Design And Simulation For Miniaturized Elements Frequency Selective Surfaces In Ka Band Based On Novel Structures

Frequency Selective Surface (FSS) is a two-dimensional period array of metalpatch elements or aperture elements formed on the metal surface with spatial filteringcharacteristics and obtained widely used in the electromagnetic field. Theoretically,frequency selective surface should be infinite periodic plane, but “infinite” cannot beachieved in practice, thus it requires that there are a large number of FSS elements infinite plane and the conventional cell size is about a half of wavelength.The oversizedelements cause that FSS is unstable for different polarization modes and incidentangles, therefore FSS element miniaturization is in urgent needs in the actual design.This paper designs three new types of Miniaturized Elements FSS（MEFSS） forKa-band based on the coupling mechanism between electric field and magnetic fieldand bending the edge of element into the inner space.Firstly, the research status of the traditional and the miniaturizd elementfrequency selective surface, applications are introduced. Then the transmissioncharacteristics of FSS, filtering mechanism, element classification, technicalindicators are described, followed by the impact of element size parameters, elementarrangement mode, loaded medium, polarization mode and incident angle of incidentelectromagnetic wave, FSS cascading, manufacturing error on the traditionalY-shaped, cross, Jerusalem cross, square ring element. Based on the above theoreticalanalysis, novel MEFSSs used in Ka-band are designed by utilizing the couplingmechanism between electric field and magnetic field and the method of meanderingelement into the inner space.The first method is achieved by using metal patches as capacitive surface andmetal grid as inductive surface, utilized the coupling mechanism between capacitivesurface and inductive surface.This paper has designed two MEFSS structures, one iscomposed of fan loop element and metal grid coupled structure, the other one isregular hexagon loop element and metal grid structure. Their center frequency are33.1GHz and33GHz, respectively, the size of element is only as small as0.1λ, the-3dB bandwidth covers the entire Ka band as TE polarized, normal incidence.Theyhave stable center frequency and low transmission loss when the polarization modeand incident angle vary. These two new structures have stable center frequency, low transmission loss, wide bandwidth, insensitive for different polarization modes andincident angles.The second method is by means of bending the edge of element into the innerspace to increase the electrical length to realize miniaturization. In this paper, aregular hexagon annulus aperture element is meandered to inner space to increaseelectric length on the fixed plane. Its center frequency is32GHz, miniaturizationdegree is0.128λ,-3dB bandwidth occupies75.5%of Ka band. Although this structureis not so good as the first two structures, it is relatively easy to manufacture actually,and it has great practical significance.