Realization of miniaturized branch-line coupler using lowpass microstrip filters

A miniaturized branch-line coupler based on lowpass microstrip filters instead of conventional transmission lines is presented in this paper. The design of proposed couplers is performed using lowpass filter of 5th, 7th and 9th order. This is done to achieve a compact circuit layout in microstrip implementation. Prototypes with these proposed structures, operating at 2 GHz frequency, have been designed and implemented using microstrip technology.