Design Of Miniaturization FSS Based On Loading Technique

Frequency selective surface (FSS) are planar periodic arrays consisted of metal patches or slots elements that function as filtering for free-space radiation. With the interaction of electromagnetic wave,the type of metal patch FSS generally shows the band-stop characteristics,and the type of slot FSS generally shows the bandpass characteristics. FSS is widely used in the fields of microwave for its specific frequency selection characteristics.This article realizes the miniaturization of the unit respectively through the technology of loading in structure and loading lumped components. It played a reference role for the practical application in the limited space and improving spatial filtering performance of FSS.First of all,we propose an improvement plan through analyzing the equivalent circuit of the square-ring-aperture FSS in the foundation of equivalent circuit theory. It increases the equivalent capacitance of the unit effectively through loading the four slot edges of square-ring-aperture unit in structure. The resonant frequency of the proposed FSS is 1.647GHz, the miniaturization effect of its unit is excellent significantly, and the unit size reaches 0.0538?×0.0538?, where ? represents the wavelength of the resonant frequency. This method makes the miniaturization effect of the unit more significantly comparing with the past loading in structure methods at a higher working frequency (above 1 GHZ). At the same time, the FSS has high polarization stability and angle stability.Secondly, in the foundation of the artificial transmission line current loop method (that is by loading lumped components on the square-ring unit,it will produce the path of the closed current which is similar to square-ring-aperture unit). It increases the length of the closed current path effectively through loading in structure of square-ring unit which has loaded on lumped components, so we propose loading-lumped-components-bend FSS with the resonant frequency is 0.3GHz,and it can control the resonant frequency of the FSS effectively through adjusting the value of the loaded capacitance and inductance. This method realizes the miniaturization of the unit well at a lower working frequency (below 1 GHZ) and the unit size reaches 0.001?×0.01?, At the same time, the FSS has high polarization stability and angle stability. Finally, in the foundation of the square-ring unit which has loaded lumped components, we propose the type of loading-lumped-components-double-square-ring FSS through loading similar square ring patch structure inside of the unit. It realizes stable double frequency resonance through adjusting the distance of the double square ring and the value of the loaded lumped components.