Bistatic Weather Radar System Analysis

Today’s weather radars operate in a monostatic configuration, with co-located transmitter and receiver observing the radar echo from hydrometeors in a back-scattered direction. Bistatic radar is a configuration in which the transmitter and receiver are separated from each other by considerable distance (eg, 10’s to 100’s of km). Such a configuration offers several potential advantages over the monostatic case, including increased storm cell detection range, retrieval of the vector wind field, and detecting clear air via Bragg scattering, all in certain regions of the bistatic area geometry. Bistatic radars present complications to the radar design related to the need to synchronize transmitter and receiver sites, changing volume resolution and Doppler spectra throughout the measurement region, more stringent sidelobe requirements, and a considerably more complicated volume coverage pattern that involves scanning both the transmitting and receiving beams. These problems can potentially be overcome using phased arrays, which is now emerging as an affordable weather radar technology.

Bistatic radar has been explored for airborne target detection, synthetic aperture radar imaging, and other applications. However this area is largely unexplored for weather surveillance. Previous investigators have explored an instance of bistatic weather radar in which a relatively simple receiver and wide-beam receiving antenna are placed far from a conventional weather radar to sense the non-radial component of the wind vector field. But the more general case, in which sophisticated, technologically-capable transmitters and receivers are widely separated for weather surveillance has seen relatively little investigation. This presentation will provide a systems analysis comparison between monostatic and bistatic weather radars. We consider the situation in which X-band phased array radars are separated from each other over variable–length baseline and we evaluate the performance advantages and disadvantages of a variety of system configurations to explore how they perform relative to the current monostatic weather radar standard.