Electronic frequency tuning of TRAPATT oscillators

Experimental results of a novel electronically tunable microstrip Trapatt oscillator employing varactor diodes arc presented. A tuning range of 20 MHz, limited by the low voltage breakdown of the varactor diodes and the number of tuning stages used, for an oscillator with a centre frequency of 1.6 GHz and an output power of 9 W, was observed and found to be in good agreement with theory.     

Experimental gain and noise figure performance of distributed MESFET amplifiers

The noise figure and gain characteristics of lossless and lossy MESFET distributed amplifiers have been theoretically investigated by various workers. In the letter, in order to support previously reported theoretical results, the experimentally measured noise figure and power gain performance of two-stage and five-stage hybrid microwave distributed amplifiers employing MESFETs are presented. The measured results are compared to theoretically obtained values and found to be in reasonable agreement over most of the band.     

Use of low dielectric constant substrates for microstrip time-delay triggered TRAPATT oscillators

Our experimentation with microstrip trapatt oscillators of the type described by Davies et al.1 has indicated that the feasibility of such a design is dependent on the ratio of strip width to dielectric height (W/h) for the substrate used for a given microstrip-line impedance. For example, realisation on a polyguide substrate (?r = 2.32) of 1.58 mm height failed to give coherent oscillation due to unexpected transient voltage variations shown up by time-domain-reflectometry tests. However, simple modifications to the microstrip design to remove the transient voltage variations led to considerable improvement in the performance of the oscillator, and coherent behaviour was then obtained.