Ka-band Communication Research Articles

East–West Station-Keeping maneuver strategy for COMS satellite using iterative process

The first Korean multi-mission geostationary satellite, Communication, Ocean, and Meteorological Satellite (COMS) will be launched in 2010. The missions of this satellite will be Ka-band communications, ocean color monitoring, and meteorological imaging. The satellite was designed with only one solar array on the south panel. This novel configuration will keep imaging instruments on the north side from heating up. Asymmetry of the spacecraft configuration requires twice-a-day thruster-based Wheel Off-Loading (WOL) operations to keep the satellite attitude for imaging and communication. Thruster firings during the WOL operations cause the satellite orbit to change two times a day. Weekly East–West Station-Keeping (EWSK) and North–South Station-Keeping (NSSK) maneuver operations are planned for the COMS satellite in order to maintain the satellite in ±0.05° box at 128.2°E longitude. The EWSK maneuver is planned to be performed two days after the NSSK maneuver to correct small side effects in East–West direction due to plume impingement against the solar array during NSSK maneuver. Normally thruster firings during the WOL operation affect the satellite orbit only in the North–South direction, but there are also small perturbations in the East–West direction. In this paper, EWSK maneuver strategy for the COMS satellite is presented. This strategy takes twice-a-day thruster-based WOL operations and plume impingement effect of the NSSK maneuver into account. And an iterative process to calculate the velocity changes and maneuver time for the EWSK maneuver is applied. One year of the EWSK and NSSK maneuver simulations are performed with twice-a-day WOL to verify the proposed strategy. The proposed strategy showed that the mean longitude of the satellite is controlled at 128.2° ± 0.007° which is three times tighter than that of non-iterative process. Required Delta velocity (Δ V) for EWSK maneuver is also slightly smaller for iterative process. Tightly controlled mean longitude guarantees a better quality of satellite communications and Earth imaging when the spacecraft attitude is well maintained by on-board control.

Ka-band High-speed Communication Systems on Small Satellites for Future Advanced Communication Networks and Earth Observations

The goal of this paper is to describe the capabilities and application methods of Ka-band communication systems for small satellites indicating contributions to future advanced communication networks and Earth observations. This study is based on the actual experience on the design of the Ka-band high-speed communication system of the small satellite Flying Laptop, which is developed at the Institute of Space Systems of the Universitat Stuttgart. The objectives of the Ka-band communication system is to demonstrate high-speed communications with a data rate of up to 500 Mbit/s as well as to conduct scientific Earth observations. Flying Laptop satellite is also equipped with a Ku-band signal transmitter. The attenuation of the two transmission signals in Ka-/Ku-bands are measured with ground stations to estimate the local precipitation rate. The mathematical background and operational scenario of this measurement is summarized. The received Ka-band transmission signal is measured in different meteorological conditions to identify attenuation characteristics of the Ka-band signal due to rain, clouds, trace gases and so forth, which is of great interest for utilization of Ka-band frequencies for future broadband communications.

Observing the Moon at Microwave Frequencies Using a Large-Diameter Deep Space Network Antenna

The Moon radiates energy at infrared and microwave wavelengths, in addition to reflecting sunlight at optical wavelengths. As a result, an antenna pointed at or near the Moon will result in an increase in system operating noise temperature, which needs to be accounted for in RF telecommunications, radio science or radiometric link calculations. The NASA Deep Space Network (DSN) may use its large-diameter antennas in future lunar robotic or human missions, and thus it is important to understand the nature of this temperature increase as a function of observing frequency, lunar phase, and angular position of the antenna beam on the lunar disk. This paper reports on a comprehensive lunar noise temperature measurement campaign and associated theoretical treatment for a 34-m diameter Deep Space Network antenna observing an extended source such as the Moon. A set of measurements over a wide range of lunar phase angles was acquired at DSS-13, a 34-m diameter beam waveguide antenna (BWG) located at Goldstone, California at 2.3 GHz (S-band), 8.4 GHz (X-band) and 32 GHz (Ka-band). For validation purposes, independent predictions of noise temperature increase were derived using a physical optics characterization of the 34-m diameter antenna gain patterns and Apollo model-based brightness temperature maps of the Moon as input. The model-based predictions of noise temperature increase were compared with the measurements at all three frequencies. In addition, a methodology is presented that relates noise temperature increase due to the Moon to disk-centered or disk-averaged brightness temperature of the Moon at the microwave frequencies of interest. Comparisons were made between the measurements and models in the domain of lunar disk-centered and disk-averaged brightness temperatures. It is anticipated that the measurements and associated theoretical development will be useful in developing telecommunications strategies for future high-rate Ka-band communications where large diameter DSN antennas will be required.

