz signals is nonetheless nontrivial and traditionally accomplished by using either free-electron radiation, optical lasers, Gunn diodes or fundamental oscillation by using III-V based HBT/HEMT technology[1-3]... We have substantially extended the operation range of deep-scaled CMOS by using a linear superimposition method, in which we have realized a 324GHz VCO in 90nm digital CMOS with 4GHz tuning range under 1V supply voltage. This may also pave the way for ultra-high data rate wireless communications beyond that of IEEE 802.15.3c and reach data rates comparable to that of fiber optical communications, such as OC768 (40Gbps) and beyond.

Beyond G-band : a 235 GHz InP MMIC amplifier

NASA Technical Reports Server (NTRS)

Dawson, Douglas; Samoska, Lorene; Fung, A. K.; Lee, Karen; Lai, Richard; Grundbacher, Ronald; Liu, Po-Hsin; Raja, Rohit

2005-01-01

We present results on an InP monolithic millimeter- wave integrated circuit (MMIC) amplifier having 10-dB gain at 235 GHz. We designed this circuit and fabricated the chip in Northrop Grumman Space Technology's (NGST) 0.07- m InP high electron mobility transistor (HEMT) process. Using a WR3 (220-325 GHz) waveguide vector network analyzer system interfaced to waveguide wafer probes, we measured this chip on-wafer for -parameters. To our knowledge, this is the first time a WR3 waveguide on-wafer measurement system has been used to measure gain in a MMIC amplifier above 230 GHz.

47 CFR 101.527 - Construction requirements for 24 GHz operations.

Code of Federal Regulations, 2010 CFR

2010-10-01

... it. (d) The frequencies associated with incumbent authorizations, licensed on a SMSA basis, that have... SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES 24 GHz Service and Digital Electronic Message Service § 101.527 Construction requirements for 24 GHz operations. (a) Each licensee must make a showing of...

47 CFR 101.527 - Construction requirements for 24 GHz operations.

Code of Federal Regulations, 2013 CFR

2013-10-01

... it. (d) The frequencies associated with incumbent authorizations, licensed on a SMSA basis, that have... SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES 24 GHz Service and Digital Electronic Message Service § 101.527 Construction requirements for 24 GHz operations. (a) Each licensee must make a showing of...

47 CFR 101.527 - Construction requirements for 24 GHz operations.

Code of Federal Regulations, 2012 CFR

2012-10-01

... it. (d) The frequencies associated with incumbent authorizations, licensed on a SMSA basis, that have... SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES 24 GHz Service and Digital Electronic Message Service § 101.527 Construction requirements for 24 GHz operations. (a) Each licensee must make a showing of...

47 CFR 101.527 - Construction requirements for 24 GHz operations.

Code of Federal Regulations, 2011 CFR

2011-10-01

... it. (d) The frequencies associated with incumbent authorizations, licensed on a SMSA basis, that have... SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES 24 GHz Service and Digital Electronic Message Service § 101.527 Construction requirements for 24 GHz operations. (a) Each licensee must make a showing of...

47 CFR 101.527 - Construction requirements for 24 GHz operations.

Code of Federal Regulations, 2014 CFR

2014-10-01

... it. (d) The frequencies associated with incumbent authorizations, licensed on a SMSA basis, that have... SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES 24 GHz Service and Digital Electronic Message Service § 101.527 Construction requirements for 24 GHz operations. (a) Each licensee must make a showing of...

Measurements of the cosmic microwave background temperature at 1.47 GHz

NASA Technical Reports Server (NTRS)

Bensadoun, M.; Bersanelli, M.; De Amici, G.; Kogut, A.; Levin, S. M.; Limon, M.; Smoot, G. F.; Witebsky, C.

1993-01-01

We have used a radio-frequency-gain total-power radiometer to measure the intensity of the cosmic microwave background (CMB) at a frequency of 1.47 GHz (20.4 cm wavelength) from White Mountain, California in 1988 September and from the South Pole in 1989 December. The CMB thermodynamic temperature, T(CMB), is 2.27 +/- 0.25 K (68 percent confidence limit) measured from White Mountain and 2.26 +/- 0.20 K from the South Pole site. The combined result is 2.26 +/- 0.19 K. The correction for Galactic emission has been derived from scaled low-frequency maps and constitutes the main source of error. The atmospheric signal is extrapolated from our zenith scan measurements at higher frequencies. These results are consistent with our previous measurement at 1.41 GHz and about 2.5 sigma from the 2.74 +/- 0.01 K global average CMB temperature.

47 CFR 27.806 - 1.4 GHz service licenses subject to competitive bidding.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 2 2011-10-01 2011-10-01 false 1.4 GHz service licenses subject to competitive bidding. 27.806 Section 27.806 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES 1.4 GHz Band § 27.806 1.4 GHz service...

47 CFR 27.806 - 1.4 GHz service licenses subject to competitive bidding.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 2 2010-10-01 2010-10-01 false 1.4 GHz service licenses subject to competitive bidding. 27.806 Section 27.806 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES 1.4 GHz Band § 27.806 1.4 GHz service...

Towards a 1 MW, 170 GHz gyrotron design for fusion application

NASA Astrophysics Data System (ADS)

Kumar, Anil; Kumar, Nitin; Singh, Udaybir; Bhattacharya, Ranajoy; Yadav, Vivek; Sinha, A. K.

2013-03-01

The electrical design of different components of 1 MW, 170 GHz gyrotron such as, magnetron injection gun, cylindrical interaction cavity and collector and RF window is presented in this article. Recently, a new project related to the development of 170 GHz, 1 MW gyrotron has been started for the Indian Tokamak. TE34,10 mode is selected as the operating mode after studied the problem of mode competition. The triode type geometry is selected for the design of magnetron injection gun (MIG) to achieve the required beam parameters. The maximum transverse velocity spread of 3.28% at the velocity ratio of 1.34 is obtained in simulations for a 40 A, 80 kV electron beam. The RF output power of more than 1 MW with 36.5% interaction efficiency without depressed collector is predicted by simulation in single-mode operation at 170 GHz frequency. The simulated single-stage depressed collector of the gyrotron predicted the overall device efficiencies >55%. Due to the very good thermal conductivity and very weak dependency of the dielectric parameters on temperature, PACVD diamond is selected for window design for the transmission of RF power. The in-house developed code MIGSYN and GCOMS are used for initial geometry design of MIG and mode selection respectively. Commercially available simulation tools MAGIC and ANSYS are used for beam-wave interaction and mechanical analysis respectively.

An FDMA system concept for 30/20 GHz high capacity domestic satellite service

NASA Technical Reports Server (NTRS)

Berk, G.; Jean, P. N.; Rotholz, E.; White, B. E.

1982-01-01

The paper summarizes a feasibility study of a multibeam FDMA satellite system operating in the 30/20 GHz band. The system must accommodate a very high volume of traffic within the restrictions of a 5 kW solar cell array and a 2.5 GHz bandwidth. Multibeam satellite operation reduces the DC power demand and allows reuse of the available bandwidth. Interferences among the beams are brought to acceptable levels by appropriate frequency assignments. A transponder design is presented; it is greatly simplified by the application of a regional concept. System analysis shows that MSK modulation is appropriate for a high-capacity system because it conserves the frequency spectrum. Rain attenuation, a serious problem in this frequency band, is combatted with sufficient power margins and with coding. Link budgets, cost analysis, and weight and power calculations are also discussed. A satellite-routed FDMA system compares favorably in performance and cost with a satellite-switched TDMA system.

Studies of Current Induced Magnetization reversal and generation of GHz radiation in magnetic nanopillars

NASA Astrophysics Data System (ADS)

Alhajdarwish, Mustafa Yousef

justifying such scaling; and (5) designing and constructing a system for frequency domain studies up to 40 GHz and for time domain studies.

A Unified Multi-Functional Dynamic Spectrum Access Framework: Tutorial, Theory and Multi-GHz Wideband Testbed

PubMed Central

Qiu, Robert; Guo, Nan; Li, Husheng; Wu, Zhiqiang; Chakravarthy, Vasu; Song, Yu; Hu, Zhen; Zhang, Peng; Chen, Zhe

2009-01-01

Dynamic spectrum access is a must-have ingredient for future sensors that are ideally cognitive. The goal of this paper is a tutorial treatment of wideband cognitive radio and radar—a convergence of (1) algorithms survey, (2) hardware platforms survey, (3) challenges for multi-function (radar/communications) multi-GHz front end, (4) compressed sensing for multi-GHz waveforms—revolutionary A/D, (5) machine learning for cognitive radio/radar, (6) quickest detection, and (7) overlay/underlay cognitive radio waveforms. One focus of this paper is to address the multi-GHz front end, which is the challenge for the next-generation cognitive sensors. The unifying theme of this paper is to spell out the convergence for cognitive radio, radar, and anti-jamming. Moore’s law drives the system functions into digital parts. From a system viewpoint, this paper gives the first comprehensive treatment for the functions and the challenges of this multi-function (wideband) system. This paper brings together the inter-disciplinary knowledge. PMID:22454598

High field Q slope and the effect of low-temperature baking at 3 GHz

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ciovati, G.; Eremeev, G.; Hannon, F.

Here, a strong degradation of the unloaded quality factor with field, called high field Q-slope, is commonly observed above Bmore » $$_{p}$$ $$\\cong$$ 100 mT in elliptical superconducting niobium cavities at 1.3 GHz and 1.5 GHz. In the present experiments several 3 GHz niobium cavities were measured up to and above B$$_{p}$$ $$\\cong$$100 mT. The measurements show that a high field Q-slope phenomenon limits the field reach at this frequency, that the high field Q-slope onset field depends weakly on the frequency, and that the high field Q-slope can be removed by the typical empirical solution of electropolishing followed by heating to 120 $$^{\\circ}$$C for 48 hrs. In addition, one of the cavities reached a quench field of 174~mT and its field dependence of the quality factor was compared against global heating predicted by a thermal feedback model.« less

High field Q slope and the effect of low-temperature baking at 3 GHz

DOE PAGES

Ciovati, G.; Eremeev, G.; Hannon, F.

2018-01-29

Here, a strong degradation of the unloaded quality factor with field, called high field Q-slope, is commonly observed above Bmore » $$_{p}$$ $$\\cong$$ 100 mT in elliptical superconducting niobium cavities at 1.3 GHz and 1.5 GHz. In the present experiments several 3 GHz niobium cavities were measured up to and above B$$_{p}$$ $$\\cong$$100 mT. The measurements show that a high field Q-slope phenomenon limits the field reach at this frequency, that the high field Q-slope onset field depends weakly on the frequency, and that the high field Q-slope can be removed by the typical empirical solution of electropolishing followed by heating to 120 $$^{\\circ}$$C for 48 hrs. In addition, one of the cavities reached a quench field of 174~mT and its field dependence of the quality factor was compared against global heating predicted by a thermal feedback model.« less

Results of RIKEN superconducting electron cyclotron resonance ion source with 28 GHz.

PubMed

Higurashi, Y; Ohnishi, J; Nakagawa, T; Haba, H; Tamura, M; Aihara, T; Fujimaki, M; Komiyama, M; Uchiyama, A; Kamigaito, O

2012-02-01

We measured the beam intensity of highly charged heavy ions and x-ray heat load for RIKEN superconducting electron cyclotron resonance ion source with 28 GHz microwaves under the various conditions. The beam intensity of Xe(20+) became maximum at B(min) ∼ 0.65 T, which was ∼65% of the magnetic field strength of electron cyclotron resonance (B(ECR)) for 28 GHz microwaves. We observed that the heat load of x-ray increased with decreasing gas pressure and field gradient at resonance zone. It seems that the beam intensity of highly charged heavy ions with 28 GHz is higher than that with 18 GHz at same RF power.

SEMICONDUCTOR INTEGRATED CIRCUITS 8.64-11.62 GHz CMOS VCO and divider in a zero-IF 802.11a/b/g WLAN and Bluetooth application

NASA Astrophysics Data System (ADS)

Yu, Sun; Niansong, Mei; Bo, Lu; Yumei, Huang; Zhiliang, Hong

2010-10-01

A fully integrated VCO and divider implemented in SMIC 0.13-μm RFCMOS 1P8M technology with a 1.2 V supply voltage is presented. The frequency of the VCO is tuning from 8.64 to 11.62 GHz while the quadrature LO signals for 802.11a WLAN in 5.8 GHz band or for 802.11b/g WLAN and Bluetooth in 2.4 GHz band can be obtained by a frequency division by 2 or 4, respectively. A 6 bit switched capacitor array is applied for precise tuning of all necessary frequency bands. The testing results show that the VCO has a phase noise of—113 dBc @ 1 MHz offset from the carrier of 5.5 GHz by dividing VCO output by two and the VCO core consumes 3.72 mW. The figure-of-merit for the tuning-range (FOMT) of the VCO is -192.6 dBc/Hz.

Low-Noise Amplifier for 100 to 180 GHz

NASA Technical Reports Server (NTRS)

Kangaslahti, Pekka; Pukala, David; Fung, King Man; Gaier, Todd; Mei, Xiaobing; Lai, Richard; Deal, William

2009-01-01

A three-stage monolithic millimeter-wave integrated-circuit (MMIC) amplifier designed to exhibit low noise in operation at frequencies from about 100 to somewhat above 180 GHz has been built and tested. This is a prototype of broadband amplifiers that have potential utility in diverse applications, including measurement of atmospheric temperature and humidity and millimeter-wave imaging for inspecting contents of opaque containers. Figure 1 depicts the amplifier as it appears before packaging. Figure 2 presents data from measurements of the performance of the amplifier as packaged in a WR-05 waveguide and tested in the frequency range from about 150 to about 190 GHz. The amplifier exhibited substantial gain throughout this frequency range. Especially notable is the fact that at 165 GHz, the noise figure was found to be 3.7 dB, and the noise temperature was found to be 370 K: This is less than half the noise temperature of the prior state of the art.

