# Why does an LHCP (or RHCP) antenna reject RHCP (or LHCP) signal?

I have no background knowledge about antennas. I am trying to intuitively understand how an antenna transmits and receives a circularly polarized (CP) Electro-Magnetic (EM) wave.

1. From the knowledge, I could gain after searching a lot about this on the internet is we can assume a transmitting antenna to have a "wave transmitter", that rotates continuously and keeps transmitting signals as it rotates. Based on the direction of rotation we can either an LHCP EM wave or RHCP EM wave gets transmitted. Is this intuitive understanding correct?

Please see this animation to get what I am trying to say:

2. If I assume the above understanding is right. I can think of a receiver antenna to be something similar - in this case, instead of a rotating wave transmitter I would have a "rotating wave receiver".

3. If we assume 2 is correct (at least intuitively), then the wave receiver could be rotating in one direction (i.e. it can have one particular CP) and the incoming EM wave might have the same or the opposite CP. Now, how can we prove that for a wave receiver with given CP - only the incoming EM waves having one particular polarization (LHCP or RHCP) get received, but the other one doesn't?

Please correct me if my understanding is wrong. I would be happy if you can also share some links where I can get to understand the above material better.

Thank you!

• the antenna does not rotate mechanically ... qsl.net/sv1bsx/antenna-pol/polarization.html Commented Nov 15, 2020 at 3:04
• Assuming that one "rotation" is completed every wave and knowing the wave length and speed of light, you can calculate the rotation speed. I think it won't be possible to rotate an antenna mechanically that fast.
– AJN
Commented Nov 15, 2020 at 4:28