Showing papers on "Ka band published in 1985"

Experimental relationships between microwave emission and vegetation features

Abstract: Radiometric features of vegetation from the X and Ka bands were investigated with ground-based radiometers in 1981–1983. Crops investigated were alfa-alfa, corn and wheat. Microwave data have been compared with physical conditions of the soil-plant-atmosphere continuum and with some biological parameters of plants. Results of these observations have shown that the difference between normalized temperatures from the Ka and X bands is sensitive to vegetation type, while the polarization index from the Ka band seems to be dependent on plant water conditions.

High-Voltage Ka-Band Gyrotron Experiment

Abstract: A new high-voltage, intense-beam, Ka-band gyrotron experiment is underway using a 350-400-keV 0.5-1-kA beam from a short-pulse Febetron pulser. High-power operation at 35 GHz has been observed, with 20 MW (±3 dB) produced at ~8.5-percent efficiency in a "whispering-gallery" TE62 mode. Operation in other modes and at other frequencies has also been studied.

A Ka-Band GaAs Power MMIC

Abstract: A Ka-band GaAs power MMIC with source island via-hole PHS structure and monolithic power divider /combiner circuits was developed and reliability study was performed. This source island via-hole technique successfully reduced both thermal resistance and source parasitic inductance of the MMIC. The 3200 µm MMIC gave power output at 1dB gain compression of 1.1 W, linear power gain of 4.0 dB and power added efficiency of 10.8 % at 28 GHz. No failure was observed in the temperature cycling, the DC running and the high temperature storage tests.

High-efficiency Ka- and Ku-band MESFET oscillators

Abstract: A relationship between GaAs MESFET oscillator efficiency and power and basic device characteristics is given. This has been confirmed by measurements on 16.8 and 28.5 GHz experimental designs, which have demonstrated efficiencies of 28 and 17.6%, respectively.

Interdisciplinary design analysis of a precision spacecraft antenna

Abstract: The Advanced Communications Technology Satellite (ACTS) will operate in the 20/30 GHz range (Ka Band), and will include a multi-beam antenna (MBA) capable of 0.3 degree scanning spot beams with very high beam-to-beam isolation. The antenna Radio Frequency (RF) performance requirements lead to stringent requirements on the antenna reflector surface shape. A prediction of RF performance of a potential flight model antenna reflector operating under space environmental conditions is made using a radiant heat input model (TRASYS), a thermal analyzer (SINDA), a structural model (NASTRAN), and RF far field pattern simulation. Interfacing software has been written to pass thermal model temperature results to the structural model, and structural model thermal deformation results to the RF far field pattern simulation. A complete analysis can be performed in a single computer run, and potential changes in design can be quickly and easily evaluated using this interdisciplinary design analysis tool.

A Field Theoretical Analysis of Ferrite-Loaded Image Line Isolators for the Ka-Band

Abstract: A ferrite isolator in image line technique is investigated both theoretically and experimentally. The used theoretical analysis method allows an exact description of the electromagnetic field in a multilayered structure. The feasibility of a dielectric image line field displacement isolator for the Ka-band is demonstrated.

A Continuously Tunable Ka-Band Gyrotron

Abstract: An experimental study was carried out to test the concept of using a gyrotron with a tapered circuit in a uniform magnetic field as a high-power tunable source of millimeter-wave radiation. It was demonstrated that the device can be used as either an oscillator or an amplifier with the operating frequency tunable by varying the magnetic field. In the oscillator mode, the tube produced a peak output power of 500-750 W with the frequency continuously tunable from 30 to 39 GHz. As an amplifier mode, the tube demonstrated an electronic gain of ~23 dB at a magnetically tunable center frequency with an instantaneous bandwidth of ~5 percent. The stability characteristics of the amplifier were also investigated.

Ka-Band FET Oscillator (Short Paper)

Abstract: The design and performance of GaAs FET oscillators operating near 36 GHz are presented. The oscillators used readily available GaAs FET's and were built in a microstrip circuit configuration. An output power of about +8 dBm was obtained with two devices in a single oscillator.

Integrated Ka-Band Front End with Monolithic Mixer

Abstract: A Ka-band front end has been developed that integrates a low-loss wide-band monolithic mixer, a two-stage IF amplifier on semi-insulating GaAs, and a lumped-element Gunn LO. Small size (0.5 in/sup 3/) and good performance (11-dB gain with a DSB noise figure of 7 dB) have been obtained by applying synergistic IC construction techniques.

