Polarity switching it really makes a difference
In the beginning when I started with satellite communication I was not able to switch my polarization and I thought it wouldn’t make a great difference. Now that I use the Maspro WHS32N (Oscar Hunters) antennas that come with the option to switch RHCP and LHCP I experience the difference, and it is really a very big. When I was searching the internet I found a Youtube movie from ON4HF that shows the difference between RHCP and LHCP. He uses a pass from AO-51 to show the difference, in the movie he is switching from RHCP to LHCP and back.
Below is a summary from a great article written by SV1BSX.
Space communication has forced the use of Circular polarization. The fundamental advantage of circular polarization is that all reflections change the direction of polarization, precluding the usual addition or subtraction of main and reflected signals. Therefore there is far less fading and flutter when circular polarization is used at each end of the link.
The use of circular polarization at one end only gives a loss of about -3dB. In order to achieve the full advantages of circular polarization it is necessary for all stations to use it. The table below shows the relationship between Horizontal, Vertical, RHCP (Right Hand Circular Polarization) & LHCP (Left Hand Circular Polarization) and Loss in dB. RHCP is also known as CW (ClockWise) Polarization and LHCP as CCW (Counter ClockWise) Polarization.
The following pictures shows the Vertical, Horizontal and Circular polarization.
More information can be found on the website from SV1BSX, the article he wrote is a great source of information if you want to learn more about polarization.