| The increasing development of communication technology brings more complex electromagnetic environment.The traditional spatial filter can no longer meet the requirements of stealth and anti-interference of wireless communication system.Therefore,a Frequency Selective Surface with different filtering characteristics is derived.absorber(FSS)is connected with Circuit analog absorber(CAA)to form Frequency Selective Rasorber(FSR),FSRS can generate both transmission passband and absorption band,so the stealth characteristics of multi-station radar systems can be greatly improved and out-of-band interference of wireless communication systems can be suppressed.At present,most of the research on FSR focuses on the performance improvement of ultra-wideband,dual-frequency absorption,tunability,etc.,while there are few studies on high-frequency harmonic suppression.Therefore,this paper mainly studies the design of high-frequency harmonic suppression FSR,and the main research contents are as follows:(1)A new miniaturized FSR is designed.The structure consists of a quadrangular ladder ring loaded with lumped resistors and slit FSS loaded,the size is 0.13λ×0.13λ(λ is the wavelength of the passband resonant frequency in free space).It has the filtering characteristics of low frequency transmission and high frequency absorption,and realizes the polarization and incident Angle insensitive characteristics.In order to explain the effectiveness of the designed FSR,the equivalent circuit analysis is carried out,and the simulation results of HFSS are compared to confirm the feasibility of the assumption.(2)A new miniaturized high frequency harmonic suppression FSS is designed.The structure is composed of a double comb grid with metal fence and a mutated square ring.Compared with similar FSS,the design uses only two layers to achieve nearly four times the high frequency harmonic suppression function.The effectiveness of the designed structure is analyzed theoretically by using the equivalent circuit analysis method,and the measured and simulated results are compared with the processed samples.(3)An FSR suitable for high frequency harmonic suppression is designed.Firstly,a wideband absorbing structure based on loaded lumped resistance is analyzed.The structure consists of metal bent metal bands with the four corners of a resonant square ring bent inward.The influence of the distance between the absorbing structure and the metal backplane and the value of lumped resistance on the absorbing performance is analyzed by simulation.Next,the FSS structure designed in Chapter 4 is used to replace the metal backplane to generate passband and reflect high frequency harmonics.Then,the high frequency harmonic suppression FSS and the wide-band absorbing structure were designed and simulated to determine the thickness of the air dielectric layer and the loading resistance between them.The test results and simulation results show that the designed FSR with high frequency harmonic suppression can achieve the absorption effect in the five harmonic frequency band range of the second order passband center frequency of 4.6GHz,and maintain good polarization and oblique incidence stability.This paper starts with a high frequency absorbing FSR and introduces its design and analysis process in detail.Then transition to high frequency harmonic suppression of FSR design,the high frequency harmonic suppression of FSS and high frequency absorber are analyzed in detail,and then combined with simulation and processing of physical test.The results show that the designed FSR with high frequency harmonic suppression achieves the absorption effect in the five times harmonic frequency band range of 4.6GHz passband center frequency,and maintains good polarization and oblique incidence stability. |
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