Synthesis of Asymmetrical Branch-Guide Directional Coupler-Impedance Transformers (Correspondence)

In a recent paper by R. Levy and L.F. Lind ["Synthesis of synunetrical branch-guide directional couplers," ibid., vol. MTT-16, pp. 80-89, February 1968] an exact synthesis procedure for the symmetrical branch-guide directional coupler was described. In this design it was assumed that all port terminating resistances were equal. An extension to this work has been found which allows one pair of terminating resistances to have a different value from the other pair. The resulting device is therefore both a branch-guide directional coupler and impedance transformer. This combination of properties may find application in antenna design work and other fields.