We propose a simple method for predicting the characteristics of Frequency Selective Surface (FSS) radome using an equivalent circuit model. The required material properties, such as the permittivity and permeability of the FSS, were extracted from a FSS equivalent circuit model using a transmission and reflection method. These parameters were then used to calculate the transmission characteristics of FSS radome. We designed a sandwich radome using a square loop FSS for a 23GHz band application. In order to demonstrate the validity of our approach, we also performed a simulation to obtain the characteristics of the FSS radome using commercial full-wave software. The results from the two approaches are in good agreement. The method proposed herein could be used for the simple and rapid calculation of the design and fabrication of a FSS radome. The FSS radome is that a square loop FSS that has a stop band at 23GHz is insulated between two dielectric materials. A simple analysis of a FSS radome requires the material constants, the permittivity and permeability of the square loop FSS, which we extracted using transmission/reflection. Using the material constants derived from a FSS equivalent circuit model, the characteristics of the FSS radome were calculated for a simple 2-D case. The results were verified using a commercial full-wave three-dimensional electromagnetic wave simulator. The resulting characteristics of the FSS radome agreed with those obtained using a full-wave simulation. We show herein that the characteristics of a FSS radome can be analyzed and predicted with relative ease using an approximate FSS to achieve a simple 2-D construction. Our method can be applied to the analysis of FSS radome for use with various communication systems and electrical instruments.