Substrate integrated waveguide phase shifter

An analogue variable phase shifter on the substrate integrated waveguide (SIW) technique operating at 26 GHz is proposed which employs varactor diodes, properly coupled to the SIW coupler to achieve a continuous electronic control of the phase shift. A vertical transition between 50 Ohm SMA and SIW is used for direct coupling. And all the connections in the phase shifter were matched in low impendence, which simplify the circuit design and get larger phase tuning range. Final, five direct serious SIW phase shifter was realized to achieve 360° phase shifting exhibiting a bandwidth of 3 GHz or 15% relative bandwidth at 26 GHz, with Sll better than -9dB.