Weather Observations With a Cylindrical Polarimetric Phased Array Radar

Much recent work in weather radar engineering has focused on the development of PPAR (polarimetric phased array radar) systems that offer the rapid updates and possible multifunctionality afforded by phased array antennas, while still retaining a high level of polarimetric data quality.  Achieving these goals in tandem has proven to be a major technical challenge due to the deleterious effects of electronic beamsteering on polarization purity and beam size/shape.  Among the proposed answers to this challenge is a CPPAR (cylindrical polarimetric phased array radar), which leverages a cylindrical array geometry to obtain high levels of polarization isolation at any steering angle.  One unique aspect of cylindrical arrays is that azimuthal scanning is performed not through changing excitation phases across the array elements, but rather by commutating the set of active elements around the cylinder.  This creates an additional obstacle to accurate calibration, as each steering angle is effectively observed with a different array.  This study utilizes the CPPAR Demonstrator, a system designed to explore the benefits and challenges associated with cylindrical arrays, to demonstrate this scanning approach and analyze its performance using observations of hydrometeors. An alternative imaging-based scan strategy, utilizing a broad transmit beam and beamforming on receive using subsets of the array elements, is also demonstrated and discussed.