Design of a Compact Dual‐Band Bandpass Filter Based on Half‐Mode Substrate‐Integrated Waveguide With CLP–SCP Resonators

This letter presents a dual‐band filter based on a universal hybrid structure that integrates a half‐mode substrate‐integrated waveguide (HMSIW) with capacitive‐loaded patches (CLPs) and short‐circuit post (SCP) resonators. The first passband, centered at 4.9 GHz with a wide fractional bandwidth of 39.8%, is realized through a CLP−SCP‐loaded HMSIW resonant cavity. The second passband, centered at 8.9 GHz with a fractional bandwidth of 13.3%, exhibits sharp skirt selectivity. This passband is achieved using an embedded CLP−SCP resonator. To improve selectivity, source–load cross‐coupling is employed, resulting in transmission zeros between the two passbands. The fabricated filter exhibits good agreement between electromagnetic simulations and experimental measurements, maintaining a compact electrical footprint of 0.38λ g × 0.56λ g .