Research On Miniaturized Dual-band Bandstop Frequency Selective Surface

The frequency selective surface(FSS)is a kind of periodic metal structure with a frequency selective function,which is formed by periodic arrangement of one or more metal sheets.The frequency-selective surface enables the screening of electromagnetic frequencies and the control of electromagnetic wave incidence,transmission and reflection.In recent years,with the continuous deepening of research on frequency selective surfaces,more and more metal cell structures and arrangements have been applied to FSS.By changing these structures,the central frequency,bandwidth,and frequency stability of FSS can be controlled.parameter.It can be applied in various aspects such as absorbing materials,anti-electromagnetic interference,electromagnetic compatibility and radar stealth technology.This paper mainly focuses on the characteristics of dual-frequency and miniaturization of frequency selective surface(FSS),and proposes a new type of miniaturized dual-frequency FSS structure.It is verified by software simulation that it has good polarization and angular stability,and is also miniaturized.Both design and dualband design achieve good results.In order to achieve a dual-band resistive frequency selection surface.The actual design of the dual-frequency miniaturized frequency selection surface was completed.Through the research and production of the dualfrequency miniaturization frequency selection surface,the parameters and the difficulties encountered in the completion process and the design process were summarized.Insufficient,and completed the test of the dual-frequency miniaturization frequency selection surface and the optimization of its parameters.Firstly,a single-frequency band-rejection frequency selective surface with a center frequency of 2.25 GHz was designed.By using a new type of folding of metal strips,the size of the unit was significantly reduced,the ratio of the unit side length to the maximum wavelength was 0.038,and plane waves were analyzed.The transmission coefficient at different incident angles,the minimum bandwidth with a transmission coefficient of less than-15 d B is 0.06 GHz,the maximum bandwidth is 0.14 GHz,and the frequency offset is less than 1.79%.The single frequency band rejection frequency selection surface was tested.The test results have a wide bandwidth,a small frequency offset rate,and good performance.Afterwards,two dual-frequency band-rejection frequency-selective surfaces were designed so that the in-band transmission coefficient was less than-15 d B while the 2.3GHz and 5.9Ghz spiral structure FSS and the 3GHz/5GHz bending structure FSS were satisfied.Helical FSS.A symmetrical metal strip structure is adopted for design,and metal vias are connected between upper and lower two metal patches.The ratio of cell side length to wavelength(maximum)is 0.039.The bending structure is composed of an outer frame and a central structure.The central structure is four fold line structures with outward openings.A metal via is designed to connect with the back at the end of each fold line structure,and the back surface is connected with a metal strip bending structure.The holes,which make good use of the back area,further reduce the size of the frequency selection surface.The electrical dimension value of this structure is 0.1,and the minimum bandwidth of this structure is 0.042 GHz.Finally,a new dual-frequency band-rejection frequency selective surface was designed.The structure consists of a medium with a dielectric constant of 4.4 mm and a top and bottom two-layer metal patch.The composition of the metal patch can be divided into two parts.The first part is that the outer frame part consists of a square metal strip with a side length of 15.4 mm,and is attached to only one side of the dielectric board.The second part is the central folded loop portion,which consists of four outwardly bent structures,and eight metal vias at the ends of the metal strip near the center are connected to the backside structure.The ratio of the side length and wavelength(maximum)of the frequency selective surface unit is 0.085,the vertical incident bandwidth is 0.1 GHz and 0.4 GHz,and the frequency offset rate is less than 2.5%,which achieves the goal of miniaturization,wide bandwidth and frequency stable.