RE: NEC-LIST: CIRCULAR POLARISATION

Yes, but be careful with reflectors. A "feed" for a reflector antenna marked
RHCP,
for example, is uncertain as to whether the marker meant *before* reflection
(the
feed inherent polarization) or *after* reflection (the *system* polarization).
After
many trials and tribulations here, we all agree: 1) Never trust "markings",
rather,
test* the darn thing and 2) Even then, you have about 50% chance of something
going wrong at one end of the link or t'other....................

Test with simple scratchbuilt ~5 turn helices; even then, don't exceed the
polarization
bandwidth limitations

At 06:22 PM 12/24/2002 +0200, zvi frank wrote:
>o.k. Thank you very much everybody .Now I will ask again the question I
>asked Jim, How about +45° antenna .Which antenna will receive it +45° or
>-45° .Think of a vertical array of 45° dipoles on a reflector
>Thanks
>,zvi
>
>-----Original Message-----
>From: rsmueller [mailto:rsmueller_at_netzero.net]
>Sent: Wednesday, December 25, 2002 4:55 PM
>To: zvi frank; nec-list_at_gweep.ca
>Subject: Re: NEC-LIST: CIRCULAR POLARISATION
>
>Zvi,
>
>Jasik is correct, like polarizations are required.
>
>If you transmit with an antenna with RHCP, you need to have an RHCP receive
>antenna. The transmitted RHCP is going away with respect to the
>transmitter. If you point your right hand thumb in the direction of
>propagation the E-field will rotate to the right in the the direct of your
>curled up fingers. for RHCP. You may think that the receiver sees the
>transmitted signal as LHCP, but that is for the opposite direction of
>propagation, coming toward the receiver. This is still RHCP, not LHCP. An
>RHCP receive antenna is still required.
>
>If that isn't good enough of an explanation, here is an analogy. Think of a
>cork screw on which a ring is moving along in a helical motion. In order
>to transfer the ring to a second cork screw, you have to have the same sense
>cork screw. A similar analogy could be a right handed screw is needed in
>order to drive it into a right handed hole, irriegardless of which end of
>the hole you are trying to drive it through.
>
>Example, now think of a helical antenna and how it is constructed. Imagine
>creating a RHCP wave that is propagated toward a receing helix. It still
>needs to be RHCP. Does this make more sense now?
>
>I hope this explanation has helped,
>
>Roland Mueller
>-----Original Message-----
>From: zvi frank <zvi_f_at_mti-group.co.il>
>To: nec-list_at_gweep.ca <nec-list_at_gweep.ca>
>Date: Tuesday, December 24, 2002 9:40 AM
>Subject: NEC-LIST: CIRCULAR POLARISATION
>
>
>>I have a question which I thought was clear to me .When one transmits with
>a
>>Right hand circular polarisation ,Should one receive with a left or right
>>hand circularly polarized antenna.? JASIK says like polarizations are
>>required which seemed logical to me till recently now I am not so sure???
>>Thanks for any comments.
>> Zvi
>>--
>>The NEC-List mailing list <nec-list_at_gweep.ca>
>>http://www.gweep.ca/mailman/listinfo.cgi/nec-list
>>
>>
>-----Original Message-----
>From: zvi frank <zvi_f_at_mti-group.co.il>
>To: nec-list_at_gweep.ca <nec-list_at_gweep.ca>
>Date: Tuesday, December 24, 2002 9:40 AM
>Subject: NEC-LIST: CIRCULAR POLARISATION
>
>
>>I have a question which I thought was clear to me .When one transmits with
>a
>>Right hand circular polarisation ,Should one receive with a left or right
>>hand circularly polarized antenna.? JASIK says like polarizations are
>>required which seemed logical to me till recently now I am not so sure???
>>Thanks for any comments.
>> Zvi
>>--
>>The NEC-List mailing list <nec-list_at_gweep.ca>
>>http://www.gweep.ca/mailman/listinfo.cgi/nec-list
>>
>>
>
>
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Dan Bathker

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