UWB phase shifter with parallel stubs terminated with virtual short and ground slots

The paper describes the design of an ultra wideband (UWB) microstrip phase shifter employing open and shortcircuited parallel stubs loading a main transmission line. To make the device fully planar, the design uses a virtual short and ground slots terminating the stubs. The proposed design strategy is demonstrated in examples of 45° and 22.5° phase shifters. The designed phase shifters exhibit an approximately constant phase shift with fine amplitude characteristics over UWB