Ultra-wideband phase shifter using broadside-coupled microstrip coplanar waveguide

A compact planar phase shifter with ultra-wideband (UWB) performance and 180 degrees differential phase shift is proposed. It utilizes a broadside-coupled microstrip/coplanar waveguide (CPW). Thus, the proposed device can be fabricated using a simple double-side printed circuit board. Four open-ended stubs are added to the microstrip patches and CPW in order to achieve the required 180 degrees phase shift. The designed phase shifter operates across the band from 4.2 GHz to 11 Ghz with less than +/-10 degrees differential phase imbalance, and less than 1 dB insertion loss