Vertically Polorized Omni Slot Antenna
 

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

Vertically Polorized Omni Slot Antenna
 

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

Vertically Polorized Omni Slot Antenna
 

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

Vertically Polorized Omni Slot Antenna
 

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

Vertically Polorized Omni Slot Antenna
 

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

Vertically Polorized Omni Slot Antenna
 

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

Vertically Polorized Omni Slot Antenna
 

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

Vertically Polorized Omni Slot Antenna
 

"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

Vertically Polorized Omni Slot Antenna
 

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

Vertically Polorized Omni Slot Antenna
 

wrote in message
oups.com...
So I guess the annular slot is the complement to a halo?


Since I think of a halo as a loop in a plane parallel to the ground, it is
difficult for me to make a comparison of it to a monopole antenna pattern.

My suggestion would be for you to re-define your needs. There are some
really good antenna designers contributing to this group.

Vertically Polorized Omni Slot Antenna
 

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

Vertically Polorized Omni Slot Antenna
 

On Mon, 17 Apr 2006 13:56:19 -0500, "Hi" no@spam wrote:

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

One can be made, but the slots have to be
oriented at a slant on the waveguide. The
trick is to make alternate slots radiate
the horizontal component of their slanted
polarization out of phase but have the
vertical component radiated in-phase. This
is a bit tricky and requires a detailed
knowledge of the standing-wave pattern inside
the waveguide at the frequencies of interest
(and therefore is left as an exercise for the
student).

Jim, K7JEB

Vertically Polorized Omni Slot Antenna
 

I'm not the one designing the antenna. I'd build a collinear. I'm
just interested in the properties of the annular slot.

What I mean by "I guess the annular slot is the complement to a halo?"
is this:

A halo as I know it is a half wave or so loop broken opposite the
feedpoint and in a plane parallel to the ground. It has an
omnidirectional azimuth pattern but radiates horizontally polarized
radiation.

It seems that the annular slot is a slot in a plane parallel to the
ground, with an omnidirectional azimuth pattern, and vertically
polarized radiation.

So, is an annular slot antenna a halo cut out of a sheet?

73,
Dan
N3OX

Vertically Polorized Omni Slot Antenna
 

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

One can be made, but the slots have to be
oriented at a slant on the waveguide. The
trick is to make alternate slots radiate
the horizontal component of their slanted
polarization out of phase but have the
vertical component radiated in-phase. This
is a bit tricky and requires a detailed
knowledge of the standing-wave pattern inside
the waveguide at the frequencies of interest
(and therefore is left as an exercise for the
student).

Do you know of any websites or books that might have further info on this?

Thanks.

Matt