Showing papers on "Ka band published in 1995"
TL;DR: In this article, a circularly polarized microstrip array with 28 dBic gain at 32 GHz was developed to minimize the insertion loss and maintain a reasonable frequency bandwidth, and the parallel/series feed technique for the array's power distribution circuit and the sequential rotation method for the element arrangement were employed to meet these objectives.
Abstract: In this article, the development of a circularly polarized microstrip array with 28 dBic of gain at 32 GHz is presented. Two primary objectives of this development are minimizing the microstrip array's insertion loss and maintaining a reasonable frequency bandwidth (3%). The parallel/series feed technique for the array's power distribution circuit and the sequential rotation method for the element arrangement are employed to meet these objectives. >
111 citations
15 Sep 1995
TL;DR: In this article, a wideband millimeter wave holographic imaging technqiue is under developement for use in concealed weapons detection system, which provides far superior images than single frequency holographic techniques on thick objects such as the human body.
Abstract: A new wideband millimeter wave holographic imaging technqiue is under developement for use in concealed weapons detection system. This new wideband technique provides far superior images than single frequency holographic techniques on thick objects such as the human body. The wideband technique obtains fully focused images over a designated volume and provides excellent lateral and depth resolution. Using this method, a 3D volumetric hologram is gathered with a millimeter wave linear array, a mechanical scanner, and a sweep frequency tranceiver. The 3D volumetric hologram is then processed by high-speed computational processors to reconstruct the fully focused image. Two prototype wide band millimeter wave holographic arrays have been developed at the Pacific Northwest Laboratory. The two arrays consist of sequentially switched 2 by 37 Ku band (12.5-18 GHz) and 2 by 64 Ka band (26.5-40 GHz) systems which are coupled to high-speed sweep frequency heterodyne transceivers. The arrays are used to obtain volumetric imaging data at high speeds by electronically sequencing and frequency sweeping the array antennas along 1D while performing a mechanical scan along the other dimension. The current prototype system scans an aperture the size of a large human body in about one second. Extensive laboratory testing has been performed with people carrying various concealed weapons and innocuous items with both imaging arrays during the first quarter of 1995.
35 citations
TL;DR: In this paper, an empirical model is developed which predicts fade time as a function of attenuation level, frequency of operation, and fade duration interval, and the predicted fade times are in good agreement with the measured values.
Abstract: Rain attenuation data from the OLYMPUS satellite beacon measurements are used to investigate fade time in the Ku and Ka bands. Using statistical procedures, an empirical model is developed which predicts fade time as a function of attenuation level, frequency of operation, and fade duration interval. Total annual fade times are predicted over a frequency span of 12-30 GHz for attenuation levels in the 3-18 dB range and for fade duration intervals of 30-60 s, 60-120 s, 2-5 min, and 5-20 min. The predicted fade times are in good agreement with the measured values. An alternate model, described by two simple relationships in two different ranges of attenuation level, is also presented by simplifying the original single-equation model. The simplified model accounts for fades associated with stratiform rain and thunderstorms separately.
25 citations
01 Nov 1995
TL;DR: Together these modems address the essential functional and implementation issues of the Ka band for digital HDTV broadcasting and demonstrates the feasibility of domestic variable rate receivers by using digital demodulation techniques suitable for very highly integrated implementations.
Abstract: This paper introduces the HD-SAT project and describes the two satellite modems designed for high definition digital television broadcasting by satellite in the 20 GHz frequency band. The graceful degradation satellite modem uses layered modulation (TCM-8PSK/QPSK) to increase service continuity in this rain-attenuation sensitive band. The 45-70 Mb/s TCM-8PSK modem demonstrates the feasibility of domestic variable rate receivers by using digital demodulation techniques suitable for very highly integrated implementations. Together these modems, both of which have been the subject of prototype demonstration and tests, address the essential functional and implementation issues of the Ka band for digital HDTV broadcasting.
24 citations
TL;DR: In this article, the first results of a coplanar SiGe HBT amplifier monolithically integrated on high resistivity silicon are reported, achieving a gain of 4 dB at 26 GHz.
