Slot-Coupled Multisection Quadrature Hybrid for UWB Applications

We present a three-section quadrature hybrid based on slot-coupled directional couplers, which operates over a bandwidth from 3.1 to 10.6 GHz. A prototype has been fabricated which exhibits a return loss better than 20 dB, isolation around 20 dB, an amplitude imbalance between output ports of less than plusmn0.75 dB and a phase imbalance between +1
^deg
and -3
^deg
across the 3.1-10.6 GHz band. This design outperforms previously reported results for ultra wide band operation.