Synthesis of Lange Couplers

This paper shows that it is possible to synthesize Lange couplers directly and thereby save considerable computing time. The procedure outlined is essentially based on two available techniques: Ou´s analysis of the Lange coupler and Akhtarzad´s design method for a pair of coupled microstrip lines. Including a correction in the latter for a single strip shape ratios less than unity, is significant. The described approach compares favorably with existing iterative methods and was used to obtain reasonably good performances on a low dielectric constant laminate.