"Dave" wrote in message
news:muPbi.10807$Ar5.10317@trndny01...

"Tom Ring" wrote in message
. ..
amdx wrote:
I'm comparing elevation plots of an antenna. They have different
forward gains, this makes it difficult to compare the lobe shape.

Is there a way to equalize the gains to do a comparison?


Example: I have an antenna that is -19dbi and one that is -23dbi.
Can I add 4db of gain to one to make the comparison easier?
Mike



I am wondering what type of antenna has -19 or -23 dBi gain. I would
speculate that they are quite omnidirectional, and the patterns wouldn't
be significantly different.

It's tough to get gain that low unintentionally. If they are commercial,
could you please point me at a web site? I'd love to see why they made
these.

tom
K0TAR

but 0dBi would be perfectly omnidirectional by definition.
Yes.
either he is reading the scale wrong
No.
or is looking at f/b ratio instead of gain,
No.
or maybe looking at depth of a null or sidelobes.
No.
Mike

"amdx" wrote in message
...

"Cecil Moore" wrote in message
et...
amdx wrote:
I'm comparing elevation plots of an antenna. They have different
forward gains, this makes it difficult to compare the lobe shape.

Is there a way to equalize the gains to do a comparison?

Example: I have an antenna that is -19dbi and one that is -23dbi.
Can I add 4db of gain to one to make the comparison easier?
Mike

Under 'Desc Options', under '2D Misc', under 'Outer Ring',
you can set the gain of the outer ring to -19 dBi for
both antennas.
--
73, Cecil http://www.w5dxp.com

Thank you Cecil, I'll give that a try.

I tried it Cecil, that only changes the scale of the plot, both antenna
patterns just move there relative positions.
I need to add gain to one pattern or subtract from the other and put them
on the same plot.
Thanks, Mike

amdx wrote:
I tried it Cecil, that only changes the scale of the plot, both antenna
patterns just move there relative positions.
I need to add gain to one pattern or subtract from the other and put them
on the same plot.

I guess I don't understand what you are wanting
to do. Is -19 dBi and -23 dBi the maximum gain
for each respective antenna? Or is that just some
point you want the radiation patterns to have in
common?
--
73, Cecil http://www.w5dxp.com

"Cecil Moore" wrote in message
et...
amdx wrote:
I tried it Cecil, that only changes the scale of the plot, both antenna
patterns just move there relative positions.
I need to add gain to one pattern or subtract from the other and put
them
on the same plot.

I guess I don't understand what you are wanting
to do. Is -19 dBi and -23 dBi the maximum gain
for each respective antenna?

Yes.

I want the maximum gain point of each antenna to
reach the same point on the plot.
As if I put a 4db amplifier on the -23dbi antenna.
Thanks, Mike

amdx wrote:
I want the maximum gain point of each antenna to
reach the same point on the plot.

If the two antennas have different take-off-angles, that
will require a graphics program capable of rotating one
of the graphics by n degrees.
--
73, Cecil, w5dxp.com

"Cecil Moore" wrote in message
et...
amdx wrote:
I want the maximum gain point of each antenna to
reach the same point on the plot.

I should have said " I want the maximum gain point of
each antenna to reach same db level on the graph."
Sorry about that confusing line.

If the two antennas have different take-off-angles, that
will require a graphics program capable of rotating one
of the graphics by n degrees.
--
73, Cecil, w5dxp.com

I have put a picture on abse to show what I want.
Subject Line: Two Flag Patterns.
Thanks, Mike

amdx wrote:
I have put a picture on abse to show what I want.
Subject Line: Two Flag Patterns.

I doubt you can do that within EZNEC. It will probably
require generating two graphics and superposing them -
which you can accomplish by changing the reference gain
of the outer ring in EZNEC and using, e.g. MS Paint
for the superposition.
--
73, Cecil, w5dxp.com

"Cecil Moore" wrote in message
et...
amdx wrote:
I have put a picture on abse to show what I want.
Subject Line: Two Flag Patterns.

I doubt you can do that within EZNEC. It will probably
require generating two graphics and superposing them -
which you can accomplish by changing the reference gain
of the outer ring in EZNEC and using, e.g. MS Paint
for the superposition.
--
73, Cecil, w5dxp.com

I'll give that one a try.
Thanks again, Mike

"amdx" wrote in message
...

"Cecil Moore" wrote in message
et...
amdx wrote:
I have put a picture on abse to show what I want.
Subject Line: Two Flag Patterns.

I doubt you can do that within EZNEC. It will probably
require generating two graphics and superposing them -
which you can accomplish by changing the reference gain
of the outer ring in EZNEC and using, e.g. MS Paint
for the superposition.
--
73, Cecil, w5dxp.com

I'll give that one a try.
Thanks again, Mike

Hey Cecil, That does exactly what I wanted, although not
in the program I wanted.
Thanks, Mike

Kinda thought so! got copy of THAT loop antenna-
Lots of loss, but abt 28 dB F-B ratio (great for
eliminateing stations off the back, and , as stated
very broadband! And the model at 12 mhz, did to
1.8 MHz , also 28 MHz- swr is flat (20:1)!, but
the directivity is seems to be flat,too. An
interesting antenna. Tks to Bill W5WVO for the
model! But the
4 db diff (on the angles of "radiation", probably
mean little on a change of pattern.maybe 2-3
degrees! (3dB points)! Definately NOT for trying
to xmit to! But with a 20 dB preamp looks like a
great recieve antenna! Jim NN7K


Example: I have an antenna that is -19dbi and one that is -23dbi.
Can I add 4db of gain to one to make the comparison easier?
Mike

I'm modeling a Flag antenna.
It is a directional antenna.
Small size for the low bands.
Btw, this site has one that has -43dbi gain.
http://taliaphoto.com/n4is/BIG_DUAL_LOOP.html
I'd like to have one!
Mike