The analysis and modeling of different configurations of loop elements based FSS, with resonant unit cells adopting an efficient vector-fitting is proposed. The elements studied are — 1) Square loop, 2) Double Square loop and 3) Gridded Square loop. The simulations of microstructure are performed with full wave simulation tool CST Microwave Studio on single- substrate for different physical parameters, oblique incidence and effect of TE/TM polarization. Then circuit models are extracted and developed using the vector fitting tool and implemented in a circuit simulator enabling both time and frequency analyses along with effect of polarization and angle of incidence. ADS SPICE generator is used for verifying circuit models developed. The developed models are within 1% of average deviation against reference data.