Non-orthogonality relations between complex-hybrid-modes: An application for the leaky-wave analysis of a laterally-shielded top-open suspended microstrip line

In this contribution, the orthogonality relations between complex modes are investigated to demonstrate the coupling effect which exists between TEz and TMz hybrid modes when power storage, loss or leakage is presented in the longitudinal direction of a transmission line. As an example, the Parallel Plate Waveguide (PPW) modes are used to study a laterally-shielded top-open microstrip line (LShMSW). The study of leaky-waves is a very interesting application of the novel orthogonality relations derived in this paper. This study is carried out using the correct and incorrect orthogonality formulations, and a comparison of results is made to check the validity of the proposed technique.