MIMO radar setups by nesting braced minimum redundancy arrays

This paper covers coherent MIMO radar with co-located antennas distributed according to minimum redundancy principles. The fundament of the first are virtual arrays which can be considered as a discrete convolution of local transmitter and receiver distributions. Now this technique shall be combined with sparse array principles considering minimum redundancy (MR) aspects. Optimal results for so-called restricted MR arrays, found by brute-force search algorithms had already been presented. However, those are usually not suited for aperture antennas since the smallest element spacing is around half or quarter of the wavelength. This paper shall not only present an analysis of the effects relevant for design of general MR arrays, but also shows results for braced and nested arrays. This leads to MR-MIMO arrays with a smallest element spacing which is larger than a wavelength, giving a higher degree of freedom in choice of antenna type. Measurement results for a radar sensor operating in lower W-band and equipped with the afore-mentioned array type, demonstrate high angular resolution with suppression of grating lobes at the same time.