Miniaturized Couplers with Combined Microstrip and Slotline Ports

This paper applies the multi-mode star junction and its equivalent circuit model in the design of novel miniaturized hybrid and rat-race couplers with different ports configuration; microstrip and slotline. The designs have an area reduction of 66.6% and 20% for the hybrid and rat-race couplers respectively. The couplers are fabricated and characterized. Measurements, which are in a very good agreement with the simulations, confirm the theoretical predictions.