  Automotive radar at terahertz (THz) band has the potential to provide compact
design. The availability of wide bandwidth at THz-band leads to high range
resolution. Further, very narrow beamwidth arising from large arrays yields
high angular resolution up to milli-degree level direction-of-arrival (DoA)
estimation. At THz frequencies and extremely large arrays, the signal wavefront
is spherical in the near-field that renders traditional far-field DoA
estimation techniques unusable. In this work, we examine near-field DoA
estimation for THz automotive radar. We propose an algorithm using multiple
signal classification (MUSIC) to estimate target DoAs and ranges while also
taking beam-squint in near-field into account. Using an array transformation
approach, we compensate for near-field beam-squint in noise subspace
computations to construct the beam-squint-free MUSIC spectra. Numerical
experiments show the effectiveness of the proposed method to accurately
estimate the target parameters.