GHz Yb:KYW oscillators in time-resolved spectroscopy

NASA Astrophysics Data System (ADS)

Li, Changxiu; Krauß, Nico; Schäfer, Gerhard; Ebner, Lukas; Kliebisch, Oliver; Schmidt, Johannes; Winnerl, Stephan; Hettich, Mike; Dekorsy, Thomas

2018-02-01

A high-speed asynchronous optical sampling system (ASOPS) based on Yb:KYW oscillators with 1-GHz repetition rate is reported. Two frequency-offset-stabilized diode-pumped Yb:KYW oscillators are employed as pump and probe source, respectively. The temporal resolution of this system within 1-ns time window is limited to 500 fs and the noise floor around 10-6 (ΔR/R) close to the shot-noise level is obtained within an acquisition time of a few seconds. Coherent acoustic phonons are investigated by measuring multilayer semiconductor structures with multiple quantum wells and aluminum/silicon membranes in this ASOPS system. A wavepacket-like phonon sequence at 360 GHz range is detected in the semiconductor structures and a decaying sequence of acoustic oscillations up to 200 GHz is obtained in the aluminum/silicon membranes. Coherent acoustic phonons generated from semiconductor structures are further manipulated by a double pump scheme through pump time delay control.

Efficient Low-Voltage Operation of a CW Gyrotron Oscillator at 233 GHz.

PubMed

Hornstein, Melissa K; Bajaj, Vikram S; Griffin, Robert G; Temkin, Richard J

2007-02-01

The gyrotron oscillator is a source of high average power millimeter-wave through terahertz radiation. In this paper, we report low beam power and high-efficiency operation of a tunable gyrotron oscillator at 233 GHz. The low-voltage operating mode provides a path to further miniaturization of the gyrotron through reduction in the size of the electron gun, power supply, collector, and cooling system, which will benefit industrial and scientific applications requiring portability. Detailed studies of low-voltage operation in the TE(2) (,) (3) (,) (1) mode reveal that the mode can be excited with less than 7 W of beam power at 3.5 kV. During CW operation with 3.5-kV beam voltage and 50-mA beam current, the gyrotron generates 12 W of RF power at 233.2 GHz. The EGUN electron optics code describes the low-voltage operation of the electron gun. Using gun-operating parameters derived from EGUN simulations, we show that a linear theory adequately predicts the low experimental starting currents.

Efficient Low-Voltage Operation of a CW Gyrotron Oscillator at 233 GHz

PubMed Central

Hornstein, Melissa K.; Bajaj, Vikram S.; Griffin, Robert G.; Temkin, Richard J.

2007-01-01

The gyrotron oscillator is a source of high average power millimeter-wave through terahertz radiation. In this paper, we report low beam power and high-efficiency operation of a tunable gyrotron oscillator at 233 GHz. The low-voltage operating mode provides a path to further miniaturization of the gyrotron through reduction in the size of the electron gun, power supply, collector, and cooling system, which will benefit industrial and scientific applications requiring portability. Detailed studies of low-voltage operation in the TE2,3,1 mode reveal that the mode can be excited with less than 7 W of beam power at 3.5 kV. During CW operation with 3.5-kV beam voltage and 50-mA beam current, the gyrotron generates 12 W of RF power at 233.2 GHz. The EGUN electron optics code describes the low-voltage operation of the electron gun. Using gun-operating parameters derived from EGUN simulations, we show that a linear theory adequately predicts the low experimental starting currents. PMID:17687412

Tunable Twin Matching Frequency (fm1/fm2) Behavior of Ni1-xZnxFe2O4/NBR Composites over 2-12.4 GHz: A Strategic Material System for Stealth Applications.

PubMed

Saini, Lokesh; Patra, Manoj Kumar; Jani, Raj Kumar; Gupta, Goutam Kumar; Dixit, Ambesh; Vadera, Sampat Raj

2017-03-15

The gel to carbonate precipitate route has been used for the synthesis of Ni 1-x Zn x Fe 2 O 4 (x = 0, 0.25, 0.5 and 0.75) bulk inverse spinel ferrite powder samples. The optimal zinc (50%) substitution has shown the maximum saturation magnetic moment and resulted into the maximum magnetic loss tangent (tanδ m ) > -1.2 over the entire 2-10 GHz frequency range with an optimum value ~-1.75 at 6 GHz. Ni 0.5 Zn 0.5 Fe 2 O 4 - Acrylo-Nitrile Butadiene Rubber (NBR) composite samples are prepared at different weight percentage (wt%) of ferrite loading fractions in rubber for microwave absorption evaluation. The 80 wt% loaded Ni 0.5 Zn 0.5 Fe 2 O 4 /NBR composite (FMAR80) sample has shown two reflection loss (RL) peaks at 5 and 10 GHz. Interestingly, a single peak at 10 GHz for 3.25 mm thickness, can be scaled down to 5 GHz by increasing the thickness up to 4.6 mm. The onset of such twin matching frequencies in FMAR80 composite sample is attributed to the spin resonance relaxation at ~5 GHz (f m1 ) and destructive interference at λ m /4 matched thickness near ~10 GHz (f m2 ) in these composite systems. These studies suggest the potential of tuning the twin frequencies in Ni 0.5 Zn 0.5 Fe 2 O 4 /NBR composite samples for possible microwave absorption applications.

Tunable Twin Matching Frequency (fm1/fm2) Behavior of Ni1-xZnxFe2O4/NBR Composites over 2-12.4 GHz: A Strategic Material System for Stealth Applications

NASA Astrophysics Data System (ADS)

Saini, Lokesh; Patra, Manoj Kumar; Jani, Raj Kumar; Gupta, Goutam Kumar; Dixit, Ambesh; Vadera, Sampat Raj

2017-03-01

The gel to carbonate precipitate route has been used for the synthesis of Ni1-xZnxFe2O4 (x = 0, 0.25, 0.5 and 0.75) bulk inverse spinel ferrite powder samples. The optimal zinc (50%) substitution has shown the maximum saturation magnetic moment and resulted into the maximum magnetic loss tangent (tanδm) > -1.2 over the entire 2-10 GHz frequency range with an optimum value ~-1.75 at 6 GHz. Ni0.5Zn0.5Fe2O4- Acrylo-Nitrile Butadiene Rubber (NBR) composite samples are prepared at different weight percentage (wt%) of ferrite loading fractions in rubber for microwave absorption evaluation. The 80 wt% loaded Ni0.5Zn0.5Fe2O4/NBR composite (FMAR80) sample has shown two reflection loss (RL) peaks at 5 and 10 GHz. Interestingly, a single peak at 10 GHz for 3.25 mm thickness, can be scaled down to 5 GHz by increasing the thickness up to 4.6 mm. The onset of such twin matching frequencies in FMAR80 composite sample is attributed to the spin resonance relaxation at ~5 GHz (fm1) and destructive interference at λm/4 matched thickness near ~10 GHz (fm2) in these composite systems. These studies suggest the potential of tuning the twin frequencies in Ni0.5Zn0.5Fe2O4/NBR composite samples for possible microwave absorption applications.

100 GHz ultra-wideband (UWB) fiber-to-the-antenna (FTTA) system for in-building and in-home networks.

PubMed

Chow, C W; Kuo, F M; Shi, J W; Yeh, C H; Wu, Y F; Wang, C H; Li, Y T; Pan, C L

2010-01-18

Fiber-to-the-antenna (FTTA) system can be a cost-effective technique for distributing high frequency signals from the head-end office to a number of remote antenna units via passive optical splitter and propagating through low-loss and low-cost optical fibers. Here, we experimentally demonstrate an optical ultra-wideband (UWB) - impulse radio (IR) FTTA system for in-building and in-home applications. The optical UWB-IR wireless link is operated in the W-band (75 GHz - 110 GHz) using our developed near-ballistic unitraveling-carrier photodiode based photonic transmitter (PT) and a 10 GHz mode-locked laser. 2.5 Gb/s UWB-IR FTTA systems with 1,024 high split-ratio and transmission over 300 m optical fiber are demonstrated using direct PT modulation.

EEG changes as heat stress reactions in rats irradiated by high intensity 35 GHz millimeter waves.

PubMed

Xie, Taorong; Pei, Jian; Cui, Yibin; Zhang, Jie; Qi, Hongxing; Chen, Shude; Qiao, Dengjiang

2011-06-01

As the application of millimeter waves for civilian and military use increases, the possibility of overexposure to millimeter waves will also increase. This paper attempts to evaluate stress reactions evoked by 35 GHz millimeter waves. The stress reactions in Sprague-Dawley (SD) rats were quantitatively studied by analyzing electroencephalogram (EEG) changes induced by overexposure to 35 GHz millimeter waves. The relative changes in average energy of the EEG and its wavelet decompositions were used for extracting the stress reaction indicators. Incident average power densities (IAPDs) of 35 GHz millimeter waves from 0.5 W cm(-2) to 7.5 W cm(-2) were employed to investigate the relation between irradiation dose and the stress reactions in the rats. Different stress reaction periods evoked by irradiation were quantitatively evaluated by EEG results. The results illustrate that stress reactions are more intense during the first part of the irradiation than during the later part. The skin temperature increase produced by millimeter wave irradiation is the principle reason for stress reactions and skin injuries. As expected, at the higher levels of irradiation, the reaction time decreases and the reaction intensity increases.

Radar backscattering properties of corn and soybeans at frequencies of 1.6, 4.75, and 13.3. GHz

NASA Technical Reports Server (NTRS)

Paris, J. F.

1983-01-01

The NASA Johnson Space Center made an observational study of the radar-backscattering properties of corn and soybeans in commercial fields in a test site in Webster County, IA. Aircraft-based radar scatterometers measured the backscattering coefficient of the crops at three frequencies, 1.6 GHz (L-band), 4.75 GHz (C-band), and 13.3 GHz (Ku-band), at 10 sensor look-angles (5 to 50 degrees from the nadir in steps of 5 degrees), and with several polarization combinations. Among other findings, it was determined that: (1) row direction differences among fields affected significantly the radar-backscattering coefficient of the fields when the radar system used like-polarization at look-angles from 5 to 25 degrees; (2) row-direction differences had no effect on radar backscattering when the system used either cross-polarization or look-angles greater than 25 degrees regardless of the polarization; (3) wet surface-soil moisture conditions resulted in significantly poorer spectral separability of the two crops as compared to dry-soil conditions; and (4) on the dry-soil date, the best channel for separating corn from soybeans was the C-band cross-polarized measurement at a look-angle of 50 degrees.

A cooled 1- to 2-GHz balanced HEMT amplifier

NASA Technical Reports Server (NTRS)

Ortiz, Gerardo G.; Padin, Steven

1991-01-01

The design details and measurement results for a cooled L-band (1 to 2 GHz) balanced high electron mobility transistor (HEMT) amplifier are presented. The amplifier uses commercially available packaged HEMT devices (Fujitsu FHR02FH). At a physical temperature of 12 K, the amplifier achieves noise temperatures between 3 and 6 K over the 1 to 2 GHz band. The associated gain is approximately 20 dB.

Prospect for a 60 GHz multicharged ECR ion source

NASA Astrophysics Data System (ADS)

Thuillier, T.; Bondoux, D.; Angot, J.; Baylac, M.; Froidefond, E.; Jacob, J.; Lamy, T.; Leduc, A.; Sole, P.; Debray, F.; Trophime, C.; Skalyga, V.; Izotov, I.

2018-05-01

The conceptual design of a fourth generation hybrid electron cyclotron resonance (ECR) ion source operated at 60 GHz is proposed. The axial magnetic mirror is generated with a set of three Nb3Sn coils, while the hexapole is made with room temperature (RT) copper coils. The motivations for such a hybrid development are to study further the ECR plasma physics and the intense multicharged ion beams' production and transport at a time when a superconducting (SC) hexapole appears unrealistic at 60 GHz. The RT hexapole coil designed is an evolution of the polyhelix technology developed at the French High Magnetic Field Facility. The axial magnetic field is generated by means of 3 Nb3Sn SC coils operated with a maximum current density of 350 A/mm2 and a maximum coil load line factor of 81%. The ECR plasma chamber resulting from the design features an inner radius of 94 mm and a length of 500 mm. The radial magnetic intensity is 4.1 T at the wall. Characteristic axial mirror peaks are 8 and 4.5 T, with 1.45 T minimum in between.

CW and pulsed electrically detected magnetic resonance spectroscopy at 263 GHz/12 T on operating amorphous silicon solar cells

NASA Astrophysics Data System (ADS)

Akhtar, W.; Schnegg, A.; Veber, S.; Meier, C.; Fehr, M.; Lips, K.

2015-08-01

Here we describe a new high frequency/high field continuous wave and pulsed electrically detected magnetic resonance (CW EDMR and pEDMR) setup, operating at 263 GHz and resonance fields between 0 and 12 T. Spin dependent transport in illuminated hydrogenated amorphous silicon p-i-n solar cells at 5 K and 90 K was studied by in operando 263 GHz CW and pEDMR alongside complementary X-band CW EDMR. Benefiting from the superior resolution at 263 GHz, we were able to better resolve EDMR signals originating from spin dependent hopping and recombination processes. 5 K EDMR spectra were found to be dominated by conduction and valence band tail states involved in spin dependent hopping, with additional contributions from triplet exciton states. 90 K EDMR spectra could be assigned to spin pair recombination involving conduction band tail states and dangling bonds as the dominating spin dependent transport process, with additional contributions from valence band tail and triplet exciton states.

TWT design requirements for 30/20 GHz digital communications' satellite

NASA Technical Reports Server (NTRS)

Stankiewicz, N.; Anzic, G.

1979-01-01

The rapid growth of communication traffic (voice, data, and video) requires the development of additional frequency bands before the 1990's. The frequencies currently in use for satellite communications at 6/4 GHz are crowded and demands for 14/12 GHz systems are increasing. Projections are that these bands will be filled to capacity by the late 1980's. The next higher frequency band allocated for satellite communications is at 30/20 GHz. For interrelated reasons of efficiency, power level, and system reliability criteria, a candidate for the downlink amplifier in a 30/20 GHz communications' satellite is a dual mode traveling wave tube (TWT) equipped with a highly efficient depressed collector. A summary is given of the analyses which determine the TWT design requirements. The overall efficiency of such a tube is then inferred from a parametric study and from experimental data on multistaged depressed collectors. The expected TWT efficiency at 4 dB below output saturation is 24 percent in the high mode and 22 percent in the low mode.

