Efficient techniques of sampling circular aperture distributions for ring array synthesis

The sampling of circular apertures with continuous distributions using discrete feeding in the form of ring arrays is considered in this paper. The generally complicated continuous aperture-feeding problem is thus transformed to simply determining the array excitation coefficients. Most of previous sampling techniques were based on discretizing apertures into rectangular grids (cells). The feeding coefficient of the corresponding array element is either taken as the actual value of the corresponding continuous aperture feeding (conventional sampling (CS)) or as the average value among the cell area (integrated sampling (IS)). We have extended this technique to synthesize concentric ring arrays with special geometry with either CS or IS feeding. The rings are discretized into radial sectors each with either equal or unequal areas. The proposed techniques have some advantages over previously used ones due to the simplicity of calculating the feeding coefficients and in using fewer array elements, in general. Numerical results demonstrate that the proposed aperture sampling techniques give approximations of the required far field patterns for many types of aperture feeding including uniform, linear taper, parabolic taper and Taylor distributions. A detailed comparative study with other techniques is also presented