Showing papers on "Ka band published in 2001"

Design of a Ka-band gyro-TWT for radar applications

Abstract: The design of a Ka-band gyrotron traveling wave tube (TWT) amplifier capable of operating over a wide range of peak powers and bandwidths is presented. The amplifier operates in the TE/sub 11/ mode at the fundamental cyclotron harmonic. Instantaneous bandwidths in the range of 2.5 to 3.9 GHz (at 1 dB below saturation) with corresponding peak powers between 92.2 and 57.9 kW can be achieved by simply adjusting the mod-anode voltage of the electron gun. The corresponding gains range from 57.1 to 36.0 dB. The design performance is obtained with a high quality, 6 A, 70 kV electron beam generated with a double-anode magnetron injection gun. This wide range performance capability in the design is achieved via the use of the distributed loss approach in the interacting circuit, which also guarantees zero-drive stability. A diffractive loading scheme is employed in the lossy section of the circuit to ensure high average power operation of the amplifier.

Ka-band land mobile satellite channel model incorporating weather effects

Abstract: A Ka-band land mobile satellite (LMS) channel model which is able to take into account weather impairments is proposed. The statistics of the received signal and the BER performance of the system under the proposed channel model are obtained and compared with the results generated using Loo's weather-affected LMS channel model. The proposed Ka-band (20/30 GHz) LMS channel model is shown to be more reasonable as it gives realistic results.

Coaxial continuous transverse stub (CTS) array

Abstract: A new coaxial continuous transverse stub (CTS) array is proposed, designed, constructed, and tested. It is an omni-directional low cost antenna array which provides good impedance matching characteristics and good tolerance to manufacturing errors. It can be simply fed by a coaxial connector and is particularly suitable for millimeter wave personal communication systems (PCS). It is shown that this type of radiating element provides high percentage of radiation, and for the simulated design of single- and multiple-element arrays, S/sub 11/ was below -10 dB across a 6 GHz frequency span at the Ka band. A three-element prototype coaxial CTS antenna array was designed, constructed, and tested in the X-band. Experimental results were in good agreement with the simulated performance. Potential application of this new antenna array in multiband operation is also described.

High-Q bulk micromachined silicon cavity resonator at Ka-band

Abstract: A novel bulk silicon micromachining technique for fabricating millimetre-wave waveguide components is presented. This technique enables the formation of deep three-dimensional stacked structures of almost constant cross-section as well as post wafer-bonding metallisation that reduces the effects of air gaps and contact resistances. With these innovations it is possible to realise high-Q devices with low-cost fabrication. Simulated and measured results for a 30 GHz silicon cavity resonator are presented.

Cryogenic, X-band and Ka-band InP HEMT based LNAs for the Deep Space Network

Abstract: Exploration of the Solar System with automated spacecraft that are more than ten astronomical units from Earth requires very large antennae employing extremely sensitive receivers. A key figure of merit in the specification of the spacecraft-to-earth telecommunications link is the ratio of the antenna gain to operational noise temperature (G/Top) of the system. The Deep Space Network (DSN) receivers are cryogenic, low-noise amplifiers (LNAs). InP HEMT LNA modules are demonstrating noise temperatures less than ten times the quantum noise limit (10 hf/k) from 1 to 100 GHz. To date, the lowest noise LNA modules developed for the DSN have demonstrated noise temperatures of under 4 K at 8.4 GHz and 11 K at 32 GHz. The development and demonstration of cryogenic, InP HEMT based front-end amplifiers for the DSN requires accurate component and module characterization, and modeling from 1 to 100 GHz at physical temperatures down to and below 12 K, because of the broad band frequency response of InP HEMTs. The characterization and modeling begins with the HEMT chip, proceeds to the multi-stage HEMT LNA module, and culminates with the complete front-end cryogenic receiver package for the antenna. This paper presents an overview of this development process with emphasis on comparison between modeled and measured results at 8.4 GHz. Results are shown for devices, LNA modules, front-end receiver packages employing these modules, and antennae employing these packages.

