Analysis of branch line coupler in suspended stripline with finite metallization thickness

An efficient analysis of a branch line coupler in suspended stripline technology is described. The finite metallization thickness on the stripline is fully accounted for by a rigorous full-wave technique. This is based on an improvement of the transverse resonance technique (TRT), which allows a resonator of fixed dimension to be considered. In this manner all the advantages of the TRT are kept (no complex modal spectra need to be computed), while repeated field analyses for searching for the resonant dimensions of the structure are avoided. The theory has been checked successfully against both experiments and theoretical results based on different numerical methods.<>