NWC REU 2016
May 23 - July 29



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UAV-Based Calibration for Polarimetric Phased Array Radar

Christian Boyer and Caleb Fulton


What is already known:

  • Previous studies have detailed the challenges in calibrating polarimetric phased array radars to provide a high degree of polarization purity.
  • Dual polarization phased array radars offer many advantages, and is a candidate for a future multifunctional phased array radar (MPAR) system that combines weather radar and air surveillance/traffic monitoring.

What this study adds:

  • A circuit, called the "Twitching Eye of Horus,” transmits horizontally- and vertically- polarized fields for calibration of the radar receiver.
  • This study created a technique for extracting estimates of a radar receiver scan-dependent polarimetric pattern from raw radar data.
  • This study enables a sensor-equipped unmanned aerial vehicle (UAV) for scan-dependent calibration of a fixed phased array radar.


Calibrating dual polarization in phased array radars is an important aspect of risk mitigation in moving towards a nationwide multifunctional phased array radar (MPAR) system for weather surveillance and to track aviation. Since dual polarization was implemented into the WSR-88D, the new products have been vital for hydrometeor classification. The calibration of scan-dependent polarization in phased arrays is a primary goal in achieving the same products provided by traditional dish-based systems. There are many challenges to the calibration process, including isolating the horizontal and vertical polarizations that are sent by the radar and making sure that their amplitudes are identical. In the project described herein, the focus is on the calibration of the radar’s receive patterns, the first step in the overall calibration process. An unmanned aerial vehicle (UAV) has been developed to facilitate scan-dependent calibration of a fixed phased array, and the focus of this part of the project is on the so-called “Twitching Eye of Horus” circuit. It provides a means for transmission of calibrated horizontal (H) and vertical (V) electric fields towards the radar in a controlled manner from the UAV, but in and of itself it requires its own processing and calibration procedures. Removal of the frequency offset between the circuit and the radar is a primary challenge. This study takes a look at the process of calibrating the radar’s receiver using a UAV and the Twitching Eye of Horus, as well as presenting initial results.

Full Paper [PDF]