| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a radar apparatus, which can remove the influence of a low-frequency noise in a mixer for a high frequency without largely attenuating a high-frequency signal, and whose detecting sensitivity can be enhanced. SOLUTION: An amplitude modulator 18 which amplitude-modulates a transmitting signal Ss at a determined modulation index (m) [where 0<m<1] according to a modulation signal Mb supplied from a sine-wave oscillator 20 via a modulation-intensity regulator 19 is provided between a distributor 16 by which a high-frequency signal, in a milliwave band generated in a voltage- controlled oscillator, is power-distributed into the transmitting signal Ss, a local signal L and a transmitting antenna 22. When a received signal Sr and the local signal L are mixed by a mixer 26 for a high frequency, a beat signal which contains a harmonic component (frequency: Fs±fu) in which the influence of a low-frequency noise is small is obtained by the frequency component (frequency: Fs) of a modulating signal Mb given to the received signal Sr. In addition, since the modulation index (m) is set at less than 1, an impedance change can be suppressed in the amplitude modulator 18, where fu represents a beat frequency.</p> |
