Investigation On Planar Wideband Wide-angle Frequency Selective Radome

With the rise of the concept of imformation warfare,imformation screening,encryption,and stealth technologies are incresasingly important.In this case,frequency selective radome has been widely used in the military.Frequency selective radome as a spatial filter,it has a selective characteristic for specific frequency electromagnetic waves in a certain angle domain.At the same time,it can also reduce the radar cross section(RCS)of the antenna.In this thesis,the following work has been done about planar wideband and wide-angle frequency selective radomes:First,by using the theories of electromagnetic waves in the multi-layered media include total transmission,total reflection and multiple reflection characteristics in multi-layered media,the transmission characteristics of electromagnetic waves in multi-layer dielectric radome were analyzed.Based on this,two types of dual-layer frequency selective surfaces with wideband characteristics in the passband and stopband were designed.The effects of various structural parameters of the FSS on their electrical performance were analyzed through simulation.And the characteristics of low insertion loss,wide-angle within the passband frequency band,and wide-angle wide-band suppression within the stopband frequency band were realized.Afterwards,corresponding objects were produced and tested.The test results are similar to simulation results.Subsequently,the frequency selective radome and the antenna were co-simulated.Comparing the antenna pattern before and after loading the frequency-selective radome to analyze the influence of the frequency-selective radome on the antenna.The effect of frequency-selective radome on the gain,beam angle direction,and the width of the lobe of the 16×16 uniform array was analyzed by array synthesis.After that,the influence of the integration distance between antenna and radome on the radiation charac-teristics of the antenna was analyzed.Experiments were conducted to verify the variation of main beam pointing offset and lobe width under various scanning angles of array antenna loaded with frequency-selective radome.Afterwards,the RCS calculation of the frequency-selective radome was performed using the method of moments(MOM).The RCS of the metal plate was calculated using the analytical formula and the fast multipole method.The RCS of the frequency-selective radome and the metal plate was compared.Then the RCS before and after antenna loading frequency selective radome was analyzed and compared,and the effect of the frequency selection radome on reducing the RCS of the antenna was verified.Finally,two methods of matching the passband of frequency-selective radome are studied.One is matching the passband of FSS by medium loading,the other is matching the passband of FSS through the inductive metal grids.Firstly,by comparing the transmission characteristics of FSS with and without media matching layer,the matching effects of the loading medium matching layer on the FSS were verified.Secondly,by analyzing the working mechanism of non-resonant unit FSS,two non-resonant unit frequency selective radome are designed.In the end,by comparing the transmission characteristics of the two non-resonant FSSs loaded and unloaded metal grids,the matching effects of the metal grids layer on the FSS passband were verified.