The Effects of Antenna Tilt in PPAR

One of the main challenges to the use of planar phased array radar for polarimetric weather observations is the presence of significant cross-polar fields away from principal planes of radiation. These can introduce unacceptable measurement biases even if the differences between the horizontal and vertical copolar antenna patterns are accounted for. This is because the isolation between coaxial cross-polar and copolar beams needs to be in excess of 50 dB to achieve acceptable differential reflectivity bias (i.e., less than 0.1 dB) using simultaneous transmission and reception of horizontal and vertical polarized waves. Because such cross-polar isolation cannot be achieved at an affordable price by the phased array antenna hardware, it is crucial to search for other ways of reducing the effects of cross-polar radiation. One approach to reduce these effects may be to tilt the array with respect to the ground. Herein, such possibility is investigated.