Study On The Suppression Of Interference With Radar Polarization Information

With the development of the radar polarization processing technology and the emerging of the new type radar with polarization measure abilities, the application of polarization information in radar interference suppressing is regarded more and more. Taking the radar interference suppressing in polarization field as a major content, the potential of polarization information processing is digged in this thesis. And the suppression of radar interference using polarization information is studied aiming some difficulties facing in radar warfare nowadays. The major content includes: the adaptive polarization canceller for suppressing the noise jamming, the optimization of receiving and emitting polarization simultaneously on the interference background, the distinguishing of active decoy in polarization field, the angle glint suppressing of invading target at low altitude using polarization information. And the polarization measurement is studied as a basement.As the precondition of polarization processing, the polarization measurement is demanded to be more precise by the interference suppression in polarization field on the more complicated electronic warfare background, and the traditional measurement method couldn't be satisfied anymore. In this thesis an instantaneous polarization measurement method using composite coded signal is produced. In this method, a code compounded with orthonormal code and PN code is used to replace the traditional PN code. The better auto correlation and cross correlation character is obtained. A better platform is provided by this method for the interference suppression algorithms such as multi-decoy distinguish.The Adaptive Polarization Canceller (APC) is the most popular polarization filter to suppress the noise jamming nowadays. With the wide usage of digital technology in radar signal processing, the traditional adaptive polarization canceller, which is built on the correlation feedback circuit, isn't applicable in the modern radar and wickeder electronic battle field anymore. So, the APC iterative algorithm is studied in this thesis. This algorithm can converge more quickly, be more stable.To optimize the radar polarization can suppress interference signal, and enhance target echo and achieve signal-to-interference ratio maximization, improve radar target detection probability and measurement precision. On account of the limited development level of polarimetric radar, the joint optimization of transmitting polarization and receiving polarization is involved rarely in the existing radar polarization optimization algorithm, therefore the polarization optimization gains is limitted. The joint optimization algorithm of transmitting polarization and receiving polarization is studied in this paper, where interference suppressing and the maximization of target receiving power are achieved at the same time. Compared to the existing polarization contrast enhancement algorithms, not only less priori knowledge is demanded (target scattering matrix and interference polarization state are unknown), but to avoid the cumbersome optimizing calculation process.The high-fidelity active decoy is a great threat to radar. The real target and the decoy can be distinguished by using the different character of the targets and the interference in polarization field. The decoys are categorized into stable polarization decoy and modulation polarization decoy. They are distinguished of the target scattering vectors by using the widely difference of polarization ratio stability and tensor multiple matrix distribution character. When the impack between targets (including the real targets and the decoys) is small, the distinguish performance is very well. The performance is descent a certain extent when the decoy number is bigger and the impack between the targets is stronger. This performance can be effectively improved by setting a adaptive limit.The angle measurement of the invading target at low altitude in 'remote area' can be affected by the multiple paths. This can be simplified by two-spot angle glint model. An polarization diversity method is produced to suppression the angle glint interference. The positive value of angle glint error can be decreased by the negative value, when the amplitude rates are symmetrical. Using this character, a better suppression performance can be obtained statistically by designing the emitting polarization. It is testified by the experiment results that this polarization diversity method has a better angle glint error suppression performance comparing with the common polarization diversity.The interference suppression methods are studied in this thesis with fully consideration of the engineering realization. The polarization information processing is analyzed in the frame of radar signal processing. The algorithm is testified on the polarization measurement simulation platform, and these interference suppressing methods have the potential to be developed in the engineering realization. The interference suppressing technology is extended and the polarization information processing theory is enriched in this thesis..