In article ,
wrote:

Well, considering that there really is no such thing as an HDTV
antenna per se, yes. HDTV in the U.S. (ATSC) uses a subset of the
same frequencies used by ATSC television, and so all the same
considerations apply.

With 2 to 4 stations on the same frequency allotment as the old analog
in some instances. At any rate some squeeze 4 in the space that used
to be used by one. They do this at the expense of bandwidth (IE
resolution)

They're actually multiplexing two or more digital data streams into a
single RF transmission, coming from a single transmitter and tower.
No matter whether they're sending one HDTV program, or four
independent SDTV digital signals, it's all just one digital bitstream
being sent to the modulator, and sent out in a single 6 MHz slice of
the spectrum (the same slice of spectrum that a single NTSC
transmission would have used).

You're correct, the extra programs are sent at the expense of the main
program... it must reduce its bit-rate, which means either switching
down to a lower resolution, or having more motion artifacts, or
sticking to programs which have relatively little motion on-screen and
are thus easier to compress via MPEG.

If you wanted to tune up only one (or a few closely-spaced) HDTV
stations with an omni, you could probably build yourself a turnstile
antenna... a crossed pair of bow-tie elements, and a 90-degree phasing
harness cut for the middle of the band would probably work. I doubt
that'll work as a general-purpose solution for the full band, though.

It does here at least out to about 40 or 50 miles from 40 feet.

Very good to know - thanks!

BTW these antennas are about 30 feet below a pair of 12L, vertically
polarized yagis and about 12 feet above the tops of a pair of Diamond
repeater antennas. The tribander is about 8 to 10 feet above the TV
antennas and the 7L 6-meter yagi is about 15 feet above the tribander.
I run the legal limit to the tribander and a 1000 to 1200 PEP on
6-meters. So far no problems.

My complements to your filters and amplifiers and your care in setting
up the whole system!

Only problem I ever had was one neighbor having a foot ball party out
in his garage using rabbit ears for an antenna about 120 feet from the
base of my tower. "Hello Test" with 50 watts to the 12L pair at 130
feet would give him a blank screen on Ch 12. I gave him a directional
TV antenna and from then on I was invited over to the parties and free
beer.

Now *that* is the kind of QRM-resolution situation we should all
strive for!

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
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