Do these exist?
If so...
* Does anyone have any web references/normal references (primarily for
VHF/UHF)?
* Would it not be easier to manufacture a yaggi looking antenna (with slots
instead of elements)
using a single sheet of metal and stamping machines?

In article , "noone" writes:

Do these exist?
If so...
* Does anyone have any web references/normal references (primarily for
VHF/UHF)?
* Would it not be easier to manufacture a yaggi looking antenna (with slots
instead of elements)
using a single sheet of metal and stamping machines?

Probably not. Commercial slot antennas are usually done with
waveguide for directivity and gain.

The Commercial Aviation section of RCA EASD in Van Nuys, CA,
was making X-Band aviation weather radar antennas using slotted
waveguide in 1975. It was lighter and more rugged with no loss of
beam pattern accuracy as compared to the old parabolic reflector
made of fiberglass-epoxy with a gold-plated mesh inlay. In order to
make it you would need aluminum dip-brazing techniques at your
disposal.

In going on down to 70 cm ham bands, a Yagi could be made with
a single-foil-layer PCB. That could be made weatherproof with an
overlay of substrate board epoxied in place. Yagi dimensions
would have to be altered for the denser medium of substrate dielectric,
but that could be determined empirically.

Slot antennas have been made for high-performance aircraft. Those
do not protrude into the airstream. However, the slot would still be
on the order of a half-wavelength long; the conducting part of the slot
antenna is the rim of the slot. No "high gain" there, only a "negative"
form of a folded dipole, pretty much the same RF characteristics.

Slot antennas have been around for about a half century in various
forms and flavors. Their chief advantage is a physical one for certain
applications. Information is in textbooks specializing on the shorter
wavelength antennas, very little quantitative info on the web.

Len Anderson
retired (from regular hours) electronic engineer person

On Tue, 20 Jan 2004 10:57:40 +0800, "noone" wrote:

* Would it not be easier to manufacture a yaggi looking antenna (with slots
instead of elements)
using a single sheet of metal and stamping machines?

Note that a sheet of metal hanging in on the wall with a horizontal
slot will radiate _vertical_ polarisation.

If a horizontal yagi would be replaced with a long sheet of metal with
slots where the yagi elements are replaced with slots, the
polarisation would be in the direction of the original yagi boom. You
might get some kind of broadside array radiating upwards if the
distance between the slots are suitable.

Paul OH3LWR