Polarimetric Calibration and Insect Orientation Estimation of High-resolution Fully Polarimetric Entomological Radar

Abstract

Migratory pests are sudden outbreaks and widespread, putting national food security at risk. Entomological radar is most effective segment in monitoring insect migration, providing critical information for early warning and pest control. Traditional entomological radar can measure biological parameters such as mass and orientation using a low-resolution waveform and rotating linear polarization antenna. The new entomological radar uses a stepped chirp high-resolution waveform and instantaneous fully polarimetric system, which can considerably improve the accuracy of measuring insect biological data. However, in addition to the traditional polarization measurement errors, the stepped chirp waveform introduces new multiplicative error components to different polarization channels, resulting in a more complex imbalance between polarization channels, which requires high-precision polarization calibration. In response to the above issues, the fully polarimetric measurement model is optimized according to the characteristics of the high-resolution system, and a high-resolution system polarization error estimation method based on a sphere and a wire is proposed in this study, which can complete polarization calibration under the loose constraint of the calibrator attitude and compensate for the influence of channel inconsistency on polarization information measurement; additionally, an insect orientation estimation method based on a biological symmetry model is proposed, and the mechanism of cross-talk between polarization channels on orientation estimation is analyzed analytically. Finally, multifrequency high-resolution fully polarimetric radar (X, Ku, Ka) is used for polarimetric calibration and insect orientation measurement experiments, and the measurement error of orientation is less than 3°, which verified the feasibility and effectiveness of the proposed method.

Keywords

• fully polarimetric entomological radar
• polarization information
• polarimetric calibration
• parameters inversion
• orientation estimation