Tunable Dual-band IFA Antenna using LC Resonators

A tunable dual-band inverted F antenna (IFA) is presented in this paper. By placing a LC resonator on the radiating arm, dual-band characteristic is achieved. Especially, the capacitor in the resonator is a tunable thin-film BST capacitor, which has a 3.3:1 tuning ratio. The capacitance of the BST capacitors can be tuned by an external DC bias voltage. By varying the capacitance, both the lower band and the upper band of the IFA antenna can be tuned. And the total bandwidth can cover six systems, i.e., GSM-850, GSM-900, GPS, DCS, PCS, and UMTS. KeywordsInverted F antenna, BST, resonators, tunable circuits and devices.