  Recently, as the drones have become smaller and smarter, they are emerging as
new threats to the military and the public. To prevent the threats, the
development of the radar to detect the small drones is needed. The frequency
modulated continuous wave (FMCW) radar is one of the radar types for the drone
detection. The heterodyne architecture for the FMCW radar is often applied to
resolve the dc offset problem. However, the leakage from a transmitter into a
receiver, the notorious problem of the FMCW radar, is still a challenging
problem. Especially, the phase noise of the leakage increases the noise floor
and deteriorates the signal to noise ratio. In order to mitigate this problem,
in this paper, the stationary point concentration technique is proposed.
Without additional hardware, the proposed technique can be implemented through
frequency planning and digital signal processing. The results show that the
proposed technique significantly lowers the noise floor over the desired range
domain.