Digital satellite receiver for wideband multi-rate Ka-band communications

This correspondence presents the architecture of a high-speed low-complexity digital receiver for wideband satellite communications supporting multiple baud rates, ranging from 10 to 200 MBaud. The design of the modem is based on the cascaded integrator-comb (CIC) scheme which exploits a parallel processing so as to provide an outstanding decimation agility. Eventually, bit error rate (BER) performance of the multi-rate receiver are assessed by floating-point simulations.

Notice of Violation of IEEE Publication Principles: Ka-band distributed MEMS phase shifters on silicon using AlSi suspended membrane

Notice of Violation of IEEE Publication Principles<br><br>"Both the authors and the Editor-in-Chief of Volume 13, number 3 of the IEEE/ASME JMEMS (June 2004, pp. 542-549) of the paper numbered JMEMS 1041 have agreed that this paper, Ka-Band Distributed MEMS Phase Shifters on Silicon Using AlSi Suspended Membrane," should not have been published. The paper would have been withdrawn had this fact been discovered before the IEEE/ASME JMEMS print date for June 2004. The authors have indicated that they will work to provide a new version their paper that will be considered for publication if it is submitted in the future. For help in coming to this decision, I would like to thank those concerned individuals, including the authors, JMEMS editors, and highly respected researchers in the MEMS and microwave communities who contributed their time and consideration to help us assure the integrity of our journal." <br><br>Richard S. Muller, Editor-in-Chief, IEEE/ASME JMEMS<br><br>This paper presents the design, fabrication, and testing of distributed MEMS phase shifters for Ka-band communication systems. The phase shift can be obtained by changing MEMS bridge capacitors located periodically over the transmission line. Simulation results of phase shifters with various structural parameters are analyzed to develop the optimized designs. The phase shifters are fabricated on the high-resistivity silicon substrate, using suspended AlSi bridge membrane. The measured results demonstrate a phase shift of 286° at 36 GHz with the actuation voltage of 25 V, and a return loss better than 10 dB over 0-40 GHz band. In addition, lifetimes of 3×10/sup 6/ cycles have been achieved for the fabricated phase shifter with all MEMS bridges held to be valid. It shows that AlSi alloy has a nice compromise between strength and resilience. <br/> This paper presents the design, fabrication, and testing of distributed MEMS phase shifters for Ka-band communication systems. The phase shift can be obtained by changing MEMS bridge capacitors located periodically over the transmission line. Simulation results of phase shifters with various structural parameters are analyzed to develop the optimized designs. The phase shifters are fabricated on the high-resistivity silicon substrate, using suspended AlSi bridge membrane. The measured results demonstrate a phase shift of 286° at 36 GHz with the actuation voltage of 25 V, and a return loss better than 10 dB over 0–40 GHz band. In addition, lifetimes of 3 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> cycles have been achieved for the fabricated phase shifter with all MEMS bridges held to be valid. It shows that AlSi alloy has a nice compromise between strength and resilience.

A Compact Broadband PHEMT MMIC Power Amplifier for K through Ka-band Applications

A compact and broadband MMIC power amplifier operating from 18 GHz to 35 GHz is developed for K- through Ka-band applications implementing a rigorous electromagnetic (EM) simulation of closely spaced matching networks. The EM simulation results in a compact chip size as small as 2.16 mm × 2.0 mm and isolations of less than -25 dB up to 40 GHz between neighboring distributed structures. The two-stage balanced power amplifier fabricated using a 0.25 µm AlGaAs/InGaAs/GaAs PHEMT technology has an average gain of 11 dB, return losses less than -10 dB, and P1 dB above 20.5 dBm from 18 GHz to 35 GHz. This compact and broadband MMIC power amplifier is suited for power amplifiers for most K through Ka-band communication systems such as the FSS, LMDS, and ITS.

Ka-band direct digital receiver

A new direct-conversion wideband (26-28.5 GHz) six-port receiver is proposed for mass-market wireless communications. This six-port receiver is designed to operate without the need for precise power reading and the use of a digital signal processor that is usually required in other receivers. The proposed receiver architecture is chosen to satisfy requirements of hardware receivers used in high-speed QPSK communications. The receiver contains a receiver front-end, QPSK demodulator, and carrier recovery module. A reverse modulation loop was used to provide a rapid carrier recovery. The maximum bit rate is determined solely by the limiting speed of the baseband module. This new hardware receiver is proposed as a robust, rugged, low-cost receiver for use in wide Ka-band wireless mass-market QPSK communications such as local multipoint distribution system services, which is a prime example of communication equipment requiring such receivers. Bit-error-rate results are presented versus the noise and reference signal phase shift.

