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