The phase shifter is a two port circuit, which can change the output phase accordingly according to the external electric control command, and can adopt a variety of different circuit forms to realize the phase shifter circuit. The selection of phase shifter network control and control elements is determined according to the required bandwidth, insertion loss, switching speed, power carrying capacity, phase-shifting accuracy and phase-shifting amount. Phase shifter is divided into analog phase shifter and numerical control phase shifter according to different phase shifting modes.