Showing papers on "Ka band published in 1996"
27 May 1996
TL;DR: This paper describes the Twin-Otter SAR Testbed developed at Sandia National Laboratories, a flexible, adaptable testbed capable of operation on four frequency bands: Ka, Ku, X, and VHF/UHF bands.
Abstract: This paper describes the Twin-Otter SAR Testbed developed at Sandia National Laboratories. This SAR is a flexible, adaptable testbed capable of operation on four frequency bands: Ka, Ku, X, and VHF/UHF bands. The SAR features real-time image formation at fine resolution in spotlight and stripmap modes. High-quality images are formed in real time using the overlapped subaperture (OSA) image-formation and phase gradient autofocus (PGA) algorithms.
42 citations
TL;DR: In this article, an experimental campaign for collection propagation data from the advanced communications technology satellite (ACTS) is described and the expected outputs of the ACTS campaign are presented, as well as the measured results and analysed data are reported.
Abstract: The congestion of the radio spectrum below about 18 GHz is causing a rush of interest in the 20/30- GHz band. Due to the shorter wavelength of these frequencies, the atmosphere, especially rain, greatly influences the transmission of signals between earth/space stations. The slant path effects in the Ka region of the radio spectrum are addressed and an experimental campaign for collection propagation data is described. This campaign uses the advanced communications technology satellite (ACTS) and consists of several measurement sites. A brief description of the spacecraft payload and the propagation terminals is given. The experiment sites are discussed. The expected outputs of the ACTS campaign are presented. Measured results and analysed data are reported.
31 citations
TL;DR: In this article, two novel types of coupled line structures have been realized on GaAs monolithic microwave integrated circuits to obtain 90° couplers operating at a center frequency of 24 GHz.
Abstract: Two novel types of coupled line structures have been realized on GaAs monolithic microwave integrated circuits to obtain 90° couplers operating at a center frequency of 24 GHz. Both of the couplers are made up of either two or three conductive layers to improve the coupling. The aim is to achieve compact couplers with smaller aspect ratios and to decrease the losses due to field crowding on the edges. Both couplers have achieved good matching and coupling. The simulation is carried out on the electromagnetic simulator em (a trademark of Sonnet Software Inc.).
28 citations
Patent•
20 Sep 1996TL;DR: In this paper, a wideband modulated data signal is used to test the response of the Ka band transponder, and a periodic test pattern, preferably a pseudo-noise (PN) sequence, modulated on a carrier, is transmitted to an onboard satellite Transponder which then retransmits the signal to a receiver where a down converter is used for output inphase and quadrature phase baseband signals which are digitized and used for measuring one or more of the following: Magnitude and phase response AM/AM and AM/PM Phase noise Bit
Abstract: Method and apparatus for performance characterization of Ka band transponders wherein measurements are made. A wideband modulated data signal is used to test the response of the Ka band transponder. A periodic test pattern, preferably a pseudo-noise (PN) sequence, modulated on a carrier, is transmitted to an onboard satellite transponder which then retransmits the signal to a receiver where a down converter is used to output inphase and quadrature phase baseband signals which are digitized and used for measuring one or more of the following: Magnitude and phase response AM/AM and AM/PM Phase noise Bit error rate Data asymmetry I/Q channel imbalance.
27 citations
TL;DR: In this article, a broadband transition from waveguide-to-coupled fin-line in its quasi-TEM mode is proposed for lownoise amplifiers or low-noise converters in millimeter-wave bands.
Abstract: A new broadband transition from waveguide-to-coupled fin-line in its quasi-TEM mode is presented. The transition is proposed for low-noise amplifiers or low-noise converters in millimeter-wave bands. Experimental results on the Ka band show a 1 dB insertion loss for a back-to-back double transition over a 10 GHz band.
23 citations
28 Apr 1996
TL;DR: This paper describes statistical models in terms of signal envelope and signal phase probability distribution for both fixed and mobile satellite communications channels at Ka band (20/30 GHz).