Very high resolution observations of SS433 at 10.65 GHz

NASA Technical Reports Server (NTRS)

Geldzahler, B. J.; Downes, A. J. B.; Shaffer, D. B.

1981-01-01

Observations of SS433 made on June 12, 1979, from West Germany, Massachusetts, and West Virginia are discussed. It is noted that SS433 did not show fringes on any baseline although all the calibration sources were seen at their expected strengths. The measured total flux density of SS433 was found to be approximately 0.5 Jy, consistent with previous observations. The source was observed by on-offs at each telescope, which indicates that they were all pointed properly during the observations. The absence of fringes is not attributed to poor observing conditions or instrumental difficulties. It is concluded that if all the 10.65 GHz radiation emanates from a single component, then that component is at least 0.005 arcsec (approximately 10 to the 14th cm) in size. The measurements made on more sensitive intercontinental baselines indicate that there is no component of SS433 smaller than 0.001 arcsec emitting 10.65 GHz radiation above a level of 50 mJy.

Observations of M87 and Hydra A at 90 GHz

NASA Technical Reports Server (NTRS)

Cotton, W. D.; Mason, B. S.; Dicker, S.; Korngut, P.; Devlin, M. J.; Aquirre, J.; Benford, D.; Moseley, H.; Staguhn, J.; Irwin, K.;

The 60 GHz IMPATT diode development

NASA Technical Reports Server (NTRS)

Dat, Rovindra; Ayyagari, Murthy; Hoag, David; Sloat, David; Anand, Yogi; Whitely, Stan

1986-01-01

The objective is to develop 60 GHz IMPATT diodes suitable for communications applications. The performance goals of the 60 GHz IMPATT is 1W CW output power with a conversion efficiency of 15 percent and 10-year lifetime. The final design of the 60 GHz IMPATT structure evolved from computer simulations performed at the University of Michigan. The initial doping profile, involving a hybrid double-drift (HDD) design, was derived from a drift-diffusion model that used the static velocity-field characteristics for GaAs. Unfortunately, the model did not consider the effects of velocity undershoot and delay of the avalanche process due to energy relaxation. Consequently, the initial devices were oscillating at a much lower frequency than anticipated. With a revised simulation program that included the two effects given above, a second HDD profile was generated and was used as a basis for fabrication efforts. In the area of device fabrication, significant progress was made in epitaxial growth and characterization, wafer processing, and die assembly. The organo-metallic chemical vapor deposition (OMCVD) was used. Starting with a baseline X-Band IMPATT technology, appropriate processing steps were modified to satisfy the device requirements at V-Band. In terms of efficiency and reliability, the device requirements dictate a reduction in its series resistance and thermal resistance values. Qualitatively, researchers were able to reduce the diodes' series resistance by reducing the thickness of the N+ GaAs substrate used in its fabrication.

Development of 24GHz Rectenna for Receiving and Rectifying Modulated Waves

NASA Astrophysics Data System (ADS)

Shinohara, Naoki; Hatano, Ken

2014-11-01

In this paper, we show experimental results of RF-DC conversion with modulated 24GHz waves. We have already developed class-F MMIC rectenna with resonators for higher harmonics at no modulated 24GHz microwave for RF energy transfer. Dimensions of the MMIC rectifying circuit is 1 mm × 3 mm on GaAs. Maximum RF-DC conversion efficiency is measured 47.9% for a 210 mW microwave input of 24 GHz with a 120 Ω load. The class-F rectenna is based on a single shunt full-wave rectifier. For future application of a simultaneous energy and information transfer system or an energy harvesting from broadcasting waves, input microwave will be modulated. In this paper, we show an experimental result of RF-DC conversion of the class-F rectenna with 24GHz waves modulated by 16QAM as 1st modulation and OFDM as 2nd modulation.

Miniature Packaging Concept for LNAs in the 200-300 GHz Range

NASA Technical Reports Server (NTRS)

Samoska, Lorene; Fung, Andy; Varonen, Mikko; Lin, Robert; Peralta, Alejandro; Soria, Mary; Lee, Choonsup; Padmanabhan, Sharmila; Sarkozy, Stephen; Lai, Richard

2016-01-01

In this work, we describe new miniaturized low noise amplifier modules which we developed for incorporation in small-scale satellites or Cubesats, and which exhibit similar or better performance compared to previously reported LNAs in the literature. We have targeted the WR4 (170-260 GHz) and WR3 (220-325 GHz) waveguide bands for the module development. The modules include two different methods of E-plane probes which have been developed for low loss, and stability at high frequencies. MMIC LNAs were also developed for these frequency ranges and fabricated in Northrop Grumman Corporation's 35 nm InP HEMT technology, and we have experimentally verified that noise performance is lower than reported in prior work. The best results include a miniature LNA module with 550K noise at 224 GHz, and a wideband LNA module with 15 dB gain from 230-280 GHz.

Cross-impact study of foreign satellite communications on NASA's 30/20 GHz program

NASA Technical Reports Server (NTRS)

1980-01-01

A comprehensive traffic demand forecast and a scenario for the transition process from current satellite systems to more advanced systems of the 1990's are presented. Systems configurations with and without the use of 30/20 GHz are described and these two alternatives are compared. It is concluded that: (1) the use of 30/20 GHz will result in increased satellite capacity, which will be needed to satisfy demand; (2) the use of 30/20 GHz will decrease the transmission cost, especially for broadband communications; (3) in some areas, particularly Europe and Japan but also the U.S., 30/20 GHz is the only available frequency band for customer premise Earth stations because of the dense terrestrial microwave networks; and (4) the development of 30/20 GHz technology will improve U.S. markets for equipment and satellites in many world regions.

Cross-impact study of foreign satellite communications on NASA's 30/20 GHz program

NASA Astrophysics Data System (ADS)

1980-08-01

A comprehensive traffic demand forecast and a scenario for the transition process from current satellite systems to more advanced systems of the 1990's are presented. Systems configurations with and without the use of 30/20 GHz are described and these two alternatives are compared. It is concluded that: (1) the use of 30/20 GHz will result in increased satellite capacity, which will be needed to satisfy demand; (2) the use of 30/20 GHz will decrease the transmission cost, especially for broadband communications; (3) in some areas, particularly Europe and Japan but also the U.S., 30/20 GHz is the only available frequency band for customer premise Earth stations because of the dense terrestrial microwave networks; and (4) the development of 30/20 GHz technology will improve U.S. markets for equipment and satellites in many world regions.

Monitoring global vegetation using Nimbus-7 37 GHz data - Some empirical relations

NASA Technical Reports Server (NTRS)

Choudhury, B. J.; Tucker, C. J.

1987-01-01

The difference of the vertically and horizontally polarized brightness temperatures observed by the 37 GHz channel of the SMMR on board the Nimbus-7 satellite are correlated temporally with three indicators of vegetation density, namely the temporal variation of the atmospheric CO2 concentration at Mauna Loa (Hawaii), rainfall over the Sahel and the normalized difference vegetation index derived from the AVHRR on board the NOAA-7 satellite. SMMR 37 GHz and AVHRR provide complementary data sets for monitoring global vegetation, the 37 GHz data being more suitable for arid and semiarid regions as these data are more sensitive to changes in sparse vegetation. The 37-GHz data might be useful for understanding desertification and indexing Co2 exchange between the biosphere and the atmosphere.

Miniaturized printed K shaped monopole antenna with truncated ground plane for 2.4/5.2/5.5/5.8 wireless lan applications

NASA Astrophysics Data System (ADS)

Chandan, Bharti, Gagandeep; Srivastava, Toolika; Rai, B. S.

2018-04-01

A novel truncated ground plane monopole antenna is proposed for wide band wireless local area network (WLAN) applications. The antenna contains a rectangular patch with a rectangular ring, a circular slot and a truncated ground plane printed on opposite sides of a low cost substrate FR4. The operating frequency bands for the antenna are band1 (2.4-2.88 GHz) and band 2 (4.8-6.3 GHz) with ≤ - 10 dB return loss which covers 2.4/5.2/5.5/5.8 GHz WLAN bands. The antenna is compact with overall dimension 26×40×0.8 mmł and with the dimension of patch 16×16×0.8 mm3. The two bands of antenna is obtained by cutting a rectangular ring and a circular slot in the patch and return loss is improved by cutting two rectangular slot in the ground plane. Performance measures of the antenna are shown in terms of return loss, current distribution, radiation pattern and gain. To verify the simulated results, the antenna is also fabricated and tested. The simulated and fabricated results have been found in good agreement.

Efficient EM Simulation of GCPW Structures Applied to a 200-GHz mHEMT Power Amplifier MMIC

NASA Astrophysics Data System (ADS)

Campos-Roca, Yolanda; Amado-Rey, Belén; Wagner, Sandrine; Leuther, Arnulf; Bangert, Axel; Gómez-Alcalá, Rafael; Tessmann, Axel

2017-05-01

The behaviour of grounded coplanar waveguide (GCPW) structures in the upper millimeter-wave range is analyzed by using full-wave electromagnetic (EM) simulations. A methodological approach to develop reliable and time-efficient simulations is proposed by investigating the impact of different simplifications in the EM modelling and simulation conditions. After experimental validation with measurements on test structures, this approach has been used to model the most critical passive structures involved in the layout of a state-of-the-art 200-GHz power amplifier based on metamorphic high electron mobility transistors (mHEMTs). This millimeter-wave monolithic integrated circuit (MMIC) has demonstrated a measured output power of 8.7 dBm for an input power of 0 dBm at 200 GHz. The measured output power density and power-added efficiency (PAE) are 46.3 mW/mm and 4.5 %, respectively. The peak measured small-signal gain is 12.7 dB (obtained at 196 GHz). A good agreement has been obtained between measurements and simulation results.

Tunable Twin Matching Frequency (fm1/fm2) Behavior of Ni1−xZnxFe2O4/NBR Composites over 2–12.4 GHz: A Strategic Material System for Stealth Applications

PubMed Central

Saini, Lokesh; Patra, Manoj Kumar; Jani, Raj Kumar; Gupta, Goutam Kumar; Dixit, Ambesh; Vadera, Sampat Raj

2017-01-01

The gel to carbonate precipitate route has been used for the synthesis of Ni1−xZnxFe2O4 (x = 0, 0.25, 0.5 and 0.75) bulk inverse spinel ferrite powder samples. The optimal zinc (50%) substitution has shown the maximum saturation magnetic moment and resulted into the maximum magnetic loss tangent (tanδm) > −1.2 over the entire 2–10 GHz frequency range with an optimum value ~−1.75 at 6 GHz. Ni0.5Zn0.5Fe2O4- Acrylo-Nitrile Butadiene Rubber (NBR) composite samples are prepared at different weight percentage (wt%) of ferrite loading fractions in rubber for microwave absorption evaluation. The 80 wt% loaded Ni0.5Zn0.5Fe2O4/NBR composite (FMAR80) sample has shown two reflection loss (RL) peaks at 5 and 10 GHz. Interestingly, a single peak at 10 GHz for 3.25 mm thickness, can be scaled down to 5 GHz by increasing the thickness up to 4.6 mm. The onset of such twin matching frequencies in FMAR80 composite sample is attributed to the spin resonance relaxation at ~5 GHz (fm1) and destructive interference at λm/4 matched thickness near ~10 GHz (fm2) in these composite systems. These studies suggest the potential of tuning the twin frequencies in Ni0.5Zn0.5Fe2O4/NBR composite samples for possible microwave absorption applications. PMID:28294151

A new class of solar burst with MM-wave emission but only at the highest frequency (90 GHz)

NASA Technical Reports Server (NTRS)

Kaufmann, P.; Correia, E.; Costa, J. E. R.; Vaz, A. M. Z.; Dennis, B. R.

1984-01-01

High sensitivity and high time resolution solar observations at 90 GHz (lambda = 3.3 mm) have identified a unique impulsive burst on May 21, 1984 with emission that was more intense at this frequency than at lower frequencies. The first major time structure of the burst was over 10 times more intense at 90 GHz than at 30 GHz, 7 GHz, or 2.8 GHz.Only 6 seconds later, the 30 GHz impulsive structures started to be observed but still with lower intensity than at 90 GHz. Hard X-ray time structures at energies above 25 keV were almost identical to the 90 GHZ structures (to better than one second). All 90 GHz major time structures consisted of trains of multiple subsecond pulses with rise times as short as 0.03 sec and amplitudes large compared to the mean flux. When detectable, the 30 GHz subsecond pulses had smaller relative amplitude and were in phase with the corresponding 90 GHz pulses.

Experimental Procedure for Determination of the Dielectric Properties of Biological Samples in the 2-50 GHz Range

PubMed Central

Odelstad, Elias; Raman, Sujith; Rydberg, Anders

2014-01-01

The objective of this paper was to test and evaluate an experimental procedure for providing data on the complex permittivity of different cell lines in the 2–50-GHz range at room temperature, for the purpose of future dosimetric studies. The complex permittivity measurements were performed on cells suspended in culture medium using an open-ended coaxial probe. Maxwell’s mixture equation then allows the calculation of the permittivity profiles of the cells from the difference in permittivity between the cell suspensions and pure culture medium. The open-ended coaxial probe turned out to be very sensitive to disturbances affecting the measurements, resulting in poor precision. Permittivity differences were not large in relation to the spread of the measurements and repeated measurements were performed to improve statistics. The 95% confidence intervals were computed for the arithmetic means of the measured permittivity differences in order to test the statistical significance. The results showed that for bone cells at the lowest tested concentration (33 500/ml), there were significance in the real part of the permittivity at frequencies above 30 GHz, and no significance in the imaginary part. For the second lowest concentration (67 000/ml) there was no significance at all. For a medium concentration of bone cells (135 000/ml) there was no significance in the real part, but there was significance in the imaginary part at frequencies below about 25 GHz. The cell suspension with a concentration of 1 350 000/ml had significance in the real part for both high (above 30 GHz) and low (below 15 GHz) frequencies. The imaginary part showed significance for frequencies below 25 GHz. In the case of an osteosarcoma cell line with a concentration of 2 700 000/ml, only the imaginary part showed significance, and only for frequencies below 15 GHz. For muscle cells at a concentration of 743 450/ml, there was only significance in the imaginary part for frequencies below 5 GHz

A Deterministic and Random Propagation Study with the Design of an Open Path 320 GHz to 340 GHz Transmissometer

NASA Astrophysics Data System (ADS)

Scally, Lawrence J.

