Objectives  Focusing on the shortcomings of limited band selection and poor control effectiveness of the current multi-band frequency selective surface, this paper designs a multi-passband frequency selection surface based on the transmission zero insertion method.

  Methods  The FSSs consist of two layers of the same combined structure and a ring-shaped patch structure. It has multiple transmission zeroes and can control the pass/stop-band independently by adjusting physical parameters. The equivalent circuit model is established according to FSS's physical structure through the equivalent circuit method. The full-wave simulation and ECM (equivalent circuit method) calculation results can be well fitted.

  Results  The simulation results show that the designed tri-passband FSS can form passbands in the C, X and Ku bands. The zero points on both sides of the passband form steep edges and a high-frequency stop band. The stop band enhances the out-of-band selection performance.

  Conclusions   The operating frequency band sees a fine polarization stability and angular stability, and the pass/stop bands have a high level of independence.