V-band cross-coupled SIW band-pass filter with an antisymmetric U-slot negative coupling structure

This study presents an low-temperature cofired ceramic (LTCC) V-band cross-coupled band-pass filter using substrate-integrated waveguide cavities. Two antisymmetric U-shaped slots connected by via is proposed to construct the negative coupling structure, which is simple and especially useful for 60 GHz applications. Moreover, the U-slot structure possesses a wide range of realizable coupling coefficients from-0.008 to-0.075. An experimental LTCC fourth-order filter was fabricated for demonstration, achieving a bandwidth of 12% (7.2 GHz) at 59.6 GHz with superior frequency selectivity.