Transmission Loss of a Millimeter Wave Pulse Through a Waveguide Window

Abstract

Millimeter waves have become increasingly important in wireless communication today. It is well known that a waveguide window exhibits almost perfect transmission for the center frequency of millimeter waves. However, this might not be true for a pulsed wave. In this work, we study the transmission loss of a millimeter wave pulse centered at 35 GHz traveling through a rectangular waveguide window. The transmission function of a continuous wave within the bandwidth from 0 to 100 GHz has been obtained using the transfer matrix method. The millimeter wave of 35 GHz pulsed from 100 ps to 1 us in time domain has been Fourier transformed to the frequency domain so that the transmittance of the pulsed wave in the frequency domain can be calculated. The transmission loss has been analyzed for various pulse durations. After inverse Fourier transform of the transmittance in the frequency domain back to the time domain, one can compare the result with the incident pulse to see the pulse distortion and transmission loss. A finite difference time domain simulation has been performed to verify the calculated results by the transfer matrix method combined with Fourier transform. Detailed methodology and analysis of the study will be presented.