Ultra-compact capacitively loaded evanescent half-mode SIW filters for LTE applications

This paper presents a novel miniaturized substrate integrated waveguide filter by combining both half-mode resonators and capacitive loading on a conventional two-layer printed circuit board (PCB) process. The resulting synthesis is successfully demonstrated in an long-term evolution application by means of a third-order filter of <225 mm² in size while featuring 2.3 dB insertion loss over a 5.5% fractional bandwidth at 3.7 GHz. Good first-iteration agreement between simulated and measured results, both in center frequency and bandwidth, are achieved.