COMMUNICATION CIRCUIT, COMMUNICATION APPARATUS, IMPEDANCE MATCHING CIRCUIT AND IMPEDANCE MATCHING CIRCUIT DESIGNING METHOD

摘要

A communication circuit (1) is provided with, for instance, an antenna section (3) such as a nonresonant antenna, and a matching section (5) for performing impedance matching by being connected to the antenna section (3). The matching section (5) is provided with a transmission line, and the electrical length and characteristic impedance of the transmission line are decided based on a frequency or frequency band where the antenna section (3) and the transmission line resonate. In the nonresonant antenna, for instance, since there is no need for matching the resonance frequency with a center frequency, the antenna can be reduced in sizes. Furthermore, a wide band can be achieved by changing the characteristic impedance of the transmission line.