Patent attributes
A distance can be measured with high resolution. A frequency controller (7) controls a voltage control oscillator (2) so as to change a signal source frequency f in a range containing two center frequencies f1 and f2 and transmits it as a traveling wave from an antenna (4) to a target (5). A reflected wave reflected by the target (5) and the traveling wave interfere each other and form a standing wave. A power detector (6) detects power corresponding to the amplitude of the standing wave and performs Fourier transform based on the two center frequencies f1 and f2 in Fourier transform means (11, 12), respectively, thereby calculating radar image functions P1(x), P2(x). The distance d to the target (5) satisfies the conditions that the phase difference of the two radar image functions zero-crosses and the amplitude of the radar image functions becomes maximum. The zero cross point of the phase difference is a zero cross point of a linear function and can be identified with high resolution.
