Synthesis of broad-band 3-dB hybrids based on the 2-way power divider

The synthesis of broad-band two-way Wilkinson hybrids is well known. The even- and odd-mode analysis results in two equivalent circuits where the synthesis of the odd mode is done by computer optimization. This paper shows an exact synthesis of two-way Wilkinson power dividers having one isolation resistor, but an arbitrary number of quarter-wave transformers. A large number of circuits have been synthesized with up to six quarter-wave transformers. The two-way Wilkinson hybrid can be extended to a four-port component. This four-port component can operate as a 180 or 90 deg 3-dB hybrid depending on the input port. The hybrid has a high directivity independent of frequency when used as a 180 deg hybrid. Experimental results are given for a two-way divider and a 3-dB hybrid built in microstrip with a center frequency of 5 GHz.