Broad band full scan coverage polarization agile spherical conformal array antennas: pseudo-uniform vs. pseudo-random element arrangements

Optimal three dimensional array configurations for adaptive applications are investigated in this paper. To accomplish uniform beam scanning, two classes of possible element arrangements are devised by placing the radiating elements at the vertices of some canonical polyhedra and by randomly dispersing the radiating elements on a spherical surface with uniform spatial density. In both these pseudo-uniform and pseudo-random configurations the advantage of polarization agility and broad band operation is achieved by using a spiral antenna as radiating element. The array radiation characteristics are evaluated by resorting to the active element pattern approach in conjunction with the method of moments (MoM), so as to properly account for mutual coupling between the elements. The scanning performance of two like size 32-element pseudo-uniform and pseudo-random arrays are thoroughly compared in terms of maximum gain, half power beamwidth and side lobe level and relevant numerical results are provided. The variations with beam steering of the active reflection coefficient are also studied.