Analyses of Transmission Loss of a Gap Waveguide Composed of a Dielectric Substrate with EBG Elements

This paper presents transmission loss characteristics of a gap waveguide composed of a dielectric substrate with EBG elements. The proposed gap waveguide consists of a top conductor plate, a bottom dielectric substrate with mushroom-like EBG elements, and an air layer between them. EBG elements prevent a leakage from the gap waveguide in the air layer and can be manufactured cost-effectively with PCB processes. Transmission loss of the gap waveguide is analyzed by numerical simulation with ANSYS HFSS at 4.7 GHz. It reveals by the simulation that smaller transmission loss of the gap waveguide of less than 1 dB/m is obtained for the cases of a large distance of the EBG elements, a large width of the ridge conductor, and a small height of the air layer in comparison with a microstrip line with the same dielectric substrate.