Re: NEC-LIST: CIRCULAR POLARISATION

Michael and Zvi,
Michael makes a good point about our careless use of the wording of
"required". However, the original question was whether a LHCP or RHCP
antenna should be used to receive an RHCP incoming signal. I wouldn't
recommend using a LHCP antenna to receive RHCP signal because you'll end up
with a large polararization mismatch loss, much greater than the 3 dB.
Regards,
Roland

-----Original Message-----
From: Michael Pender <michael.pender_at_nanochron.com>
To: rsmueller <rsmueller_at_netzero.net>; zvi frank <zvi_f_at_mti-group.co.il>;
nec-list_at_gweep.ca <nec-list_at_gweep.ca>
Date: Friday, December 27, 2002 1:42 PM
Subject: Re: NEC-LIST: CIRCULAR POLARISATION

>Actually, like polarizations are "best," but it is an overstatement to say
>they are *required*.
>
>For example if you regularly work with both RHCP and LHCP antennas then you
>could transmit/eceive to either using a linearly polarized antenna, such as
>a dipole. However, there will be a polarization loss of ~3 dB when
>exchanging signals between antennas.
>
>- Mike
>
>Executive Manager
>Nanochron, LLC
>
>
>> 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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>>
>
>
>

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