Realization of Alumina based Pressure Window at Microwave Frequencies

Abstract

Pressure windows form critical component that provide access to communication payloads when the aerospace system is undergoing thermo-vacuum testing. In this article design, fabrication and testing of microwave pressure windows used for aerospace system thermo-vacuum testing is presented. Alumina is chosen as the dielectric material. Design and simulation of the window is carried out in standard software tool. Thin film metal pattern generation techniques on alumina are used for implementing matching inductive iris. A compact size window is implemented on a metallic flange using silicone rubber material. The metallic flange is fixed to waveguide portions, which are interfaced to thermo vacuum chamber. Realized pressure window is tested for electrical, environmental and leak rate performance. The realized window achieved a relative bandwidth of 20% with a reflection of–18.5 dB (max) in the X -band (8.5-10.5 GHz), and the corresponding transmission loss is over –0.7 dB. Leak rate of better than 10-9 atm.cc/s is achieved in assembled window.