DEVELOPMENT OF MONOSTATIC ANTENNA SYSTEM FOR W-BAND HI-RESOLUTION DOPPLER RADAR.

Observation of clouds with radars in millimeter wave range is one of the most powerful remote sensing methods to derive information on interior of clouds. We have developed and are operating a cloud profiling FMCW (Frequency Modulated Continuous Wave) Doppler radar named FALCON-I (FMCW Radar for Cloud Observations) at 95GHz. It is a bistatic antenna system, which is usually used for FMCW radar, and consists of two 1m-diameter antennas with high spatial resolution of 0.18 degree FWHM. A High range resolution of 15m is realized with the FMCW type radar, which is about 10 times higher than that of normal pulse type radar. FALCON-I has enough sensitivities for faint clouds at high altitude and has high resolution in Doppler measurements. We are developing a monostatic antenna system of FMCW Doppler radar. A monostatic antenna system does not have any beam discrepancies between the transmitting and the receiving antenna. One of the most difficult points for a monostatic antenna system is contamination of transmitting power into the receiving section. In order to reduce the contamination, we introduce a cancel system of power in the frontend of the radar. The cancel system consists of a power spritter, an attenuator, and a phase shifter in W-band and produces an antiphase signal against to the contamination power. By using the cancel system, we can reduce the contamination power by -40 dB and can observe clouds and rains. [ABSTRACT FROM AUTHOR]