Design of the Compact Eighth-Mode Substrate Integrated Waveguide Filter with Multilayer Structure

This paper presents an eighth-mode substrate integrated waveguide (EMSIW) bandpass filter. The proposed filter exhibits four-order Chebyshev frequency response. The filter is designed on a multi-layered printed circuit board (PCB) process to obtain compact size. The vertical coupling structure is achieved by etching the aperture on the middle layer. The coupling strength between upper and lower substrates depends on the dimensions and locations of the aperture. The filter is designed, fabricated and measured to verify the proposed concepts. The measured results exhibit good agreements with the simulated ones.