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This study presents new antenna schemes suitable for cognitive radio communications. The antenna structures consist of a ultra wide band (UWB) sensing antenna, and a frequency reconfigurable communicating antenna both incorporated into the same substrate. Two different techniques to achieve the required frequency agility are proposed. The first one is based on a rotational motion of the radiating patch whereas the second is based on optical switching. The importance of these techniques is that no bias lines are needed as is seen in the case of RF MEMs, PIN diodes and lumped elements. Prototype antennas were fabricated and a good agreement was observed between the simulated and the measured data.

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