Half-mode SIW negative group delay compensating circ1uit with improved left-handed material

This work reports a half-mode substrate integrated waveguide (HMSIW) negative group delay (NGD) compensating circuit based on the equivalent left-handed material coupling mechanism. The proposed microwave NGD compensating circuit mainly consists of a HMSIW section, a split-ring resonator (SRR) with a metalized via and a grounded metal patch at the center of SRR, as well as a hollow structure located at the bottom of the circuit for NGD response enhancement. In specific certain frequency band, the SRR is able to generate magnetic plasma effect and exhibit negative permeability. Simultaneously, negative permittivity can be produced by negative capacitance, which is created by the J-inverter between the HMSIW section and the SRR. Thus, the proposed circuit will behave as an equivalent left-handed material to realize bandpass negative group delay function. Then, the analytical model allowing to determine the group delay is established from equivalent circuit approach. Then, to validate the proposed NGD function, a prototyped circuit is designed, simulated and fabricated. Bandpass NGD operation was realized, with a center frequency of 6.04 GHz, an effective bandwidth of 40 MHz, and a maximum NGD of -1.75 ns.