Research On Polarization Stability Of FSS Spatial Filter

Frequency selective surface is a spatial electromagnetic wave filtering device, compared with traditional filter, the device has the unique superiority in space electromagnetic wave signal selection,the tremendous value in the electromagnetic stealth, electronic warfare and other fields make it widely used in military and civilian areas,the most important application is used as stealth radome in the military application.The FSS was studied and discussed from aspects of theory and engineering simulation.In the respect of theory,FSS basic theory is introduced,including basic theoretical analysis, physical work mechanism, common FSS unit types and their corresponding equivalent circuit model. On engineering simulation side, unit arm length,dielectric layer thickness, dielectric constant, dielectric layer loading method, unit arm width, incident wave angle and polarization mode,etc is analyzed by simulating the model changed above basic parameters respectively.Mode matching method and spectral domain method are used to analyze gap unit and patch unit electromagnetic scattering parameters. Electromagnetic wave polarization concept,polarization type and corresponding representation method are elaborated on emphasis.Simulation analysis is carried out by adjusting Y loop unit and Y patch unit geometric parameters respectively.By changing array pattern and the rotation angle of Y loop and Y patch FSS unit, better polarization stability characteristics is obtained in square array and triangular array pattern after FSS unit is rotated certain angle.In the respect of comprehensive simulation design,multi-layer FSS electromagnetic scattering parameters analysis methods are introduced, square loop FSS unit is adopted to explore multi-screen FSS design method.Multi-screen FSS has wider transmission bandwidth,steeper sideband characteristic and more stable frequency response performance.but the design difficulty coefficient is high and passband insertion loss increases. From the perspective of FSS compaction and unit miniaturization, simulation results of traditional cross unit and size reduced unit are compared conclusion has been drawn that the miniaturized FSS transmission performance improves significantly.A novel miniaturized with highpolarization transmission response stability is designed to be double screen structure loading dielectric layer, stable incident wave angle and polarization mode transmission curve is eventually obtained by repeated optimizing dielectric layer thickness and dielectric constant.