A miniaturized planar crossover using dual transmission lines

This paper presents a miniaturized four-port crossover consisting two cascaded branch-line couplers implemented by dual transmission lines. A dual transmission line is composed of two parallel-connected transmission lines with high impedance and different electrical lengths. This design has the advantage of circuit layout flexibility and size reduction. The electrical size is 21% reduced comparing with the size of a crossover utilized with two cascaded branch-line couplers.