Double cone ultra wide band unit cell in ridge gap waveguides

Ridge gap waveguides are proposed for high frequency applications. The propagating mode inside these structures is the Quasi TEM mode, where the signal is propagating between two parallel electric conducting surfaces and attenuated off its intended path by replacing the off path surface by an artificial magnetic conductor (AMC). The operating bandwidth of the ridge gap waveguides is a function of the stop band of the unit cells that form the AMC. The bandwidth of the basic shapes of the Bed of Nail Unit Cells (BNUC) is about 2:1 and some trials were presented to propose different shapes of bandwidth about 3:1. This work introduces a different nail shape that provides a bandwidth ratio of almost 5:1. Parametric investigations are presented to clarify the critical parameters that affect the bandwidth as well as a study of complete design using the proposed cell structure.