Substrate integrated circuits concept applied to the nonradiative dielectric guide

A novel technique for designing and realising nonradiative dielectric (NRD) waveguide circuits based on the concept of substrate integrated circuits (SICs) is proposed and demonstrated for the first time. In this new scheme, the substrate integrated NRD (SINRD) guide is created or synthesised by drilling a pattern of air holes in a planar dielectric substrate. Furthermore, metallised holes are also introduced to enclose the NRD guide. Using this configuration, an integrated waveguide transition and mode suppressor can be realised. Dispersion analysis and design considerations for the proposed structure are presented and discussed. It is shown that this new approach can be applied over a wide range of microwave and millimetre-wave frequencies for high-density circuit integration and low-cost system applications. Measured results of a number of showcase circuits validate the design method, which include a bandpass filter, a directional coupler and an integrated transition between an SINRD guide and a rectangular waveguide.