On Tue, 15 Jul 2003 11:56:58 GMT, Dale Parfitt wrote:


Is it my browser or are the images on that page next to useless? I could
not figure out the antenna's configuration, or read the graph ordinates?
Text was less helpful.
Is there another site that discusses this antenna Richard?

Dale

Hi Dale,

Graphics straight from EZNEC which has served this group for years.
Select any graphic and simply ask the browser to view that page. If
you are unfamiliar with the drawing conventions I would suggest
getting the free version and becoming adept. The SWR drawings show 40
data points quite clearly between 440 and 460 (every 0.5MHz) no more
resolution is required, there are no surprise resonances hidden
between data points.

This is a very simple antenna, the description of the main radiator:
"This is a low, long antenna roughly quarter wavelength from the
ground point, up to the bend, out to the end. The drive point was
found by trial and error."
is quite explicit but I already admit may be confusing, thus the
attending illustration. There is only one ground, there is only one
bend, there is only one feed. The name describes it as well:
"Inverted F" The letter F certainly is descriptive. The only
embellishment is that it is constructed with a sheet rather than a
wire, but both sheet and wire models' SWR are also shown and
discussed:
"Because of the sheet metal form, this qualifies as a thick
radiator. The SWR curve on the left confirms this when compared to
the SWR curve below."
"This is the SWR curve for a one wire model of the design modeled
here."

The design couldn't be simpler for those already adept at building
grounded verticals with a gamma feed - and without the cap of the
gamma feed. The vertical is simply folded over at the feed.

73's
Richard Clark, KB7QHC