| 摘要 |
A variable directivity antenna (2) has directivity direction angularly variable stepwise about itself. A tuner (8) selects a desired one from high frequency signals received at the antenna (2). The tuner (8) detects the level of the received signal and supplies it to a control unit (10). The control unit (10) searches for received signal levels, equal to or higher than a threshold level, of the received signal received in plural states in which the directivity of the antenna (2) is placed in different ones of directivity directions, and detects a slope of the received signal levels within a frequency range of the received signal. The control unit (10) employs the searched directivity direction for the smallest one of the detected slopes as the direction to which the antenna (2) is directed to receive the signal.
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