Array Antennas With Jointly Optimized Elements Positions and Dimensions Part II: Planar Circular Arrays

The paper describes a deterministic algorithm based on simple analytical equations for designing planar circular sparse array antennas where the positions and the dimensions of the radiating elements are jointly exploited and optimized. The proposed solution permits addressing one of the main limitations associated to sparse arrays, i.e., their poor aperture efficiency especially when patterns with low sidelobe levels are obtained using only the density of the elements avoiding any amplitude tapering. The accuracy of the method is guaranteed by the fact that the achieved directivity differs from the target value, associated to a continuous reference aperture distribution, by a quantity asymptotically equal to the factor π/4 (corresponding to about -1.05 dB) representing the filling factor of a circular planar array organized in concentric rings populated by circular apertures. As required for several applications, the method includes the possibility to add a constraint on the maximum scanning angle with respect to the boresight direction.