Extended Port Dual Band Planar Branch Line Coupler

Modern communication systems need various hybrids to enable digital data transmit via microwave bands. Thus several types of microwave quadrature hybrids have been reported for the realization of balanced circuits, matched attenuators, and phase shifter. The branch line coupler is one of the most popular hybrids for the convenience of design and implementation. But it offers limited bandwidth and requires a large circuit area. A Novel branch line coupler which can operate at two frequencies is presented in this paper. The proposed planar topology, which is different from the conventional one ,is analyzed and designed. To validate our idea quadrature hybrid coupler operated at 1.5/3.5 GHz are designed using microstrip technology. The simulated result show good agreement with theoretical analysis.