To accurately detect a direction of a transmitting means and a distance between the transmitting means and a receiving means.

Directional antennas 21a and 21b of a receiving means 2 are directed to face the direction 31 of a directional antenna of a transmitting means 1, and timing, an amplitude, a frequency, or a phase of a high frequency signal received when the antennas 21a and 21b are switched over, or a combination thereof is detected to detect the direction of the transmitting means 1 or the distance between the transmitting means 1 and the receiving means 2. During the above process, a signal extracted by a receiver of the receiving means 2 is converted into a digital signal with a sampling frequency synchronized with a reference oscillator with at least one cycle of the extracted signal as a unit. Sum-of-product arithmetic of the digital signal and a lookup table of Sin and Cos is carried out, in which a multiplication of -1 is performed by calculating a complementary number of the digital signal.

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