Efficient Surface-wave Excitation by Parallel-Plate Waveguide for Substrate Integrated Image Guides

In this paper, a study of surface-wave (SW) excitation by means of a simple parallel-plate waveguide (PPW) for substrate integrated image guides (SIIGs) is proposed. As a proof of concept, a wideband, low profile and fully planar feeding network is designed. It consists of a surface-wave launcher (SWL) based on a truncated PPW with the addition of a sub-wavelength matching section. This method for SW excitation is intended to overcome the feeding limitations encountered when using SIIG-based antennas or other non-radiating structures at microwave frequencies. A comparison between the performance of the proposed excitation method and structures that can be found in the literature are reported showing an improved bandwidth of more than 50% with respect to previous studies. In addition, this simple feed system has a reduced volume of more than 95% when compared with other alternatives, demonstrating its compactness. Applications include new SW driven feeds, leaky-wave antennas, sensors, or novel passive structures.