[opendtv] Re: Doug Lung: DTV Coverage Problems
- From: Richard Hollandsworth <holl_ands@xxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Thu, 13 Aug 2009 11:05:51 -0700 (PDT)
Rabbit Ears provide both Horiz. and Vert. Gain response when forming a "VEE".
UHF Loop Antennas do NOT have much in the way of usable Vertical Gain unless
you tilt them over
so the feed point is on the SIDE, at which point they lose their primary
Horizontal Gain.
I added some Horiz. and Vert. 3D Gain patterns to the fol. UHF Circular Loop
Analysis:
http://imageevent.com/holl_ands/loops/uhfcircular
There is a small amount of Vertical Gain but it's directly OVERHEAD at low
freqs and off to
the SIDE at the highest freqs (well beyond the New UHF Band).
PS: Just above the title line, you'll find navigation controls to other 4nec2
Sim runs...or use:
http://imageevent.com/holl_ands/
Vertically polarized gap fillers would not be very effective FOR TV at UHF
unless the user
changed to a different antenna (e.g. Circular Polarization). It would be
easier for the
Gap Filler to implement an Elliptically or Circularly Polarized
Antenna/Transmitter(s).....
holl_ands
===============================================
--- On Wed, 8/12/09, Manfredi, Albert E <albert.e.manfredi@xxxxxxxxxx> wrote:
From: Manfredi, Albert E <albert.e.manfredi@xxxxxxxxxx>
Subject: [opendtv] Re: Doug Lung: DTV Coverage Problems
To: opendtv@xxxxxxxxxxxxx
Date: Wednesday, August 12, 2009, 9:52 AM
Dan Grimes wrote:
> "The second is to use vertical polarization for the gap filler.
> This could be useful to reduce the gap filler's impact on outdoor
> antennas, in areas where the signals from both transmitters are
> weak."
>
> My outdoor TV antenna is horizontal and I believe nearly all are.
> Unless all stations use vertically polarized repeaters, it would
> require the reception side to have two antennas, whether
> constructed that way or one combined two separate antennas.
True enough. Although I think that Doug was positing that the gap
fillers were primarily intended to facilitate indoor reception or
reception with mobile devices. Either way, with some exceptions like the
Silver Sensor (or my indoor DB4 antennas), indoor and mobile reception
is done with antennas that are not strictly horizontally polarized. Like
UHF loops or rabbit ears.
He did say that in the shadow zones he had considered, an outdoor
antenna would have worked anyway. So the signal from the gap filler,
which potentially could have become a problem to high gain outdoor
antennas, was less likely to if vertically polarized.
Bert
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