Comparing miniaturization techniques for microstrip 180° hybrid ring junctions

Several miniaturization approaches are applied to microstrip 180° hybrid ring junctions designed for a frequency of operation of 2 GHz. These ring junctions are compared in terms of occupied area on the circuit board, frequency bandwidth and power loss. The miniaturization techniques include open stubs added, lumped-element capacitive shunt loading, stepped-impedance slow-wave lines and series-connected EBG cells. Generally observable trends show that bandwidth is linearly proportional to the occupied board area and power loss is inversely linear proportional to area. Small deviations from these trends, for specific miniaturization approaches, are discussed in the paper.