Increasing the Power Compression Factor by Overmoded Waveguide for Subnanosecond Microwave Pulse Generation

In our previous study, we successfully generated subnanosecond microwave pulses with a high power compression factor using a standard rectangular waveguide. However, the compressor loss is substantial due to the operating frequency being close to the cutoff frequency, which greatly limits the power compression factor. The novelty of this manuscript is using a unilateral overmoded waveguide to mitigate the loss, thereby improving the efficiency and the power compression factor. Calculations indicate that the compressor loss could potentially be reduced by 48.9%, while the optimal power compression factor could increase by 104.5%, rising from 58.5 to 119.7, compared with the result of the standard waveguide. Under our current experimental conditions, we used a 5-m long overmoded waveguide compressor for proof of principle and generated an ultrashort pulse with a power compression factor of 50.2 and a 3 dB pulsewidth of 266 ps. Compared with the standard waveguide, the compressor loss was reduced by 13.5%, and the power compression factor increased by 13.6%. The experimental results are in good agreement with the simulations, indicating that this method has the potential to enhance the power compression factor and enable it to exceed 100.