AUTOMATIC ANTENNA TUNING/MATCHING APPARATUS

PROBLEM TO BE SOLVED: To automatically and promptly perform tuning and matching, when a frequency is changed in an automatic antenna tuning/matching apparatus, including a movable member which is driven to change an inductance value or a capacitance value.SOLUTION: A voltage signal of a high-frequency signal flowing in a coaxial cable 3 for connecting a shortwave radio transceiver 1 and an antenna 2 is detected by a voltage detecting section 52, and a current signal of the high frequency signal is detected by a current detecting section 53. A matching determining section 54 compares the current signal with the voltage signal and outputs a voltage/current ratio signal, representing a matching state. Furthermore, a tuning determining section 55 compares the phase of the current signal with that of the voltage signal and outputs a phase difference signal representing a tuning state; and on the basis of the voltage/current ratio signal and the phase difference signal, a motor rotating direction control circuit 56 and a motor stop circuit 57 then control a motor 51, and the movable member is driven to automatically and promptly perform tuning and matching.