The Design Of Algorithm Applied In Adaptive Anti-jam Nulling Antenna Array

As to the adaptive nulling antenna array system, the design of antenna element, array arrangement and the adaptive algorithm used in signal processing module have great influence on the effect of anti-jam in the receiver. With the development of satellite communication technique and electronic warfare, the adaptive nulling antenna array technique is widely applied in the domain of communication. And researchers spent lots of time on studying more effective adaptive algorithm to achieve good nulling performance.In this dissertation, we use power inversion array, which is widely used in strong interference environment. Here we discuss the influence of the design of antenna element and array arrangement, which include the number of antenna elements, the distance between adjacent element and the array structure. In order to get good omni-directional pattern before nulling, the optimization for antenna array with variable phases and constrained amplitude is discussed to achieve such goal. Phase-only broadening for passive array is required. First, we present the uniform circular array with cells of rectangle dual-pin fed circularly polarized patch antennas and calculate respective pattern of each element in CST microwave studio including mutual coupling. Then, based on the symmetry of phases of the antennas, we use the Steepest Descent Method (SDM) to optimize the phases of antennas in order to obtain better low elevation performance. The optimized results show the availability of the optimization technique compared to the array using the same phase excitation.Moreover, we propose a beam forming architecture for improving the power-inversion algorithm that is most commonly used in nulling antenna systems. To prevent the possible degradation of the original gain of a nulling antenna in the circumstance when there exists strong interference, we multiplex the output of the physical array in digital domain with a power-inversion array (PIA) and a primitive array (PA), and then form the desired radiation pattern by multiplying the outputs from PIA and PA, to obtain expected narrow nulls in the directions of the interference and in the meantime roughly maintain the original gain of the main lobe. Simulation fits well with the analysis, showing the effectiveness of the proposed approach.The potential application is briefly introduced in this dissertation, and at the end of this dissertation, the author makes the conclusion and points out the direction of the future research work on this topic.