Research On Distributed Arrays Synthesis

The array signal processing is widely used in radar, sonar and communication engineering , particularly,the modern radar has to adapt the request of modern war, which have good performance on anti- reconnaissance, anti- destroy and anti- interference. As the working frequency of HF radar is relatively low (3~30MHz), the wavelength is long. In order to maintain the performance of radar system, such as signal-to-noise ratio (SNR) and angular resolution, the size of receiving antenna array is always very large and exceeds ten thousand square meters. The large size not only makes the radar easy to be detected, but also increases engineering costs for the'golden seashore'it occupied. Furthermore, large size brings serious troubles in the antenna setting-field choosing, installation and maintenance. Distributed array is one of the solution way. Therefore, research on Distributed array becomes urgency. In this dissertation, the key techniques in distributed arrays synthesis are studied in detail, and the tolerance is distributed arrays analyzed.Firstly, the basic theories and parameters of antenna arrays is studied, and the conception of arrays synthesis is given. On the basis of discussion about the existing pattern synthesis method. A new pattern synthesis method with quadratic pattern constraints is presented in this dissertation. The method uses both linearly constraints and quadratic pattern constraints to control the beam pattern, which is used in arbitrary array synthesis. It is simple effective and feasible. The basic theory of thinning arrays is introduced simply.On the base of above it ,this paper discuss the synthesis of optimum distributed arrays by nonuniform spacing in the sense of Dolph-Chebyshev. Having derived the equations of optimum element distribution, we analyze the exponentially spaced array, which are optimum when the elements are isotropic and equally weighted, and the array by general raised cosine function. The formulate for estimating the sidelobe envelope,beamwidth of the array pattern and clean region width are obtained. Also, the relationship between the nearby sidelobe lever and the array parameters is given. As these results, a simple synthesis method of optimum thinning arrays with any desired nearby (mainlobe)...