Reduction of In-Band Interfering Signals and Minimize Emission in Out-of-Band Frequencies for EMI/EMC Applications

The proposed work aims to reduce the impact of interfering signals existing in the ultrawideband spectrum and minimize emission in out-of-band frequencies to protect other circuits or components against interference. A single tunable notch or two independently tunable notches have been achieved to block interfering signals in the ultrawideband frequency range, while out-of-band rejection is achieved by designing a proper mode transition. Due to the high sensitivity of field configuration in spoof surface plasmon polariton (SSPP) mode, it becomes possible to achieve such a wide tuning range by using SSPP based transmission lines. Here, it is achieved after loading a slot resonator into the SSPP transmission line. A single tunable notch in the frequency range of 3.5–10.5 GHz and two tunable notches in the frequency range of 3.5–6 GHz and 6–10.5 GHz have been obtained after applying different bias voltages across the varactor diodes. The SSPP line structure specifically the geometry of the unit cells is exploited enough to minimize emission in the out-of-band frequencies. The overall structure is designed so that it diminishes the higher order modes and gives a wide upper stopband to make it a good candidate for electromagnetic interference/electromagnetic compatibility applications. The proposed idea is verified through circuit analysis, simulations, and then measurements. Performance of unit cell in terms of dispersion diagrams while performance of the line structure in terms of S-parameters are reported.