Abstract: Design, technology and first results of a coplanar SiGe HBT amplifier monolithically integrated on high resistivity silicon are reported. The circuit provides a gain of 4 dB at 26 GHz.
22 citations
TL;DR: In this article, a model based on the Radiative transfer theory was proposed to estimate the visual ability of agricultural crops to discriminate different field types, and the importance of a realistic choice of the dimensions, orientation and relative position of the scattering elements within a vegetation layer was pointed out.
Abstract: Emissivity of agricultural crops is theoretically estimated through a model based on the Radiative Transfer Theory, and then compared with experimental data collected at X and Ka bands. The test is in general positive. The model and the experimental data agree in showing the ability of a dual-frequency radiometer system to discriminate different field types. The importance of a realistic choice of the dimensions, orientation and relative position of the scattering elements within a vegetation layer is pointed out.
20 citations
29 Oct 1995
TL;DR: In this paper, a power MMIC, employing a unique series bias scheme, is reported operating over the 32 to 34.5 GHz band with a power-added efficiency (PAE) of greater than 33%.
Abstract: A power MMIC, employing a unique series bias scheme, is reported operating over the 32 to 34.5 GHz band with a power-added efficiency (PAE) of greater than 33%. Operating at 20 volts, this IC has demonstrated an output power of 0.66 watt at 33 GHz with an associated PAE of 41.1%. This is the highest reported efficiency for an MMIC operating at Ka-band frequencies. Biased at 28 volts for power, another IC produced an output power of 1.1 watt with an associated PAE of 35.8%. The chip is a compact 2/spl times/3.84 mm/sup 2/.
16 citations
01 Jan 1995
TL;DR: The main characteristics of the satellite extremely high frequency (EHF) communication of multimedia mobile services (SECOMS) system are given and the results of the preliminary analysis are included.
Abstract: The main characteristics of the satellite extremely high frequency (EHF) communication of multimedia mobile services (SECOMS) system are given and the results of the preliminary analysis are included. The SECOMS provides a first generation Ka band system with coverage over Western Europe, in order to satisfy business user needs of very large bandwidths and terminal mobility. The satellite system also provides a second generation EHF enhanced system with increased capacity and enlarged coverage, to serve all of Europe and the nearby countries.
10 citations
15 May 1995
TL;DR: In this article, a satellite system utilizing frequency diversity has been dimensioned and the advantages in terms of power margin and then of technology have been shown, among the several operating situations analyzed, the best one, from complexity/benefits point of view, seems to be to utilize a portion of Ku band as shared resource sufficient to assist the 10% of the stations simultaneously, choosing the operating point on probability curves in the first portion of the "knee".
Abstract: Some of the problems concerning the use of Ka band for satellite systems have been investigated and many fade countermeasures have been described. Frequency diversity has been analyzed and characterized in detail verifying the variability of its performance as a function of several system parameters. A satellite system utilizing frequency diversity has been dimensioned and the advantages in terms of power margin and then of technology have been shown. Among the several operating situations analyzed, the best one, from complexity/benefits point of view, seems to be to utilize a portion of Ku band as shared resource sufficient to assist the 10% of the stations simultaneously, choosing the operating point on probability curves in the first portion of the "knee".
9 citations
16 May 1995
TL;DR: In this article, the authors presented the performance of the first planar microstrip Ka-band frequency tripler based on a stacked symmetric heterostructure barrier varactor (HBV) structure with a minimum conversion loss of 11.2 dB with a maximum power output of 10.78 dBm at 40.35 GHz.
Abstract: The symmetric heterostructure barrier varactor (HBV) lends itself to frequency tripling with no need for bias or for a second harmonic idler circuit. This paper presents the performance of the first planar microstrip Ka-band frequency tripler based on a stacked HBV structure. A minimum conversion loss of 11.2 dB with a maximum power output of 10.78 dBm at 40.35 GHz is obtained. >
8 citations
01 Jan 1995
TL;DR: In this article, a short description of the equipment used, lists the activities of the experimental campaign and presents the first statistical evaluation of the recorded data are given. But due to the restricted size of the document only few results are reported.
