A radar includes a transmitter circuit, a receiver circuit, an antenna and a circulator. The receiver circuit includes a low-noise amplifier which amplifies a received signal fed from the antenna through the circulator. A local oscillator provided in the receiver circuit generates a local oscillator signal of which frequency is approximately half the frequency of the received signal, and the local oscillator signal is amplified by a buffer amplifier. An even harmonic mixer including an anti-parallel diode pair also provided in the receiver circuit as a frequency converter mixes the received signal output from the low-noise amplifier with the local oscillator signal output from the buffer amplifier to generate and output an intermediate frequency signal.