[opendtv] Re: Omnidirectional RECEIVE antennas with gain

Doug,
There are omni directional antennas, but they add as many problems as
they fix.  The most significant issue for DTV is multipath.  Omni
antennas will pass multipath to the receiver as well as the main signal.
As next generation receivers get better at rejecting multipath, this
will be less of an issue. =20

There are several omni TV antennas that are built for RV, boat and
automobile reception.  In the US, they are all designed for analog, but
work just fine for DTV in my tests.  Check out
http://www.shakespeare-marine.com/antennas/tvant.htm for an example.

There are also some DVB-T antennas in use in Europe that work in the
same frequency range (or close enough) that work over here.  I have had
great success with a new 4th gen receiver and a DVB-T antenna for
portable reception.  We are also working with a manufacturer to build a
5th gen data receiver that I hope will be ready to show at NAB that
should really solve this problem.

I will be showing what we are doing with some of this new stuff at NAB.
I will be doing some live datacasting demonstrations and showing how
first responders are using this now.  We will be in the ATSC hotspot in
the south hall entrance (APTS booth).=20

Mark O'Brien
SpectraRep
mobrien@xxxxxxxxxxxxxx
703-802-2975


-----Original Message-----
From: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx]
On Behalf Of Doug McDonald
Sent: Thursday, April 07, 2005 10:52 AM
To: opendtv@xxxxxxxxxxxxx
Subject: [opendtv] Omnidirectional RECEIVE antennas with gain

Why can't we buy omnidirectional RECEIVE antennas with gain?

It looks like we may soon need such a beast around here, what
with a new and distant PBS station being built, and a new Fox
with different programming now running, 1 million watts but distant.

We will have stations at about 45, 90, 175, 255, 260, and 315
degrees on the compass, the ones at 45, 175, and 315 being
weak at least some places in town.

It looks like what we need is a four or five bay turnstyle or
batwing, or maybe just a four or five bay "cheapie FM transmitting"
antenna. This is UHF ... our VHF station is relatively close and
never behind a hill and should "just work".

Doug McDonald
=20
=20
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