Tunable 3.5GHz and 1.5GHz chip antennas based on thin-film BaSrTiO3 capacitors

Tunable 3.5GHz and 1.5GHz chip antennas are presented in this paper. By applying tunable matching networks, the chip antennas show tunable characteristic. Especially, the capacitors in the matching networks are tunable thin-film BST capacitors, which have a 3∶1 tuning ratio. The capacitance of the BST capacitors can be tuned by an external DC bias voltage. By varying the capacitance, the tunable matching networks increased the bandwidth of the 3.5GHz antenna by 80%, and the 1.5GHz antenna by 26%.