Abstract: This paper gives a short description of the equipment used, lists the activities of the experimental campaign and presents the first statistical evaluation of the recorded data. Due to the restricted size of the document only few results are reported.
TL;DR: In this article, the power performance degradations of interdigitated HEMTs in millimeter wave range as the total gate width increases are analyzed. And the possibility of optimizing the device topology by combining a limited number of via holes and airbridge source connections in order to offer a good cost-performance trade off is investigated.
Abstract: This paper provides an analysis of the power performance degradations of interdigitated HEMTs in millimeter wave range as the total gate width increases. It investigates the possibility of optimizing the device topology by combining a limited number of via holes and airbridge source connections in order to offer a good cost-performance trade off. >
04 Apr 1995
TL;DR: In this article, the results of frequency scaling were deduced at Coventry University using Olympus data measured by the Rutherford Appleton Laboratory (RAL) at their site at Chilton (UK).
Abstract: Due to the increasing demand in capacity of satellite communication and the present congestion of both C and Ku bands, the use of the Ka band will become a fully operational reality in a very near future. To design an effective and reliable satellite system at such frequencies, it is essential to consider the statistics of different propagation aspects on both a long term and short term basis. This is particularly true for high frequency systems where water absorption is predominant and can not be counteracted permanently using a fixed power margin. The results of frequency scaling were deduced at Coventry University. These are based on Olympus data measured by the Rutherford Appleton Laboratory (RAL) at their site at Chilton (UK). These results are compared with the CCIR models and show a good agreement.
17 May 1995
TL;DR: In this paper, an MMIC chip set for the realization of the millimeter-wave front-end has been developed using a common 0.25 /spl mu/m PMHFET technology allowing the future integration of several key components on a single chip.
Abstract: A number of civil applications such as motion sensors and communications systems are planned to use the Ka-band frequency range. An MMIC chip set for the realization of the millimeter-wave front-end has been developed. The key MMIC circuit functions for Ka-band communication systems have been fabricated. Low noise amplifiers, a medium power amplifier, mixers and a dielectric resonator oscillator (DRO) have been developed using a common 0.25 /spl mu/m PMHFET technology allowing the future integration of several key components on a single chip. A voltage controlled oscillator has been realized in a GaInP-GaAs HBT technology for improvement of the phase noise performance. Low noise Schottky diode upconverter and downconverter are also available in 0.25 /spl mu/m MESFET technology with buried n/sup +/ layer.
TL;DR: In this article, a 5-stage MMIC amplifier based on 50% idss self-biasing using a single power supply achieved 2-3 dB noise figure with 30 dB associated gain at 33 GHz.
Abstract: Ka-band monolithic low-noise amplifiers using low cost direct ion-implanted GaAs MESFETs with 0.25 /spl mu/m "T"-gates have been developed for use at 27 to 34 GHz. The five stage MMIC amplifier is designed based on 50% Idss self-biasing using a single power supply. These amplifiers achieved 2-3 dB noise figure with 30 dB associated gain at 33 GHz. These results, using low cost ion implantation techniques, rival the best GaAs p-HEMT MMIC results to date. >
16 May 1995
TL;DR: In this article, experimental results of optical control of millimeter-wave HJFET MMIC oscillators and FET model parameter analysis with illumination were obtained using a noncoherent optical source, the maximum optical tuning ranges of 32 MHz around 30 GHz and 260 MHz around 51 GHz were obtained.
Abstract: This paper reports experimental results of optical control of millimeter-wave HJFET MMIC oscillators and FET model parameter analysis with illumination. Using a noncoherent optical source, the maximum optical tuning ranges of 32 MHz around 30 GHz and 260 MHz around 51 GHz were obtained. By means of parameter extraction, a 46.6% increase in Cgd and a 19.1% decrease in Cds due to the illumination and their frequency dependence were appreciated. >
Journal Article•
TL;DR: The Advanced Communications Technology Satellite (ACTS) as mentioned in this paper is a digital experimental communications test bed that incorporates gigahertz bandwidth transponders operating at Ka band, hopping spot beams, on-board storage and switching, and dynamic rain fade compensation.
