Nonstandard Hybrid and Crossover Design With Branch-Line Structures

Abstract

In this paper, we tried to use a symbolic math function of Matlab to derive theoretical S-parameters of a general branch-line structure; and we then managed to obtain design equations for 90°, 180° hybrids, and crossovers with the derived <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> -parameter expressions. We found that we can obtain several types of useful configurations for hybrid and crossover design by varying branch-line lengths of the structure. Besides standard designs, more interesting nonstandard 90°, 180° hybrids, and crossovers can be designed with suggested configurations of the design equations. Several example designs were built and tested; what is more, a nonstandard combiner/divider working on 5.8-7.2 GHz was designed to provide compact size and lower insertion loss for high-power very small aperture terminal amplifiers.