Design of lumped element quadrature hybrid

At the lower microwave frequency range, distributed element hybrids consume too great a circuit area. To reduce the surface area without degrading electrical performance, a lumped element hybrid can be used. A new lumped hybrid design method is presented which uses a combination of T-networks and pi-networks to achieve an improved magnitude balance. A prototype of the lumped element hybrid is fabricated by using the conventional microwave integrated circuit technique to verify the design concept. The measurement results show good agreement with the theoretical prediction. This quadrature hybrid structure is compact and applicable to monolithic microwave integrated circuit realisation.