Patent ID: 9160073
Filing Date: 2015-10-13
Classification: H01Q,H03J,H03K,H04B

Abstract:
1. An antenna device that performs at least one of transmission of radio waves in a first frequency band and radio waves in a second frequency band that is lower in frequency than the first frequency band or reception of radio waves in the first frequency band and radio waves in the second frequency band, comprising: an antenna unit that includes an antenna element and a variable capacitance element that is variable in capacitance in accordance with a voltage applied to the variable capacitance element, and that resonates in such a manner that the antenna element and the variable capacitance element cooperate with each other; a power supply terminal that supplies the voltage applied to the variable capacitance element; a time constant circuit that gradually increases the voltage applied to the variable capacitance element when a voltage applied to the power supply terminal is changed from an off state to an on state, wherein the time constant circuit includes a resistor and a capacitor that are connected in series, one end of each of the resistor and the capacitor is connected to a node of the variable capacitance element and the antenna element, the other end of the capacitor is grounded, and the other end of the resistor is connected to the power supply terminal, and wherein the time constant circuit has a time constant that is longer than a duration during which the voltage applied to the power supply terminal is in an on state; and a discharge unit that discharges electric charge stored in the capacitor when the voltage applied to the power supply terminal is changed from the on state to the off state.