Abstract: The Advanced Communications Technology Satellite (ACTS), developed and built by Lockheed Martin Astro Space for the NASA Lewis Research Center, was launched in September 1993 on the Shuttle STS 51 mission. ACTS is a digital experimental communications test bed that incorporates gigahertz bandwidth transponders operating at Ka band, hopping spot beams, on-board storage and switching, and dynamic rain fade compensation. This paper describes the ACTS enabling technologies, the design of the communications payload, and some of the terrestrial and aeronautical mobile experiments that have been conducted to date.
TL;DR: In this paper, Litton EDD developed a new class of Ka-band traveling-wave tubes (TWTs) that use a novel integral-polepiece folded-waveguide circuit to generate peak and average powers up to 1,500 watts.
Abstract: Litton EDD is developing a new class of Ka-band traveling-wave tubes (TWTs) that use a novel integral-polepiece folded-waveguide circuit to generate peak and average powers up to 1,500 watts. Rugged and highly reliable, this new technology is especially suited for airborne radars. Ongoing developments to increase the average power, the bandwidth and the frequency may be useful for future designs. >
01 Sep 1995
TL;DR: The Advanced Communications Technology Satellite (ACTS) as mentioned in this paper is a digital experimental communications test bed that incorporates gigahertz bandwidth transponders operating at Ka band, hopping spot beams, on-board storage and switching, and dynamic rain fade compensation.
Abstract: The Advanced Communications Technology Satellite (ACTS), developed and built by Lockheed Martin Astro space for the NASA Lewis Research Center, was launched in September 1993 on the shuttle STS 51 mission. ACTS is a digital experimental communications test bed that incorporates gigahertz bandwidth transponders operating at Ka band, hopping spot beams, on-board storage and switching, and dynamic rain fade compensation. This paper describes the ACTS enabling technologies, the design of the communications payload, the constraints imposed on the spacecraft bus, and the measurements conducted to verify the performance of the system in orbit.
17 May 1995
TL;DR: In this paper, a P-HEMT-based foundry service from TRW was selected to design an integrated front-end for a Ka band phased array antenna, where the MMIC-based antenna front is designed to perform three important functions of (i) generation of phase and frequency stable local oscillator, (ii) downconversion (up-conversion) of the modulated RF (IF) carrier, and (iii) and 0-360/spl deg/phase control of the modulation for beam steering.
Abstract: It is well documented that fiber optic remoting of information to the millimeter wave distributed antennas is viable only when the modulated carrier is constructed at the antenna front end. The MMIC based antenna front is designed to perform three important functions of (i) generation of phase and frequency stable local oscillator, (ii) down-conversion (up-conversion) of the modulated RF (IF) carrier, (iii) and 0-360/spl deg/ phase control of the modulated RF (IF) for beam steering. This paper presents design and experimental evaluation of a MMIC front end circuit designed for a Ka band phased array antenna. A P-HEMT based foundry service from TRW was selected to design this integrated front end.
01 Jan 1995
TL;DR: In this paper, Litton EDD developed a new class of Ka-band traveling-wave tubes (TWTs) that use a novel integralpolepiece folded-waveguide circuit to generate peak and average powers up to 1,500 watts.
Abstract: Litton EDD is developing a new class of Ka-band traveling-wave tubes (TWTs) that use a novel integralpolepiece folded-waveguide circuit to generate peak and average powers up to 1,500 watts. Rugged and highly reliable, this new technology is especially suited for airborne radars. Ongoing developments to increase the average power, the bandwidth and the frequency may be useful for future designs.
TL;DR: In this article, a coherent wideband millimeter wave (mmW) imaging radar which operates in two different imaging modes is briefly described and the principles of two-dimensional (2-D) high resolution imaging are introduced.
