For the array and phase advance in Problem 4.2, calculate the distance from the tower in which nulls may occur in the radiation pattern.
Problem 4.2
If the 14 dBi antenna array described in Problem 4.3 is mounted on top of a 50 m tall tower, calculate the phase advance across the entire length of the array to ensure that the outer edge of the 3 dB beamwidth hits the ground at a distance of 1 km from the tower.