Electronically tunable graphene-based half-mode SIW phase shifter

This paper presents a proof of concept for the first graphene-based half-mode substrate integrated waveguide (GHMSIW) phase shifter. The GHMSIW phase shifter comprises a half-mode substrate integrated waveguide (SIW) transmission line and a single stub of full-mode SIW. Graphene has been deposited at the edges of the full-mode SIW stub to reconfigure the phase of the HMSIW phase shifter. Excitation of the TE10 mode of the HMSIW is evident from the E-field distribution of the phase shifter. With a high biasing voltage, the resistance of graphene is low, and the signal moves through the stub, inducing a high phase shift in the transmission coefficient. This allows the proposed phase shifter to have a phase shift of 40° with an additional amplitude variation of less than 1.5 dB. The operating frequency of the phase shifter is 7.5–9.5 GHz, and it offers several advantages, including its integration with SIW-based feeding networks for graphene-based microwave applications. The proposed technique demonstrates that the phase of microwave signals can be tuned in SIW-based devices without the use of localized surface-mounted devices (SMDs) or complex realization techniques. This work offers a compact solution for integration into SIW-based phased array systems.