Research On Multi-mode-resonance Filter And Spoof Surface Plasmon Polariton Filter

As essential frequency-selecting components which are located in the front of communication system,filters determine the noise magnitude.The crowd situation of frequency resource and the development of modern technology urge researchers to pursue filter structures with compact size and high performance.This article puts forward three filter structures at different frequency bands based on different theories.The main work of this article constitutes three aspects as following:1?A multimode band-pass filter works at X-band is designed and developed in this part,and both the simulated and measured results are presented.A constant-impedance stub loaded with three stepped-impedance stubs constitutes the main structure of this filter.Surface current distribution maps are utilized to acquire parameters which influence the distribution of transmission poles.For further enhancing the suppression of stop band,a pair of parallel coupled lines are joined up in series at both sides to introduce a transmission zero at 14 GHz.The simulated and measured results show that the proposed structure own good filtering performance.2?A single-frequency-point notch filter based on spoof surface plasmon polaritons is proposed in this part.First,we put forward a spiral-shape SSPPs waveguide unit,and analyze the dispersion relations and structure parameters.Following,based on spiral-shape units,we design an SSPPs waveguide with excellent low-pass performance.Next,a ring resonator structure is presented.Parameters that determine the resonant frequency is studied thoroughly.Finally,combining the SSPPs waveguide and the ring resonator,we devise a single-frequency-point notch filter with excellent suppression ability at the resonant frequency of the ring resonator3?A new type band-pass filter with slots at double sides based on substrate integrated waveguide and spoof surface plasmon polaritons is proposed in this part.We first analyse the transmission characteristics of substrate integrated waveguide.Then,we come up with a new kind of SSPPs unit with compact size and stronger field confinement ability by slotting at both sides of substrate integrated waveguide.Finally,combining the loss-pass characteristic of SSPPs waveguide and high-pass characteristic of SIW,we devise a band-pass filter.Simulated results show that this kind of filter owns efficient transmission ratio at pass-band and high suppression ability out of pass-band.The proposed microwave and THz filters may have great application potentials in communication system at microwave and THz bands.