Polarimetry on ultra-wideband phased arrays at wide scan angles off principal planes

Ultra-wideband dual-polarized arrays are commonly used in polarimetry applications. However, poor orthogonality between the two desired polarizations is observed at wide scan angles. This paper investigates the behavior using a Vivaldi wideband array and compares its pattern characteristics to a narrowband patch antenna array. An elegant two-port approach is presented to compensate for this phenomenon and produce the desired orthogonal polarizations.