This program was implemented by Lawrence J. Scally for a Ph.D. under the EECE department at the University of Colorado at Boulder with most funding provided by the U.S. Army. Professor Gasiewski is the advisor and guider for the entire program; he has a strong history decades ago in this type of program. This program is developing a more advanced than previous years transmissometer, called Terahertz Atmospheric and Ionospheric Propagation, Absorption and Scattering System (TAIPAS), on an open path between the University of Colorado EE building roof and the mesa on owned by National Institute of Standards and Technology (NIST); NIST has invested money, location and support for the program. Besides designing and building the transmissometer, that has never be accomplished at this level, the system also analyzes the atmospheric propagation of frequencies by scanning between 320 GHz and 340 GHz, which includes the peak absorption frequency at 325.1529 GHz due to water absorption. The processing and characterization of the deterministic and random propagation characteristics of the atmosphere in the real world was significantly started; this will be executed with varies aerosols for decades on the permanently mounted system that is accessible 24/7 via a network over the CU Virtual Private Network (VPN).

The 18/30 GHz fixed communications system service demand assessment. Volume 1: Executive summary

NASA Technical Reports Server (NTRS)

Gabriszeski, T.; Reiner, P.; Rogers, J.; Terbo, W.

1979-01-01

The total demand for voice, video, and data communications services, and satellite transmission services at the 4/6 GHz, 12/14 GHz, and 18/30 GHz frequencies is discussed. Major study objectives, overall methodology, results, and general observations about a satellite systems market characteristics and trends are summarized.

12.2-GHz methanol maser MMB follow-up catalogue - IV. Longitude range 20°-60°

NASA Astrophysics Data System (ADS)

Breen, S. L.; Ellingsen, S. P.; Caswell, J. L.; Green, J. A.; Voronkov, M. A.; Avison, A.; Fuller, G. A.; Quinn, L. J.

2016-07-01

This is the fourth and final instalment of a series of catalogues presenting 12.2-GHz methanol maser observations made towards each of the 6.7-GHz methanol masers detected in the Methanol Multibeam (MMB) survey. This final portion of the survey covers the 20°-60° longitude range, increasing the 12.2-GHz follow-up range to the full MMB coverage of 186° ≥ l ≤ 60° and |b| ≤ 2°. Towards a total of 260 6.7-GHz MMB methanol masers (we were unable to observe five of the MMB sources in this longitude range) we detect 116 12.2-GHz masers counterparts, 64 of which were discovered in this survey. Including data from the literature, we find that there are 12.2-GHz methanol masers towards 47.1 per cent of the 6.7-GHz methanol masers in this portion of the Galaxy. Across the entire MMB survey range, we find a detection rate of 45.3 per cent. We find that the detection rate of 12.2-GHz methanol masers as a function of Galactic longitude is not uniform and there is an excess of masers with broad velocity ranges at longitudes near 30° and 330°. Comparing the occurrence of 12.2-GHz methanol masers with MMB-targeted CO observations has shown that those outflows associated with a 12.2-GHz source have a larger average dynamical time-scale than those associated with only 6.7-GHz methanol masers, supporting the notion that the 12.2-GHz masers are associated with a later phase of high-mass star formation.

A 3.2-GHz fully integrated low-phase noise CMOS VCO with self-biasing current source for the IEEE 802.11a/hiperLAN WLAN standard

NASA Astrophysics Data System (ADS)

Quemada, C.; Adin, I.; Bistue, G.; Berenguer, R.; Mendizabal, J.

2005-06-01

A 3.3V, fully integrated 3.2-GHz voltage-controlled oscillator (VCO) is designed in a 0.18μm CMOS technology for the IEE 802.11a/HiperLAN WLAN standard for the UNII band from 5.15 to 5.35 GHz. The VCO is tunable between 2.85 GHz and 3.31 GHz. NMOS architecture with self-biasing current of the tank source is chosen. A startup circuit has been employed to avoid zero initial current. Current variation is lower than 1% for voltage supply variations of 10%. The use of a self-biasing current source in the tank provides a greater safety in the transconductance value and allows running along more extreme point operation The designed VCO displays a phase noise and output power of -98dBc/Hz (at 100 KHz offset frequency) and 0dBm respectively. This phase noise has been obtained with inductors of 2.2nH and quality factor of 12 at 3.2 GHz, and P-N junction varactors whose quality factor is estimated to exceed 40 at 3.2 GHz. These passive components have been fabricated, measured and modeled previously. The core of the VCO consumes 33mW DC power.

Perturbative studies of toroidal momentum transport in KSTAR H-mode and the effect of ion temperature perturbation

NASA Astrophysics Data System (ADS)

Yang, S. M.; Na, Yong-Su; Na, D. H.; Park, J.-K.; Shi, Y. J.; Ko, W. H.; Lee, S. G.; Hahm, T. S.

2018-06-01

Perturbative experiments have been carried out using tangential neutral beam injection (NBI) and non-resonant magnetic perturbation (NRMP) to analyze the momentum transport properties in KSTAR H-modes. Diffusive and non-diffusive terms of momentum transport are evaluated from the transient analysis. Although the operating conditions and methodologies applied in the two cases are similar, the momentum transport properties obtained show clear differences. The estimated momentum diffusivity and pinch obtained in the NBI modulation experiments is larger than that in the NRMP modulation experiments. We found that this discrepancy could be a result of uncertainties in the assumption for the analysis. By introducing time varying momentum transport coefficients depending on the temperature gradient, the linearized equation shows that if the temperature perturbation exists, the evolution of toroidal rotation perturbation could be faster than the transport rate of mean quantity, since the evolution of toroidal rotation perturbation is related to , a momentum diffusivity from perturbative analysis. This could explain the estimated higher momentum diffusivity using time independent transport coefficients in NBI experiments with higher ion temperature perturbation compared to that in NRMP modulation experiments. The differences in the momentum transport coefficient with NRMP and NBI are much reduced by considering time varying momentum transport coefficients in the time dependent transport simulation.

A 94 GHz RF Electronics Subsystem for the CloudSat Cloud Profiling Radar

NASA Technical Reports Server (NTRS)

LaBelle, Remi C.; Girard, Ralph; Arbery, Graham

2003-01-01

The CloudSat spacecraft, scheduled for launch in 2004, will carry the 94 GHz Cloud Profiling Radar (CPR) instrument. The design, assembly and test of the flight Radio Frequency Electronics Subsystem (RFES) for this instrument has been completed and is presented here. The RFES consists of an Upconverter (which includes an Exciter and two Drive Amplifiers (DA's)), a Receiver, and a Transmitter Calibrator assembly. Some key performance parameters of the RFES are as follows: dual 100 mW pulse-modulated drive outputs at 94 GHz, overall Receiver noise figure < 5.0 dB, a highly stable W-band noise source to provide knowledge accuracy of Receiver gain of < 0.4 dB over the 2 year mission life, and a W-band peak power detector to monitor the transmitter output power to within 0.5 dB over life. Some recent monolithic microwave integrated circuit (MMIC) designs were utilized which implement the DA's in 0.1 micron GaAs high electron-mobility transistor (HEMT) technology and the Receiver low-noise amplifier (LNA) in 0.1 micron InP HEMT technology.

8-12 GHz Radio Observations of Flare Activity On M dwarf CN Leo

NASA Astrophysics Data System (ADS)

Wofford, Alia; Villadsen, Jackie; Quintana, Elisa; Barclay, Thomas; Thackeray, Beverly

2018-01-01

Red dwarfs are cool stars that make up 70% of all stars. Red dwarfs can be utilized to detect potentially habitable planets but they have particularly strong magnetic activity that can be detrimental to orbiting planets’ atmospheres and habitability. A coronal mass ejection (CME) is an eruption of magnetized plasma from the star that is ejected into the interplanetary medium which can erode a planet’s atmosphere daily. Based on the sun CMEs are expected to produce very bright radio bursts along with optical flares. We are using M dwarf CN Leo, a well studied flare star that was in the K2 campaign field in summer 2017, as a template to understand the relationship between radio and optical flares and the space weather conditions impacting M dwarf planets. Using radio frequencies ranging from 0.22 GHz-12 GHz we search for simultaneous radio bursts and optical flares to infer if CMEs, flares or aurorae are occurring on the star. I will present the 8-12 GHz radio data from eight 1.5-hour observations with simultaneous optical data. CN Leo produced a bright non-thermal radio flare that lasted approximately for a day during two consecutive observations, with a gyrosynchrotron emission mechanism.

Controlled Teleportation of a Qudit State by Partially Entangled GHZ States

NASA Astrophysics Data System (ADS)

Wang, Jin-wei; Shu, Lan; Mo, Zhi-wen; Zhang, Zhi-hua

2014-08-01

In this paper, we propose a controlled teleportation scheme which communicates an arbitrary ququart state via two sets of partially entangled GHZ state. The necessary measurements and operations are given detailedly. Furthmore the scheme is generalized to teleport a qudit state via s sets of partially entangled GHZ state.

Icecube: Spaceflight Validation of an 874-GHz Submillimeter Wave Radiometer for Ice Cloud Remote Sensing

NASA Astrophysics Data System (ADS)

Wu, D. L.; Esper, J.; Ehsan, N.; Piepmeier, J. R.; Racette, P.

2014-12-01

Ice clouds play a key role in the Earth's radiation budget, mostly through their strong regulation of infrared radiation exchange. Submillimeter wave remote sensing offers a unique capability to improve cloud ice measurements from space. At 874 GHz cloud scattering produces a larger brightness temperature depression from cirrus than lower frequencies, which can be used to retrieve vertically-integrated cloud ice water path (IWP) and ice particle size. The objective of the IceCube project is to retire risks of 874-GHz receiver technology by raising its TRL from 5 to 7. The project will demonstrate, on a 3-U CubeSat in a low Earth orbit (LEO) environment, the 874-GHz receiver system with noise equivalent differential temperature (NEDT) of ~0.2 K for 1-second integration and calibration error of 2.0 K or less as measured from deep-space observations. The Goddard Space Flight Center (GSFC) is partnering with Virginia Diodes, Inc (VDI) to qualify commercially available 874-GHz receiver technology for spaceflight, and demonstrate the radiometer performance. The instrument (submm-wave cloud radiometer, or SCR), along with the CubeSat system developed and integrated by GSFC, will be ready for launch in two years. The instrument subsystem includes a reflector antenna, sub-millimeter wave mixer, frequency multipliers and stable local oscillator, an intermediate frequency (IF) circuit with noise injection, and data-power boards. The mixer and frequency multipliers are procured from VDI with GSFC insight into fabrication and testing processes to ensure scalability to spaceflight beyond TRL 7. The remaining components are a combination of GSFC-designed and commercial off-the-shelf (COTS) at TRLs of 5 or higher. The spacecraft system is specified by GSFC and comprises COTS components including three-axis stabilizer and sun sensor, GPS receiver, deployable solar arrays, UHF radio, and 2 GB of on-board storage. The spacecraft and instrument are integrated and flight qualified

A Ka-band (32 GHz) beacon link experiment (KABLE) with Mars Observer

NASA Technical Reports Server (NTRS)

Riley, A. L.; Hansen, D. M.; Mileant, A.; Hartop, R. W.

1987-01-01

A proposal for a Ka-Band (32 GHz) Link Experiment (KABLE) with the Mars Observer mission was submitted to NASA. The experiment will rely on the fourth harmonic of the spacecraft X-band transmitter to generate a 33.6 GHz signal. The experiment will rely also on the Deep Space Network (DSN) receiving station equipped to simultaneously receive X- and Ka-band signals. The experiment will accurately measure the spacecraft-to-Earth telecommunication link performance at Ka-band and X-band (8.4 GHz).

802GHz integrated horn antennas imaging array

NASA Technical Reports Server (NTRS)

Ali-Ahmad, Walid Y.; Rebeiz, Gabriel M.; Dave, Hemant; Chin, Gordon

1991-01-01

Pattern measurements at 802GHz of a single element in 256-element integrated horn imaging array are presented. The integrated-horn antenna consists of a dipole-antenna suspended on a 1-micron dielectric membrane inside a pyramidal cavity etched in silicon. The theoretical far-field patterns, calculated using reciprocity and Floquet-modes representation of the free-space field, agree well with the measured far-field patterns at 802GHz. The associated directivity for a 1.40 lambda horn aperture, calculated from the measured E and H-plane patterns is 12.3dB + or - 0.2dB. This work demonstrates that high-efficiency integrated-horn antennas are easily scalable to terahertz frequencies and could be used for radio-astronomical and plasma-diagnostic applications.

