Switching system for single antenna operation of an S-band FMCW radar

Increasing interest is being shown in frequency modulated continuous wave (FMCW) radars due to their advantages of compact size, low peak power requirement, good range resolution and low interference to other systems. A major disadvantage of FMCW systems is the need to use two separate, well shielded antennas for transmission and reception. Several schemes have been devised to enable FMCW radars to operate with a single antenna. The authors describe a ground based S-band ocean surface remote sensing FMCW radar that has been adapted for single antenna operation by alternately switching the single antenna between the transmitter and the receiver. Even though this frequency modulated interrupted continuous wave (FMICW) system is no longer a true continuous wave radar, the essential properties of the FMCW waveform are preserved, provided some conditions on the switching speed and FMCW parameters are met. The purpose of the radar is to deduce ocean wave and current parameters by measuring ocean surface velocities. The radar was tested operationally by comparing ocean surface data from both the single antenna (FMICW) and dual antenna (FMCW) systems recorded under similar conditions.