Ka-band aeronautical satellite communications experiments using COMETS

This paper describes the results of evaluation tests of an aeronautical satellite communications experiments system in the Ka-band using Japan's communications and broadcasting engineering test satellite (COMETS). An active phased-array antenna with an open-loop satellite tracking capability operating in the Ka-band was installed just behind the passenger window of an airplane to receive a satellite signal. The propagation measurements showed that the received signal power was stable within a signal-power variation of 1 dBp-p while the airplane was cruising at 600 km/h. At specific directions of the antenna, the radiowave reflected from the wing of the airplane was measured to be 18.5 dB lower in power compared with the line-of-sight signal. To confirm the designed link budget, the multibeam antenna pattern of COMETS' on-board antenna was measured while the airplane flew across two antenna beams. The antenna pattern matched the one measured in a ground test before launch. Two binary phase-shift keying (BPSK) modems, one for pilot-assisted coherent detection and the other for multiple-symbol differential detection, were used to measure the bit-error rate (BER). The measured received signal energy per bit per noise power density (E/sub b//N/sub 0/) at a BER of 10/sup -4/ showed only a small degradation of about 1 dB from that measured in a translator loop-back test.

A three-site comparison of fade-duration measurements

Important elements in the design of Ka-band communication systems are the duration of fade and nonfade events at a particular fade depth. The choice of modulation and forward error correcting codes will depend on both the fading time dynamics and annual fade occurrence statistics. This paper examines the fade duration measured at locations in three of the Advanced Communications Technology Satellite (ACTS) propagation experimental regions, namely, Florida (rain zone N of the radiocommunications sector of the International Telecommunications Union ~ITU-R\ model), New Mexico State University (ITU-R rain zone M), and Alaska (ITU-R rain zone C). Within each region, measures of the underlying uniformity are described and an interregional comparison examines the ability to scale the local results.

Dynamic response of long optical-cavity laser diode for Ka-band communication satellites

This paper presents the performance of a novel Fabry-Perot (FP) laser diode. The laser is composed of a long gain section, and a multiple-quantum-well (MQW) electroabsorption (E/A) modulator. The laser diode is mode locked using the integrated E/A modulator at 19.3 GHz. Sub-carrier data signals at S-band and a frequency reference of 19.3 GHz are simultaneously distributed using modulation of the gain and E/A sections of the laser, respectively. This paper also compares performance of this laser diode at various operation points in terms of pulsewidth, pulse-to-pulse coherency, phase-noise degradation of the frequency reference, and two-tone spurious-free dynamic range. Implication of this laser's performance as an optical transmitter is also evaluated for a fiber-optic (FO) distribution network in Ka-band phased-array antennas for satellite communications.

The Ka-Band Communication Systems of the Lincoln Experimental Satellites LES-8 and LES-9

Introduction L INCOLN Experimental Satellites LES-8 and LES-9 are a pair of experimental communication satellites designed and built to operate in a synchronous ecliptic orbit and to communicate on a crosslink from satellite to satellite as well as with surface terminals. At synchronous-orbit altitude, each satellite has a groundvisibility area about 8000 miles in diameter. With crosslink communication between two satellites spaced thousands of miles apart, a single pair of satellites could provide communications among terminals anywhere in an area covering more than 3/4 of the surface of the Earth. Communication links are possible at both UHF and Ka-band at approximately 37 GHz. Figure 1 shows a cutaway drawing of LES-9. The side facing the Earth is the forward platform, which is used for mounting and precision alignment of the Ka-band antennas and the Earth sensors. The Ka-band receiver diplexer filters and front ends are mounted as close as possible to the diplexer polarizer mounted on each antenna. The Ka-band transmitter power amplifiers are mounted on sections of the internal decagon adjacent to the forward platform to minimize the length of the waveguide runs to the antennas. LES-8 and LES-9 each utilize two independent Ka-band communication systems (see Fig. 2). The Ka-dish system uses a fixed paraboloidal reflector in conjunction with a steerable flat reflector to provide a narrow beam, tracking antenna for crosslink or uplink/downlink communications. The Ka-horn system includes a fixed horn to provide a wide-beam antenna coverage. Local oscillator requirements for both systems are provided by a single Ka-band local oscillator. Each receiver subsystem features a broadband low-noise mixer utilizing Schottky-barrier diodes to achieve a typical system noise figure of less than 8 dB. Each transmitter includes an array of solid-state amplifiers which utilize IMPATT diodes, and delivers 0.5 W of power to the antenna. The transmitter signal is modulated at a lower frequency and is upconverted to Kaband using a mixer similar to that used in the low-noise receiver. This paper will discuss the Ka-band systems carried on LES8 and LES-9, which were built to demonstrate component and