Design And Fabrication Method Of An Integrated FSS Radome

In the 21st century,the stealth of flying weapons has become one of the highest competition point of the core technologies in the modern military field.The antenna structure in the aircraft radome is a strong scattering source for radar signals and contributes more than 40%to the Radar Cross Section(RCS).The application of Frequency Selective Surface(FSS)to the radome is the best choice to effectively reduce the aircraft’s RCS and improve stealth capability.The frequency selective surface refers to a periodically-arranged apertures or metal patches a metal surface,and is essentially a free-space electromagnetic wave filter.The FSS with the band-pass nature enables the electromagnetic waves in band to pass through with low insertion loss,while the signals outside the pass-band are reflected,thus realizing the stealth of flying weapons.However,there are a large number of FSS units on a large non-developable surface,and the structure and arrangement are complex.In terms of the FSS radar cover’s overall simulation and integrated machining methods,China still has a long way to catch up other centuries such as the United States,Britain,Russia.In this thesis,we first utilized COMSOL/CST simulation software to model and analyze the electromagnetic filtering characteristics and comprehensive service performance of the FSS radome.Starting with the analysis of infinite FSS on a plane,a Y-shape band-pass FSS with a center frequency of 17GHz was designed.The polarization stability and angle stability of the FSS were analyzed,and the influence of cell structural parameters on the electromagnetic transmission performance was studied.In order to realize the integral simulation analysis of the curved FSS,the phased array antenna was designed,and the FSS units were arranged on the curved surface based on a spatial quasi-periodic method,through analyzing an integrated model of the curved FSS radome and the phased array antenna,we extracted the key electromagnetic parameters of the curved FSS radome from the antenna’s far-field radiation pattern.To solve the integrated machining problem of curved FSS radomes,we proposes a novel comprehensive machining method that employs a six-degrees-of-freedom laser robot and a rotary table to realize non-contact processing on the radome surface,avoiding the deformation of the radome associated with traditional mechanical processing.The FSS radome was comprehensively tested in a microwave anechoic chamber.The results show that the designed conformal curved FSS radome demonstrates good electromagnetic transmission characteristics.In view of the fact that the conventional FSS radome cannot help reducing the RCS with a dual-station radar,an integrated FSS composite cascade structure with both absorbing and transmitting features in different bands was investigated.By adopting a design with the metal band-pass FSS structure and the resistive FSS patch located on each side of the medium,we obtained a composite cascade structure with broadband pass and low-reflectivity at high frequencies.The simulation results show that this kind of structure can effectively reduce the out-of-band RCS,and it has a great application prospect in reducing the RCS for the dual-station radar.