A three-element linear array of isotropic sources aligned along the z-axis has an interele...

A three-element linear array of isotropic sources aligned along the z-axis has an interelement spacing of λ/4 (Fig.). The amplitude excitation of the center element is twice that of the bottom and top elements, and the phases are −π/2 for the bottom element and π/2 for the top element, relative to that of the center element. Determine the array factor and plot it in the elevation plane.

Figure P. Three-element array of Problem