Planar Broad-Band 180° Hybrid Power Divider/Combiner Circuit

A planar broad-band 180° hybrid is presented. The hybrid is realized using a 3-dB 90° hybrid and a 0-dB 90° tandem hybrid. An interdigitated version of the hybrid fabricated on alumina substrate performed well over the 4-8-GHz band. The hybrid has an insertion loss of 0.5 dB, phase imbalance of +-7°, and an isolation of better than 18 dB over the band.