Design a 3-element, -40 dB side lobe level Dolph-Tschebyscheff array of isotropic elements placed symmetrically along the z-axis. Find the
(a) amplitude excitation coefficients
(b) array factor
(c) angles where the nulls occur for d = 3λ/4 ( 0° ≤ θ ≤ 180° )
(d) directivity for d = 3λ/4
(e) half-power beamwidth for d = 3λ/4