A 9 Bit DIFM Receiver for Ka-Band

Abstract: A digital instantaneous frequency measuring receiver (DIFM) has been built at Ka-band with a frequency resolution of 25 MHz (9 bit) using a five discriminator binary system digitised to 11.25 degrees. Absolute frequency accuracy is dispersion limited to 100 MHz. A simplified system block diagram is shown in fig. 1. Advanced technology is used in each of the three sections to obtain a compact unit with a performance limit set by the inherent frequency dispersion in the microstrip discriminator circuitry. This paper describes the design. construction and performance of the complete DIFM receiver with special attention given to the CAD techniques based on circuit modelling to allow microwave discriminator design to be carried out under conditions of severe frequency dispersion.

Discussion on the progress and future of satellite communication (Japan)

Abstract: The current status of communications satellite development in Japan is presented It is shown that beginning with research on satellite communucations in the late 1950's, progress was made in the areas of communications, remote sensing, and technology experimentation The current status of communication satellites is presented, stressing development in the areas of CFRP construction elements, the use of LSI and MIC circuits, advanced multibeam antenna systems, Ku and Ka band transmission systems, and the shift to small-scale earth stations Methods for reducing costs and increasing transmission efficiency are shown The technical specifications of all satellite projects currently under development are given Users of Japanese communications satellite are presented

Time Domain Measurements in KA Band (26.5-40.0 GHz) Using a WR28 5 Port Junction

Abstract: This paper describes the use of a WR28 5 port junction to make time domain measurements in Ka band (26.5 - 40.0 GHz) via the 6-port measurement technique. A solid state signal generator, with about one milliwatt of output power, is used as the signal source. Results on the time domain analysis of narrow height WR28 mismatch standards open at the ends are presented. The two reflections from the junction where the waveguide height narrows, and from the open end are well separated.

The Effects of Mode Impurity of Ka-band System Performance

Abstract: Problems associated with spurious mode generation in the proposed Ka-Band gyroklystron transmitter tube, overmoded transmission line, and feed are discussed. A brief description of the overall problem is presented. The theory used to evaluate feed and antenna performance when spurious modes are present is given. Results for feed patterns and overall antenna patterns for various levels and types of spurious modes are presented. Worst case antenna efficiency is calculated as a function of spurious mode level. Conclusions are drawn regarding the results of this study and their application to specifications on the transmitter tube and transmission line system.

A 35 GHz Proximetry Microwave Sensor

Abstract: At the end of the century, Europe will realise rendez-vous between satellites in space. Basic studies have already started at CNES (Centre National d'Etudes Spatiales). A breadboard model of a radar which provides the necessary information during an automatic docking manoeuver is presented. This FM-CW, Ka band radar will be located on the arm extremity of a robotised hunting satellite. The main feature of this instrument is to measure, relative distance, relative speed and angular position at very short distances (inferior to one metre).

Ka BAND DUAL SIX PORT MEASUREMENTS

Abstract: An automatic dual six port network analyzer has been designed and tested over the frequency band of 26.5 to 40 GHz. The six port design utilizes a matched symmetrical five port waveguide junction. A method of matching avoiding the use of tuning screws is discussed, and an analysis of the sensitivity of six port parameters to the matching of the star junction is presented.

High-Voltage Ka-Band GyrotronExpenrment

Abstract: A newhigh-voltage, intense-beam, Ka-band gyrotron ex- periment isunderway using a350-400-keV 0.5-1-kA beamfromashort- pulse Febetron pulser. High-power operation at35GHzhasbeenob- served, with20MW (±3dB)produced at- 8.5-percent efficiency ina "whispering-gallery" TE62mode.Operation inothermodesandat other frequencies hasalsobeenstudied.

A dual frequency microstrip antenna for Ka band

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

Integrated Ka-Band Fin-Line Six-Port

Abstract: The design and performance of an integrated mm-wave 6-port is presented. The design uses Fin-Line technology and beam-lead diode detectors in a Ka-full-band application. The high precision measurement capability of the 6-port device has been verified in an automated 6-port network analyzer setup.