The Method Of Forming And Synthesis For Circular Array Beams

With the requirements on the detection for spatial signals and parameter estimate heightening, the array signals processing presented as one main way in spatial analysis is progressing rapidly and especially the adaptive digital beamforming(ADBF)technology is one main content within these array signal processing. The main purpose of digital beamforming lies in to make the main lobe in array pattern point to the direction needed, while null falling adjust to interfere direction and by this way, the array output demanding signals' intensity is strengthened as much as possible, meanwhile the interfere signals' intensity is weakened and thereby the SINR of array output obtain a enhancement and in the essence this is one multi-channel array signal processing system. In this paper, the circular array pattern synthesis and adaptive null forming are studied in comparative system mode. The main work includes: 1. Adaptive antenna system as well as three usual optimal weight coefficient rules is introduced briefly and some usual algorithms about adaptive digital beamforming are discussed. 2. The characteristics of circular array pattern are analysed and the advantages as well as disadvantages of this pattern are pointed; the side lobe level of circular array can be reduced effectively by synthesizing circular array pattern with introducing directional elements and choosing suitable directional elements radiating functions; adaptive null forming technology of circular array with uniform distributed directional elements is studied by utilizing Gram-Schmidt algorithm. 3. On the basis of given desired circular array pattern, the pattern for circular arrays of uniform distributed directional elements is synthesized by using of improved Woodward-Lawson sample method; simultaneously, according to the optimal rule with minimum of mean square distance between given desired pattern and being synthesized pattern, the pattern for circular arrays of uniform distributed directional elements is synthesized by using optimal weight vector method, and adaptive nulls are formed at the pointing interfere direction by appending constrained conditions. 4. One unified array pattern function is provided for cylindrical arrays, conical arrays and hemisphere arrays, in addition the distributed characteristics of respective pattern are formulated and the concerned performances are analysed and compared.