Outer calibration system for high-precision SAR (Synthetic Aperture Radar) active scaler

Abstract

The invention discloses an outer calibration system for an SAR (Synthetic Aperture Radar) active scaler, and relates to the remote sensing satellite technology. The outer calibration system comprises a laser range finder, a standard reflection device, and wave-absorbing materials, wherein the laser range finder is fixed at the symmetric central line of a sending antenna and a receiving antenna of the active scaler through a switching device, and the fact that the direction which a laser beam points to is parallel to the mouth surface normals of the two antennas is ensured; the standard reflection device comprises a standard reflection disk, a four-dimensional adjusting mechanism and a support; the standard reflection disk can be used as a standard to reflect laser to further realize the alignment with the active scaler, has the function of reflecting electromagnetic signals and providing sectional area standard of a radar, and enables the active scaler to be aligned with the reflection disk through the servo transmission of the four-dimensional adjusting mechanism and the adjustment of a control mechanism; the support supports the standard reflection disk to a certain height; the wave-absorbing materials are laid at an appropriate position between the active scaler and the standard reflection disk to reduce the interference of multipath noise signals.

Description

technical field [0001] The invention relates to the technical field of remote sensing satellites, and relates to an external calibration system of a high-precision SAR active scaler, which is used for the self-calibration test of the SAR active scaler. Background technique [0002] The active calibrator needs to calibrate its nominal radar cross-section (RCS) value before use. There are two usual calibration methods: [0003] Method 1: Subsection measurement method, according to the calculation formula of active scaler RCS: [0004] σ = λ 2 4 π · G a G T G R [0005] Among them: σ represents the radar cross-sectional area of ​​the active scaler, λ represents the wavelength of electromagnetic waves, and G a Indicates the active scaler channel...

AI Technical Summary

Problems solved by technology

This method uses a separate measurement of G a , G T , G R , and then calculate σ according to the formula and the measured value. The disadvantage of this method is that the cumulative error of the test instrument used for three independent measurements will be large

[0007] Method 2: According to the inadequacies of method 1, an improved test method was proposed later, namely: the G a , G T , G R One-time measurement, the specific method is: arrange the receiving and transmitting antennas according to the far-field conditions, ensure that the polarization and pointing of the transmitting and receiving antennas are aligned correctly, measure the entire open-loop gain with an instrument, and then deduct the empty attenuation to measure σ. This method The cumulative error is avoided, but the instrument measurement error in the one-time measurement cannot be avoided, and during the test, there are great difficulties in the polarization adjustment and alignment of the transmitting and receiving antennas, and a very long RF cable is required to measure the open-loop gain. Lead to greater damage, but also affect the measurement accuracy

Images