Metasurface-Loaded Wideband Transmission Structure with Inherent Common-Mode Suppression and Reflectionless Differential-Mode Band-Notch

Novel metasurface loaded wideband differential transmission structure is proposed with reflectionless band-notch response for differential-mode (DM) and inherent suppression for common-mode (CM). The proposed differential transmission structure is constructed by two balanced microstrip structures and a long slot transmission line with two open terminals. Owing to the mode mismatch between CM and slot mode, the inherent CM suppression is realized. Furthermore, a resistor-free absorptive metasurface composed of split-ring resonator cells is introduced above the slot transmission line. Under DM excitation, the resonance of metasurface could be excited effectively by slot transmission line, which would contribute to the enhancement of conductor and dielectric losses around resonant frequencies. Therefore, reflectionless band-notch response is achieved for DM based on inherent conductor and dielectric losses without lumped resistors loading. Simulation results show that the proposed wideband differential transmission structure exhibits inherent CM suppression and reflectionless band-notch response for DM from 5.22 to 6.05 GHz (Sdd21<-10 dB, Sdd11<-10 dB).