This year is being called the “first year of electric vehicles,” and electric vehicles have come on the market in earnest. This trend is expected to continue and even accelerate with the diffusion of electric vehicles. However, manually charging the battery for electric vehicles is a tedious process. Therefore, an automatic, wireless charging system for electric vehicle is greatly desired. There are some types of wireless power transfer systems. In particular, electromagnetic resonant coupling is a promising technology for wireless power transfer because power can be transferred over a large air gap; this method is more practical and efficient than the conventional methods. This technology has been proposed recently, and detailed study on the repeater antenna is yet to begin. The air gap can be extended by placing a repeater antenna between the transmitting antenna and receiving antenna when it is possible to use only the transmitting antenna and receiving antenna because this method is limited by the length of the air gap. This technology offers an easy way to extend the air gap by placing a repeater antenna and expand the feeding zone for electric vehicles at a car park. In future, this method can be used to feed moving electric vehicles on highways by arranging repeater antennas along the road. Until now, repeater antennas have been studied by performing an electromagnetic field analysis; however, the analysis does not include a theoretical study of the equivalent circuit. In this paper, a model of the equivalent circuit for repeater antennas with and without cross coupling is proposed.