Rotatable double-antenna PARC (polarimetric active radar calibrator) and polarimetric active radar calibration method thereof

Abstract

The invention discloses a rotatable double-antenna PARC (polarimetric active radar calibrator) and a polarimetric active radar calibration method thereof. According to the PARC, polarization filters are additionally mounted at apertures of a receiving antenna and a transmitting antenna; the rotatable double-antenna design is adopted, and different posture combinations of the receiving antenna and the transmitting antenna can form different polarization combinations. Each antenna of the designed rotatable double-antenna PARC can rotate independently, the receiving antenna and the transmitting antenna of the PARC are controlled to be combined in different polarization manners, and multiple forms of polarimetric scattering matrixes of the PARC can be obtained. During mounting of the PARC, the delay parameter is adjusted, and a rotating mechanism is controlled, and the PARC rotates at constant and slow speeds, and any to-be-calibrated objects can be calibrated. The polarization filters are additionally mounted at the apertures of the antennas, so that the polarimetric isolation of each of the receiving antenna and the transmitting antenna can be greatly increased, and the polarimetric calibration accuracy is improved.

Description

technical field [0001] The invention relates to the technical field of antenna active polarization calibration, in particular to a rotatable dual-antenna active polarization calibration device and a polarization calibration method thereof. Background technique [0002] In the measurement of the radar target polarimetric scattering matrix (PSM), the received signal is not only related to the polarimetric scattering matrix of the target to be measured, but also related to the characteristics of the transmitting channel and receiving channel of the measurement system. Considering the existence of cross-coupling and gain imbalance between the polarization channels of the radar, the relationship between the PSM measured by the target and the real value is as follows: figure 1 Shown (see literature [1] Xiao Zhihe, Chao Zengming, Jiang Xin, Wang Chen. Radar target polarization scattering measurement technology [J]. Systems Engineering and Electronic Technology, 1996, (3): 13-32.). ...

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Problems solved by technology

[0029] (1) The receive polarization and transmit polarization of the PARC antenna are always orthogonal to each other, and the polarization of the transmit and receive antennas cannot be combined arbitrarily, which greatly reduces the form of its theoretical polarization scattering matrix, and many special forms of polarization scattering The matrix cannot be obtained by this single-antenna PARC, such as the identity matrix, which limits its application range;

[0030] (2) Since the solution is to measure the PARC of several antenna rotation angles to obtain the measured data, when there is a small rotation angle error in the measurement, it will affect the calibration accuracy;

[0031] (3) The robustness of the polarization calibration parameter extraction algorithm using this PARC is poor: once there is an abnormal value or a large error in the system measurement value at a certain moment during the calibration process, the accuracy of the extracted calibration parameters will be greatly reduced;

[0032] (4) Since a pair of orthogonally polarized feed sources work at the same time, it is impossible to use a polarization filter device to improve the polarization isolation of the antenna, which greatly affects the polarization calibration accuracy

[0041] (1) The technical design is very complex

This kind of digital PARC has very high requirements on the sampling rate of A / D and D / A. The timing logic of the digital radio frequency memory circuit is complex, and the writing and reading of signals and delay processing and other operations need to be controlled by clocks. In the running circuit, competition and risk are prone to occur (see literature [4] Xiao Hanbo. Digital radio frequency memory and its application in radar signal simulation [J]. Guidance and Fuze, 2002,23(3):25-29.) , so that the whole system cannot work stably and normally;

[0042] (2) The calibration parameter solution process and algorithm are complex;

[0043] (3) The cost is high, the reliability and stability need to be verified, and there are no real products and practical application reports.

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