Use the drawing (viewed as its own page)
Maybe I'm not getting it, but you seem to imply that there are things on your page to click
on to open in a larger window????

When I load the webpage there is not "Larger" link and the pictures on the webpage are too small to read.

Paul (KL7JG)



On Tue, 15 Jul 2003 17:06:25 GMT, Richard Clark wrote:

On Tue, 15 Jul 2003 09:25:07 -0700, wrote:

I'm not antenna adept, so in trying to read between the lines I have a few questions

Here is my ASCII art diagram....


XMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
M F
M F
M F
M F
M F
M F
M F
M F
GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGG

yup


M= metal strip.
X= corner where metal strip is bent.
F = feed
G = ground plane.


How is the feed setup?
If I am driving it with coax the ground braid ends at the ground plane and the center conductor goes
up to the FM junction point?

perfect



The strip is 1/4 wavelength off of the ground plane, but how long is it from the bend to the end?
How wide is it?

What frequency did you build it for?

How did it work?

Paul KL7JG


Hi Paul,

Total radiator length (M) is ¼ wavelength (approx).

Use the drawing (viewed as its own page) to print a copy and scale all
dimensions by wavelength. Do not presume any correction factors,
simply use one Meter to be one Meter (not 0.95 Meter) at one Meter
wavelength. I deliberately left the segments visible to aid in
scaling. You should be able to perceive that the structure folds at
roughly 0.04 wavelength, which is also the height above the ground
plane. The foreshortened width of the sheet metal is also on the
scale of 0.04 wavelength.

For your application at 900MHz be aware that even thin wire (as in the
feed) becomes significantly thick enough to change resonance and feed
resistance through slight geometrical variations. This is true for
any construction. That is why I provided the caution that it was
chosen (or discovered) by trial and error. Given the 10MHz wide 2:1
BW, discovery covers a lot of turf. By purposely using thick
components, this becomes less an issue. At these very short
wavelengths, it is a rather simple matter to build deliberately wide
resonant (low Q) structures.

73's
Richard Clark, KB7QHC