Technical Notes > Radiated Fields > Antenna Parameters           

Polarization of the Electric Field

At each aspect angle in the far field of a radiating source, the electric and magnetic field vectors lie in a fixed plane. Over time, the instantaneous electric field vector traces out a figure or shape in this plane. This figure defines the polarization state of the field.

In general, this figure is an ellipse and is called the polarization ellipse. The wave is said to be elliptically polarized when the instantaneous electric field traces out an ellipse. As a special case, the polarization ellipse may be a circle, in which case the wave is circularly polarized. Elliptical and circular polarization have two different states, left and right, distinguished by the sense of rotation of the electric field vector. Some of these figures, or states, are shown below. In each case the direction of propagation is off the screen.

A second special case occurs when the polarization ellipse degenerates to a straight line. In this case the wave is linearly polarized.

To completely describe the polarization state of a radiated field, two independent components are required. HFSS supports three types of descriptions:

• Spherical polar

• Ludwig-3

• Circular