Plotting the Far Field Spectrum

Far-field frequency spectra are obtained when a simulation is performed by specifying a list of frequencies or conducting a frequency sweep. For each frequency, the far-field is calculated at various directions determined by the zenith (Theta) and azimuth (Phi) angular ranges, and the distance specified in the Far-Field panel of the Setup tabsheet. Therefore, you must select a fixed direction (Theta, Phi) to plot the far-field versus frequency.

Go to Results > Plot Far-Field Spectrum in the main menu to plot the far-field spectrum. This command will display the Select Far-Field Point dialog box (see Fig. 1), where you can select the fixed Theta and Phi angles. After clicking the OK button, the AN-XY Chart application will display the frequency spectrum of the total E-field (refer to Fig. 2).

You can also plot the linearly polarized field components, E-theta and E-phi, as well as the circularly polarized components, E-right and E-left, in amplitude, phase, real, and imaginary parts by selecting these options under the Plot menu in the AN-XY Chart application. Additionally, you can plot the Axial Ratio, defined as the minor to the major axis ratio of the polarization ellipse, as a function of frequency.

The far-field spectrum for a selected far-field point can also be tabulated. To do this, go to Results > List Far-Field Spectrum in the AN-SOF main menu. This action will display the Select Far-Field Point dialog box where you can select fixed values for Phi and Theta. Afterward, a list of the far-field components versus frequency will be shown, and you can plot it by clicking the Plot button (as shown in Fig. 3).