Design of Asymmetric Multi-Element Directional Couplers with Tandem Section as the First Element

An analysis is presented of a class of asymmetric multi-element directional couplers (ADC) for any number of elements and with tandem section (TS) as the first of its. A table of element values is given for three-and four-element 3-dB couplers for various ripple levels. It is shown that described approach overcomes the tight coupling problem associated with the method proposed by R. Levy, but that it introduces a bandwidth contraction penalty.