Simulated Vortex Detection Using a Four-Face Phased-Array Doppler Radar

The National Weather Radar Testbed was established in Norman, Oklahoma, in 2002 to evaluate, in part, the feasibility of eventually replacing mechanically scanned parabolic antennas with electronically scanned phased-array antennas on weather surveillance radars. If a phased-array antenna system is to replace the current antenna, among the important decisions that must be made are the design (flat faces, cylinder, etc.) that will be needed to cover 360 degrees in azimuth and the choice of an acceptable beamwidth. Investigating the flat-face option, four faces seem to be a reasonable choice for providing adequate coverage. To help with the beamwidth decision-making process, the influence of beamwidth on the resolution of various-sized simulated vortices is investigated. It is found that the half-power beamwidth across the antenna should be no more than 1.0 degrees (equating to a broadside beamwidth of 0.75 degrees) in order to provide National Weather Service forecasters with at least the same quality of data resolution that is currently available for making tornado and severe storm warnings.