Two-Material-Filled Ridge Half-Mode Substrate Integrated Waveguide for Monomode Bandwidth Enhancement

Abstract

In this letter, a two-material-filled ridge half-mode substrate integrated waveguide (2M-RHMSIW) is proposed for monomode bandwidth (MMB) enhancement. The cutoff frequency of the dominant mode decreases with the permittivity of the material filling in the bottom layer increasing. The cutoff frequency of the second mode increases as the permittivity of the material filled in the top layer decreases. Therefore, the proposed structure uses low-permittivity material for the top substrate layer and high-permittivity material for the bottom substrate layer, to widen the MMB. In addition, a series of air holes are drilled in the top substrate layer to reduce its effective permittivity, which further widens the MMB. A prototype of the proposed structure is fabricated under PCB process, which MMB is from 2 to 14 GHz.