In this letter, a novel design of independently reconfigurable upper and lower bands of a Yagi-Uda antenna is presented. The reconfiguration approach used in this antenna is based on keeping either the upper or lower band edge fixed with gradually increasing the bandwidth to the lower or upper ones. In this system, PIN diodes are used to control the length of the resonator and the slot-line of Yagi-Uda antenna to achieve upper and lower bandwidths limit reconfigurability. An antenna prototype was fabricated and tested in order to validate the design approach of the bandwidth reconfiguration. The proposed antenna has several different modes of operation with capability of tuning the fractional bandwidth (FBW) from 7% to 33% and 18% to 72% when using resonator and slot-line, respectively. This antenna can be a good candidate for cognitive radio applications that need adjusting the frequency bandwidth.
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