Compression of frequency-modulated pulses by helically corrugated waveguide

The peak power of a frequency-modulated microwave pulse could be improved greatly by the compression of the helically corrugated waveguide. Firstly, the dispersion relations of the helical corrugated waveguide are calculated and analyzed using the code programmed with Matlab. The dispersion characteristics on the variation of the amplitude and period of the corrugation are obtained. Then the power compression ratios are calculated under some typical conditions. Calculation results show that: the power compression ratio is very sensitive to the format of the frequency modulation. Under the same format of frequency modulation, the power compression ratio increases with the increasing of the time width and frequency width of the input pulse. For an input pulse of 40 ns and a frequency width 0.7 GHz(from 8.8 GHz to 9.5 GHz), the format of the frequency modulation is matched to the dispersion characteristics of the helically corrugated waveguide, the power compression ratio reaches 15, and the compression efficiency is about 40%.