A new frontier for mobile radar—the Atmospheric Imaging Radar: design specifications and experimental functionality

Many mobile radar systems have proven extremely useful in the field of meteorology, especially for rapidly evolving severe weather phenomena. One sought-after feature of mobile radar systems is a fast revisit time, or how quickly the radar can gather a volume of data and return to a specific point. Imaging radars, similar in some respects to phased arrays, steer the radar beam in software requiring no physical motion. In contrast to phased arrays, imaging radars gather data for an entire volume simultaneously, forming the individual radar beams using digital beamforming techniques within the field-of-view (FOV) of the radar, which is defined by the spoiled transmit beam. As a result, imaging radars provide update rates far exceeding those of existing mobile radars, including phased arrays. The Atmospheric Radar Research Center (ARRC) at the University of Oklahoma (OU) is currently designing and building the world's first mobile imaging weather radar. An X-band Traveling Wave Tube (TWT) powers the system and the transmit beam provides a FOV of twenty-five degrees in the vertical dimension and one degree in the horizontal, essentially creating an instantaneous Range Height Indicator (RHI) scan. Twenty-four independent receivers, arranged linearly, surround the transmit horn and allow beam formation along a single baseline. In-house student teams were commissioned to design significant components of the radar, including the radar pedestal and eight-channel digital receivers. At a minimum, beamforming techniques coupled with pulse compression algorithms will allow the Atmospheric Imaging Radar (AIR) to match conventional radar spatial resolutions. However, the temporal resolution will be far superior on the order of a single dwell (tens of milliseconds). The AIR will provide a comprehensive mobile testbed for the latest radar imaging and array processing techniques in addition to serving as a platform for future innovations. It will be shown that as an algorithmic testbed, considerable design attention was given to allow sufficient flexibility in the AIR capabilities, mainly in the array configurability. This flexibility makes it possible to examine advanced techniques to reduce the impact of clutter and increase spatial resolution through adaptive beamforming. Further, a detailed design of the radar system will be provided along with a radar sensitivity study including simulated beam patterns. The AIR represents a turning point in the field of mobile radars significantly improving temporal resolution by utilizing the latest in adaptive array processing techniques.