22 GHz VLBI Survey: Status Report and Preliminary Results

NASA Technical Reports Server (NTRS)

Moellenbrock, G.; Fujisawa, K.; Preston, R.; Gurvits, L.; Dewey, R.; Hirabayashi, H.; Inoue, M.; Jauncey, D.; Migenes, V.; Roberts, D.;

Development of a 150-GHz MMIC Module Prototype for Large-Scale CMB Radiation

NASA Technical Reports Server (NTRS)

Kangaslahti, Pekka P.; Samoska, Lorene A.; Gaier, Todd C.; Soria, Mary M.; Lau, Judy M.; Sieth, Matthew M.; VanWinkle, Daniel; Tantawi, Sami

2011-01-01

HEMT-based receiver arrays with excellent noise and scalability are already starting to be manufactured at 100 GHz, but the advances in technology should make it possible to develop receiver modules with even greater operation frequency up to 200 GHz. A prototype heterodyne amplifier module has been developed for operation from 140 to 170 GHz using monolithic millimeter-wave integrated circuit (MMIC) low-noise InP high electron mobility transistor (HEMT) amplifiers. The compact, scalable module is centered on the 150-GHz atmospheric window using components known to operate well at these frequencies. Arrays equipped with hundreds of these modules can be optimized for many different astrophysical measurement techniques, including spectroscopy and interferometry. This module is a heterodyne receiver module that is extremely compact, and makes use of 35-nm InP HEMT technology, and which has been shown to have excellent noise temperatures when cooled cryogenically to 30 K. This reduction in system noise over prior art has been demonstrated in commercial mixers (uncooled) at frequencies of 160-180 GHz. The module is expected to achieve a system noise temperature of 60 K when cooled. An MMIC amplifier module has been designed to demonstrate the feasibility of expanding heterodyne amplifier technology to the 140 to 170-GHz frequency range for astronomical observations. The miniaturization of many standard components and the refinement of RF interconnect technology have cleared the way to mass-production of heterodyne amplifier receivers, making it a feasible technology for many large-population arrays. This work furthers the recent research efforts in compact coherent receiver modules, including the development of the Q/U Imaging ExperimenT (QUIET) modules centered at 40 and 90 GHz, and the production of heterodyne module prototypes at 90 GHz.

A 32-GHz solid-state power amplifier for deep space communications

NASA Technical Reports Server (NTRS)

Wamhof, P. D.; Rascoe, D. L.; Lee, K. A.; Lansing, F. S.

1994-01-01

A 1.5-W solid-state power amplifier (SSPA) has been demonstrated as part of an effort to develop and evaluate state-of-the-art transmitter and receiver components at 32 and 35 GHz for future deep space missions. Output power and efficiency measurements for a monolithic millimeter-wave integrated circuit (MMIC)-based SSPA are reported. Technical design details for the various modules and a thermal analysis are discussed, as well as future plans.

Simulation of 100-300 GHz solid-state harmonic sources

NASA Technical Reports Server (NTRS)

Zybura, Michael F.; Jones, J. Robert; Jones, Stephen H.; Tait, Gregory B.

1995-01-01

Accurate and efficient simulations of the large-signal time-dependent characteristics of second-harmonic Transferred Electron Oscillators (TEO's) and Heterostructure Barrier Varactor (HBV) frequency triplers have been obtained. This is accomplished by using a novel and efficient harmonic-balance circuit analysis technique which facilitates the integration of physics-based hydrodynamic device simulators. The integrated hydrodynamic device/harmonic-balance circuit simulators allow TEO and HBV circuits to be co-designed from both a device and a circuit point of view. Comparisons have been made with published experimental data for both TEO's and HBV's. For TEO's, excellent correlation has been obtained at 140 GHz and 188 GHz in second-harmonic operation. Excellent correlation has also been obtained for HBV frequency triplers operating near 200 GHz. For HBV's, both a lumped quasi-static equivalent circuit model and the hydrodynamic device simulator have been linked to the harmonic-balance circuit simulator. This comparison illustrates the importance of representing active devices with physics-based numerical device models rather than analytical device models.

Vertical InAs nanowire wrap gate transistors with f(t) > 7 GHz and f(max) > 20 GHz.

PubMed

Egard, M; Johansson, S; Johansson, A-C; Persson, K-M; Dey, A W; Borg, B M; Thelander, C; Wernersson, L-E; Lind, E

2010-03-10

In this letter we report on high-frequency measurements on vertically standing III-V nanowire wrap-gate MOSFETs (metal-oxide-semiconductor field-effect transistors). The nanowire transistors are fabricated from InAs nanowires that are epitaxially grown on a semi-insulating InP substrate. All three terminals of the MOSFETs are defined by wrap around contacts. This makes it possible to perform high-frequency measurements on the vertical InAs MOSFETs. We present S-parameter measurements performed on a matrix consisting of 70 InAs nanowire MOSFETs, which have a gate length of about 100 nm. The highest unity current gain cutoff frequency, f(t), extracted from these measurements is 7.4 GHz and the maximum frequency of oscillation, f(max), is higher than 20 GHz. This demonstrates that this is a viable technique for fabricating high-frequency integrated circuits consisting of vertical nanowires.

The Use of a 28 GHz Gyrotron for EBW Startup Experiments on MAST

NASA Astrophysics Data System (ADS)

Caughman, J. B.; Bigelow, T. S.; Diem, S. J.; Peng, Y. K. M.; Rasmussen, D. A.; Shevchenko, V.; Hawes, J.; Lloyd, B.

2009-11-01

The use of electron Bernstein waves for non-inductive plasma current startup in MAST has recently been demonstrated [1]. The injection of 100 kW at 28 GHz generated plasma currents of up to 33 kA without the use of solenoid flux, and limited solenoid assist resulted in up to 55 kA of plasma current. A higher power 28 GHz gyrotron, with power levels of up to 300 kW for 0.5 seconds, is currently being commissioned. It is being used to investigate the scaling of startup current with microwave power and power profile as a function of time. Power modulation experiments are also being explored. Gyrotron performance and experimental results will be presented. [4pt] [1] V. Shevchenko, et al., Proceedings of the 15^th Joint Workshop on ECE and ECRH, Yosimite, USA, p. 68 (2009)

47 CFR 101.17 - Performance requirements for the 38.6-40.0 GHz frequency band.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 47 Telecommunication 5 2013-10-01 2013-10-01 false Performance requirements for the 38.6-40.0 GHz frequency band. 101.17 Section 101.17 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Applications and Licenses General Filing...

47 CFR 101.17 - Performance requirements for the 38.6-40.0 GHz frequency band.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 47 Telecommunication 5 2014-10-01 2014-10-01 false Performance requirements for the 38.6-40.0 GHz frequency band. 101.17 Section 101.17 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Applications and Licenses General Filing...

47 CFR 101.17 - Performance requirements for the 38.6-40.0 GHz frequency band.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 5 2010-10-01 2010-10-01 false Performance requirements for the 38.6-40.0 GHz frequency band. 101.17 Section 101.17 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Applications and Licenses General Filing...

47 CFR 101.17 - Performance requirements for the 38.6-40.0 GHz frequency band.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 5 2011-10-01 2011-10-01 false Performance requirements for the 38.6-40.0 GHz frequency band. 101.17 Section 101.17 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Applications and Licenses General Filing...

47 CFR 101.17 - Performance requirements for the 38.6-40.0 GHz frequency band.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 47 Telecommunication 5 2012-10-01 2012-10-01 false Performance requirements for the 38.6-40.0 GHz frequency band. 101.17 Section 101.17 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Applications and Licenses General Filing...

A 90 GHz Amplifier Assembled Using a Bump-Bonded InP-Based HEMT

NASA Technical Reports Server (NTRS)

Pinsukanjana, Paul R.; Samoska, Lorene A.; Gaier, Todd C.; Smith, R. Peter; Ksendzov, Alexander; Fitzsimmons, Michael J.; Martin, Suzanne C.

1998-01-01

We report on the performance of a novel W-band amplifier fabricated utilizing very compact bump bonds. We bump-bonded a high-speed, low-noise InP high electron mobility transistor (HEMT) onto a separately fabricated passive circuit having a GaAs substrate. The compact bumps and small chip size were used for efficient coupling and maximum circuit design flexibility. This new quasi-monolithic millimeter-wave integrated circuit (Q-MMIC) amplifier exhibits a peak gain of 5.8 dB at approx. 90 GHz and a 3 dB bandwidth of greater than 25%. To our knowledge, this is the highest frequency amplifier assembled using bump-bonded technology. Our bump-bonding technique is a useful alternative to the high cost of monolithic millimeter-wave integrated circuits (MMIC's). Effects of the bumps on the circuit appear to be minimal. We used the simple matching circuit for demonstrating the technology - future circuits would have all of the elements (resistors, via holes, bias lines, etc.) included 'in conventional MMIC's. Our design in different from other investigators' efforts in that the bumps are only 8 microns thick by 15 microns wide. The bump sizes were sufficiently small that the devices, originally designed for W-band hybrid circuits, could be bonded without alteration. Figure 3 shows the measured and simulated magnitude of S-parameters from 85-120 GHz, of the InP HEMT bump-bonded to the low noise amplifier (LNA) passive. The maximum gain is 5.8 dB at approx. 90 GHz, and gain extends to 117 GHz. Measurement of a single device (without matching networks) shows approx. 1 dB of gain at 90 GHz. The measured gain of the amplifier agrees well with the design in the center of the measurement band, and the agreement falls off at the band edges. Since no accommodation for the bump-bonding parasitics was made in the design, the result implies that the parasitic elements associated with the bonding itself do not dominate the performance of the LNA circuit. It should be noted that this

GHz low noise short wavelength infrared (SWIR) photoreceivers

NASA Astrophysics Data System (ADS)

Bai, Xiaogang; Yuan, Ping; McDonald, Paul; Boisvert, Joseph; Chang, James; Woo, Robyn; Labios, Eduardo; Sudharsanan, Rengarajan; Krainak, Michael; Yang, Guangning; Sun, Xiaoli; Lu, Wei; McIntosh, Dion; Zhou, Qiugui; Campbell, Joe

2011-06-01

Next generation LIDAR mapping systems require multiple channels of sensitive photoreceivers that operate in the wavelength region of 1.06 to 1.55 microns, with GHz bandwidth and sensitivity less than 300 fW/√Hz. Spectrolab has been developing high sensitivity photoreceivers using InAlAs impact ionization engineering (I2E) avalanche photodiodes (APDs) structures for this application. APD structures were grown using metal organic vapor epitaxy (MOVPE) and mesa devices were fabricated using these structures. We have achieved low excess noise at high gain in these APD devices; an impact ionization parameter, k, of about 0.15 has been achieved at gains >20 using InAlAs/InGaAlAs as a multiplier layer. Electrical characterization data of these devices show dark current less than 2 nA at a gain of 20 at room temperature; and capacitance of 0.4 pF for a typical 75 micron diameter APD. Photoreceivers were built by integrating I2E APDs with a low noise GHz transimpedance amplifier (TIA). The photoreceivers showed a bandwidth of 1 GHz and a noise equivalent power (NEP) of 150 fW/rt(Hz) at room temperature.

Waveguide Power-Amplifier Module for 80 to 150 GHz

NASA Technical Reports Server (NTRS)

Samoska, Lorene; Weinreb, Sander; Peralta, Alejandro

2006-01-01

A waveguide power-amplifier module capable of operating over the frequency range from 80 to 150 GHz has been constructed. The module comprises a previously reported power amplifier packaged in a waveguide housing that is compatible with WR-8 waveguides. (WR- 8 is a standard waveguide size for the nominal frequency range from 90 to 140 GHz.) The waveguide power-amplifier module is robust and can be bolted to test equipment and to other electronic circuits with which the amplifier must be connected for normal operation.

Oscillations up to 712 GHz in InAs/AlSb resonant-tunneling diodes

NASA Technical Reports Server (NTRS)

Brown, E. R.; Parker, C. D.; Mahoney, L. J.; Molvar, K. M.; Soderstrom, J. R.

1991-01-01

Oscillations have been obtained at frequencies from 100 to 712 GHz in InAs/AlSb double-barrier resonant-tunneling diodes at room temperature. The measured power density at 360 GHz was 90 W/sq cm, which is 50 times that generated by GaAs/AlAs diodes at essentially the same frequency. The oscillation at 712 GHz represents the highest frequency reported to date from a solid-state electronic oscillator at room temperature.

A Multi-Feed Receiver in the 18 to 26.5 GHz Band for Radio Astronomy

NASA Astrophysics Data System (ADS)

Orfei, A.; Carbonaro, L.; Cattani, A.; Cremonini, A.; Cresci, L.; Fiocchi, F.; Maccaferri, A.; Maccaferri, G.; Mariotti, S.; Monari, J.; Morsiani, M.; Natale, V.; Nesti, R.; Panella, D.; Poloni, M.; Roda, J.; Scalambra, A.; Tofani, G.

2010-08-01

A large-bandwidth, state-of-the-art multi-feed receiver has been constructed to be used on the new 64 m Sardinia Radio Telescope (SRT) (http://www.srt.inaf.itl), an antenna aiming to work from 300 MHz to 100 GHz with an almost continuous frequency coverage. The goal of this new receiver is to speed up the survey of the sky with high sensitivity in a frequency band that is very interesting to radio astronomers. In the meantime, the antenna erection has been finalized, and the receiver has been mounted on the Medicina 32 m antenna to be tested (http://www.med.ira.inaf.itl). We present a complete description of the system, including a dedicated backend, and the results of the tests.

Propagation handbook, frequencies above 10 GHz

NASA Technical Reports Server (NTRS)

Ippolito, Louis J.

1988-01-01

The progress and accomplishments in the developmet of the Fourth Edition of the NASA Propagation Effects Handbook for Satellite Systems Design, for frequencies 10 to 100 GHz, NASA Reference Publication 1082(04), dated May 1988, prepared by Westighouse Electric Corporation for the Jet Propulsion Laboratory are discussed.

A new structure of superconducting magnetic system for 50 GHz operations (invited).

PubMed

Xie, D Z

2012-02-01

High field and high frequency have been leading the development of electron cyclotron resonance ion sources (ECRISs) in the past decade as demonstrated by the achieved great performance. The present superconducting magnet structures built with NbTi wires have reached an axial field of 3.5-4.0 T and a radial field of 2.0 T for operating frequency up to 28 GHz. Further increase of the magnetic field strength will require higher current superconductor, i.e., Nb(3)Sn wires. This paper will present the features of a new superconducting magnet structure and review of the existing structures. Using NbTi wires, the new magnet structure could be able to produce maximum fields of 7.0 T on axis and radial field of 3.7 T at a hexagonal plasma chamber wall for ECRIS operations up to 50 GHz. If this new magnet can be built with Nb(3)Sn wires, much higher fields can be expected.