Abstract: A coherent wideband millimeter wave (mmW) imaging radar which operates in two different imaging modes is briefly described. The principles of two-dimensional (2-D) high resolution imaging are introduced. The image reconstruction algorithm together with image enhancement techniques are discussed. Some experiments imaging on both scaled aircraft model and full-size large scale vehicle are presented. >
Journal Article•
Dissertation•
01 Jan 1995
TL;DR: In this article, a detailed theoretical and experimental study of tropospheric scintillation has been carried out and it is shown that amplitude scintillant is a significant cause of degradation in several emerging low availability satellite communication systems operating at 20 40 GHz and using small aperture antennas.
Abstract: A detailed theoretical and experimental study of tropospheric scintillation has been carried out. It is shown that amplitude scintillation is a significant cause of degradation in several emerging low availability satellite communication systems operating at Ka-Band frequencies (20 40 GHz) and using small aperture antennas. Three components of tropospheric scintillation are identified, namely, that due to turbulence developed by convective heating and wind gradients, that due to pure scattering by a random distribution of scatterers (mostly rain drops), and apparent scintillation caused by temporal variation of rain drop size distribution which produces a rapidly varying signal attenuation. This is perceived in the receiver as scintillation superimposed on the mean fade depth. Theoretical expressions are obtained for the variance of each component of scintillation and it is shown that the second is negligible in finite aperture receivers which intercept only a small fraction of the scattered energy. Experimental measurements of scintillation at three sites in the United Kingdom using the European Space Agency's Olympus satellite are described. The experiments also included a concurrent distrometer measurement of rain drop size distribution in one site. A digital processing method is devised for extracting scintillation-induced fluctuations and rain attenuation time series from the jumble of fluctuations in raw propagation data. Results of an extensive analysis of measurements on the Olympus-Sparsholt downlink ( at a frequency of 20 GHz and path elevation of 29.2°) are presented. Peak-to-peak scintillation amplitude exceeded 1.35 dB during 1% of one-minute intervals in the year. The mean corner frequency of scintillation power spectral density was 0.27 Hz. The variation of hourly scintillation intensity was well approximated by a lognormal distribution, although a Gamma distribution was followed as well in some months. Scintillation amplitude followed a normal distribution over short term intervals of weak-to-moderate turbulence. There was good agreement with the ITU-R prediction of seasonal and annual average scintillation intensity and with their prediction of scintillation fade distributions at annual time percentages above 0.4%. The Moulsley-Vilar model gave good prediction of scintillation fade for annual time percentages above 0.01%, but consistently overestimated scintillation enhancements. Semi-empirical models are developed which give the annual cumulative probability distribution of scintillation fade and enhancement. A model for worst month scintillation statistics is also derived. These new models gave excellent agreement with our measurements and are applicable to any satellite link. Diurnal and seasonal trends of scintillation are discussed. It is shown that scintillation is polarisation sensitive, being more pronounced on vertically polarised signals than on signals transmitted with horizontal polarisation. The impact of scintillation on satellite communication systems is discussed and a scheme is developed for applying scintillation measurements on a satellite downlink to remote sensing of the atmosphere.
15 May 1995
TL;DR: In this article, a multipurpose MMIC gate mixer has been designed, fabricated and measured, which exhibits a maximum conversion gain of about 0 dB in the frequency range of 32 GHz-38 GHz with an intermediate frequency (IF) of 100 MHz and an IF load of 50 /spl Omega/.
Abstract: A multipurpose MMIC gate mixer has been designed, fabricated and measured. The mixer exhibits a maximum conversion gain of about 0 dB in the frequency range of 32 GHz-38 GHz with an intermediate frequency (IF) of 100 MHz and an IF load of 50 /spl Omega/. With an external IF matching network a conversion gain up to 5 dB can be achieved. The mixer which consists of one pseudomorphic HFET represents state of the art performance. >
11 Apr 1995-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, the design and performance calculations for a coaxial hybrid iron (CHI) free-electron laser configuration are presented, and key considerations for the experimental design are outlined and discussed.
