Multiway uniform combline directional couplers for microwave frequencies

An improved optimization technique for multiway uniform forward-directional couplers is presented using a previously published matrix theory of coupled transmission lines. With the help of this computer optimization method, microwave mode-interference combline directional couplers having an arbitrary number of lines can be designed for arbitrary power distribution. Theoretical designs ranging from two-way to nine-way couplers have been tested with success. The observed behavior of some of these couplers is briefly discussed. Typically these couplers exhibited octave bandwidth. A five-way design example of an equal power splitting combline coupler was fabricated using an open microstrip configuration for operation within 1.6-3.2 GHz. The measured characteristics show good agreement with the computed values