A Ka-band indium-antimonide junction circulator

Abstract: Following a brief overview of the underlying theory, experimental results are presented for the first time showing circulator action in a semiconductor junction structure. An axially magnetized indium-antimonide disc fixed in a three-port finline structure and cooled to the temperature of boiling nitrogen, 77 K gives circulation across K/spl alpha/-band. For a dc magnetic bias of 0.73 T, a 15-dB isolation is recorded from 28 to 40 GHz, or a fractional bandwidth of at least 35%. Typical insertion loss is less than 1.5 dB from the WG22 reference plane at the test fixture ports. Continued operation above 40 GHz is predicted, but has not yet been measured. Measurement suggests that circulation is evident even where the effective propagation constant is imaginary, although better theoretical agreement is achieved when this is a real quantity. This new device makes millimeter-wave broad-band circulation a possibility and confirms the current model based upon the Drude-Zener approximation. A theoretical example is then given for a design operating to 140 GHz, yielding a fractional bandwidth of 110%.

60-GHz space TWT to address future market

Abstract: The market situation of space traveling wave tubes (TWTs) over the last four years is reviewed. It is exemplified that space TWTs are not only the key components for the traditional frequency ranges in C- and Ku-band, but also for new satellite communication systems as digital audio broadcasting in the lower L- and S-band frequency range and the planned, new global multimedia systems. There, Thomson Tubes Electroniques GmbH (TTEG) has developed the new family of Ka band TWTs, which provide the large bandwidth and power requirements for high data rate transmission. TTEG is also developing 60-GHz TWTs as RF intersatellite-links for global satellite systems. The promising results of the 560 g lightweight, 25 W, broadband helix TWT are mainly reported and the requirements compared with those for a parallel 60 W 60-GHz interdigital line TWT development.

Maximization of Data Return at X-Band and Ka-Band on the DSN's 34-Meter Beam-Waveguide Antennas

Abstract: In this article, three new approaches to evaluating the performance advantage of the 32-GHz (Ka-band) frequency over the 8.4-GHz (X-band) frequency for receiving spacecraft downlink from deep-space missions are ofiered. For a given elevation proflle for a pass, these approaches use atmospheric noise temperature statistics to select either the optimum data rate or the optimum data rate proflle that maximizes the total data-return volume over the pass. For illustration purposes, these approaches are used to optimize the performance of a link for both X-band and Ka-band at Deep Space Network (DSN) 34-m beam-waveguide tracking stations at both Madrid, Spain, and Goldstone, California. Calculations show that by using these approaches an optimized Ka-band link, depending on the pass and the optimization method, ofiers between 4.7 dB and 7.2 dB more data volume than an optimized X-band link and between 7.0 dB and 10.9 dB more than an X-band link as currently operated by the DSN. These approaches provide performance gains in terms of average data return at the cost of reliability of the link or reduced tracking time or both. The reduced reliability of the link can have adverse efiects in the continuity of the data returned, which in turn can make the link performance unacceptable.

Improvement of the three-meter Ka-band inflatable reflectarray antenna

Abstract: An inflatable Ka-band (32 GHz) three-meter reflectarray is being developed to achieve low mass and small launch-vehicle stowage volume for future deep-space spacecraft telecommunication antenna applications. The reflectarray's reflecting array surface, being a flat "natural" thin-membrane surface, is believed to have better reliability for long space missions than a curved thin membrane "nonnatural" parabolic surface. A technology demonstration model of the inflatable reflectarray was previously developed with excellent radiation pattern characteristics but poor aperture efficiency. This article presents the development of a second model that has significantly improved the efficiency from the previous 10% to 30%. This improvement was achieved primarily by a correct new element design. The previous inflatable mechanical structure, developed for ground demonstration purposes, has also been improved to approach being a space-flight design.

Ka-band dipole holographic antennas

Abstract: Dipole holographic antennas are investigated as an alternative technology to reflectors and microstrip phased arrays for use in Ka-band applications. These antennas combine the advantages of low-profile printed technology with an unconstrained feed to avoid the excessive losses associated with conventional phased array feeds. Various single-layer and two-layer designs are described. Measurements show that the efficiency of the holographic antennas is comparable with that of Ka-band passive phased arrays with conventional microstrip feeds. However, holoraphic antennas are less complex than conventional microstrip phased arrays, making them a good candidate for low-cost local multipoint communication system (LMCS) and satellite communication (SATCOM) terminals.

Security scanning at 35 GHz

Abstract: It has been known for some time that millimeter waves can pas through clothing. In short range applications such as in the scanning of people for security purposes, operating at Ka band can be an advantage. The penetration through clothing is increased and the cost of the equipment when compared to operation at W band. In this paper a Ka band mechanically scanned imager designed for security scanning is discussed. This imager is based on the folded conical scan technology previously reported. It is constructed from low cost materials such as polystyrene and printed circuit board. The trade off between image spatial resolution and the number of receivers will be described and solutions, which minimize this number discussed.

