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Eight channel matrix beam forming network

Keywords:

I.A. Fanyaev


Often array antenna dividers are made using printed circuit technology. They have good weight and size characteristics and low cost of manufacture. The main disadvantage which prevents multibeam antenna arrays usage in practice, is the design and technological complexity of the beamforming network (BFN). This shortcoming is particularly evident with the number of rays of the multibeam antenna array. Therefore, the main goal is to find a new principle of construction of the BFN, which allows simplifying the design of its implementation. For the construction of new schemes of synthesis procedure was used. New scheme distribution multi-port circuit with a given scattering matrix accounted for as a cascade connection of the elementary distribution multi-port circuits of the same dimension, that is with the same number N of input and output lines. As a result solution of synthesis we obtain of new beamforming network with a simple schematic drawing. The scheme has 14 crossings of transmission lines, if we exclude the sequential numbering of the inputs. The total number of crossings is 22 – is the on of 6 crossings less than in classical Butler matrix. Synthesized scheme, as well as the Butler matrix has a symmetrical structure. Shows one way to implement technological synthesized BFN without crossing transmission lines. The scheme is implemented on a tripartite board. The presented topology of the BFN based on the identical hybrid couplers 18 and 9 vertical inter-connections. Mathematically, the calculations were carried out and analysis of key parameters (insertion loss, isolation, the coupling coefficients, the amplitude-phase distribution) Butler matrix 8×8 outputs and the synthesized circuit in the frequency band 9-11 GHz. For comparison, shows the frequency dependence of S-parameters (dB) of the two schemes. Were obtained by plots of the amplitude, phase of the frequency, respectively. At a certain frequency band based values (from minimum to maximum) of the amplitude (phase), which appear on all outputs BFN by a signal on a particular input. Thus allow constructed the assessment of the frequency dependence of the amplitude unbalance (phase) and to analyze the obtained values of all outputs simultaneously BFN. To power the multibeam antenna array beamforming proposed a new scheme, which in comparison with the classical Butler matrix has on 6 crossings of transmission lines is less and, therefore, is structurally simpler. Proposed new technological solution to BFN without crossing transmission lines, and sequential numbering of inputs and outputs by using slot-coupled transitions. In mathematical analysis of the synthesized scheme and the classical Butler matrix 8×8 I found that the main characteristics of the circuits on all the considered frequency band 9-11 GHz behave almost identically.
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