PURPOSE:To improve an SN ratio as a beam switching type FM-CW radar by switching an intermediate frequency, obtained by mixing a reflected wave and a sent wave with different local oscillation frequencies, in two stages so that data processing for angle and distance arithmetic can be performed. CONSTITUTION:The output of an FM-CW wave source 100 is led to respective transmitting and receiving circuits 50 on a time-division basis and separated to paths for transmission and reception, and they are filtered by BPFs(band-pass filter) 15 and 17 after being multiplied 14 and 16 to become an RF(radio frequency for transmission) signal and an Lo(local oscillation) signal. A reflected signal from a target is passed through a distributor 30 and a circulator 18 and frequency-mixed by a mixer 19 with the Lo signal, thereby obtaining the same 1st intermediate frequency as the frequency of the CW wave source 100. Then a selector 40 selects it on a time-division basis and the selected frequency is mixed by a mixer 41 with a properly selected local oscillation signal 42 to obtain the IF signal of frequency which enables the digital processing for the angle and distance arithmetic, etc. Thus, the SN ratio is increased to improve distance resolution and angle accuracy.
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