Staggered Filter Topology for Robust Fabrication of Air-Filled Substrate-Integrated-Waveguide Filters

In this work, a novel air-filled substrate-integrated waveguide (AFSIW) filter topology is proposed to overcome the challenges of AFSIW printed circuit board (PCB) fabrication by eliminating small protrusions and feature sizes. The topology is further enhanced with a coupling slot to improve the out-of-band rejection by 20 dB. A prototype covering the n257 (26.5 GHz-29.5 GHz) band is synthesized, fabricated and measured to validate the topology, demonstrating its applicability at millimeterwave (mmWave) frequencies with a measured insertion loss of 2.7 dB and out-of-band rejection of over 30 dB.