θ is measured from broadside. AF(θ) = Σ wₙ ejnψ, ψ = 2π(d/λ)(sin θ − sin θ₀).
Chebyshev weights are synthesized by sampling TN−1(x₀cos ψ/2) and inverse-DFT.
Directivity is computed numerically assuming a z-axis array of isotropic elements
(azimuthal symmetry); the element pattern multiplies the cut but the D card always
states what it includes. Planar mode shows the two principal cuts of a separable
rectangular array (x-cut and y-cut) and estimates D ≈ π·Dx·Dy.