Measurement Section

The Measurement Section defines the polarization used in the presently selected curve in the Curves Section.

Polarization: You select the type of polarization from the drop list. There are three types of polarization available in the Far Field Viewer. Theta/Phi, Circular, Ludwig-3. They are described below along with the components available when that type of polarization is selected.

Theta/Phi

This is the default polarization. The components are E-Theta and E-Phi. E stands for the electric field. The theta and phi directions are shown in the figure in the Spherical Coordinate System.  Close to the horizon, theta polarization corresponds to vertical polarization, while phi polarization corresponds to horizontal polarization. Click on the checkboxes for the components of the E field that you wish to display.

Circular

The second polarization choice is circular. For this polarization, the left-hand circular polarized (LHP) component and the right-hand circular polarized (RHP) component of the radiated field can be displayed. The Axial Ratio of the electric field is the ratio of the magnitudes of the major and minor axis of your plot. Click on the checkboxes for the components of the E field that you wish to display.

LUDWIG-3

The Far Field Viewer also allows the use of Ludwig’s third definition of polarization and cross-polarization. This definition allows the analysis of polarization and cross-polarization in much the same manner as it is often measured. Therefore the two components are co-polarization (Co-pole) and cross-polarization (Cross-pole). Click on the checkboxes for the components of the E field that you wish to display.

To use Ludwig-3, the user needs to enter a reference angle, in degrees. This angle is the angle of the polarization at beam center. Thus, at beam center there is zero cross-polarization by definition.

A detailed description of Ludwig-3 is beyond the scope of this topic. More detail is available in the original reference: A. C. Ludwig, "The Definition of Cross Polarization,” IEEE Trans. Ant. and Prop., January, 1973, pp. 116 - 119.