Design of passive vector sum phase shifters

In this paper, a novel circuit composed of the topology of loaded-line for phase shifter is proposed based on vector sum theory. Compared with the traditional loaded-line phase shifter with only one path from the input port to the output port, the novel design possesses multiple paths. Single-pole single-throw switches (SPSTs) are introduced in each path to alter loaded stubs, resulting in phase shift between different states. As examples, a 3-bit phase shifter is designed and fabricated. The experimental results demonstrate advantages of compact size, low insertion loss, convenient control and easy fabrication.