Matrix beam-forming scheme of a digital antenna array
The presented article regards issues of developing and modelling a digital beam-forming architecture of a digital antenna array based on a problem of homogeneous electro-magnetic wave incidence on a curtain of a linear digital antenna array. It presents requirements and basic suppositions for realizing modelling process of digital beam-forming algorithm based on matrix beam-forming scheme. Analysis of previous generation transceivers structures and their differences from the structures of modules, which could be built based on the up-to-date technological level, was performed. The issues of digital antenna arrays building, employing state-of-the-art units for digital signal processing, involving functional schemes and data processing algorithms of higher-end, are tackled as well. The article offers a modification of the of matrix beam-forming algorithm, employing discrete Fourier transform, as well its modification, ensuring numerical simulation modeling. A feature of the beam-forming scheme algorithm operation is that the process of beam forming is performed separately for each spectral component of the input digital signal. It allows eliminate the beam frequency variation effect, and improve thereby directional and frequency properties of the array as a whole. The article considers all steps of the input digital signal conversion throughout the beam-forming scheme. Methods for phasing and spectral matrices computing, as well as their application for digital signal computing at the output of the beam-forming scheme, are presented as well. The article presents a technique for the digital direction pattern and its characteristics evaluating for digital antenna array with the digital beam-forming method under consideration. Numerical simulation results of the system operation, including parameters evaluation of the direction pattern for harmonic input signal and it spectrum, as well as examples of digital signal and its spectrum at the output of the beam-forming scheme being modelled are presented. It is shown that the presented algorithm ensures forming of the angle selectivity properties of the antenna array. In conclusion, considerations on the possibility of application of up-to-date high-performance hardware for analog-to-digital conversion and signal processing are presented. The results of the presented work can be applied for developing state-of-the-art and prospective digital antenna arrays for communication or radar systems. Such kind of systems impose high requirements on the processed signal bandwidth, number of ranges of adaptive radiation pattern forming and possibility of multi-beam reception.