A rotatable reconfigurable antenna for cognitive radio applications

This paper presents an antenna scheme suitable for cognitive radio applications. A UWB sensing antenna and a frequency reconfigurable communicating antenna are incorporated together into the same antenna substrate. The UWB antenna searches for available spectrum holes while the reconfigurable antenna simultaneously tunes its operating frequency to the corresponding frequency determined by the sensing antenna. A new technique to achieve the required frequency reconfigurability is implemented via a rotational motion of a series of antenna patches. This eliminates the use of any bias lines as with the case of RF MEMs, PIN diodes and lumped elements. A prototype antenna was fabricated to test the proposed method. In the fabricated prototype, a stepper motor is incorporated and controlled via a computer. The use of this antenna structure in a cognitive radio communication link is demonstrated.