Non-matrix closed-form accurate expressions of the CRBs of the azimuth, elevation and range of a narrowband near-field source impinging on a planar array derived from the exact expression of the time delay are given.

New conditions on the array geometry are proposed that allow decoupling of azimuth, elevation and range parameters to a certain order in 1=r (in which r denotes the range).

Application to concentric uniform circular-based arrays, cross and square-based centro-symmetric arrays are derived.

Two geometric parameters are identified that determine the near-field accuracy of the cross and square-based centro-symmetric arrays.

A methodology is developed to obtain non-uniform square and cross-based centro-symmetric arrays with improved near-field range estimation capabilities and controlled DOA ambiguity.