Ka‐band compact and high‐performance bandpass filter based on multilayer air‐filled SIW

Abstract

A substantial reduction of substrate integrated waveguide (SIW) insertion loss can be achieved through the use of air as dielectric instead of usual dielectric material. However, air‐filled SIW (AFSIW) circuits exhibit larger footprint compared with their dielectric‐filled counterparts. A compact multilayer AFSIW bandpass filter is proposed to realise both high‐performance and small footprint. For demonstration purpose, a Ka‐band multilayer fourth‐order AFSIW bandpass filter has been designed and fabricated. Measured and simulated results are in good agreement. Retro‐simulations, taking into account fabrication tolerances, are also presented. Finally, a performance comparison with other multilayer technologies is presented.