Research And Design Of Multi-Frequency Frequency Selection Surface

Nowadays,communication technology is developing faster and faster,and the requirements for communication equipment are getting higher and higher.Single-frequency devices are no longer able to meet the high-speed and large-channel capacity of today's communications,and the demand for multi-band antennas is growing.The Frequency Selective Surface(FSS)is a spatial filter that exhibits total or full transmission filtering at certain frequencies.Therefore,the application of FSS to the multi-frequency domain not only supports transmission in multiple frequency bands,but also has frequency selection characteristics.It is of great value both in the civilian field of satellite communications and in the military field of researching flying weapons.This paper focuses on the improvement and research of the design of traditional multi-frequency FSS.The main innovations are as follows:(1)Firstly,the research background and significance of FSS are briefly explained,and the current research status of FSS at home and abroad is roughly described.Then the filtering mechanism and common classification of FSS,the Influence parameters of FSS transmission characteristics,the formation principle and suppression of the grating lobes,and the theoretical methods of FSS such as the pattern matching method and the spectral domain method based on Floquet theorem are introduced in detail.(2)The traditional square ring of medium loading and its complementary structure were simulated and studied.Then,a new type of dual-passband FSS was designed on the basis of the double-quad square ring structure.The two passbands were found in the X-band and Ka-band by HFSS software simulation.Compared to the traditional structure,the new FSS achieves wider passband,in-band flatness and steep cut-off filtering characteristics.Then the simulation of its polarization mode and angle variation shows that the two have good stability.The reason of the formation of two resonance points of the new dual-frequency FSS is explained by the current density.Finally,the effects of changes in dielectric thickness and relative dielectric constant on the novel dual-frequency FSS were studied.(3)The traditional tri-band FSS is designed based on the hexagonal square ring complementary structure of the medium loading.Then,based on this,a compact tri-band FSS is designed with the same dimensions.The upper layer is composed of two hexagonal square rings,the middle layer is the medium and the lower layer is the complementary structure.Compared with the traditional tri-band FSS,it is found that the three resonance points of the new tri-band FSS have different degrees of reduction to achieve compactness.Finally,the simulation and research on the polarization mode and angle variation of the structure show that the two have good stability.(4)A traditional four-band FSS is designed and simulated.The upper layer of the structure is composed of two quadrilateral square ring patches and one circular patch.The middle layer is the medium and the lower layer is two quadrilateral square ring patches.Then based on the improvement of the traditional quad-band FSS superstructure and adding a quadrilateral square ring patch on the outermost layer,a multi-layer dielectric layer is designed to load the four-band FSS of the same metal patch.The structure has four frequency bands,a stop band in the X-band,and a pass band in the Ku,K,and Ka bands,and the pass band is flat inside.Finally,the simulation and research on the polarization mode and angle variation of the new quad-band FSS are carried out.The results show that the two have good stability.