Design Of Dual-band Frequency Selective Surface Radome

In electronic countermeasure weapons equipment such as ships and aircraft,usually one frequency band performs electronic reconnaissance,and the other frequency band performs electromagnetic interference on enemy weapons.Therefore,the Frequency Selective Surface(FSS)radome matched with the countermeasure equipment should be maintain good pass band characteristics in the two frequency bands.Furthermore,the polarization reconfigurable FSS radome can play an important role in avoiding the interference of the same frequency and the same polarization signal.However,there are few studies on the polarization reconfigurable FSS.So the study of dual-band FSS radome and polarization reconfigurable FSS is very important.In this paper,four kinds of dual-band FSS radomes and two light-controlled polarization reconfigurable FSS radome are designed.The main research contents of the thesis are as follows:The basic concepts and analysis methods of FSS are briefly introduced.The filtering characteristics,unit classification and the factors affecting transmission performance of FSS are elaborated,and the causes and avoidance methods of FSS grating and Bragg flaps are introduced.Based on the characteristics of the two-layer and multi-layer FSS structure designed in this paper,the three methods of FSS equivalent circuit method,pattern matching method and generalized scattering matrix method are introduced.Secondly,the dual-band FSS with good flatness and steep cut-off performance are designed.A three-layer dual-band FSS structure,a four-layer miniaturized dual-band FSS structure based on the complementary zigzag line principle,a two-layer cascade zigzag three-wire dual-band FSS structure based on the equivalent circuit principle,and a two-layer zigzag dumbbell type dual-band FSS structure are proposed.Then we analyzed the equivalent circuit diagram,frequency response curve,dual-polarization stability,angular stability,and surface electric field distribution of those dual-band FSS.Through the analysis of the results,the four dual-band FSS structures have good band-pass characteristics,in-band flatness and steep cut-off characteristics in the C-band(6.5 GHz ~7.2 GHz)and X-band(9.2 GHz ~ 9.7 GHz)to meet the design requirements.And the four dual-band FSS achieve no more than 0.5d B of filter loss in the pass band and good angular stability.Based on the four dual-pass FSS unit structures,the transmission characteristics and electromagnetic performance of 5×5,10×10,20×20 finite FSS are analyzed.As the number of FSS arrays increases,the frequency response of a finite FSS is closer to the frequency response of an infinite FSS.Then,the FSS radome and the horn antenna are integrated and simulated.After the FSS radome is loaded,the far-field pattern of the horn antenna changes little.and the Radar Cross Section has obvious Reduce,so as to achieve the stealth effect of the antenna,to meet the design requirements of the passband FSS radome.Finally,two light-controlled polarization reconfigurable FSS for avoiding the interference of the same frequency and the same polarization signal are designed.The light-controlled microwave switch is made based on the photoconductive effect,and the on-off of each light-controlled microwave switch is controlled by the optical fiber,thereby controlling the structure of the FSS and realizing the polarization reconfigurable function of the FSS.The two polarization reconfigurable FSS are capable of linear polarization reconfigurable of 0°/90° and 45°/90°,respectively,and maintain a pass band response with a loss of no more than 1 dB.