Array Antenna Completely Overlapping Sub Butler Matrix

In recent years, with the fast development in communication technology and pattern synthesis technology of array antenna, completely-overlapped array antenna is getting more and more attention. Studies show that if flat-pattern synthesis technique is applied to large overlapped sub-matrix, not only can effectively inhibit the grating lobe, but also can reduce the number of arrays. Butler multi-beam forming network is a kind of nondestructive gain passive network, which can form orthogonal beams, these features are useful for the synthesis of complex antenna pattern. As a powerful tool for antenna pattern synthesis, it’s important to use Butler matrix for the beam-forming. This main research content of this article is to use FFT algorithm and Woodward Lawson sampling algorithm to design Butler flat-topped beam-feeding system combined with phase-shifters.This article first introduces the basic principles of Butler matrix and FFT, then FFT algorithm is deduced in details to design4×4and8×8Butler flat-topped beam-feeding network. In the Ansoft Designer, theoretical results are simulated respectively to verify the correctness of the theory.Secondly, according to the Butler matrix and Woodward sampling method, the basic principle of Woodward is deduced in details to design4×4and8×8Butler flat-topped beam-feeding network. In the Designer software, simulations are done respectively to verify the correctness of the theoretical results.Finally, this paper adopts Woodward Lawson sampling method as theoretical derivation results to design flat-topped beam feeding network, combining with the design of broadband antenna, implementing a flat-topped beam feeding system. The measured results verify the feasibility of the methods.