ANTENNA DEVICE

摘要

A stray capacitance is generated between an antenna element and a ground electrode. A capacitance detection circuit detects the stray capacitance. An antenna matching circuit, is provided along a wireless communication signal path, which is a transmission path between the antenna element and a feeder circuit. A feedback control circuit transmits a control signal to the variable matching circuit on the basis of a detection result of the capacitance detection circuit in accordance with the stray capacitance. The capacitance detection circuit includes a constant current source and a timing circuit to measure the time taken to charge the antenna from the constant current source and for the voltage to reach a predetermined voltage.

主权项

1. An antenna device comprising
an antenna element, an antenna matching circuit connected between the antenna element and a feeder unit, a capacitance detection circuit connected to the antenna element and detecting a stray capacitance of the antenna element, and a feedback control circuit controlling the antenna matching circuit in accordance with an output signal of the capacitance detection circuit, the capacitance detection circuit including a constant current source and a timing circuit measuring a time taken to charge an antenna from the constant current source and for a voltage to reach a predetermined voltage.