Abstract: This paper describes statistical models in terms of signal envelope and signal phase probability distribution for both fixed and mobile satellite communications channels at Ka band (20/30 GHz). Statistical models for eleven different weather conditions are given for the fixed satellite communications channels. Also, statistical models for light to medium shadowing, medium to heavy shadowing and heavy shadowing are given for the land mobile satellite communications channels at Ka band. The results described should be useful for the design of fixed and mobile satellite communications at Ka band.
22 citations
TL;DR: In this article, the operating characteristics of a two-cavity third harmonic gyroklystron experiment were presented, where the input cavity utilizes a 9854 GHz TE011 mode driven by a 100 kW magnetron and the output cavity has a resonant frequency of 2957 GHz.
Abstract: We present the operating characteristics of a two‐cavity third harmonic gyroklystron experiment The input cavity utilizes a 9854 GHz TE011 mode which is driven by a 100 kW magnetron The TE031 output cavity has a resonant frequency of 2957 GHz The nominal beam voltage and current are 435 kV and 210 A, respectively The pulse length is about 1 μs and the average ratio of parallel to perpendicular velocity is near one Peak powers above 18 MW are achieved with an efficiency of about 2% and a gain of 14 dB The theoretical simulations are in good agreement with the experimental results
21 citations
17 Jun 1996
TL;DR: In this article, a high-gain, high-efficiency Ka band MMIC power amplifier with pHEMT process technology is presented, achieving an average 35% power-added efficiency (378 peak) over a 26.5 to 28 GHz band using 0.25 /spl mu/m AlGaAs/InGaAs pseudomorphic HEMT (HEMT) process technology.
Abstract: We have demonstrated a high-gain, high-efficiency Ka band three-stage MMIC power amplifier providing >1 watt CW output power, >20 dB power gain, with an average 35% power-added efficiency (378 peak) over a 26.5 to 28 GHz band using 0.25 /spl mu/m AlGaAs/InGaAs pseudomorphic HEMT (HEMT) process technology. The pHEMT amplifiers exhibit third-order intermodulation products >29 dBc with the output power backed off by 5 dB. As an alternate low-cost solution, we processed three wafers of the Ka-band monolithic amplifier designed with pHEMT technology using direct ion-implanted 0.2 /spl mu/m GaAs MESFETs achieving >1 watt CW output power, >18 dB power gain, with an average 24% power-added efficiency (27% peak) over the band. The MESFET amplifiers demonstrate third-order intermodulation products >21 dBc with the output power backed off by 5 dB. All amplifier results reported here contain no de-embedding of fixture and connector losses. This paper presents 0.25 /spl mu/m pHEMT and 0.2 pm MESFET device results, as well as amplifier design and performance over a 26.5 to 28 GHz band.
17 citations
TL;DR: It is found that with suitable post-processing, the RCA can provide reasonable (conservative) data rate estimates without making excessive data rate changes, i.e., data rate change fluctuations.
Abstract: A rain compensation algorithm (RCA) has been developed for use in the ACTS Mobile Terminal (AMT) system. The basic goal of the RCA is to control the transmitted data rates (9.6, 4.8, or 2.4 kbps) in the forward and return links so that a 3 db link margin is maintained at the highest possible transmitted data rate.
13 citations
TL;DR: In this paper, the integration and reliability testing of micromachined, membrane-supported transmission line circuits are described, which employ a 1.4/spl mu/m-thick dielectric membrane to support thin-film conducting lines above an air substrate.
Abstract: This paper describes recent results which pertain to the integration and reliability testing of micromachined, membrane-supported transmission line circuits. These circuits employ a 1.4-/spl mu/m-thick dielectric membrane to support thin-film conducting lines above an air substrate. With regard to integration, the development of a Ka-band solid state power amplifier (SSPA) is presented. The design includes a membrane-supported Wilkinson power divider/combiner with 0.2 dB loss, along with a commercially available monolithic microwave/millimeter wave integrated circuit (MMIC) amplifier stage. Also reported are tests which investigated the survivability of membrane lines under space qualification conditions. No failures occurred as a result of thermal cycling and vibration testing at levels which reached 39.6 grms.
11 citations
15 Feb 1996
TL;DR: In this paper, a prototype five-layer Ka-/Ka-band dichroic plate was fabricated and measured to pass Ka-band uplink (34.2-34.7 GHz) and downlink (31.8-32.3 GHz) operation in the Deep Space Network to support the future Cassini mission.