Abstract: Design and performance calculations for a coaxial hybrid iron (CHI) wiggler free-electron laser configuration are presented. The capability of generating high fields at short periods, as well as good beam focusing properties, make it a desirable configuration for high power coherent radiation sources in relatively compact systems. In addition to a description of the geometry, numerical calculations detailing the magnetostatic wiggler fields, the beam dynamics, and the interaction of the beam with the electromagnetic waves in the K a -band (26–40 GHz) will be presented. Key considerations for the experimental design will be outlined and discussed.
TL;DR: In this article, a GaAs Gunn diodes were fabricated for pulse source application at 8 mm wave band and operated with pulsewidths of 0.05 to 2.0 microseconds and duty cycles of0.001 to 0.01.
Abstract: GaAs Gunn diodes were fabricated for pulse source application at 8 mm wave band and operated with pulsewidths of 0.05 to 2.0 microseconds and duty cycles of 0.001 to 0.01. Peak pulse output power levels of 0.8–1.2W are achieved and the maximum available power is 1.6W with the highest efficiency of 6.5 percent. A simple and compact pulsed power combiner is also given in this paper.
15 Aug 1995
TL;DR: In this article, the design concepts applied in the development of and advanced Ka-band transponder breadboard for the next generation of space communications systems applications are summarized, and the results show a receiver tracking threshold of -149 dBm with a dynamic range of 80 dB and a downlink phase jitter of 7 deg rms.
Abstract: This article summarizes the design concepts applied in the development of and advanced Ka-band (34.4 GHz/32 GHz) transponder breadboard for the next generation of space communications systems applications. The selected architecture upgrades the X-band (7.2 GHz/8.4 GHz) deep-space transponder (DST) to provide Da-band up/Ka- and X-band down capability. The Ka-band transponder breadboard incorporates several state-of-the-art components, including sampling mixers, a Ka-band dielectric resonator oscillator, and microwave monolithic integrated circuits (MMICs). The MMICs that were tested in the breadboard include upconverters, downconverters, automatic gain control circuits, mixers, phase modulators, and amplifiers. The measured receiver dynamic range, tracking range, acquisition rate, static phase error, and phase jitter characteristics of the Ka-band breadboard interfaced to the advanced engineering model X-band DST are in good agreement with the expected performance. The results show a receiver tracking threshold of -149 dBm with a dynamic range of 80 dB and a downlink phase jitter of 7 deg rms. The analytical results of phase noise and Allan standard deviation are in good agreement with the experimental results.
24 Jul 1995
TL;DR: In this article, the authors deal with the severe propagation problems that will be probably encountered in designing the future satellite communication systems in the Ka band and above and with some possible advanced solutions based on the knowledge of the local climatology.
Abstract: The paper deals with the severe propagation problems that will be probably encountered in designing the future satellite communication systems in the Ka band and above and with some possible advanced solutions based on the knowledge of the local climatology. Within the very wide spectrum of new envisaged systems two particularly significant examples have been selected: the TV-sat at 22 GHz and the feeder-links at 20-30 GHz when site diversity configurations will be necessary as expected with low elevation orbiting satellites. As shown in the paper, by exploiting to the maximum extent the available meteorological information, very effective fading and power-saving countermeasures can be envisaged.
NEC1
TL;DR: AlGaAs/GaAs power HBTs have been developed for operation in the 26 GHz band as discussed by the authors, and they have achieved a 0.65 W CW output power with 34% collector efficiency, 16% power-added efficiency, and 6 dB linear power gain at 26.85 GHz.
Abstract: AlGaAs/GaAs power HBTs have been developed for operation in the 26 GHz band. The HBTs were designed for improved thermal stability and power gain. A common-base HBT with a 480-/spl mu/m/sup 2/ emitter area achieved a 0.65 W CW output power with 34% collector efficiency, 16% power-added efficiency, and 6 dB linear power gain at 26.85 GHz. A 960-/spl mu/m/sup 2/ CB HBT produced an output power of 0.8 W with 5.6 dB linear power gain at 26.2 GHz.