Multilayer phase shifter with wide range of phase and ultra-wideband performance

A compact planar phase shifter with ultra-wideband (UWB) performance and wide range of differential phase shift is proposed. To achieve that performance, the device uses broadside electromagnetic coupling between top and bottom microstrip patches via a slot located in the middle layer that forms the ground plane. Two short-ended stubs are connected to the microstrip patches to expand the range of the phase shift up to 270°. The theory of operation for the proposed device is derived. Three designed phase shifters demonstrate a differential phase of 90°, 180°, and 270° across the band from 3.1 GHz to 10.6 GHz with less than ± 8 ° differential phase imbalance, and less than 0.8 dB insertion loss.