Demonstration of a High-Order Mode Input Coupler for a 220-GHz Confocal Gyrotron Traveling Wave Tube

NASA Astrophysics Data System (ADS)

Guan, Xiaotong; Fu, Wenjie; Yan, Yang

2018-02-01

A design of high-order mode input coupler for 220-GHz confocal gyrotron travelling wave tube is proposed, simulated, and demonstrated by experimental tests. This input coupler is designed to excite confocal TE 06 mode from rectangle waveguide TE 10 mode over a broadband frequency range. Simulation results predict that the optimized conversion loss is about 2.72 dB with a mode purity excess of 99%. Considering of the gyrotron interaction theory, an effective bandwidth of 5 GHz is obtained, in which the beam-wave coupling efficiency is higher than half of maximum. The field pattern under low power demonstrates that TE 06 mode is successfully excited in confocal waveguide at 220 GHz. Cold test results from the vector network analyzer perform good agreements with simulation results. Both simulation and experimental results illustrate that the reflection at input port S11 is sensitive to the perpendicular separation of two mirrors. It provides an engineering possibility for estimating the assembly precision.

AlGaInN laser diode technology for GHz high-speed visible light communication through plastic optical fiber and water

NASA Astrophysics Data System (ADS)

Najda, Stephen P.; Perlin, Piotr; Suski, Tadek; Marona, Lucja; Leszczyński, Mike; Wisniewski, Przemek; Czernecki, Robert; Kucharski, Robert; Targowski, Grzegorz; Watson, Malcolm A.; White, Henry; Watson, Scott; Kelly, Antony E.

2016-02-01

AlGaInN ridge waveguide laser diodes are fabricated to achieve single-mode operation with optical powers up to 100 mW at ˜420 nm for visible free-space, underwater, and plastic optical fiber communication. We report high-frequency operation of AlGaInN laser diodes with data transmission up to 2.5 GHz for free-space and underwater communication and up to 1.38 GHz through 10 m of plastic optical fiber.

Continuous-Wave Operation of a 460-GHz Second Harmonic Gyrotron Oscillator

PubMed Central

Hornstein, Melissa K.; Bajaj, Vikram S.; Griffin, Robert G.; Temkin, Richard J.

2007-01-01

We report the regulated continuous-wave (CW) operation of a second harmonic gyrotron oscillator at output power levels of over 8 W (12.4 kV and 135 mA beam voltage and current) in the TE0,6,1 mode near 460 GHz. The gyrotron also operates in the second harmonic TE2,6,1 mode at 456 GHz and in the TE2,3,1 fundamental mode at 233 GHz. CW operation was demonstrated for a one-hour period in the TE0,6,1 mode with better than 1% power stability, where the power was regulated using feedback control. Nonlinear simulations of the gyrotron operation agree with the experimentally measured output power and radio-frequency (RF) efficiency when cavity ohmic losses are included in the analysis. The output radiation pattern was measured using a pyroelectric camera and is highly Gaussian, with an ellipticity of 4%. The 460-GHz gyrotron will serve as a millimeter-wave source for sensitivity-enhanced nuclear magnetic resonance (dynamic nuclear polarization) experiments at a magnetic field of 16.4 T. PMID:17710187

A 0.4 to 10 GHz airborne electromagnetic environment survey of USA urban areas

NASA Technical Reports Server (NTRS)

Taylor, R. E.; Hill, J. S.

1976-01-01

An airborne electromagnetic-environment survey of some U.S. metropolitan areas measured terrestrial emissions within the broad frequency spectrum from 0.4 to 10 GHz. A Cessna 402 commercial aircraft was fitted with both nadir-viewing and horizon-viewing antennas and instrumentation, including a spectrum analyzer, a 35 mm continuous film camera, and a magnetic tape recorder. Most of the flights were made at a nominal altitude of 10,000 feet, and Washington, D. C., Baltimore, Philadelphia, New York, and Chicago were surveyed. The 450 to 470 MHz land-mobile UHF band is especially crowded, and the 400 to 406 MHz space bands are less active. This paper discusses test measurements obtained up to 10 GHz. Sample spectrum analyzer photograhs were selected from a total of 5,750 frames representing 38 hours of data.

The cosmology large angular scale surveyor (CLASS): 40 GHz optical design

NASA Astrophysics Data System (ADS)

Eimer, Joseph R.; Bennett, Charles L.; Chuss, David T.; Marriage, Tobias; Wollack, Edward J.; Zeng, Lingzhen

2012-09-01

The Cosmology Large Angular Scale Surveyor (CLASS) instrument will measure the polarization of the cosmic microwave background at 40, 90, and 150 GHz from Cerro Toco in the Atacama desert of northern Chile. In this paper, we describe the optical design of the 40 GHz telescope system. The telescope is a diffraction limited catadioptric design consisting of a front-end Variable-delay Polarization Modulator (VPM), two ambient temperature mirrors, two cryogenic dielectric lenses, thermal blocking filters, and an array of 36 smooth-wall scalar feedhorn antennas. The feed horns guide the signal to antenna-coupled transition-edge sensor (TES) bolometers. Polarization diplexing and bandpass definition are handled on the same microchip as the TES. The feed horn beams are truncated with 10 dB edge taper by a 4 K Lyot-stop to limit detector loading from stray light and control the edge illumination of the front-end VPM. The field-of-view is 19° x 14° with a resolution for each beam on the sky of 1.5° FWHM.

The Cosmology Large Angular Scale Surveyor (CLASS): 40 GHz Optical Design

NASA Technical Reports Server (NTRS)

Eimer, Joseph R.; Bennett, Charles L.; Chuss, David T.; Marriage, Tobias; Wollack, Edward J.; Zeng, Lingzhen

2012-01-01

The Cosmology Large Angular Scale Surveyor (CLASS) instrument will measure the polarization of the cosmic microwave background at 40, 90, and 150 GHz from Cerro Toco in the Atacama desert of northern Chile. In this paper, we describe the optical design of the 40 GHz telescope system. The telescope is a diffraction limited catadioptric design consisting of a front-end Variable-delay Polarization Modulator (VPM), two ambient temperature mirrors, two cryogenic dielectric lenses, thermal blocking filters, and an array of 36 smooth-wall scalar feedhorn antennas. The feed horns guide the signal to antenna-coupled transition-edge sensor (TES) bolometers. Polarization diplexing and bandpass definition are handled on the same microchip as the TES. The feed horn beams are truncated with 10 dB edge taper by a 4 K Lyot-stop to limit detector loading from stray light and control the edge illumination of the front-end VPM. The field-of-view is 19 deg x 14 deg with a resolution for each beam on the sky of 1.5 deg. FWHM.

Superconductive hot-electron-bolometer mixer receiver for 800-GHz operation

NASA Astrophysics Data System (ADS)

Kawamura, J.; Blundell, R.; Tong, C.-Y. E.; Papa, D. C.; Hunter, T. R.; Paine, S. N.; Patt, F.; Gol'Tsman, G.; Cherednichenko, S.; Voronov, B.; Gershenzon, E.

2000-04-01

In this paper, we describe a superconductive hot-electron-bolometer mixer receiver designed to operate in the partially transmissive 350-μm atmospheric window. The receiver employs an NbN thin-film microbridge as the mixer element, in which the main cooling mechanism of the hot electrons is through electron-phonon interaction. At a local-oscillator frequency of 808 GHz, the measured double-sideband receiver noise temperature is Trx=970 K, across a 1-GHz intermediate-frequency bandwidth centered at 1.8 GHz. We have measured the linearity of the receiver and the amount of local-oscillator power incident on the mixer for optimal operation, which is PLO ≈ 1 microwatt. This receiver was used in making observations as a facility instrument at the Heinrich Hertz Telescope, Mt. Graham, AZ, during the 1998-1999 winter observing season.

32 GHz Celestial Reference Frame Survey for Dec < -45 deg.

NASA Astrophysics Data System (ADS)

Horiuchi, Shinji; Phillips, Chris; Stevens, Jamie; Jacobs, Christopher; Sotuela, Ioana; Garcia miro, Cristina

2013-04-01

(We resubmit this proposal to extend from the previous semester. The 24 hour blocks for ATCA and Mopra were granted in May 2012 but canceled because fringe test before the scheduled experiment failed although fringes were detected between Mopra and Tidbinbilla. As it turned out ATCA had an issue with frequency standard, which has now been resolved.) We propose to conduct a LBA survey of compact radio sources at 32 GHz near the south pole region. This is the first attempt to fill the gap in the existing 32 GHz catalogue establish by NASA Deep Space Network toward completing the full sky celestial reference frame at 32 GHz. The catalogue will be used for future spacecraft navigation by NASA and other space agencies as well as for radio astronomical observations with southern radio telescope arrays such as ATCA and LBA.

Relating SMMR 37 GHz polarization difference to precipitation and atmospheric carbon dioxide concentration - A reappraisal

NASA Technical Reports Server (NTRS)

Tucker, C. J.

1992-01-01

The relations of Scanning Multi-channel Microwave Radiometer (SMMR) 37 GHz polarization difference to precipitation and atmospheric carbon dioxide (CO2) concentrations are reviewed. Annual precipitation data, a surrogate for green leaf vegetation density, are compared with the coincident SMMR 37 GHz polarization difference from arid and semi-arid West Africa for 1982-85. The SMMR 37 GHz polarization difference was found to be poorly correlated with precipitation in arid and semi-arid zones, contrary to previous reports. Coincident SMMR 37 GHz polarization difference and atmospheric CO2 concentration data from July 1981 to June 1983 are also reviewed. Previously suggested relations of the SMMR 37 GHz polarization difference to atmospheric CO2 concentrations were found to be heavily biased by winter conditions in the Northern Hemisphere. The use of the SMMR 37 GHz polarization difference for determining green leaf vegetation density, net primary production, atmospheric CO2 draw-down and related processes is questioned.

Control system renewal for efficient operation in RIKEN 18 GHz electron cyclotron resonance ion source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Uchiyama, A., E-mail: a-uchi@riken.jp; Ozeki, K.; Higurashi, Y.

A RIKEN 18 GHz electron cyclotron resonance ion source (18 GHz ECRIS) is used as an external ion source at the Radioactive Ion Beam Factory (RIBF) accelerator complex to produce an intense beam of medium-mass heavy ions (e.g., Ca and Ar). In most components that comprise the RIBF, the control systems (CSs) are integrated by the Experimental Physics and Industrial Control System (EPICS). On the other hand, a non-EPICS-based system has hardwired controllers, and it is used in the 18 GHz ECRIS CS as an independent system. In terms of efficient and effective operation, the 18 GHz ECRIS CS asmore » well as the RIBF CS should be renewed using EPICS. Therefore, we constructed an 18 GHz ECRIS CS by using programmable logic controllers with embedded EPICS technology. In the renewed system, an operational log system was developed as a new feature, for supporting of the 18 GHz ECRIS operation.« less

Modeling of NASA's 30/20 GHz satellite communications system

NASA Technical Reports Server (NTRS)

Kwatra, S. C.; Maples, B. W.; Stevens, G. A.

1984-01-01

NASA is in the process of developing technology for a 30/20 GHz satellite communications link. Currently hardware is being assembled for a test transponder. A simulation package is being developed to study the link performance in the presence of interference and noise. This requires developing models for the components of the system. This paper describes techniques used to model the components for which data is available. Results of experiments performed using these models are described. A brief overview of NASA's 30/20 GHz communications satellite program is also included.

Low-noise 115-GHz receiver using superconducting tunnel junctions

NASA Technical Reports Server (NTRS)

Pan, S.-K.; Feldman, M. J.; Kerr, A. R.; Timble, P.

1983-01-01

A 110-118-GHz receiver based on a superconducting quasiparticle tunnel junction mixer is described. The single-sideband noise temperature is as low as 68 + or - 3 K. This is nearly twice the sensitivity of any other receiver at this frequency. The receiver was designed using a low-frequency scale model in conjunction with the quantum mixer theory. A scaled version of the receiver for operation at 46 GHz has a single-sideband noise temperature of 55 K. The factors leading to the success of this design are discussed.

670-GHz Down- and Up-Converting HEMT-Based Mixers

NASA Technical Reports Server (NTRS)

Schlecht, Enrich T.; Chattopadhyay, Goutam; Lin, Robert H.; Sin, Seth; Deal, William; Rodriquez, Bryan; Bayuk, Brian; Leong, Kevin; Mei, Gerry

2012-01-01

A large category of scientific investigation takes advantage of the interactions of signals in the frequency range from 300 to 1,000 GHz and higher. This includes astronomy and atmospheric science, where spectral observations in this frequency range give information about molecular abundances, pressures, and temperatures of small-sized molecules such as water. Additionally, there is a minimum in the atmospheric absorption at around 670 GHz that makes this frequency useful for terrestrial imaging, radar, and possibly communications purposes. This is because 670 GHz is a good compromise for imaging and radar applications between spatial resolution (for a given antenna size) that favors higher frequencies, and atmospheric losses that favor lower frequencies. A similar trade-off applies to communications link budgets: higher frequencies allow smaller antennas, but incur a higher loss. All of these applications usually require converting the RF (radio frequency) signal at 670 GHz to a lower IF (intermediate frequency) for processing. Further, transmitting for communication and radar generally requires up-conversion from IF to the RF. The current state-of-the-art device for performing the frequency conversion is based on Schottky diode mixers for both up and down conversion in this frequency range for room-temperature operation. Devices that can operate at room temperature are generally required for terrestrial, military, and planetary applications that cannot tolerate the mass, bulk, and power consumption of cryogenic cooling. The technology has recently advanced to the point that amplifiers in the region up to nearly 1,000 GHz are feasible. Almost all of these have been based on indium phosphide pseudomorphic high-electron mobility transistors (pHEMTs), in the form of monolithic microwave integrated circuits (MMICs). Since the processing of HEMT amplifiers is quite differ en t from that of Schottky diodes, use of Schottky mixers requires separate MMICs for the mixers

Solar transits radio measurements on 12 and 24 ghz - january 2013 campaign. (French Title: Transits solaires 12 et 24 ghz - campagne de mesures janvier 2013)

NASA Astrophysics Data System (ADS)

Palancade, J. P.