Abstract: A prototype five-layer Ka-/Ka-band dichroic plate was fabricated and measured. This dichroic plate was designed to pass Ka-band uplink (34.2-34.7 GHz) and to reflect Ka-band downlink (31.8-32.3 GHz) for dual-frequency operation in the Deep Space Network to support the future Cassini mission. The theoretical calculation and the experimental measurement of the reflected resonant frequencies were within 0.24 percent for circular polarization. The computer program, which was used to design the dichroic plate with stepped apertures, was then verified.
17 Jun 1996
TL;DR: In this paper, a Ka-band GaInP/GaAs HBT four-stage MMIC LNA has been designed and fabricated for local multipoint distribution systems (LMDS) which include both analog and digital transmission.
Abstract: A Ka-band GaInP/GaAs HBT four-stage MMIC LNA has been designed and fabricated. This circuit is to be used in a multifunction T/R module for local multipoint distribution systems (LMDS) which include both analog and digital transmission. An average noise figure of 6 dB from 27 GHz to 30 GHz, and a gain of greater than 15 dB were measured. These results are the best reported at Ka-band for a LNA using transistors from digital HBT library.
24 Sep 1996
TL;DR: In this paper, the relative significance of scintillation fading and rain attenuation on low-availability VSAT satellite systems operating at the Ka and EHF bands is examined and the influence of such parameters as signal frequency, path elevation, time percentage, and climate is discussed.
Abstract: The relative significance of scintillation fading and rain attenuation on low-availability VSAT satellite systems operating at the Ka and EHF bands is examined. The influence of such parameters as signal frequency, path elevation, time percentage, and climate is discussed. The study employs the simple rain attenuation model (SAM) and a scintillation fade model developed from Olympus satellite measurements in the United Kingdom.
17 Jun 1996
TL;DR: In this paper, the authors describe the development of an advanced single-chip Ka-band transceiver for military applications, and the in-fixture measured performance of the transceiver chip is presented.
Abstract: This paper describes the development of an advanced single-chip Ka-band transceiver for military applications. The in-fixture measured performance of the transceiver chip is presented. The transceiver chip monolithically integrates seven separate chips and one filter onto a single chip. In-fixture, the monolithic transceiver chip has demonstrated measured receiver noise figure of less than 6.5 dB across the RF band from 38.0-38.5 GHz at an IF of 2.45 GHz under -10 dBm LO drive. The transmitter output power was measured to be greater than 17.5 dBm across the 38.0-38.5 GHz band.
01 Sep 1996
TL;DR: The first experimental communications satellite using Ka-band technology is the NASA Advanced Communications Technology Satellite (ACTS) as discussed by the authors, which was deployed into a geostationary orbit near 100 degrees W longitude by the space shuttle Discovery.
Abstract: One of the first experimental communications satellites using Ka-band technology is the NASA Advanced Communications Technology Satellite (ACTS). In September 1993, ACTS was deployed into a geostationary orbit near 100 degrees W longitude by the space shuttle Discovery. The ACTS system supports both communication and propagation experiments at the 20/30 GHz frequency bands. The propagation experiment involves multi-year attenuation measurements along the satellite-Earth slant path.
TL;DR: 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 are described.
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.
25 Feb 1996
TL;DR: In this paper, an advanced payload for mobile communication at the L band (LLM) is presented, and the design and performance of the LLM payload are discussed. But the authors focus on the use of the multiport amplifier technique and multibeam generation.
Abstract: ARTEMIS is a communication satellite of ESA, developed in the framework of the Data Relay and Technological Mission program (DRTM). ARTEMIS will provide in orbit demonstration of interorbit links at S band, Ka band, and optical frequencies. Moreover, it handles an advanced payload for mobile communication at L band (LLM). This paper concentrates on the LLM payload, reports on its design and performance, and focuses on some key features, such as the use of the multiport amplifier technique and multibeam generation. (Author)
21 Jul 1996
TL;DR: In this article, a new Ku/Ka dual-band feed is proposed to provide efficient illumination on the deployable mesh reflector and perform the tracking function (in both Ku- and Ka-bands) and be capable of both RHCP and LHCP operations.