Satellite communication antenna pointing system

Abstract: An antenna pointing system automatically aligns an antenna with a geo-synchronous satellite using a Ku band signal, which has a relatively broad bandwidth, with sufficient accuracy for Ka band signal transmission, which has a relatively narrow bandwidth. Initially, the antenna is pointed at the selected satellite so as to receive the Ku band signal. The system obtains a series of signal strength readings over a predetermined azimuth (or elevation) region, such as plus/minus two degrees, from which a new peak location is selected. Signal strength data is then obtained over a predetermined elevation (or azimuth) region. Another signal peak location is selected based on the elevation data. Azimuth and elevation data are alternately collected for refining the peak of the Ku signal so as to optimize Ka signal transmission capability.

A high stability ka-band radiometer for tropospheric water vapor measurements

Abstract: The design of two new high stability microwave water vapor radiometers is presented along with a performance evaluation. The radiometers operate next to a spacecraft tracking station at NASA's Goldstone facility in California where they will be used to calibrate tropospheric path delay fluctuations during an upcoming gravity wave search experiment (GWE) involving the Cassini spacecraft. Observing frequencies of the radiometers are 22.2 GHz, 23.8 GHz, and 31.4 GHz, and the antenna beamwidth is 1 degree. The instruments are room temperature Dicke radiometers with additive noise injection for gain calibration. Design highlights include: (1) a practical temperature control system capable of stabilizing the entire receiver to a few millikelvin from day to night; (2) redundant noise diode injection circuits with 30 parts per million RF power stability; and (3) a voice coil actuated waveguide vane attenuator which is used as a high performance Dicke switch. Performance of the radiometers is evaluated from inter-comparisons of the two radiometers and from continuous tip-curve calibrations spanning nearly one year. Structure function analysis of the intercomparison data indicates that the brightness temperature stability of these radiometers is better than 0.01 Kelvin on 1,000 to 10,000 second time scales. Analysis of tip-curve calibrations indicate RMS errors of approximately 0.05 K on 30-day time scales, and 0.15 K on one year time scales.

A novel Ka-band 1 to 8 power divider/combiner

Abstract: In this paper, a 1-to-8 traveling wave power divider/combiner design at Ka-band is presented. This power divider/combiner is composed of eight units coupling power from rectangular waveguide to microstrip lines. Coupling is achieved through longitudinal slots in the broad wall of the waveguide. Shorting posts inside the waveguide are used to adjust the coupling values. Experiments on the eight-way passive divider/combiner back-to-back design demonstrates a minimum overall insertion loss of 1.8 dB at 32.5 GHz with a 3 dB bandwidth of 15%.

Planar Ka-band high temperature superconducting filters for space applications

Abstract: The impressive explosion of the satellite communication systems during the last few years has led to new constraints in regards to filtering requirements. The development of multimedia satellites and the saturation of the operational frequency bands, necessitates an increase in frequency coverage. This paper presents the design of High Temperature Superconducting (HTS) preselect receive fitters for communication satellites. Attention has been focused on obtaining low insertion loss and small dimensions, at frequencies of 4 GHz and 30 GHz.

Development of a 7.2-, 8.4-, and 32-Gigahertz (X-/X-/Ka-Band) Three-Frequency Feed for the Deep Space Network

Abstract: This article summarizes the design of a three-frequency feed for the Deep Space Network supporting the 32-GHz downlink, 8.4-GHz downlink, and 7.2-GHz uplink bands simultaneously. Monopulse tracking is also provided at 32 GHz. The design combines high-power uplink operation and ultra-low-noise receive capability in a single feed with no need for frequency-selective surfaces or external diplexers. The key components of the feed will be described along with special considerations taken into account during their design. Experimental results, lessons learned, and ideas for future improvement are also included.

