A compact wideband hybrid ring for S-band pulsed and CW applications

This paper describes the design of a compact two section micro strip rat-race hybrid ring to increase the bandwidth as well as size compactness. The bandwidth is achieved from 2 to 3 GHz with amplitude imbalance of 0.4 dB. The isolation between two inputs is ≥ 30dB, while the isolation between the outputs is ≥ 20dB. The return loss at all ports is ≥ 15 dB. Moreover, the attractive feature of uniplanar transmission lines is that the signal strip and ground plane are on the same side of the substrate. The proposed design also validates the measured four-port parameters. Moreover the circuit is simple, easy to design and requires no extra PTH or bonding wires.