Scanned directivity of linear arrays

Expressions for directivity as a function of spacing, scan angle, and current distribution are presented for uniformly spaced linear arrays subject to the assumption that the element radiation intensity function of each radiator can be expressed in either of the following forms:(1 - sin² θ cos² Φ)Porsin2P θ sin2Q zero or positive integers. By proper choice ofPandQ, these expressions can be used to approximate the element radiation intensity function associated with a linear array of isotropic radiators, parallel short dipoles, collinear short dipoles, and planar equiangular spiral antennas. Analytical results are given for a number of cases, and graphical results are presented for directivity in the direction of scan angle for a linear array of radiators with a uniform current distribution and an element radiation intensity given by the expressionsin² θ sin² Phiin the regiony ≥ 0and zero in the regiony < 0.