A space-qualified, hermetically-sealed, Ka-band LNA with 2.0dB noise figure

Abstract: A space-qualified, hermetically-sealed, Ka-Band LNA with 2.0dB typical noise figure and greater than 38dB of temperature compensated gain has been built tested, and integrated into commercial satellite payloads. Noise figures as low as 1.7dB at 25deg C, have been recorded. A novel matching technique was used to minimize noise figure. This involved designing the LNA input stage with the waveguide to microstrip transition as part of the matching circuitry. In this way, input loss was minimized. Additionally, some tuning elements at the input enhanced the consistency of the design by allowing for device and assembly variations. This paper will describe the design and performance of the LNA. This will include a physical description, LNA design drivers and approach, waveguide to microstrip design, production LNA performance, and some ideas for future improvements. To the author's knowledge, this is the lowest Ka-Band noise figure reported, from a hermetically-sealed, commercial space module currently in production.

A broadband, four-bit, KA-band MMIC phase shifter

Abstract: A compact, robust and broadband, four-bit, Ka-band phase shifter was designed and fabricated in a standard 0.25 μm PHEMT GaAs process. Design trade-offs, simulation versus measured results and architectures for the various bits to achieve broadband performance are discussed. Electro-magnetic (EM) and linear analyses combined with measurements of the first pass design are used to refine a second pass fabrication, which includes a potential future fifth bit. Based on first pass results, a second pass four-bit phase shifter was designed to operate from 28 to 36 GHz with 8′1 dB of insertion loss.

Frequency estimation and tracking for low earth orbit satellites

Abstract: We consider the frequency compensation problem for Ka Band low earth orbit (LEO) satellites. At Ka band both the local oscillator (LO) drifts and the Doppler shifts become significant. These must be estimated and removed before communication with the satellite is established. Large sampling rates result in short processing times and make the reduction of the estimator computation load imperative. A new algorithm, named guided search of the periodogram, is obtained by combining the dichotomous search algorithm and the interpolation on Fourier coefficients estimator. The new algorithm has improved performance with respect to the other two algorithms.

Ultra-efficient X-band and linear-efficient Ka-band power amplifiers using indium phosphide double heterojunction bipolar transistors

Abstract: We report on an ultra-efficient circuit at X-band and a linear-efficient circuit at Ka-band using InP double heterojunction bipolar transistors (DHBTs). The high efficiency circuit employs a transmission line Class-E topology to achieve 61.1% PAE, 20.1-dBm output power, and 9.8-dB gain at 10 GHz. The linear efficient circuit combines four unit cells of 1.5 /spl mu/m /spl times/ 30 /spl mu/m /spl times/ 2 fingers that yielded 25.2 dBm output power, 8.4-dB linear gain, and 35.2% PAE at 28 GHz. This circuit also achieved 31 to 34 dBm output IP3.

Low cost Ka band transmitter modules for LMDS equipment mass production

Abstract: Two different Ka band medium power transmitters for LMDS (Local Multipoint Distribution System) applications have been designed proving successful performance while introducing low cost components and simple mounting techniques for industrial purposes. Commercially available BGA and LM packaged components are attached with epoxy dispensing procedures to a 0.254 mm height cost effective plastic substrate. The output power stages are die form MMIC amplifiers which are first mounted on separate carriers. A novel epoxy-on-bonding die attaching technique is used in order to prevent undesired bonding to plastic quality and performance. New active biasing networks are employed so that no later adjustment is necessary to control the overall transmitter behaviour. Active biasing also allows higher PAE than usual resistor dividers for gate biasing while preserving linearity and P1 dB output power. The transmitter modules work at 31.15 GHz and 25.7 GHz respectively. The measured P1 dB was 26.5 dBm and PAE at P1 dB was 16%.

Accurate design of Ka-band flat scanning antennas for mobile satellite terminals

Abstract: Because of its good efficiency and relatively low cost slotted waveguide technology is a promising candidate for the fabrication of electronically scanning antennas for advanced communication services. Such antennas can typically be used for mobile satellite terminals. For practical implementation of the beam steering, however, the problem of grating lobes must be solved. In this paper, Elliott design method [1,3] has been extended to large slotted waveguide scanning arrays. Dielectric filling has been employed to reduce the distance between radiating elements. The synthesis of the scanning planar array is based on a rigorous FDTD characterization of the isolated slot in terms of an equivalent shunt admittance. The computed results are shown to be in good agreement with other methods. As an example, a 30° ÷ 50° scanning array with 32 × 20 slots has been designed showing 30dB minimum gain over 500 MHz bandwidth at 30 GHz; a pointing error less than 0.5° is obtained with 3-bit phase shifters.