Abstract: The current NASA TDRSS (Telemetry Data Relay Satellite System) provides service at S- and Ku-bands. The next generation TDRSS will extend the service to Ka-band, in addition to the existing S- and Ku-bands. One approach to achieve this enhancement is to replace the Ku-band feed assembly of the existing single access antennas (SAAs) with a new Ku/Ka dual-band feed. This approach has the advantage of minimum breakage to the existing hardware, which has seven flight heritage. The new Ku/Ka dual-band feed is required to provide efficient illumination on the deployable mesh reflector and perform the tracking function (in both Ku- and Ka-bands) and be capable of both RHCP and LHCP operations. In addition, the new feed assembly has to be sufficiently compact to fit into the existing feed tower so that the costly redesign of the reflector system and the deployment mechanism is avoided. This paper describes the design approach, the breadboard model fabrication, and the measured performance of such a feed assembly. The new feed is designed for the following operating frequencies: 13.775 to 13.805 GHz for Ku-transmit, 14.888 to 15.113 GHz for Ku-receive, 22.55 to 23.55 GHz for Ka-transmit, and 25.255 to 27.505 GHz for Ka-receive.
25 Feb 1996
TL;DR: The architecture and the performance of an on-board digital Processor providing full interconnectivity among (16) uplink beams and (5 to 16) down-link beams, as needed for a 20/30 GHz communications payload supporting a capacity of more than 2,000 channels, in conjunction with Very Small Aperture Terminals (VSATs).
Abstract: This paper describes the architecture and the performance of an on-board digital Processor providing full interconnectivity among (16) uplink beams and (5 to 16) down-link beams, as needed for a 20/30 GHz communications payload supporting a capacity of more than 2,000 channels (at 64 Kbit/s), in conjunction with Very Small Aperture Terminals (VSATs). In the considered payload up-link signals are not demodulated, this feature making it transparent to virtually any signal format, even those not envisaged at payload design time. A wide range of different carrier types can so be accommodated, as long as they are consistent with the bandwidth, power & dynamic-range constraints. The Processor implements, by means of Digital Signal Processing (DSP) algorithms, the filtering, multiplexing and routing functions necessary to establish variable-bandwidth paths between pairs of upand down-link beams. Compared to "analog" solutions (i.e. those utilizing physical filters, frequency converters, switches, etc.), digital approaches yield a very good bandwidth management flexibility, and offer several new interesting features. The subject Processor adopts a FrequencyDomain Switching (FDS) architecture (covered by a Space Engineering patent), according to which beam-routing is directly performed on the frequency-domain samples generated by the onboard digital demultiplexers, this scheme allowing to save both a frequency-to-time and a time-tofrequency conversion. More detailed information on FDS algorithms, implementation and performance are available in literature'. This paper is derived from a study performed on contract to ESA. An RFP for the development of a processor breadboard representative of the herein illustrated architecture has recently been issued. C. Soprano ESTEC P. O. Box 299 2200 AG Naordwijk The Netherlands
26 May 1996
TL;DR: In this paper, the authors investigated the performance of HBT devices as mixers, specifically as upconverters in the transmitter path, using a proprietary HBT model implemented on Libra/sup TM/ by the Communications Research Centre.
Abstract: Heterojunction bipolar transistors (HBTs) are attracting interest around the world, finding use in power amplifiers and low phase noise oscillators. There is little information, however, on the performance of HBT devices as mixers, specifically as upconverters in the transmitter path. Using a proprietary HBT model implemented on Libra/sup TM/ by the Communications Research Centre, the HBT is investigated for its suitability as a mixer. A single-ended microwave monolithic integrated circuit (MMIC) upconverter is designed with the IF and LO fed through the base and emitter, respectively, thereby eliminating the need for a diplexer. The simulated upconverter (IF=3.6 GHz and RF=30.1 GHz) yields a conversion gain greater than 2 dB over a bandwidth of 300 MHz. At the RF port, the IF, LO and image frequency isolations are 19 dB, 18 dB and 13 dB respectively, while at the IF port, the RF, LO and image frequency isolations are all greater than 40 dB.
