Riassunto analitico
The main goal of this thesis, whose activities have been accomplished in collaboration with CNH Modena, is to investigate the application of the Virtual Array concept in MIMO radars. Our investigation has concerned the implementation of virtual arrays for two stepped frequency MIMO radars, characterized by different configurations for the antenna array and different numbers of antennas (and, consequently, by distinct angular resolutions).
The virtual array concept plays an important role in defining the capabilities of MIMO radars, since it defines a set of sampling points, such that a single monostatic radar placed at each of these point would produce a received signal having the same complex amplitude as that observed by the actual and physical T-R pair. The structure of the virtual array specifies other important properties of the antenna system (in particular, the gain, angular resolution and sidelobes). If the coordinates of the physical elements (with respect to the center of the system) forming the array are known, the positions of the virtual elements forming the virtual array can be easily evaluated.
Even if a certain number of papers is available in the literature about the use of virtual arrays for radar imaging, very few papers deals with its use in estimation algorithms devised for stepped frequency and colocated MIMO radars. In this work, virtual arrays are exploited in deterministic algorithms for the estimation of radar targets. Such algorithms are represented by the periodogram-based method, the so called CLEAN algorithm together with also some interpolation techniques for delay and direction-of-arrival estimation with very low computational complexity. All of them allow to estimate range, azimuth and elevation of multiple targets which are tested on two commercial radar devices, both manufactured by the Vayyar company.
At the end of the work, experimental results will be given. The investigated algorithms may achieve substantially different performance in the presence of multiple targets in terms of range and angular resolution capability and require substantially different computational complexities.
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