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

[Chuck Harris]

Not quite.

"The definition of right-hand circular polarization, as standardized by
the IRE... is as follows:  For an observer looking in the direction of
propagation, the rotation of the electric-field vector in a transverse
plane is clockwise." - Jasik, "Antenna Engineering Handbook", First
Edition,  p17-3

A right-hand circularly polarized antenna both transmits and receives
RHCP.  What is confusing people is a reflection of a RHCP wave is a
LHCP wave.

-Chuck Harris

Magnus Danielson wrote:
> On 05/06/12 00:30, Dr. David Kirkby wrote:
>> This is not exactly a time related question, but I'm sure the subject
>> must be of interest to time-nuts using GPS.
>>
>> If one transmits from an antenna such as a helical one, RHCP, can the
>> same antenna be used for reception, or does the helix need to be wound
>> the other way?
>>
>> If you google this topic, there seems to be a lot of confusion about
>> whether the TX antenna and RX antenna need to both have RHCP or whether
>> one needs to be LHCP and the other RHCP.
>>
>> Given GPS uses circular polarization, I'm hoping someone here will know.
>>
>> It would appear there are different definitions of "circular
>> polarization", with one considering it from the point of view of the
>> source, and the other considering it from the point of view of the
>> receiver. The IEEE apparently uses the former, and others (especially
>> optics) use the opposite.
>>
>> http://en.wikipedia.org/wiki/Circular_polarization
>>
>> My aim was to make a gain measurement of two circular polarized
>> antennas. I have two identical antennas, but are unsure if the signals
>> should be received strongly, or whether theoretically no signal would be
>> received. (Of course in practice, one never achieves perfect
>> polarization, so there will always be a signal detected, even if
>> cross-polarized.
>
> They would have to have opposite rotation.
>
> The waveform rotation will follow the transmitter antenna into the receiver antenna.
> The receiver antenna follows the same rotation that the transmitter antenna has, it's
> just that the face each other, so when you turn one of the 180 degrees such that they
> face the same direction you would see that they are in fact rotated in opposite
> directions.
>
> I'm sure the sat folks can confirm this.
>
> Cheers,
> Magnus
>
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