This paper presents a beamspace version of ESPRIT for uniform rectangu
lar arrays that supports closed-form 2-D angle estimation, automatical
ly couples the two components of the source directions, and works with
any front end beamformer. The proposed algorithm is based on the obse
rvation that beamspace noise eigenvectors can be transformed to vector
s that are bandpass and have spectral nulls at the inband source locat
ions. This facilitates multirate processing (involving modulation to b
aseband, filtering, and decimation) and yields a space with dimensiona
lity equal to the number of beams used to probe the subband rather tha
n the number of elements in the sensor array. The MUSIC algorithm can
be applied to this noise subspace. Alternatively, a transformation mat
rix can be computed a pylori, which maps the beamspace signal eigenvec
tors to the corresponding signal subspace that has the ESPRIT structur
e. The TLS-ESPRIT algorithm is then modified to obtain the two directi
ons for each source from a single eigenvalue-eigenvector pair. Hence,
they are automatically coupled.