IMPEDANCE CONVERSION DEVICE, ANTENNA DEVICE AND COMMUNICATION TERMINAL DEVICE

摘要

In a case in which a capacitor is not provided in parallel with a second inductance element, the impedance ratio between a first inductance element and the second inductance element is constant regardless of the frequency, but when a capacitor is provided, the parallel impedance of the capacitor and the second inductance element gradually increases at frequencies equal to and below the resonant frequency. Consequently, at frequencies equal to or below the resonant frequency, the higher the frequency becomes, the larger the value of the real portion of the impedance observed on a high-frequency-circuit side becomes. Therefore, by appropriately setting the values of the first inductance element, the second inductance element, and the capacitor, the frequency characteristics of the real portion of the impedance observed on the high-frequency-circuit side can be set to be similar to the frequency characteristics of the radiation resistance of the antenna.

主权项

1. An impedance conversion device arranged to be inserted between an antenna element and a feeder circuit, the impedance conversion device comprising:
a first circuit including a first inductance element connected to the feeder circuit; and a second circuit including a second inductance element connected to the antenna element and coupled with the first inductance element; wherein the second circuit includes a capacitor connected to the second inductance element.