Gap Waveguide PMC Packaging for Two-Layer PEC Surfaces

This paper shows the investigation of gap waveguide (GW) packaging for an irregular perfect electric conductor (PEC) composed of two layers of metal surfaces. The stopband for a GW with two-layer PEC surfaces is carefully studied, considering the top-layer PEC width, pin size, pin height, columns of pins, as well as dielectric substrate thickness and permittivity. A strategy of the GW packaging for such an irregular PEC surface is presented. In addition to the unit cell-based stopband study, such GW packaging is also demonstrated for a substrate-integrated waveguide (SIW)-microstrip line structure, which is typical of the circuit with two-layer PEC surfaces. A Chebyshev bandpass filter built on the SIW and microstrip line is finally designed and fabricated to provide experimental verifications. In particular, a dedicated defect of the side air gap existing in the SIW-based circuits using the GW PMC packaging is found, and an effective remedy is presented.