An airborne phased array radar concept for atmospheric research

Airborne phased array radars have been used in military aircraft for more than thirty years, but have yet to find their way into a platform for atmospheric research. This was largely due to the huge costs associated with such systems. The principle cost driver of these radars is the transmit/receive (T/R) element. Advances in Monolithic Microwave Integrated Circuit (MMIC) technology has reduced the per element cost of an Active Electronically Scanned Array (AESA) by nearly two orders of magnitude. This has enabled their consideration for use in atmospheric research.

An airborne centimeter wavelength dual-polarization, Doppler, phased array radar has been proposed as one component of the Community Airborne Platform Remote-sensing Interdisciplinary Suite (CAPRIS). The proposed system would consist of four AESAs strategically placed on the fuselage of the NSF/NCAR C-130. The “composite” scanning of all four AESAs yields full 360° dual Doppler coverage, as in the current NCAR ELDORA.

This radar is intended to replace the aging ELDORA and provide new research capabilities as well. It should provide twice the along-track resolution of ELDORA to yield higher resolution wind fields, while dual-polarization capability will provide microphysical information and aide in QPE. Another important advantage over ELDORA is the ability to scan in azimuth as well. This feature, used in conjunction with data from the C-130's WXR-700C weather avoidance radar, will be exploited to produce a composite PPI “surveillance” scan. This “surveillance” mode is essential to provide safety in single aircraft missions and will also aide in mission flight planning while in the air.

This paper describes the features and characteristics of the centimeter wavelength phased array radar as proposed for CAPRIS. Three possible airborne configurations will be discussed: X-Band, C-Band and Wide-Band, covering frequencies from C-Band thru X-band. A mobile, ground-based configuration will also be presented.