Polarity Rotator (shown with 222 MHz Feed)

This page describes a system for rotating a parabolic dish Feed in polarity to compensate

for geometric (spatial) polarity difference and Faraday rotation between my location and

the other station location.

Step one is to determine the geometric angle. This assumes both stations are horizontally

polarized. Look at the first photo below,” 6deg.jpg.” The red plus is on New Jersey

and the polarity difference is 6 degrees counter clockwise. Rotate the feed to -6 and

press the "GEO" button on the control panel shown below in "IMG_3553.JPG"

Step two is Rotate the feed in search of the best signal, shown at 25 degrees clockwise in

photo "Pol-Rot-EQ4.gif" below, and then press the "RX" button on the control panel.

The processor in the control panel will now compute the best angle to transmit to a

station in the New Jersey area, and if the "Auto" switch is selected, will automatically

rotate to that position when the Transmitter is enabled. When returning to Receive, the

rotor will automatically return to the optimum RX position.

6deg.jpg
92.20 KB

EL9c.gif
77.05 KB

Additional examples of polarity calculations are shown here: Polarity Examples

Detailed Flow Diagram of Proposed Solution for Auto TX Positioning Routine http://alaska.net/~ptt/polarity/tx-flow.pdf

Working code for Auto TX Positioning Routine http://alaska.net/~ptt/polarity/polrotW.pdf

Central States VHF Conference 2023

For questions or comments contact Mike at KL6M