Mutual coupling suppression of two dipole antennas backed by optimized reflector

In a repeater antenna for wireless communications, suppression of mutual coupling between transmitting and receiving antenna is required to reduce the weight and size of the antenna system even if the antenna separation is very small. On the other hand, for a dipole antenna backed by a reflector, it has already been proposed that the enhancement of FB (front-to-back) ratio of a dipole antenna can be achieved by optimizing the reflector shape. Miniaturization of the reflector can be achieved by using an optimum size for the FB ratio (see Rikuta, Y. et al., Asia-Pacific Microwave Conference, vol.3, p.1068-71, 2001). An antenna with high FB ratio has little influence on the backward direction. This paper presents the suppression of mutual coupling with a small distance between antennas by using two antennas with high FB ratio back to back. We investigate a rectangular reflector and a dual boxing reflector. The characteristics of mutual coupling of these antennas are calculated by FDTD analysis.