Hello,
Here are my settings for the phase center of my antenna. I need to know what are
1)The best values for Angular limit around Z' axis.
2)Phase center values in the left box? (0,0,58.45, Sigma=13.72).
(if 58.45 is the Z value, why it is not a negative value? or where is origin?)
3)IF this antenna is going to be used as a reflector antenna's feed, where is the phase center location distance from the feed antenna?
Thank you.
Farfield Plot – Phase Center
📷 Farfield Plot: Plot Properties > Properties > Phase Center
The phase center is calculated using the phase of the phi or theta component of the electric field. The calculation is limited by an angle around the z'-axis. The z'-axis may be either the main lobe or a user defined axis as entered in the Farfield Plot - Axes page. The phase center is calculated from phase values in two planes for a constant reference distance. One plane is defined by the polarization vector (y'-axis) and the z'-axis called E-Plane. The other plane is defined by the x'-axis and the z'-axis perpendicular to the E-Plane called H-Plane. Depending on the selected plane the phase center will be calculated for the E-Plane, H-Plane or for both planes. If both planes are calculated the phase center location is averaged afterwards.
The results of the phase center calculation will be displayed in the lower left corner of the 3D farfield plot in global cartesian coordinates. In addition, the maximum standard deviation "Sigma" of the phase center location is shown. To validate the results set the origin of the farfield to the phase center location in the Farfield Plot - Origin page and select the phase of the selected field component in the Navigation Tree to get a 3D plot of the phase.
Testing the Phase center result: You may check the behavior of phase by entering the phase center result coordinates as new Box origin and then plotting the phase. Because the spherical unit vector theta changes its direction in the most interesting point around the z' axis, the E-theta phase has a 180 degree phase jump at theta = 0. It is therefore recommended to switch to the Ludwig3 representation of the farfield to check the constant field around the z' axis (around theta = 0).
Calculate phase center
Activate to enable the calculation of the phase center.
The phase centre may change across the feed beam. In that case the phase front is not spherical and you will have to assess the effect of the phase variation across the main aperture. Usually the phase centre doesn't move much across the angular width of the feed beam. If it moves less than 1/8 wavelength the loss in gain will be vey small. Antenna design books show the effect of small phase errors in terms of RMS deviation.
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