Ultra wide band slotline hybrid ring couplers

The design procedure and results for two newly developed hybrid ring couplers using microstrip-coupled slotline rings are presented. The couplers have a wider bandwidth with an excellent power dividing balance and a fairly good isolation compared to the conventional microstrip hybrid ring coupler. The slotline cross-over hybrid ring coupler exhibits greater than 35-dB isolation and a good power dividing balance of +or-0.2 dB over an 80% bandwidth from 1.8 to 4.2 GHz. The experimental results agree very well with the theoretical prediction. With the advantage of allowing easy series or shunt insertion of devices, these couplers are useful in many applications for MICs (microwave ICs) and MMICs (monolithic MICs).<>