[time-nuts] Antenna question about RHCP/LHCP I'm sure a time-nut can answer

Chuck Harris cfharris at erols.com
Tue Jun 5 13:23:38 UTC 2012


I guarantee you it doesn't cause any controversy among those that
use circularly polarized antennas.

That the polarization changes from RHCP to LHCP when reflected is
certainly the cause of some confusion about the antennas.  A RHCP
antenna that directly emits a wave towards the source will become a LHCP
antenna if it is illuminating a parabolic dish.

The easiest way to think about it is to mentally think of the path from
the transmitter to the receiver as a very long piece of threaded rod, and
the wave being emitted as being a nut traveling on the rod.  No matter
which side of the rod you are observing from, you will observe a nut
traveling away from that end turning in the same direction (clockwise
for RHCP).

Another point of confusion could be that if you are standing at the
transmitter watching the nut travel away from you, it will be rotating
clockwise.... but if you are standing at the receiver watching the
nut traveling towards you, it will be rotating counter-clockwise.

Both cases are RHCP.

If I hired an engineer to work on circularly polarized antennas and he
didn't know this, I too would be thinking of firing him!

-Chuck Harris


David Kirkby wrote:
> On 5 June 2012 01:12, Dave Martindale<dave.martindale at gmail.com>  wrote:
>> I don't think that's correct.
>
> This is a funny topic. No matter where see it discussed, there are
> people with different views on it. I looked on the edaforum
>
> http://www.edaboard.com/forum26.html
>
> and found a thread (can't find it now unfortunatey), where someone was
> adament they needed to be one way (I forget whether both RHCP or
> RHCP+LHCP), and someone else was adament a colleague nearly lost his
> job after making that mistake. I think there was about a 50:50 mix of
> views on the topic
>



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