Question

A half wavelength dipole is kept in the x-y plane and oriented along ${45}^{\circ }$ from the x-axis. Determine the direction of null in the radiation pattern for $0\le \varphi \le \pi$. Here the angle $\theta (0\le \theta \le \pi )$ is measured from the z-axis, and the angle $\varphi (0\le \varphi \le 2\pi )$ is measured from the x-axis in the x-y plane.

Answer 1

Ans : (a)

XY plane means Z = 0 with Z = rcos$\theta$ (spherical coordinates)$\theta ={90}^{\circ }$

With null points along the axis of the dipole it is $\varphi ={45}^{\circ }and{225}^{\circ }$