A Spectral Domain Hybrid Field Analysis of Periodically Inhomogeneous Microstrip Lines

Single and coupled periodically inhomogeneous microstrip lines have been analyzed using a hybrid mode spectral domain field analysis. The field computation method will be explained principally, the convergence of the method and the numerical effort will be critically discussed. Applications of the theoretical results have been applied to the design of microstrip- and waveguide filters, to antennas and to the design of a Podell-coupler with equalized even and odd mode phase velocities and a high directivity. Measurements are compared to the theoretical results.