Consider an alignment of isotropic antennas excited with in phase and arranged along the x axis (figure below). If the excitation amplitude of antenna # 1 is equal to +2 and that of antennas # 2 and # 3 is equal to +1, calculate the overall array factor of the alignment, the maximum directivity, and the relative zeros within the visible region assuming d = 2 / 2. #3 d. #1 d #2 X