Hartwig W. Thim

A microwave position sensor with sub-millimeter accuracy

Design and characteristics of a prototype distance sensor are presented. The radar front-end operates at 35 GHz and applies six-port technology and direct frequency measurement. The sensor makes use of both FS-CW and interferometer principles and is capable of measuring distance with 0.1 mm accuracy.

A 60-GHz MMIC-compatible TED-oscillator

Experimental results achieved with planar GaAs transferred electron oscillators at V-band frequencies are reported in this contribution. The active devices are MESFET-like structures with a Schottky-gate controlling the electron injection into the drift region. The electron injection is adjusted to a level yielding a frequency independent negative differential resistance which is exploited for millimeter-wave power generation. The highest measured CW output power and efficiency are 6.72 mW and 1.3% at 60.33 GHz, respectively. These results are comparable to those obtained with transistor oscillators which are much more difficult to fabricate due to their extremely small dimensions in the 0.1 μm range.

A voltage tunable 35 GHz monolithic GaAs FECTED oscillator

Monolithically integrated FECTED (field-effect controlled transferred electron device) oscillators have been fabricated with high yield, high reliability, and precise frequency control. With unoptimized circuits, 12 mW with 1.4% efficiency in CW (continuous wave) operation and 25 mW with 2% efficiency in pulsed operation have been obtained. These results represent the highest power output and efficiency yet for monolithic TED and FET oscillator in this frequency range.<<ETX>>

Development of a low-cost 35 GHz radar sensor

Two different 35 GHz low-cost rf front-end Doppler units suited for automotive applications have been constructed. The homodyne unit consists of both receiving and transmitting corporate-fed microstrip patch array antennas, a microstrip directional coupler, a monolithic GaAs fected oscillator and an integrated single Schottky diode mixer. The autodyne configuration uses only one antenna and the fected as a self-oscillating mixer. Inexpensive microstrip technology has been used which yields a good compromise between cost factor and technical performance.RféuméDeux unités d’entrée radiofréquence Doppler adaptées à des applications en automobile ont été construites. La configuration homodyne comprend les antennes d’émission et de réception, qui sont des antennes plaques en réseau réalisées en technologie microruban et alimentées selon une méthode originale, un coupleur directif en microruban, un oscillateur fected (dispositif à transfert d’électrons commandé par effet de champ) en technologie monolithique au GaAs, et un melangeur intégré à diode Schottky. La configuration autodyne n’utilise qu’une seule antenne et un fected servant de mélangeur auto-oscillant. Une technologie microruban peu coûteuse offre un bon compromis entre coût et performance technique.

Response: The case of absence of transverse Doppler effect

Measurements that were done have yielded a gamma factor due to the quantum-mechanical absorption of photons in the detectors, thereby transferring the mass of photons into the detectors. It is said that if reflectors were used instead of detectors, then no gamma factor would have been obtained. Hence, it has not been demonstrated in the comment that the equations of the relativistic Doppler effect had been misapplied. In fact, it seems that those equations may have been improperly applied in the comment.

MMIC-compatible 55 mW InP and GaAs 30-40 GHz field controlled TE-oscillators

It is demonstrated that planar GaAs and InP field-effect-controlled transferred electron device oscillators are attractive MMIC (monolithic microwave integrated circuit) compatible candidates for local oscillator applications at Ka-band and possibly at higher frequencies, as they are not transit-time-limited as conventional transferred electron oscillators and field-effect transistors are. 55-mW 34-GHz InP, 56-mW 29-GHz GaAs, and 39-mW 37-GHz GaAs lateral MMIC-compatible transferred electron oscillators with MESFET injection contacts have been fabricated exhibiting 2.9, 5.3, and 4.9% efficiencies, respectively. Continuous-wave power levels are somewhat lower (30 mW).<<ETX>>

Ground profile sensing by radar for harvesting applications

A microwave based sensor concept for measuring the ground profile is presented. It offers the advantage of detecting even hidden obstacles as radar signals penetrate a covering layer. Advanced algorithms such as reconstruction by range stacking are investigated for accurate ground profile determination.

35-GHz 6-port receiver for radar applications

The application of six-port technology in the receiving part of a radar front-end is described in this contribution. This receiver allows measuring magnitude and phase of the radar signal without the need of down-conversion. According to the applications and the availability of the devices needed for assembling the prototype sensor the frequency of operation was set to 35 GHz. The structure of the six-port as well as the calibration and measurement algorithms are described in detail. The accuracy of the phase measurement is 2 - 10 degrees depending on the power level of the signal. Another key element of the proposed radar sensor is a direct frequency counter. With this circuit it is possible to measure the frequency of operation within 120 microseconds. The accuracy of the distance reading of the radar is directly related to the accuracy of the frequency measurement and has reached 0.1 mm.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.