On the Design of Broadband Rectangular Waveguide Pressure Windows

Abstract

In this article, the design of full-band rectangular waveguide pressure windows for high power applications is presented. The proposed design features a compact size, low loss, and a simplified fabrication process. A short impedance step is deployed to achieve a deep matching level over the full band of the standard waveguide. An approximate circuit model is proposed to select the initial dimensions for the proposed design to reduce the design time frame. Despite the wide use of pressure windows in many applications, the need for an accurate model still exists. The proposed model has been validated over different rectangular waveguide standards through numerical simulations with a maximum mean square error of 3%. Based on the proposed model, standard WR90 and WR28 waveguide Teflon-based windows are fabricated and measured. The measured results show a VSWR below 1.15 with an average low insertion loss of 0.08 dB. In addition, the pressure effect on the electrical performance of the pressure window is assessed. A pressure test is carried out, showing that the proposed pressure window designs are suitable for pressures up to 45 and 75 Ib/in 2 without any significant deterioration for WR90 and WR28 waveguide windows, respectively. The proposed pressure windows show superior electrical and mechanical specifications compared with both the state-of-the-art in the literature and the industrial products.