Consider four short dipoles of length AL, carrying triangular currents I = a, l with a maximum amplitude of I. The dipoles are positioned along the z-direction as shown in the figure and have a radiation pattern of F() = sin . If the phase shift and spacing between adjacent elements are, respectively, = 0 and (1) d = /2 and (2d = 3/4, in the x-z plane:
1. Find the electric fields in the far-field zone.
2. Sketch the radiation patterns.
3. Calculate the main beam directions.
4. Calculate the null directions.
5. Set the phase shift for the main beam direction at 0 = 45.
6. Check if there is any grating lobe as 0. If yes, set the range of phase shift to avoid the grating lobes in the visible regions of TWO arrays.
