An Overview of Phased-Array Weather Radar Research and Development at the Advanced Radar Research Center at the University of Oklahoma

In 2005, the University of Oklahoma (OU) established the Advanced Radar Research Center (ARRC) with the goal of becoming a leading academic force in the field of radar meteorology. With 20 faculty members, a strong engineering staff, and over 100 interdisciplinary graduate students from meteorology and engineering, the ARRC has become the largest academic research program in the country focused on advancements in radar and applied electromagnetics. With strong collaboration with NOAA’s National Severe Storms Laboratory (NSSL) in Norman, the ARRC has emphasized all steps in the development of fielded radars, especially advanced systems based on phased array concepts. One of the first mobile systems developed was the X-band Atmospheric Imaging Radar (AIR), which was designed for field operations and to provide the best possible temporal resolution by using digital beamforming –a software-based phased array technique. Although not polarimetric, the AIR continues to provide a wealth of new insights into rapidly evolving weather phenomena, especially tornadoes. Promising results from the AIR were the main drivers that allowed the ARRC to obtain NSF funding to begin development of the C-band Polarimetric AIR (PAIR). In collaboration with NSSL and with the impetus of the Multi-mission Phased Array Radar (MPAR) program, the ARRC began to consider other ideas for effectively combining polarimetry with phased array technology. The Cylindrical Polarimetric Phased Array Radar (CPPAR) was developed as an S-band demonstrator for one promising idea for overcoming the polarimetry/phased array challenge. By steering the radar in azimuth using commutation on the cylinder, rather than by conventional phased array methods with a planar array, the potential for significant advantages were envisioned. Finally, the ARRC is also developing an all-digital polarimetric phased array radar called “Horus”. This S-band radar is a planar polarimetric phased array but with transmit and receive independence on each element of the array and each polarization. Currently under development, the Horus radar will eventually have 1024 (32x32) independent dual-polarization channels. With this level of control over both the transmit and receive channels on the phased array, it will be possible to provide high-quality polarimetric weather radar data with the rapid-scanning capability of a phased array. Furthermore, the Horus radar will have the utmost capability for meeting the multi-mission goal (simultaneous weather and aircraft surveillance) of the MPAR program. This presentation will provide an overview of the R&D activities currently underway in the ARRC in the area of phased array weather radar. The operational goals and architecture of each system will be compared and contrasted in the hope of providing someone new to phased array weather radar the fundamental concepts of this promising technology.