Research On Beamforming And Polarization Synthesis For Polarized Phased Array Radar

Compared with traditional phased array radar, the polarized phased array radar(PPAR) can synthesize beam pattern with extra polarization modulation, which means it has the capability to acquire the spatial and polarized information of interested objects simultaneously. This fact demonstrates that PPAR has great potential on interference rejection, signal detection, high-resolution and polarization multi-access. Therefore, Polarized phased array radars play an important role in both military and civil areas because of these advantages. This work focuses on the beamforming and polarization synthesis of the polarized phased array radar. The thesis is organized as follows.In the first part, beamforming for phased array radar is investigated. First of all, the beamforming for uniform linear array is studied, the objective function for pattern synthesis is derived based on the criterion of integral sidelobe level and null region. Next, the case of uniform linear array is extended to a uniform plane array. Finally, considering that the realistic scenario is not completely consistent with the ideal mathematical model, the negative effects of random errors including magnitude and phase errors are analyzed. The simulation result has demonstrate the effectiveness of the proposed methods.In the second part, polarization synthesis is considered. Firstly, wave polarization status is studied, including the definition of the completely polarized wave, the description of polarized wave and polarization transformation. Next, on the basis of polarized phased array, the function of the signal radiated by this array in polarizedspatial domain is established. The problem of optional polarized beam pattern synthesis using a pair of orthogonal electric dipoles has been analyzed in detail. Finally, the relationship of beamforming and polarization synthesis is showed by computer simulation.In the third part, the optimal polarized beam pattern synthesis is studied. First of all, on the basis of polarized phased array of which the orientation of dipoles is identical and fixed, by designing the weights of the electric fields emitted from these dipoles, the desired beam pattern can be achieved. The synthesis of array pattern can be reformulated as a mathematical convex optimization problem with constraints, which is solvable by using various convex optimization algorithms. Next, Algorithms for sidelobe polarization optimization, null constraint, and joint null-sidelobe optimization have been derived to combat active noise and interference, so the performance of polarized phased array is improved. Finally, according to the actual situation, the optimization problem for optimal polarization synthesis of arbitrary array which the orientation of dipoles is different and random is formulated as a second order cone program(SOCP) problem which can be efficiently solved by convex optimization algorithms, consequently the desired polarized beam pattern can achieved.