A Broadband Millimeter-Wave Waveguide Window: A Low-Cost Design for Environmental Protection

In this paper, a full W-band waveguide window for the protection of components from the environment is presented. The window is based on rectangular dielectric block placed inside the rectangular waveguide. Electrical design steps for broadband performance are presented, and a simple cost effective mechanical process flow is employed for the fabrication of windows. Four different dielectric windows are evaluated, and they exhibited less than 0.3-dB insertion loss and better than 20-dB return loss: two windows over full W-band, whereas other two over 3-GHz bandwidth. Temperature testing is carried out for 4 h at -40 degrees C and +70 degrees C, and the humidity level is set at 95% at +70 degrees C. Minimum insertion loss variation of +/- 0.5 dB over the temperature range is observed. To check the compatibility of the windows with millimeter-wave components, a W-band switch is tested with the windows at its input and output ports. The experimental results show that the windows have low-loss characteristics and are free from ghost modes.