Monolithic Ka-band even-harmonic quadrature resistive mixer for direct conversion receivers

Abstract: This paper describes the design and measured performance of a Ka-band even-harmonic quadrature mixer which employs PHEMT resistive mixer elements. By employing the even-harmonic technique, with local oscillator at half the RF input frequency, the mixer is better suited for direct conversion receiver application. The chip operates In the 30 to 40 GHz range and has been used to successfully demodulate a 4 Mb/s 16-QAM signal at 38 GHz.

Modelling of Ka-band satellite communication channel and system performance simulation

Abstract: This paper presents a general method for satellite communication system design,modelling and simulation.Stress is placed on modelling and simulation of a Ka band satellite communication channel.Statistical characteristics and model of the channel at Ka band are given firstly,then we conducted the system performance simulations based on the channel and system simulation model proposed by this paper.Finally the analytical derivation of the performance of coherent BPSK signal at Ka band is described and a useful conclusion is drawn by comparing with the simulation results.

Experimental observation of modulation modes of powerful microwave pulses produced by a 5-nanosecond width Ka-band backward wave oscillator

Abstract: Summary form only given, as follows. The operating regime (stationary, self-modulated, or chaotic) of a relativistic backward-wave oscillator (BWO) depends on how much the generators operating current exceeds the starting current. A BWO in the self-modulation or chaotic mode can, upon a lapse of transit time generate a train of short microwave radiation spikes with a power level even higher than that in the stationary mode. For an oscillator pertaining to the Ka frequency band (38-GHz), the characteristic value of transit time lies in the range of hundreds of picoseconds. So, even 5 ns width beam current is enough for excitation of the train of subnanosecond microwave spikes. Practical experimental realization of the non-stationary generation regime of the microwave device was performed by invoking a compact high-current electron accelerator (/spl sim/200 to 250 keV, /spl sim/1.5 kA) built around a RADAN-303B pulser equipped with a subnanosecond peaker (slicer). The device features a smoothly controllable wavefront risetime (0.3-1.5 ns), and an accelerating-voltage pulse duration (0.5-5) ns. To attain self-modulation or chaotic regime for the beam current being constant, the ratio (operating current/starting current) was varied based on the strong dependence of a BWO's starting current from the length of the slow-wave system. The report presents the comparison of experimental results and the data of numerical PIC-simulations that, for example, shows a different nature of modulation of the BWO microwave pulse generated at various magnetic fields applied for transportation of an electron beam.

Ka‐Band pulsed propagation through rain‐filled atmosphere

Abstract: An atmosphere of rain offers a dispersive medium for the propagation of radio signals above 10 GHz. The effect of dispersion, in terms of differential attenuation and phase dispersion, is insignificant for narrowband signals. Signals modulated with very short pulses can have a wide bandwidth over which dispersion will be appreciable, causing significant signal distortion. The propagation of pulsed signals under varying propagation conditions has been studied with the Fourier transform technique. The transfer function of the rain atmosphere is obtained using propagation models that include clear-air effects and scattering effects due to raindrops. The carrier signal at 30 GHz is considered to be modulated by a raised-cosine pulse with a base bandwidth of 1–3 GHz. A technique for the mitigation of pulse distortion using an FIR filter is presented to restore the distorted pulse to its original shape and position to a significant extent. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 105–109, 2001.

An original micromachined planar Ka band filter based on a resonant coupling irises topology

Abstract: An original low cost and miniature bandstop filter for earth terminals in Ka-band satellite communications has been implemented on silicon membrane. In addition to an high attenuation (at least 24.5 dB) in the uplink band the filter exhibits very low insertion losses (close to 0.3 dB) in the downlink band.

Ka band power pHEMT technology for space power flip-chip assembly

Abstract: This paper proposes a released power pHEMT process for flip-chip mounting. The potential of this flip-chip process is demonstrated for power and low-noise applications in Ka-band.

Active antennas incorporating tunnel diodes-large signal model approach

Abstract: In this letter, a comprehensive dc and RF model of heterostructure interband tunnel diodes (HITDs) is extracted. Active antennas incorporating tunnel diodes are analyzed in the time domain using this tunnel diode model. The simulated and measured results are in good agreement in terms of oscillation frequencies of the active antennas. Phase noise of -114.67 dBc/Hz @1.0 MHz offset is achieved for injection-locked active antennas. The simulated injection locking range of a Ka band active antenna array is investigated.