Design and Optimization of Planar Directional Couplers

As a result of the theory of coupled lines the scattering parameters of common nonideal directional coupler arrangements are discussed. Under certain conditions the transmission behaviour results in a codirectioanl, resp. a contradirectional coupling. The conditions to obtain optimum behaviour for a codirectional or a contradirectional coupler are described, as is the consequence of deviations from these optimum conditions - the design goals. For the treatment of planar and quasi-planar directional coupler arrangements a numerical analysis program is presented. With this prgram nearly all directional coupler arrangements for microwave integrated circuits of practical interest can be computed.