The Reasearch Of Beam-Space DOA Estimation Based On Non-Uniform Array

With the continuous development of modern wireless technology, techniques of smart antennas, multiple input and multiple output systems, radar and sonar improve which all together relying on the higher requirements of direction of arrival (DOA) estimation which become a pivotal research field among scholars nowadays. Because the non-uniform antenna array and beam-space preprocessing both can reduce the dimension of the signals to be analyzed and promote resolution ratio, so they are widely used in various DOA estimation situations. In this dissertation, beam-space preprocessing DOA estimation based on Butler network, optimal beam-space DOA estimation based on non-uniform linear array and DOA techniques about beam-space and ESPRIT based on four arms logarithm spiral array are studied.Above all, I propose a DOA estimation technique based on one-dimensional Butler network. In this technique, the signals received from linear array form the beam-space signals by passing the Butler network first, and we extract several beam-space signals to estimate DOA using MUSIC algorithm. This technique can exploits Butler network being used to measure the directions, the variance is lower than typical methods; compared to MUSIC algorithm directly, the computational loading and threshold of signal noise ratio (SNR) is lower and when the distance of two array elements are larger than half of wavelength, the technique can cancel the false peaks according to the network characteristic.Where after, I study an optimal beam-space DOA estimation algorithm based on an non-uniform linear array. A beam transforming matrix is designed to achieve the element signal Cramer Rao Bound (CRB), then an non-uniform linear array is designed using particle swarm optimization (PSO) to meet the ideal beams gain. Because of the low variance and approaching ideal beams gain, this algorithm has the advantages of high resolution ratio and suppressing interference signals. The simulation demonstrates that compared to other falgorithm, it has higher success probability to distinct the directions.Then, a four arms logarithm spiral array is designed because of narrow main beam width, low side lobe antenna pattern, hence with a high resolution ratio. Secondly, an equilateral triangle dual-polarized micro-strip antenna is adopted as element of antenna array. Then an uniform scanning beam-space preprocessing is proposed to estimate DOA based on the four arms logarithm spiral dual-polarized array. The simulation result verified the effectiveness of this algorithm.At last, conformal transformation is used to map logarithm spiral array to rectangle in a bid to use ESPRIT algorithm to estimate the DOA. The simulation validate the correctness.