This is a horizontally powerized omni slot antenna.

http://tinyurl.com/kbwkf

Does anyone know if its possible to make a vertically polerized omni slot
antenna?

Matt

If I recall correctly, nope.

A vertically polarized slot antenna will have an azimuth pattern like a
dipole.

If you want a vertically polarized omnidirectional antenna, you build a
collinear array of vertical elements. If you want a horizontally
polarized omnidirectional antenna, you build a collinear array of
everything EXCEPT those elements, and feed that. A slot radiates the
same way that an antenna element of the same size and shape would
radiate, but the E and H fields are interchanged, and therefore has the
opposite polarization.

Look up Babinet.

73,
Dan
N3OX
www.n3ox.net

If I recall correctly, nope.

A vertically polarized slot antenna will have an azimuth pattern like a
dipole.

I was thinking if the slots were cut horizontally rather then vertically.
Won't work?

Matt


If you want a vertically polarized omnidirectional antenna, you build a
collinear array of vertical elements. If you want a horizontally
polarized omnidirectional antenna, you build a collinear array of
everything EXCEPT those elements, and feed that. A slot radiates the
same way that an antenna element of the same size and shape would
radiate, but the E and H fields are interchanged, and therefore has the
opposite polarization.

Look up Babinet.

73,
Dan
N3OX
www.n3ox.net

It will be an antenna, it will be vertically polarized, but it won't be
omnidirectional. It will look just like the familiar horizontal dipole
pattern.

-Dan

On Mon, 17 Apr 2006 14:34:44 -0500, "Hi" no@spam wrote:

I was thinking if the slots were cut horizontally rather then vertically.
Won't work?

Hi Matt,

No, it won't.

73's
Richard Clark, KB7QHC

I was thinking if the slots were cut horizontally rather then vertically.
Won't work?

Hi Matt,

No, it won't.

Thanks for the response. Any sort of waveguide based antenna that will work
as vertical omni?

Matt

On Mon, 17 Apr 2006 18:08:39 -0500, "Hi" no@spam wrote:
Thanks for the response. Any sort of waveguide based antenna that will work
as vertical omni?

Hi Matt,

You are bucking the dominant waveguide mode with the design you've
found. Turning the slots will kill it. Just turn the design you've
found sideways.

The alternative is you choose a larger waveguide and introduce iris
apertures inside the waveguide to force a mode that would allow turned
slots. This is all in presumption that you want a vertically oriented
fixture (taller than wide) to give you vertically polarized signals.

Other options include horns and truncated parabolic reflectors - or
something as simple as a 90 degree sweep with a small flared opening
for matching. This would no longer make it omni though.

73's
Richard Clark, KB7QHC

Wow, Matt, that must be close to a record: three uses of "polarized"
and they are all spelled differently (and all, um, 'non-standard').

A vertical slot antenna is horizontally polarized. A horizontal slot
antenna, while vertically polarized, emits in a standard dipole azimuth
pattern. You could try a pair of crossed horizontal slot antennas, fed
90 degrees out of phase, like the "turnstile" crossed dipole antenna.
(I don't see how you would actually do it, but you could try.) But why
bother, when it's easy to make an omnidirectional vertically polarized
antenna in other ways? I'm not saying there couldn't be reasons for
doing it, but please let us know what they are.

Cheers,
Tom

"Hi" no@spam wrote in message ...
This is a horizontally powerized omni slot antenna.

http://tinyurl.com/kbwkf

Does anyone know if its possible to make a vertically polerized omni slot
antenna?

Matt

Hi Matt

You probably want an antenna with an omniazimuth, vertically polarized
pattern and some elevation plane narrowing, ie Gain
It is very easy to build a flush mounted antenna that has the radiation
pattern shape equivalent to a quarter wave monopole. Although that would
satisfy the specs you have presented, I doubt the broad elevation plane
pattern is what you are looking foe since the kbwkf site shows antennas with
gain.

Search on Annular Slot for info on a flush mounted antenna with the
vertically polarized omniazimuth antenna.

Jerry

So I guess the annular slot is the complement to a halo?