Automatic tunable antenna system using MEMS variable capacitors and a probe triggered by TPC

Built-in antennas in mobile equipment are often subject to changes in input impedance due to the proximity of objects, e.g. a user´s hand/head, a desk, etc. To compensate this mismatch, an automatic tunable antenna system using Micro-Electro-Mechanical System (MEMS) variable capacitors and a probe is proposed in this paper. The system controls MEMS variable capacitors based on the received power of the probe and triggered by the Transmission Power Control (TPC). A prototype using a square-law detector, an Analog-to-Digital Converter (ADC), a Field Programmable Gate Array (FPGA) and a matching circuit containing MEMS variable capacitors is also demonstrated.