Fast Algorithm For Airborne Anti-jamming Of Spaceborne Smart Antennas

Low earth orbit(LEO)satellite communication has the characteristics of less signal propagation delay and low path loss,which can easily realize the mobile communications all over the world.It has become a hotspot in the field of satellite communication.This paper will focus on the research of smart antenna techniques in LEO satellite communication.Firstly,for the "near-far effect" problem in LEO satellite communication and the dynamic change of terrestrial users and interferences during the communication process,the fast beamforming and anti-jamming pattern synthesis methods are researched.A fast nulling beamforming algorithm based on jammer subspace orthogonal projection is proposed.The algorithm uses the IFT technique to realize the fast conversion between the weight vector and the pattern.It can synthesize patterns of arbitrary shape,meeting the needs of "equal-flux".Moreover,it is fast and can guarantee real-time null-tracing of interferences while ensuring the high gain coverage of the pattern main-lobe during the communication.Secondly,in order to solve the problem that it's necessary to get the directions of all the interferences before the beamforming,adaptive beamforming algorithms with conformal mainlobe features for patterns in arbitrary shapes are developed.An adaptive main-lobe maintaining beam-forming algorithm under diagonal loading is presented.The algorithm is based on linear least squares variance(LCMV)criterion,and realizes the main-lobe gain control by the main-lobe subspace constraint and the quadratic constraint of the weight vector.The construction of the main-lobe subspace constraint is given,and the relationship between the diagonal loading and the constraint of weight modulo is deduced.The diagonal loading realization model under GSC architecture is obtained at last.This algorithm can not only realize the main-lobe maintaining and adaptive anti-jamming of the wide beam,but also reduces the computation complexity with the GSC reduced rank structure.Finally,the proposed two algorithms are validated on a 19-element triangular grid array smart antenna demonstration system.A smart antenna demonstration system testing software is designed,which is used to test the three-dimensional pattern in compact anechoic chamber automaticly and demarcate the gain of the pattern.The DSP transplantation and the verification of algorithm performance are completed.The experimental results verify the correctness,effectiveness and real-time of the fast nulling beamforming algorithm and the main-lobe maintaining adaptive anti-jamming algorithm,providing an effective solution for the on-board application of smart antenna technology.