Design Of Single-layer Multi-band Dual-polarization Frequency Selective Surface

The Miniaturized-Element Frequency Selective Surface(MEFSS)improves the stability of incident angle,by increasing the resonant frequency of Bloch wave caused by the unit cell beyond the observation area.This dissertation purpose a novel design method of MEFSS.The common resonance of non-adjacent structures,that further reduced the size and period of the unit cell,is investigated.In the realization scheme,the two resonant structures are placed as close as possible,and the displacement current between them is excited.The resonant length of MEFSS is the sum of the dimensions of the inner and the outer ring,whose physical mechanism is the joint resonance induced by displacement current to connect two non-adjacent structure.Based on this scheme,a tri-band frequency selective surface with center frequencies of 9.1GHz and 13.5GHz in the transmission passband and 10.7GHz in the stopband is designed.Specifically,the higher transmission passband is determined by the inner ring.What is more,the lower transmission passband is yield on the joint resonance between the inner ring and the outer ring.The rest part of metal structure between the two rings is determined the reflection band.The bandwidth of each of three bands is more than 0.6GHz.The equivalent circuit of this type of MEFSS is proposed.The basic topological structure of the circuit is analyzed.The equivalent self-capacitance of the outer ring is in series with the equivalent inductance of the intermediate metal structure of the two rings.And then the equivalent self-capacitance of the inner ring is in parallel with the former structure.What is more,the equivalent inductance of the metal structure of the outer ring is in series with the circuit mentioned.The physical mechanism of tri-band MEFSS is clarified,and the formulas of resonant frequency are deducted.This MEFSS is fabricated by the process of corrosion on ultra-thin material,according to the tolerance requirements.The transmission confidence of sample is tested by link method.The aberration of antenna pattern caused by the MEFSS is evaluated by the near field and far field transformation method.The beam distortion of the antenna pattern is calculated quantitatively.The experimental data shows that this scheme is an effective way to realize the MEFSS,which hints that the one separates three frequency bands with the stability of incident angle.The transmission coefficient is better than-1dB in each pass band,and the one in the stop band is better than-10dB.The beam distortion calibrated by coupling coefficient in the pass band is controlled at 98.8%.What is more,the main beam of the antenna is eliminated by the scattering of the MEFSS in the stop band.