15 Feb 1996
TL;DR: This article presents system modeling, signal processing, simulation, and implementation of Ka-band monopulse tracking feed for antennas in NASA/DSN ground stations as well as single-pulse processing for acquisition and tracking.
Abstract: NASA 's Deep Space Network (DSN) has been using both 70-m and 34-m reflector antennas to communicate with spacecraft at S-band (2.3 GHz) and X-band (8.45 GHz). To improve the quality of telecommunication and to meet future mission requirements, JPL has been developing 34-m Ka-band (32-GHz) beam waveguide antennas. Presently, antenna pointing operates in either the open-loop mode with blind pointing using navigation predicts or the closed-loop mode with conical scan (conscan). Pointing accuracy under normal conscan operating conditions is in the neighborhood of 5 mdeg. This is acceptable at S- and X-bands, but not enough at Ka-band. Due to the narrow beamwidth at Ka-band, it is important to improve pointing accuracy significantly (approximately 2 mdeg). Monopulse antenna tracking is one scheme being developed to meet the stringent pointing-accuracy requirement at Ka-band. Other advantages of monopulse tracking include low sensitivity to signal amplitude fluctuations as well as single-pulse processing for acquisition and tracking. This article presents system modeling, signal processing, simulation, and implementation of Ka-band monopulse tracking feed for antennas in NASA/DSN ground stations.
TL;DR: In this paper, the design of two MMIC KA band oscillators compatible with the Philips DO2AH process is described, one employs separate gate and drain bias supplies, the other includes bias resistors on chip.
Abstract: The design of two MMIC KA band oscillators compatible with the Philips DO2AH process is outlined Both designs use 02 µm PHEMT devices: the first employs separate gate and drain bias supplies, the other includes bias resistors on chip Design procedures and results obtained from simulations and measurements are presented
TL;DR: The aim of the paper is to introduce a design methodology and to show the advantages obtainable using frequency diversity for a Ka-band system with higher performances than common VSATs.
Abstract: The growth of the demand for telecommunication services is going to saturate the frequency bands usually used (C or Ku) For this reason the Ka-band is much considered and is going to be highly used
To meet the requirements of a more developed market a satellite system in Ka-band with European coverage and better performance than those of common VSATs, especially in terms of capacity and of link availability, is proposed and characterized
The negative effect due to the high rain attenuation, that represents the main impairment using Ka-band, can be mitigated using one or more fade countermeasures
Frequency diversity, which well suites the characteristics of the proposed systems, has been analysed and characterized in detail using a model developed at Politecnico di Milano Its performances are shown as a function of different system parameters such as total number of stations, number of assisted stations, link availability and statistical dependence among stations
The aim of the paper is to introduce a design methodology and to show the advantages obtainable using frequency diversity for a Ka-band system with higher performances than common VSATs
The advantages achieved for rain margins are shown and system design parameters are then compared with those of an uncompensated system
Using this type of countermeasure, the dimensioning of the whole system (both payload and earth-station) is proved to be much less severe
01 Jan 1996
TL;DR: In this article, the authors focus on the signal attenuation statistics, results are compared to predictions of the ITU and Global rain models for a site located in Tampa, Florida (ITU Region N).
Abstract: NASA’s Advanced Communications Technology Satellite (ACTS) was developed to assist the creation and validation of communication technology as it expands into the Ka Band (20/30 GHz) region. These frequencies are particularly affected by intense weather phenomena, hence reliable signal transmission system design will rely heavily on both measurement data bases and validated models of channel characterization. Two years of propagation data have been collected and analyzed for a site located in Tampa, Florida (ITU Region N). This site experiences intense weather activity similar to equatorial regions. This paper will focus on the signal attenuation statistics, results are compared to predictions of the ITU and Global rain models.
01 Jan 1996
TL;DR: In this paper, the failure and recovery statistics of these Ka-band weather-dependent links were examined and the renewal theory was employed to examine the failure/recovery statistics.
