Abstract-Conventional adaptive array consists of several antennas. However, for vehicular industrial design, it is preferable not to use additional antenna elements. Therefore, we propose a multiband shared aperture adaptive array antenna using a rear defogger. In addition, RSAA (reactive steered adaptive array) concept is applied for simplification and low power consumption. From simulation and experiments results, it shows that the proposed adaptive antenna can operate at 100 MHz (ISDB-T SB ) and 210 MHz (ISDB-T MM ) band and that it also has the phase diversity capabilities in the Rayleigh fading environment.