Circular polarization

The polarization of the wave refers to the time evolution of the electric field vector. An interesting situation occurs if the same signal is fed to the two dipoles, but the signal to the z axis is given an extra $\pi/2$ phase . The electric field now is

$$\vec E ( x,t) = E \left[ \cos ( \omega t - k x) \widehat j + \cos ( \omega t - kx + \pi /2 ) \widehat k \right]$$ (8.4)

$$= E \left[ \cos ( \omega t - kx ) \widehat j - \sin ( \omega t - kx ) \widehat k \right]$$ (8.5)

If we now follow the evolution of $\vec E (t)$ at a fixed point, we see that the tip of the vector $\vec E (t)$ moves on a circle of radius E clockwise (when the observer looks towards the source) as shown in Figure 19.3

Figure 8.3: Circular polarization

We call such a wave right circularly polarized. The electric field would have rotated in the opposite direction had we applied a phase lag of . We would then have obtained a left circularly polarized wave.