Abstract: Ka-band (32-GHz) radio communication links are more adversely affected by atmospheric noise temperature than X-band (8.4-GHz) or S-band (2.9-GHz) links. As a result, the strategy for telecommunications between a spacecraft employing Ka-band and the Deep Space Network is necessarily different from that employed at the lower frequencies. To aid in the development of new communication strategies, several years of 31.4-GHz water vapor radiometer data from the Goldstone and Madrid sites were reduced. Renewal theory was employed to examine the failure and recovery statistics of these Ka-band weather-dependent links.
21 Jul 1996
TL;DR: The application of photonics in beam forming and steering of large phased array antennas onboard satcom/avionics systems is addressed in this paper, where several optical beamforming and steering feed architectures using fiber optic true time delay elements, integrated optical phase and frequency shifters, and coherent Fourier optical processors are assessed for their capability and technology feasibility in spaceborne systems in the Ka/Ku band.
Abstract: The application of photonics in beam forming and steering of large phased array antennas onboard satcom/avionics systems is addressed. Several optical beam forming and steering feed architectures using fiber optic true time delay elements, integrated optical phase and frequency shifters, and coherent Fourier optical processors are assessed for their capability and technology feasibility in spaceborne systems in the Ka/Ku band.
26 May 1996
TL;DR: In this article, a Ka-band GaInP/GaAs HBT four-stage LNA has been designed and fabricated for local multipoint distribution systems (LMDS) which include both analog and digital transmission.
Abstract: A Ka-band GaInP/GaAs HBT four-stage LNA has been designed and fabricated. This circuit is to be used in a multifunction transmit/receive (T/R) module for local multipoint distribution systems (LMDS) which include both analog and digital transmission. An average noise figure of 6 dB from 27 to 30 GHz, and a gain of greater than 15 dB were measured. These results are the best reported at Ka-band for a LNA using transistors from a digital HBT library.
TL;DR: In this paper, a new open-loop technique for estimating and correcting Doppler frequency shift in K/Ka-band communication systems with special reference to the advanced communications technology satellite (ACTS) mobile terminal (AMT) modem, which utilizes square-wave pulse-shaped, binary differential phase shift-keyed (DPSK) modulation.
Abstract: This paper presents a new open-loop technique for estimating and correcting Doppler frequency shift in K/Ka-band communication systems with special reference to the advanced communications technology satellite (ACTS) mobile terminal (AMT) modem, which utilizes square-wave pulse-shaped, binary differential phase shift-keyed (DPSK) modulation. The novelty of this estimation scheme is that it exploits the Doppler-induced phase shift over a fraction of a symbol interval to provide an estimate of the Doppler offset, without requiring symbol synchronization. Furthermore, by utilizing time-differential detection (delay-and-multiply), the proposed technique can tolerate much larger frequency offsets than existing open- or closed-loop techniques. Analytical results are provided for the variance of the above estimator and the error probability performance of the AMT is evaluated in the presence of the Doppler correction. Practical design considerations are also discussed, including a method for modifying the front end, digital bandlimiting filter in such a way that Doppler bias effects in the new estimator are eliminated. Simulation results reveal that, in general, performance improves with increasing data rates, i.e., the new frequency offset estimation/compensation algorithm induces a degradation from ideal of approximately 1 dB at a 6 dB energy per data symbol (bit) and a 2.4 kbps data rate. However, there is no appreciable degradation when the data rate is increased to 9.6 or 19.2 kbps.
21 Jul 1996
TL;DR: In this article, a multiuser horn for simultaneous X/X/Ka-band operation in a beam waveguide antenna was designed for circularly polarized wave operation and low loss (noise) and high power (up to 20 kilowatts) operation were considered.
Abstract: The NASA's Deep Space Network has a need for a multifrequency horn for simultaneous X/X/Ka-band operation in a beam waveguide antenna. The multifrequency horn will receive an X-band downlink (8.4-8.5 GHz) and a Ka-band downlink (31.8-32.3 GHz), and transmit an X-band uplink (7.145-7.235 GHz) signals simultaneously. The horn is designed for circularly polarized wave operation. Low loss (noise) and high power (up to 20 kilowatts) operation are considered in the horn design.