In article ,
Hal Rosser wrote:

If I did that, the omi-directionality (if that's a word) would go away and
so would most of the compactness needed foe stealthiness.

So - does anyone know of an omni directional horizontally polarized wide
band antenna?

If you want a truly-omnidirectional (or close to it) antenna, with no
significant pattern variation or serious sensitivity variation in
frequency over the TV band, horizontally polarized, with no
requirement for electronic switching of elements and no mechanical
rotator... I sure don't. I skimmed through the antenna designs given
in Bailey's "Television and other Receiving Antennas" book a few days
ago, and didn't see any which come close to this.

I think you're going to have to "give" on at least one of the above
issues in order to get something realizable.

There are probably a number of approaches:

- Use a wideband, rotatable dipole. At least one of the "saucer
radome" antennas comes with an internal rotator, control box, and
IR remote. You program in the bearing to each station you want,
hit a button on the remote, and the rotator swings the (inside-the-
radome) elements into line. See the HDMS9100 antenna at the top
of the page:

http://www.starkelectronic.com/allomni.htm

In this approach you give up on "no rotator". Doesn't work
terribly well with DVRs, since the DVR may have a scheduled
recording to make and can't push the button to rotate the antenna.

- Use a wideband dipole (e.g. several dipoles of different lengths,
mounted in the same plane, with a common feedpoint), and simply
align it in a way which gives you acceptable signal quality for all
of the stations you care about. The null off the end of a dipole
isn't all that wide, and you may find that you may be able to "aim"
these two nulls in a direction which doesn't place any of the
transmitters into a substantial null. There may be one or more
"compromise" settings in which you get a plenty-good signal on all
of the stations.

In this approach you give up on true omnidirectionality.

I think that the Channel Master 3000A (listed further down on the
page above) is of this general sort. If I recall correctly, it has
a single folded dipole element internally, with the ends of the
dipole swept into an "S" shape in side the radome - this lessens
the depth of the null off the end and (I think) makes the direction
of the actual null somewhat frequency-sensitive.

- Install two such broadband dipoles at 90-degree angles, with a
remotely operated switch/relay, and select one or the other
depending on channel.

Not truly omnidirectional , requires manual switching.

- Install two or more dipoles of different lengths, at different
angles, with a common feedpoint, with each dipole cut to the
frequency of a specific station and aligned broadside to that
station's transmitter. The resulting pattern will no doubt have
lobes and cancellations, but (if the channels are far apart enough
in frequency) will probably work reasonably well.

Not truly omnidirectional at any single frequency; needs to be
designed for your specific location and frequency considerations.

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