The Study Of Ultra-Wideband Frequency Selective Surfaces Based On Non-Resonant Elements

In this thesis,the study of ultra-wideband bandpass frequency selective surfaces(FSSs)was based on the non-resonant Miniaturized Element Frequency Selective Surface(MEFSS).At the beginning,the bandpass MEFSS structure and its equivalent circuit were studied.And a suitable range of the equivalent circuit in the MEFSS design was given after the study of the relationship between equivalent formulas and the geometry parameters of the units.Then,a high transmittance and high selectivity bandpass MEFSS was designed according to the general method of designing an MEFSS.Then the sample was fabricated and measured after simulated in the full-wave simulator HFSS.The results of measurement were agreed with simulation and expectation.Wideband and ultra-wideband MEFSS that based on the general units and structures were investigated.Then the relationship between geometry parameters and operation bandwidth were studied.In order to achieve a higher equivalent shunt inductance,a width tapered cross element was proposed in the ultra-wideband design,which finally realized an MEFSS with 40% fractional bandwidth and maintaining high transmittance and high selectivity.At last,the phase characteristics of the bandpass MEFSS that the phase difference between the both side of MEFSS can be controlled by varying the permittivity of the substrates was investigated.Taking the advantages of ultra-wideband and phase characteristics,a planar lens and a transmitarray can respectively be used in gain improvement and beam steering.