Cost-Effective GaAs Read IMPATT Transmitters.
Final rept. 29 Mar 76-31 Oct 77,
RAYTHEON CO WALTHAM MASS RESEARCH DIV
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The objective of this program was to develop a low-cost 5-GHz 40-W FM CW transmitter, using GaAs Read IMPATT diodes as RF power-generating elements, suitable for data-link applications. The transmitter actually produced during the course of the program met most of the RF performance goals established initially, but the goals for size, weight, cost, and primary power consumption were not achieved. The transmitter system was divided into four major subassemblies a VCO-driver, a multidiode output stage, a multichannel current regulator, and a DC-to-DC inverter. The VCO-driver produced a 3.3W CW output in the 4.97 - 5.03 GHz operating band, and was capable of more than 20 MHz peak-to-peak frequency deviation with modulating frequencies between 50 kHz and 12 MHz. The output stage combined four high-power single-diode modules, operating in the injection-locked oscillator mode, through a nonresonant multiport hybrid. Compact coaxial cavity oscillator circuits were used for the diode modules. The four-port hybrid was formed by cascading two-port power splitters of the type described by Gysel. The power combining circuitry was constructed in trapped inverted microstrip TIM line. The transistorized multichannel current regulator permitted control of the operating bias of the output stage without excessive power dissipation.
- Solid State Physics
- Non-Radio Communications