Polarimetry With Phased Array Antennas: Theoretical Framework and Definitions

IEEE Transactions on Antennas and Propagation (Impact Factor: 2.18). 02/2012; 60(1):184 - 196. DOI: 10.1109/TAP.2011.2167926
Source: IEEE Xplore


For phased array receivers, the accuracy with which the polarization state of a received signal can be measured depends on the antenna configuration, array calibration process, and beamforming algorithms. A signal and noise model for a dual-polarized array is developed and related to standard polarimetric antenna figures of merit, and the ideal polarimetrically calibrated, maximum-sensitivity beamforming solution for a dual-polarized phased array feed is derived. A practical polarimetric beamformer solution that does not require exact knowledge of the array polarimetric response is shown to be equivalent to the optimal solution in the sense that when the practical beamformers are calibrated, the optimal solution is obtained. To provide a rough initial polarimetric calibration for the practical beamformer solution, an approximate single-source polarimetric calibration method is developed. The modeled instrumental polarization error for a dipole phased array feed with the practical beamformer solution and single-source polarimetric calibration was -10 dB or lower over the array field of view for elements with alignments perturbed by random rotations with 5 degree standard deviation.

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    • "Much effort was invested in developing optimal beamforming and calibration methods for polarimetric observations [16][17]. This resulted in a practical polarimetric calibration strategy for PAF systems that works on unpolarized sources by relying on the intrinsic polarimetric quality of the receiving elements [18]. "
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    • "In recent years, the calibration of PAF systems was developed from scratch by a collaboration between ASTRON, Chalmers University and Brigham Young University. This led to a theoretically optimal beamforming strategy that optimizes sensitivity while providing a perfect polarimetric response in the beam center [16]. This result was used to validate a practical calibration approach that relies on the intrinsic polarimetric performance of the antennas to calibrate the PAF beamformer using an unpolarized source [17]. "
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