FCA-ESPRIT: a closed-form 2-D angle estimation algorithm for filled circular arrays with arbitrary sampling lattices

This article addresses the simultaneous estimation of the azimuth and elevation angles of multiple co-channel signals incident upon an array of antennas. A new closed-form algorithm that is applicable with filled circular arrays (FCAs) is presented. The algorithm, which is called FCA-ESPRIT, is applicable with any FCA geometry, e.g., FCAs constructed using rectangular, hexagonal, polar, or random sampling lattices. The only constraint imposed on the FCA geometry is that the spacing between adjacent sensors should be half a wavelength or less on average across the entire aperture. The algorithm provides automatically paired azimuth and elevation angle estimates by solving a set of ESPRIT-like equations wherein the unknowns have the form sin(θ _i)e^jφ(i) (where θ_i and φ _i are the elevation and azimuth angles of the ith source, respectively). The algorithm provides arrival angle estimates via a closed-form procedure-it does not require computationally expensive search or optimization procedures