"Cecil Moore" wrote in message
...
JB wrote:
Discone is vertically polarized and TV is horizontal. Results in a 15db
or
more loss in signal.

How about a dual-discone mounted horizontally?
--
73, Cecil http://www.w5dxp.com

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?

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


Had something like that on the roof of my RV. A Wineguard Roadstar
2000 omnidirectional antenna ought to be just what you're looking for.
Paint it black, if you want even more stealth.

such as at: http://www.amazon.com/Canon-Winegard-Roadstar-2000-
Antenna/dp/B000R2YB0G

Ed

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


Had something like that on the roof of my RV. A Wineguard Roadstar
2000 omnidirectional antenna ought to be just what you're looking for.
Paint it black, if you want even more stealth.

such as at: http://www.amazon.com/Canon-Winegard-Roadstar-2000-
Antenna/dp/B000R2YB0G

Ed


This is a phased array and can be steered electrically:

http://sadoun.com/Sat/Products/Wineg...irectional.htm

Dave wrote:
Ed wrote:
So - does anyone know of an omni directional horizontally polarized
wide band antenna?


Had something like that on the roof of my RV. A Wineguard
Roadstar 2000 omnidirectional antenna ought to be just what you're
looking for. Paint it black, if you want even more stealth.

such as at: http://www.amazon.com/Canon-Winegard-Roadstar-2000-
Antenna/dp/B000R2YB0G

Ed


This is a phased array and can be steered electrically:

http://sadoun.com/Sat/Products/Wineg...irectional.htm

Here's a bunch of cheapies:

http://www.summitsource.com/outdoor-...-47_57_65.html

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
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

On Wed, 17 Dec 2008 18:36:49 -0800, (Dave Platt)
wrote:

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.

A closer reading (skimming) would reveal:
Data sheet 10-15 Biconical Full Wave Antenna
Data sheet 10-30 Crossed Dipoles (Turnstile)
Data sheet 10-32 Slot Antenna
Data sheet 10-33 Slotted Cylinder Antenna

Basically, the take-home for widebandedness is a thick antenna (or its
skeletal equivalent). Many are vertical designs, but you simply build
the mirrored half and turn the assembly 90 degrees.

Although not the widest of designs (but wider than most), I would add
the Inverted F, example to be found at:
http://www.qsl.net/kb7qhc/antenna/In...%20F/index.htm
Make it thicker to make it wider (or fan out the segments). This is a
very low profile antenna by the way.

As for Ed's repeated advice for paint it black (Rolling Stones?), no.
Paint it off-white or a paler shade of blue (Procol Harumish). In
experiments during WWII, they discovered that lighting targets against
the sky made them disappear - not darkening them which offered
contrast. Oxidized aluminum is probably the best coloration.

73's
Richard Clark, KB7QHC

As for Ed's repeated advice for paint it black (Rolling Stones?), no.
Paint it off-white or a paler shade of blue (Procol Harumish). In
experiments during WWII, they discovered that lighting targets against
the sky made them disappear - not darkening them which offered
contrast. Oxidized aluminum is probably the best coloration.


No, not Rolling Stones.... never was a fan. And I stand corrected. I
know better, but here in Oregon, most of my outside stuff has a "dark
Green" folage background and I was thinking of that instead of the sky.


Ed K7AAT

Hal Rosser wrote:
"Cecil Moore" wrote in message
...
JB wrote:
Discone is vertically polarized and TV is horizontal. Results in a 15db
or
more loss in signal.
How about a dual-discone mounted horizontally?
--
73, Cecil http://www.w5dxp.com

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?



Somewhat tricky..

Two crossed dipoles fed with the correct phasing is very close to that.

Check out "Lindenblad" or "turnstile"

In article ,
Jim Lux wrote:

Somewhat tricky..

Two crossed dipoles fed with the correct phasing is very close to that.

The tricky part, I believe, is maintaining the correct phasing between
dipoles over a sufficiently wide frequency range.

For narrow-band applications, using an additional quarter-wavelength
feedline phasing section would do.

For somewhat wider-band applications (say, 2:1 frequency range) a
broadband 90-degree hybrid ought to work... Minicircuits sells some
such.

I'm not at all sure how to do this for an antenna intended to cover
everything from VHF low-band up to the 700 MHz end of the new UHF
channel range. This is more than a full decade of frequencies... is
there a single broadband 90-degree hybrid that can do the job?

It feels like it might be necessary to split the signals into multiple
bands (VHF / UHF at least, possibly VHF-low / VHF-high / UHF) and then
do the phase shifting on each band individually and then recombine.
Pretty complex...

Or is there an approach I've missed?

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

"Jim Lux" wrote in message
...
Hal Rosser wrote:
"Cecil Moore" wrote in message
...
JB wrote:
Discone is vertically polarized and TV is horizontal. Results in a
15db or
more loss in signal.
How about a dual-discone mounted horizontally?
--
73, Cecil http://www.w5dxp.com

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?

Somewhat tricky..

Two crossed dipoles fed with the correct phasing is very close to that.

Check out "Lindenblad" or "turnstile"


A Lindenblad array (e.g. http://www.bbc.co.uk/rd/pubs/reports/1991-15.pdf
Page 9) can provide good circular polarisation over much of a sphere and is
a relatively complicated antenna to design if it is to match properly -
probably over the top for the stated application. But the turnstile, and
the Alford loop
(http://books.google.co.uk/books?id=1...sult#PPA123,M1
as used at DVOR stations), are simpler and can provide good omni patterns in
the horizontal plane and thereabouts for horizontal polarisation.

Chris