Research On Ku-band Reconfigurable Frequency Selective Surface Broadband Technology

With the increasing development of electronic information technology,conventional frequency selective surface is no longer well adapted to the increasingly complex external electromagnetic environment,which promotes the development of reconfigurable frequency selective surface.Considering the requirements of convenience,low cost and high performance in practical engineering applications,this paper employs liquid crystal materials with dielectric constants adjusted by applied bias voltage for reconfigurable design of frequency selective surface.Compared with narrowband frequency selective surface designed for specific operating frequencies,broadband frequency selective surface can be applied to more scenarios and possesses better application values.Therefore,this paper investigates the design of broadband reconfigurable frequency selective surface based on liquid crystal materials,simulationally analyzes different design schemes of broadband frequency selective surface,improves the designed reconfigurable frequency selective surface with considering the actual engineering implementation,and finally obtains a broadband reconfigurable frequency selective surface with multilayer structure.After completing the design of the frequency selective surface,this paper also gives a brief introduction to the application scenarios of the designed frequency selective surface.This paper firstly introduces the tuning principle of liquid crystal materials,illustrates the theory related to frequency selective surfaces,describes the electromagnetic analysis method of frequency selective surfaces based on the Floquet theorem and the grating lobe phenomenon,and explains the design method of broadband frequency selective surface based on interlayer coupling,low-loss dielectric substrate loading and multilayer cascading.In the next section,several methods for designing broadband frequency selective surface are analyzed.A reconfigurable frequency selective surface structure with a resistance band bandwidth of 2 GHz below-10 d B is obtained based on the multilayer coupling structure.The-10 d B passband bandwidth of the frequency selective surface of the single-layer resonant patch structure is increased to 2.34 GHz by low-loss substrate loading,and the-10 d B passband bandwidth of the frequency selective surface of the multilayer coupling structure is increased to 4.36 GHz.An ultra-broadband structure design with a passband bandwidth of 5.71 GHz is realized in the light of the multilayer cascade structure.Finally,this paper designs a multilayer coupled structure of reconfigurable broadband frequency selective surface of liquid crystal materials with rectangular grid and triangular grid for the layout array design.It is known from the measured results that the rectangular grid array can achieve 0.80 GHz frequency reconfiguration and the triangular grid array can achieve 0.50 GHz frequency reconfiguration.A brief analysis of the horn-aperture-filter antenna based on the reconfigurable frequency selective surface is carried out,and the design idea of applying the reconfigurable frequency selective surface based on liquid crystal materials to the transmission array antenna is proposed.