Equipment for measuring electrical parameters of heated solid dielectrics in the 8-mm wavelength range

Abstract

The block schematic of the equipment in question is shown in Fig. 1. The UHF generator I (type G3-30) is provided with supply unit 2 and modulated with respect to two electrodes. The reflecting electrode is fed from generator 12 with a saw-tooth voltage at 50 Hz, thus frequency-modulating the klystron. The focusing electrode is fed from generator 11 with a square wave at 100 kHz, thus providing amplitude modulation. The resulting output of generator i consists of an amplitude-modula ted signal with a variable frequency within pulses. This signal is divided by directional-coup ler 3 between channels I and II which incorporate the measuring and reference resonators 6 and 7. The first channel contains calibrated measuring attenuator 5. Deeoupling attenuators 4 serve to reduce the mismatching errors. The amplitude-modula ted signals are fed from the high-frequency detectors 8 to amplifiers 13 and 14. The amplified signals are transmitted through linear detectors and fed alternately by electronic switch 15 to oscillograph 10 on whose screen the resonance curve of the measuring and reference resonators can be observed. The reference resonator remains cold during heating tests and therefore serves, as it were,as a store for the resonant frequency and the power level at the output of the measuring resonator before it is fed to the dielectric specimen.