Wireless communication has been developed rapidly in the past decade and it has already has a dramatic impact in the people' lives. In the past few years, the development of WLAN, LTE and WiMAX represents one of the principle interests in the information and communication field. A compact frequency reconfigurable U slot circular microstrip patch antenna is proposed for LTE, WLAN and WiMAX applications. PIN diodes are appropriately positioned to alter the electrical length of U slot arm to achieve the frequency selectivity. The proposed antenna is radiated for 4.3-5.1GHz LTE band, 5.5-5.85GHz WLAN band and 3.5GHz WiMAX band.