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Old February 6th 05, 01:42 PM
 
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Default SUPER J-POLE BEATS YAGI BY 1 dB

Hi,

Well, our Super J-pole:
http://users.marktwain.net/aschmitz/...jpolecalc.html


Is beating our Yagi in ALL directions,
even in the forward lobe!


Here is the theoretical H-plane plot of our Yagi:

http://www.drslick.org/Temp1/yagiplot.jpg

And a photo:

http://www.drslick.org/Temp1/yagi929.jpg



So if you assume the theoretical
2.5 dBi of a regular J-pole, then the Super
J-pole has about 3 dB over that, so about
5.5 dBi all around.

So we have about 4.52 dB in the
forward lobe of our Yagi, so even there,
we beat it by about 1 dB with the Super
J-pole. That's like 238 watts versus
300 watts.
It's even worse in the back
lobe, where it's a -12 dB difference.
That's like 19 watts versus 300 watts!

It's only a theoretical
yagi optimization plot, and i don't think
it sounded like 19 versus 300 watts in the
back, but it's a BIG difference, even in the
areas that were already strong....almost
full quieting.

And yeah, we didn't really optimize
the yagi for a strong, narrow lobe...it was
designed for a 180 degree pattern, so the
gain ain't great, but you still have some
control over directivity. It's still
not really a fair comparison.

At any rate, if you need an
omnidirectional, i highly recommend the
Super J-pole!

Here's another site if you are
interested:

http://www.geocities.com/n2uhc/jpole.html


Questions and comments appreciated!

Dr. Slick