Compact MIMO Radar of Improved Angular Resolution Using Interleaved Array Geometry
Ananya Mukherjee, Debdeep Sarkar
Abstract
In this paper, a compact two transmitter-four receiver (2Tx-4Rx) multiple input multiple output (MIMO) Radar based on binomially tapered-series fed patch (BT-SFP) antenna has been designed at 76 GHz mm-wave band for autonomous driving applications with high angular resolution. Considering three different MIMO Radar topologies, the efficient target detection have been studied by using suitable Radar performance metrics like ambiguity function and field of view (FOV), besides antenna parameters like impedance matching and mutual coupling. An improved angular resolution has been obtained by judicial placement of antenna elements in the proposed interleaved MIMO array topology, which leads to a minimally redundant array configuration having more extensive virtual aperture of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$1.4\lambda$</tex-math></inline-formula> (here <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\lambda$</tex-math></inline-formula> is the free-space wavelength at 76 GHz), improved isolation and broad ambiguity free region in the azimuthal plane. The proposed interleaved MIMO array topology yielded a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$12^{\circ }$</tex-math></inline-formula> angular resolution in single layer configuration having total area of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$30 \times \rm{18}~mm^{2}$</tex-math></inline-formula> (35.42 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\lambda ^{2}$</tex-math></inline-formula> ), which renders it as a simple cost-effective design that exhibit less spectral broadening in frequency domain and thus less sensitive to the environmental noise. To validate the proposed methodology, a scaled structure of the interleaved MIMO array operating at 24 GHz has been realized using full-wave solver CST-MWS. Furthermore, the interleaved MIMO array prototype at 24 GHz is fabricated, and reasonable match between simulated results (S-parameters and patterns) and experimental data is obtained.