A compact millimeter wave radar for airborne studies of clouds and precipitation

We present a compact 95 GHz radar designed for cloud and precipitation research. This instrument is suitable for deployment on a wide variety of aircraft including an unmanned aerospace vehicle (UAV). The radar was designed and is being built at the University of Massachusetts to fly with a suite of instruments in the Atmospheric Radiation Measurement-Unmanned Aerospace Vehicle (ARM-UAV) program. Novel millimeter wave devices and signal processing hardware have been employed to miniaturize the instrument to approximately 1.75 cubic feet and reduce the power consumption to 150 W. A solid-state transmitter was used in place of the much larger alternative, an extended interaction amplifier (EIA). The peak power of the solid state transmitter is 15 dB lower than that available from an EIA. Much of the sensitivity is recovered through improvements in receiver noise performance and increased efficiency in the signal processing. The compactness of the instrument will facilitate rapid installation in manned aircraft and allows deployment in situations where a full-sized cloud radar could not be installed. The radar produces profiles of reflectivity and Doppler velocity with a range resolution of 16 meters. An internal calibration is used to correct for transmitter and receiver variations.