Equivalent circuit model of multilayer double square loop FSS using vector-fitting

We present the analysis and modeling of multilayer double square loop frequency selective surface adopting vector fitting procedure. The simulations of microstructure are performed with full wave simulation tool CST Microwave Studio on multilayer substrates with permittivity ranges from 2.2 - 4.3 in the frequency range 1 GHz - 30 GHz and substrate thickness ranges from 0.5 mm - 2 mm for different physical parameters. Then circuit models are extracted and developed using the vector fitting tool and implemented in a circuit simulator enabling both time and frequency analyses which includes the effect of polarization and angle of incidence. ADS SPICE generator is used for verifying circuit models developed using simulated results. The developed model is within 1% of average deviation against reference data.