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

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

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

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