Analysis and design of lumped- and lumped-distributed-element directional couplers for MIC and MMIC applications

An analysis of lumped-element and lumped-distributed-element directional couplers is described. The assumed generality of the ring-type four-port enables different types of directionality to be developed. The equations that make possible an idealized design of co-, contra- and trans-directional couplers for arbitrary power division and transformation ratio are derived. A design procedure for three-branch, lumped-element directional couplers that allows an impedance transformation between the input and output ports is also included. Computer simulations of the performance of various couplers with lumped elements represented by realistic models are included.<
>