2012-12-01

Above 1GHz, the qualification of a receiving radio-equipment is not an easy task for radio amateurs. The available measurement equipments is generally not accessible most of the time for reasons such as price, availability and knowledge to use them. The results of these measurements are generally very sensitive to the way they are performed and each parameter has to be carefully controlled and taken into account to limit the range of possible results interpretation. Fortunately one of the best tool to check a microwave receiving installation is the sun. The most popular measurement used by amateur people is the comparison of the signal intensity between the sun and a cold sky region, by simply pointing the antenna (named Cs/Sun). The present study , after a short description of the home made radio equipment involved, aims to present the results of a measurements campaign of solar transits on 11.2 and 24 GHz during 28 consecutive days in January 2013. Preliminary results of the present study tend to show that if, the amplitude fluctuations recorded on 11.2 GHz can be correlated with radio solar flux variations, on 24 GHz, the same radio solar flux variations are hidden by meteorological events such as clouds coverage and probably hygrometry.

Single-dish high sensitivity determination of solar limb emission at 22 and 44 GHz

NASA Technical Reports Server (NTRS)

Costa, J. E. R.; Homor, J. L.; Kaufmann, P.

1986-01-01

A large number of solar maps were obtained with the use of Itapetinga 45 ft antenna at 22 GHz and 44 GHz. A statistical study of these maps, reduced using original techniques, permitted the establishment of the solar radius with great accuracy at the two frequencies. It is found that 22 GHz and 44 BHz radiation originates at 16,00 km and 12,500 km above the photosphere, respectively. Excess emission due to active regions was clearly identified at lower solar latitudes above and below the equator, extending up to 26,000 km and 16,500 km above the photosphere, at 22 GHs and 44 GHz, respectively.

Design and simulation of a ~390 GHz seventh harmonic gyrotron using a large orbit electron beam

NASA Astrophysics Data System (ADS)

Li, Fengping; He, Wenlong; Cross, Adrian W.; Donaldson, Craig R.; Zhang, Liang; Phelps, Alan D. R.; Ronald, Kevin

2010-04-01

A ~390 GHz harmonic gyrotron based on a cusp electron gun has been designed and numerically modelled. The gyrotron operates at the seventh harmonic of the electron cyclotron frequency with the beam interacting with a TE71 waveguide mode. Theoretical as well as numerical simulation results using the 3D particle-in-cell code MAGIC are presented. The cusp gun generated an axis-encircling, annular shaped electron beam of energy 40 keV, current 1.5 A with a velocity ratio α of 3. Smooth cylindrical waveguides have been studied as the interaction cavities and their cavity Q optimized for 390 GHz operation. In the simulations ~600 W of output power at the design frequency has been demonstrated.

Radio variability in complete samples of extragalactic radio sources at 1.4 GHz

NASA Astrophysics Data System (ADS)

Rys, S.; Machalski, J.

1990-09-01

Complete samples of extragalactic radio sources obtained in 1970-1975 and the sky survey of Condon and Broderick (1983) were used to select sources variable at 1.4 GHz, and to investigate the characteristics of variability in the whole population of sources at this frequency. The radio structures, radio spectral types, and optical identifications of the selected variables are discussed. Only compact flat-spectrum sources vary at 1.4 GHz, and all but four are identified with QSOs, BL Lacs, or other (unconfirmed spectroscopically) stellar objects. No correlation of degree of variability at 1.4 GHz with Galactic latitude or variability at 408 MHz has been found, suggesting that most of the 1.4-GHz variability is intrinsic and not caused by refractive scintillations. Numerical models of the variability have been computed.

ATLAS 10 GHz ECR ions source upgrade project.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moehs, D. P.; Pardo, R. C.; Vondrasek, R.

1999-08-10

A major upgrade of the first ATLAS 10 GHz ECR ion source, which began operations in 1987, is in the planning and procurement phase. The new design will convert the old two-stage source into a single-stage source with an electron donor disk and high gradient magnetic field that preserves radial access for solid material feeds and pumping of the plasma chamber. The new magnetic field profile allows for the possibility of a second ECR zone at a frequency of 14 GHz. An open hexapole configuration, using a high energy-product Nd-Fe-B magnet material, having an inner diameter of 8.8 cm andmore » pole gaps of 2.4 cm has been adopted. Models indicate that the field strengths at the chamber wall, 4 cm in radius, will be 9.3 kG along the magnet poles and 5.6 kG along the pole gaps. The individual magnet bars will be housed in austenitic stainless steel allowing the magnet housing within the aluminum plasma chamber to be used as a water channel for direct cooling of the magnets. Eight solenoid coils from the existing ECR will be enclosed in an iron yoke to produce the axial mirror. Based on a current of 500 A, the final model predicts a minimum B field of 3 kG with injection and extraction mirror ratios of 4.4 and 2.9 respectively.« less

Short-lived solar burst spectral component at f approximately 100 GHz

NASA Technical Reports Server (NTRS)

Kaufmann, P.; Correia, E.; Costa, J. E. R.; Vaz, A. M. Z.

1986-01-01

A new kind of burst emission component was discovered, exhibiting fast and distinct pulses (approx. 60 ms durations), with spectral peak emission at f approx. 100 GHz, and onset time coincident to hard X-rays to within approx. 128 ms. These features pose serious constraints for the interpretation using current models. One suggestion assumes the f approx. 100 GHz pulses emission by synchrotron mechanism of electrons accelerated to ultrarelativistic energies. The hard X-rays originate from inverse Compton scattering of the electrons on the synchrotron photons. Several crucial observational tests are needed for the understanding of the phenomenon, requiring high sensitivity and high time resolution (approx. 1 ms) simultaneous to high spatial resolution (0.1 arcsec) at f approx. 110 GHz and hard X-rays.

20/30 GHz satellite systems technology needs assessment. [for domestic communications

NASA Technical Reports Server (NTRS)

Stevens, G.; Wright, D.

1978-01-01

The paper surveys the system and market work done at NASA-Lewis with regard to exploring the potential of the 20/30 GHz bands for domestic satellite communications. The 20/30 GHz bands appear attractive economically and, with certain technology advances, appear to offer a virtually unlimited spectrum resource. This attractiveness is especially relevant to high density trunking where there is sufficient traffic to justify dual-station site diversity. Ongoing system and market studies actively involve satellite system suppliers and carriers as well as the government in a cooperative, mutually beneficial effort. It is considered that this is the approach most likely to result in a spectrum-efficient acceptable-risk high-capacity 30/30 GHz satellite system which is relevant to anticipated markets.

32 GHz Celestial Reference Frame Survey for Dec < -45 deg.

NASA Astrophysics Data System (ADS)

Horiuchi, Shinji; Phillips, Chris; Stevens, Jamie; Jacobs, Christopher; Sotuela, Ioana; Garcia miro, Cristina

2014-04-01

(We resubmit this proposal to extend from the previous semester. The 24 hour blocks for ATCA and Mopra were granted in May 2012 but canceled because fringe test before the scheduled experiment failed although fringes were detected between Mopra and Tidbinbilla. During the last scheduled LBA session for this project we discovered ATCA/Mopra had an issue with frequency standard, which has now been resolved.) We propose to conduct a LBA survey of compact radio sources at 32 GHz near the south pole region. This is the first attempt to fill the gap in the existing 32 GHz catalogue establish by NASA Deep Space Network toward completing the full sky celestial reference frame at 32 GHz. The catalogue will be used for future spacecraft navigation by NASA and other space agencies as well as for radio astronomical observations with southern radio telescope arrays such as ATCA and LBA.

Thermoregulatory responses of rats exposed to 9. 3-GHz radio-frequency radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frei, M.R.; Jauchem, J.R.; Heinmets, F.

1987-10-15

Ketamine-anesthetized Sprague-Dawley rats were exposed in H orientation to far-field 9.3-GHz continuous-wave (CW) and pulsed (2 microseconds 500 pps) radiofrequency radiation (RFR) at average power densities of 30 and 60 mW/sq. cm (whole-body average specific absorption rates of 9.3 and 18.6 W/kg, respectively). Irradiation was conducted to cyclicly increase colonic temperature from 38.5 to 39.5 C. Colonic, tympanic, and subcutaneous temperatures, ECG, blood pressure, and respiratory rate were continuously recorded during experimentation. At both power densities, the subcutaneous and tympanic temperature increases significantly exceeded the colonic temperature increase. At both exposure levels, heart rate increased significantly during irradiation and returnedmore » to baseline when exposure was discontinued. Blood pressure and respiratory rate did not significantly change during irradiation. There were no significant differences between the effects of CW and pulsed RFR exposure. The levels of subcutaneous heating and heart rate change were greater, and the times required to achieve and to recover from a 1 C colonic temperature increase were longer than in previous studies conducted at 2.8 GHz. Results of these studies indicate that the carrier frequency used during irradiation markedly affects the pattern of heat distribution and the physiological responses of RF-irradiated animals.« less

Tree attenuation at 20 GHz: Foliage effects

NASA Technical Reports Server (NTRS)

Vogel, Wolfhard J.; Goldhirsh, Julius

1993-01-01

Static tree attenuation measurements at 20 GHz (K-Band) on a 30 deg slant path through a mature Pecan tree with and without leaves showed median fades exceeding approximately 23 dB and 7 dB, respectively. The corresponding 1% probability fades were 43 dB and 25 dB. Previous 1.6 GHz (L-Band) measurements for the bare tree case showed fades larger than those at K-Band by 3.4 dB for the median and smaller by approximately 7 dB at the 1% probability. While the presence of foliage had only a small effect on fading at L-Band (approximately 1 dB additional for the median to 1% probability range), the attenuation increase was significant at K-Band, where it increased by about 17 dB over the same probability range.

Tree attenuation at 20 GHz: Foliage effects

NASA Astrophysics Data System (ADS)

Vogel, Wolfhard J.; Goldhirsh, Julius

1993-08-01

Static tree attenuation measurements at 20 GHz (K-Band) on a 30 deg slant path through a mature Pecan tree with and without leaves showed median fades exceeding approximately 23 dB and 7 dB, respectively. The corresponding 1% probability fades were 43 dB and 25 dB. Previous 1.6 GHz (L-Band) measurements for the bare tree case showed fades larger than those at K-Band by 3.4 dB for the median and smaller by approximately 7 dB at the 1% probability. While the presence of foliage had only a small effect on fading at L-Band (approximately 1 dB additional for the median to 1% probability range), the attenuation increase was significant at K-Band, where it increased by about 17 dB over the same probability range.

Multi-GHz Synchronous Waveform Acquisition With Real-Time Pattern-Matching Trigger Generation

NASA Astrophysics Data System (ADS)

Kleinfelder, Stuart A.; Chiang, Shiuh-hua Wood; Huang, Wei

2013-10-01

A transient waveform capture and digitization circuit with continuous synchronous 2-GHz sampling capability and real-time programmable windowed trigger generation has been fabricated and tested. Designed in 0.25 μm CMOS, the digitizer contains a circular array of 128 sample and hold circuits for continuous sample acquisition, and attains 2-GHz sample speeds with over 800-MHz analog bandwidth. Sample clock generation is synchronous, combining a phase-locked loop for high-speed clock generation and a high-speed fully-differential shift register for distributing clocks to all 128 sample circuits. Using two comparators per sample, the sampled voltage levels are compared against two reference levels, a high threshold and a low threshold, that are set via per-comparator digital to analog converters (DACs). The 256 per-comparator 5-bit DACs compensate for comparator offsets and allow for fine reference level adjustment. The comparator results are matched in 8-sample-wide windows against up to 72 programmable patterns in real time using an on-chip programmable logic array. Each 8-sample trigger window is equivalent to 4 ns of acquisition, overlapped sample by sample in a circular fashion through the entire 128-sample array. The 72 pattern-matching trigger criteria can be programmed to be any combination of High-above the high threshold, Low-below the low threshold, Middle-between the two thresholds, or “Don't Care”-any state is accepted. A trigger pattern of “HLHLHLHL,” for example, watches for a waveform that is oscillating at about 1 GHz given the 2-GHz sample rate. A trigger is flagged in under 20 ns if there is a match, after which sampling is stopped, and on-chip digitization can proceed via 128 parallel 10-bit converters, or off-chip conversion can proceed via an analog readout. The chip exceeds 11 bits of dynamic range, nets over 800-MHz -3-dB bandwidth in a realistic system, and jitter in the PLL-based sampling clock has been measured to be about 1 part

Observation of resonant and non-resonant magnetic braking in the n = 1 non-axisymmetric configurations on KSTAR

NASA Astrophysics Data System (ADS)

Kim, Kimin; Choe, W.; In, Y.; Ko, W. H.; Choi, M. J.; Bak, J. G.; Kim, H. S.; Jeon, Y. M.; Kwak, J. G.; Yoon, S. W.; Oh, Y. K.; Park, J.-K.

2017-12-01

Toroidal rotation braking by neoclassical toroidal viscosity driven by non-axisymmetric (3D) magnetic fields, called magnetic braking, has great potential to control rotation profile, and thereby modify tokamak stability and performance. In order to characterize magnetic braking in the various 3D field configurations, dedicated experiments have been carried out in KSTAR, applying a variety of static n=1 , 3D fields of different phasing of -90 , 0, and +90 . Resonant-type magnetic braking was achieved by -90 phasing fields, accompanied by strong density pump-out and confinement degradation, and explained by excitation of kink response captured by ideal plasma response calculation. Strong resonant plasma response was also observed under +90 phasing at q95 ∼ 6 , leading to severe confinement degradation and eventual disruption by locked modes. Such a strong resonant transport was substantially modified to non-resonant-type transport at higher q95 ∼ 7.2 , as the resonant particle transport was significantly reduced and the rotation braking was pushed to plasma edge. This is well explained by ideal perturbed equilibrium calculations indicating the strong kink coupling at lower q95 is reduced at higher q95 discharge. The 0 phasing fields achieved quiescent magnetic braking without density pump-out and confinement degradation, which is consistent with vacuum and ideal plasma response analysis predicting deeply penetrating 3D fields without an excitation of strong kink response.

