[opendtv] Re: Circular, elliptical antenna polarization improves mobile DTV reception reliability
- From: Mark Aitken <maitken@xxxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Wed, 27 Apr 2011 20:47:16 -0400 (EDT)
Dale, correct to both of your points. As to "advantage" of CW or CCW true
circular...only needed to provide isolation or discrimination from opposing
rotational emissions... used in space activities for example for DTTH
satellite.
Regards,
Mark
----- Original Message -----
From: "Dale Kelly" <dalekelly@xxxxxxxxxxx>
To: "OPENDTV" <opendtv@xxxxxxxxxxxxx>
Sent: Wednesday, April 27, 2011 7:31:11 PM
Subject: [opendtv] Circular, elliptical antenna polarization improves mobile
DTV reception reliability
On 4/25/2011 4:32 PM, Hunold, Ken wrote
Mark,
>> I notice that you (correctly, I believe) did NOT make a reference to
>> “circular” polarization in your reply. Should these types of
>> transmissions be referred to as “dual” polarization?
Semantically you are correct.
Practically however, if a dipole antenna directed at a transmit antenna
having equally powered dual polarization, is rotated 360 degrees on it's
axis, it should receive equal amounts of power at all degrees of the circle.
>> I’m curious about this. Lacking a circularly polarized receiving
>> antenna, is there any advantage to true circular polarization with
>> digital signal? You can’t see the ghosts anymore to help you orient the
>> antenna. What do you think?
My initial reaction is that there would be little or no advantage to
"true" C.P. in the mobile environment but I do stand to be corrected. Mobile
handheld devices are the worse case for DTV reception (the small marginal
antenna will most always be out of alignment) and would definitely benefit
from dual polarization.
However my original concern was; "but at what cost?"
Dale
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