IMPEDANCE MATCHING CIRCUIT AND ANTENNA USING IMPEDANCE MATCHING CIRCUIT

摘要

One matching circuit (8-2) comprises a transmission line (6b) of a predetermined electrical length and a parallel resonance circuit (5) connect ed in parallel with the transmission line. The resonance circuit has a resonant frequency f2 and a predetermined susceptance at a frequency f1 lower than th e frequency f2. Another matching circuit (8-1) comprises a transmission line (6a) of a predetermined electrical length and a capacitor element (3a) connected in series with the transmission line between an input terminal (2) of an antenna (1) and the matching circuit (8-2) so that the input impedance of the antenna at the frequency f2 may match the characteristic impedance of an external circuit (10).