9C spectral-index distributions and source-count estimates from 15 to 93 GHz - a re-assessment

NASA Astrophysics Data System (ADS)

Waldram, E. M.; Bolton, R. C.; Riley, J. M.; Pooley, G. G.

2018-01-01

In an earlier paper (2007), we used follow-up observations of a sample of sources from the 9C survey at 15.2 GHz to derive a set of spectral-index distributions up to a frequency of 90 GHz. These were based on simultaneous measurements made at 15.2 GHz with the Ryle telescope and at 22 and 43 GHz with the Karl G. Jansky Very Large Array (VLA). We used these distributions to make empirical estimates of source counts at 22, 30, 43, 70 and 90 GHz. In a later paper (2013), we took data at 15.7 GHz from the Arcminute Microkelvin Imager (AMI) and data at 93.2 GHz from the Combined Array for Research in Millimetre-wave Astronomy (CARMA) and estimated the source count at 93.2 GHz. In this paper, we re-examine the data used in both papers and now believe that the VLA flux densities we measured at 43 GHz were significantly in error, being on average only about 70 per cent of their correct values. Here, we present strong evidence for this conclusion and discuss the effect on the source-count estimates made in the 2007 paper. The source-count prediction in the 2013 paper is also revised. We make comparisons with spectral-index distributions and source counts from other telescopes, in particular with a recent deep 95 GHz source count measured by the South Pole Telescope. We investigate reasons for the problem of the low VLA 43-GHz values and find a number of possible contributory factors, but none is sufficient on its own to account for such a large deficit.

The 20/30 GHz satellite systems technology needs assessment

NASA Technical Reports Server (NTRS)

Stevens, G.; Wright, D.

1978-01-01

Rain attenuation in the 20/30 GHz bands, and the resultant impact on system user costs were estimated for a variety of satellite communication system concepts. Results of previous and current NASA Lewis contractual and in-house studies on system design are reported as well as market studies conducted to evaluate the concepts and test their relevancy against forecasted market needs. The 20/30 GHz bands appear attractive economically and, with certain technology, appear to offer a virtually unlimited spectrum resource. This attractiveness is especially relevant to high density trunking where there is sufficient traffic to justify dual-station site diversity.

Alternative laser system for cesium magneto-optical trap via optical injection locking to sideband of a 9-GHz current-modulated diode laser.

PubMed

Diao, Wenting; He, Jun; Liu, Zhi; Yang, Baodong; Wang, Junmin

2012-03-26

By optical injection of an 852-nm extended-cavity diode laser (master laser) to lock the + 1-order sideband of a ~9-GHz-current-modulated diode laser (slave laser), we generate a pair of phase-locked lasers with a frequency difference up to ~9-GHz for a cesium (Cs) magneto-optical trap (MOT) with convenient tuning capability. For a cesium MOT, the master laser acts as repumping laser, locked to the Cs 6S₁/₂ (F = 3) - 6P₃/₂ (F' = 4) transition. When the + 1-order sideband of the 8.9536-GHz-current-modulated slave laser is optically injection-locked, the carrier operates on the Cs 6S₁/₂ (F = 4) - 6P₃/₂ (F' = 5) cooling cycle transition with -12 MHz detuning and acts as cooling/trapping laser. When carrying a 9.1926-GHz modulation signal, this phase-locked laser system can be applied in the fields of coherent population trapping and coherent manipulation of Cs atomic ground states.

Brightness temperature and attenuation diversity statistics at 20.6 and 31.65 GHz for the Colorado Research Network

NASA Technical Reports Server (NTRS)

Westwater, Ed R.; Falls, M. J.; Fionda, E.

1992-01-01

A limited network of four dual-channel microwave radiometers, with frequencies of 20.6 and 31.65 GHz, was operated in the front range of eastern Colorado from 1985 to 1988. Data, from November 1987 through October 1988 are analyzed to determine both single-station and joint-station brightness temperature and attenuation statistics. Only zenith observations were made. The spatial separations of the stations varied from 50 km to 190 km. Before the statistics were developed, the data were screened by rigorous quality control methods. One such method, that of 20.6 vs. 31.65 GHz scatter plots, is analyzed in detail, and comparisons are made of measured vs calculated data. At 20.6 and 31.65 GHz, vertical attenuations of 5 and 8 dB are exceeded 0.01 percent of the time. For these four stations and at the same 0.01 percent level, diversity gains from 6 to 8 dB are possible with the 50 to 190 km separations.

Fin-line PIN-diode attenuators and switches for 94 GHz range

NASA Astrophysics Data System (ADS)

Meinel, H.; Callsen, H.

1982-06-01

The letter reports new results of fin-line PIN-diode attenuators and switches for the 94 GHz range. Design and performance of SPST and SPDT switches - single pole single throw and single pole double throw, respectively - will be presented. The attenuation of the SPST switch, for example, can be adjusted between 2 and 35 dB over the entire waveguide band from 75 to 110 GHz.

Search for the 22 GHz water maser emission in selected comets

NASA Astrophysics Data System (ADS)

Cosmovici, C. B.; Pluchino, S.; Montebugnoli, S.; Pogrebenko, S.

2014-06-01

Following the first evidence of planetary water maser emission induced by the collision of comet Shoemaker/Levy with Jupiter and the puzzling detection of the 22 GHz water emission line in Comet Hyakutake we started in the period 2002-2008 systematic observations of selected comets at 22 GHz (1.35 cm) with the aim of clarifying the unusual behavior of the maser line in the cometary “scenario”. Using a fast multichannel spectrometer coupled to the 32 m dish of the Medicina (Bologna, Italy) Radio Telescope we investigated 6 bright or sungrazing comets down to a heliocentric distance of 0.11 AU: 96P/Machholz, 153P/ Ikeya-Zhang, C/2002 V1 (NEAT), C/2002 X5 (Kudo-Fujikawa), C/2002 T7 (Linear), and 73P/Schwassmann-Wachmann 3. All of them, similarly to Comet Hyakutake, demonstrate spectral features that, if real and due to the 1.35 cm water vapor transition, are strongly (up to tens of km/s) shifted relative to the radial velocity of the nucleus and, at least sometimes, seem to be present as two separate peaks. If our interpretation of these spectral peaks is correct, there must be some mechanism of acceleration of neutral water molecules up to the velocities of ions. We discuss here the results achieved and the possible explanation of the chemo-physical constraints. First possible detection of the water maser emission line at 22 GHz in sun-grazing comets Observed puzzling acceleration of neutral water molecules at ion velocities and split of the line in two components. Evidence of plasma-grain interaction in sun-grazing comets. Possible new detections in six peculiar comets.

A 17 GHz molecular rectifier

PubMed Central

Trasobares, J.; Vuillaume, D.; Théron, D.; Clément, N.

2016-01-01

Molecular electronics originally proposed that small molecules sandwiched between electrodes would accomplish electronic functions and enable ultimate scaling to be reached. However, so far, functional molecular devices have only been demonstrated at low frequency. Here, we demonstrate molecular diodes operating up to 17.8 GHz. Direct current and radio frequency (RF) properties were simultaneously measured on a large array of molecular junctions composed of gold nanocrystal electrodes, ferrocenyl undecanethiol molecules and the tip of an interferometric scanning microwave microscope. The present nanometre-scale molecular diodes offer a current density increase by several orders of magnitude compared with that of micrometre-scale molecular diodes, allowing RF operation. The measured S11 parameters show a diode rectification ratio of 12 dB which is linked to the rectification behaviour of the direct current conductance. From the RF measurements, we extrapolate a cut-off frequency of 520 GHz. A comparison with the silicon RF-Schottky diodes, architecture suggests that the RF-molecular diodes are extremely attractive for scaling and high-frequency operation. PMID:27694833

The Most Compact Bright Radio-loud AGNs. II. VLBA Observations of 10 Sources at 43 and 86 GHz

NASA Astrophysics Data System (ADS)

Cheng, X.-P.; An, T.; Hong, X.-Y.; Yang, J.; Mohan, P.; Kellermann, K. I.; Lister, M. L.; Frey, S.; Zhao, W.; Zhang, Z.-L.; Wu, X.-C.; Li, X.-F.; Zhang, Y.-K.

2018-01-01

Radio-loud active galactic nuclei (AGNs), hosting powerful relativistic jet outflows, provide an excellent laboratory for studying jet physics. Very long baseline interferometry (VLBI) enables high-resolution imaging on milli-arcsecond (mas) and sub-mas scales, making it a powerful tool to explore the inner jet structure, shedding light on the formation, acceleration, and collimation of AGN jets. In this paper, we present Very Long Baseline Array observations of 10 radio-loud AGNs at 43 and 86 GHz that were selected from the Planck catalog of compact sources and are among the brightest in published VLBI images at and below 15 GHz. The image noise levels in our observations are typically 0.3 and 1.5 mJy beam‑1 at 43 and 86 GHz, respectively. Compared with the VLBI data observed at lower frequencies from the literature, our observations with higher resolutions (with the highest resolution being up to 0.07 mas at 86 GHz and 0.18 mas at 43 GHz) and at higher frequencies detected new jet components at sub-parsec scales, offering valuable data for studies of the physical properties of the innermost jets. These include the compactness factor of the radio structure (the ratio of core flux density to total flux density), and core brightness temperature ({T}{{b}}). In all these sources, the compact core accounts for a significant fraction (> 60 % ) of the total flux density. Their correlated flux density at the longest baselines is higher than 0.16 Jy. The compactness of these sources make them good phase calibrators of millimeter-wavelength ground-based and space VLBI.

Core-shifts and proper-motion constraints in the S5 polar cap sample at the 15 and 43 GHz bands

NASA Astrophysics Data System (ADS)

Abellán, F. J.; Martí-Vidal, I.; Marcaide, J. M.; Guirado, J. C.

2018-06-01

We have studied a complete radio sample of active galactic nuclei with the very-long-baseline-interferometry (VLBI) technique and for the first time successfully obtained high-precision phase-delay astrometry at Q band (43 GHz) from observations acquired in 2010. We have compared our astrometric results with those obtained with the same technique at U band (15 GHz) from data collected in 2000. The differences in source separations among all the source pairs observed in common at the two epochs are compatible at the 1σ level between U and Q bands. With the benefit of quasi-simultaneous U and Q band observations in 2010, we have studied chromatic effects (core-shift) at the radio source cores with three different methods. The magnitudes of the core-shifts are of the same order (about 0.1 mas) for all methods. However, some discrepancies arise in the orientation of the core-shifts determined through the different methods. In some cases these discrepancies are due to insufficient signal for the method used. In others, the discrepancies reflect assumptions of the methods and could be explained by curvatures in the jets and departures from conical jets.

TlCaBaCuO high Tc superconducting microstrip ring resonators designed for 12 GHz

NASA Technical Reports Server (NTRS)

Subramanyam, G.; Kapoor, V. J.; Chorey, C. M.; Bhasin, K. B.

1993-01-01

Microwave properties of sputtered Tl-Ca-Ba-Cu-O thin films were investigated by designing, fabricating, and testing microstrip ring resonators. Ring resonators designed for 12 GHz fundamental resonance frequency, were fabricated and tested. From the unloaded Q values for the resonators, the surface resistance was calculated by separating the conductor losses from the total losses. The penetration depth was obtained from the temperature dependence of resonance frequency, assuming that the shift in resonance frequency is mainly due to the temperature dependence of penetration depth. The effective surface resistance at 12 GHz and 77 K was determined to be between 1.5 and 2.75 mOmega, almost an order lower than Cu at the same temperature and frequency. The effective penetration depth at 0 K is approximately 7000 A.

Observations of electron heating during 28 GHz microwave power application in proto-MPEX

DOE PAGES

Biewer, Theodore M.; Bigelow, Tim S.; Caneses Marin, Juan F.; ...

2018-02-01

The Prototype Material Plasma Exposure Experiment at the Oak Ridge National Laboratory utilizes a variety of power systems to generate and deliver a high heat flux plasma onto the surface of material targets. In the experiments described here, a deuterium plasma is produced via a ~100 kW, 13.56 MHz RF helicon source, to which ~20 kW of 28 GHz microwave power is applied. The electron density and temperature profiles are measured using a Thomson scattering (TS) diagnostic, and indicate that the electron density is centrally peaked. In the core of the plasma column, the electron density is higher than themore » cut-off density (~0.9 × 1019 m -3) for the launched mixture of X- and O-mode electron cyclotron heating waves to propagate. TS measurements indicate electron temperature increases from ~5 eV to ~20 eV during 28 GHz power application when the neutral deuterium pressure is reduced below 0.13 Pa (~1 mTorr.).« less

Observations of electron heating during 28 GHz microwave power application in proto-MPEX

NASA Astrophysics Data System (ADS)

Biewer, T. M.; Bigelow, T. S.; Caneses, J. F.; Diem, S. J.; Green, D. L.; Kafle, N.; Rapp, J.; Proto-MPEX Team

2018-02-01

The Prototype Material Plasma Exposure Experiment at the Oak Ridge National Laboratory utilizes a variety of power systems to generate and deliver a high heat flux plasma onto the surface of material targets. In the experiments described here, a deuterium plasma is produced via a ˜100 kW, 13.56 MHz RF helicon source, to which ˜20 kW of 28 GHz microwave power is applied. The electron density and temperature profiles are measured using a Thomson scattering (TS) diagnostic, and indicate that the electron density is centrally peaked. In the core of the plasma column, the electron density is higher than the cut-off density (˜0.9 × 1019 m-3) for the launched mixture of X- and O-mode electron cyclotron heating waves to propagate. TS measurements indicate electron temperature increases from ˜5 eV to ˜20 eV during 28 GHz power application when the neutral deuterium pressure is reduced below 0.13 Pa (˜1 mTorr.).

First imagery generated by near-field real-time aperture synthesis passive millimetre wave imagers at 94 GHz and 183 GHz