"Reg Edwards" wrote in message
...
If you are considering a new vertical antenna, instead of guesswork
and copying somebody else's un-thought-out efforts, download program
RADIAL_3 from website below.

The program assists with choosing an economic length and number of
shallow-buried ground radials. It takes a new look at how radials work
by considering them to be lossy, single-wire transmission lines,
open-circuit at the other end.

RADIAL_3 is a self contained file, 55 kilibytes. Easy to use. No
training needed. Download in a few seconds and run immediately.
----
.................................................. .........
Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
.................................................. .........



That is quite a bold statement and looks like trivilializing, ignoring the
real workings of vertical antennas and radials!

What would NEC4 say?

73 Yuri, K3BU

What would NEC4 say?

Who or what is NEC4?

"Reg Edwards" wrote in message
...

What would NEC4 say?

Who or what is NEC4?

http://en.wikipedia.org/wiki/Numeric...magnetics_Code

You need at least an odd number of 1/4 wavelengths to satisfy the boundary
conditions.
You need at least three to define a plane (or cone, if you want a 50 ohm
feedpoint)

73
H.
NQ5H

That is quite a bold statement and looks like trivilializing, ignoring the
real workings of vertical antennas and radials!

What would NEC4 say?

73 Yuri, K3BU

NEC 4 produces significantly different results. I can provide NEC code
and NEC 4 output files if anybody is interested.

73,

Frank
(VE6CB)

Frank,

How about posting a summary of them, for my example in an earlier post (I
listed all the input values for Reg's program). I'd LOVE to have the data
for my measurement verification!.

If you need the my values I can send them to you for a run. I'd be very
excited to see what NEC-4 says, and use them to validate my measurements.

73,

....hasan, N0AN
"Frank" wrote in message
news:NTLvg.147445$771.19250@edtnps89...
That is quite a bold statement and looks like trivilializing, ignoring
the real workings of vertical antennas and radials!

What would NEC4 say?

73 Yuri, K3BU

NEC 4 produces significantly different results. I can provide NEC code
and NEC 4 output files if anybody is interested.

73,

Frank
(VE6CB)

Frank,

How about posting a summary of them, for my example in an earlier post (I
listed all the input values for Reg's program). I'd LOVE to have the data
for my measurement verification!.

If you need the my values I can send them to you for a run. I'd be very
excited to see what NEC-4 says, and use them to validate my measurements.

73,

Hasan,

I ran a sample model from Cebik's 2nd book, and compared it with results
from Reg's program. The antenna used in the example is a 160 m vertical,
with
four buried radials. The height of the vertical is 40 m, and the radial
lengths
are 40.95526 m. The diameter of the vertical section is 25 mm, and the
radials
2 mm. Ground Er = 20, and conductivity 30.3 mS/m (33 ohm-m). The radials
are buried 0.163821 m (0.001 WL). The test frequency is 1.83 MHz.
NEC 4 shows in input Z of 47.2 + j 14.44 ohms. Max gain 2.11 dBi at
17 degree elevation angle. At the moment I have not figured out how
to obtain the total radiated power from NEC, other than the numerical
integration of the normalized far field data. For a symmetrical pattern
this is fairly trivial using Excel. The model does not include copper
losses,
so this should be added for accuracy. Reg's program computes the
input impedance as 30.35 - j 53.1.

I think I have all the data for your antenna from your previous post. There
may be some difficulty in actually running it in NEC 4 with the parameters
you have provided. The depth of the radials is so small (1mm), in relation
to the wire diameter of 4 mm. Wire junctions must occur at Z = 0,
and the wire diameter must be less than the segment length, which
obviously cannot be met. Also segment length tapering would be
required in order to keep the number of segments at a minimum, and
avoid excessively long run times. In effect your radials are close enough
to be considered laying directly on the surface of the ground. Cebik
does imply this is acceptable in his book, but on his web site
states that NEC 4 becomes unstable with wires in the region of Z = 0.
I assume this also applies to wires below ground. Under certain
conditions wires can approach the ground to within 10^(-6) Lambda
(about 0.1 mm at 3.62 MHz). Based on these constraints I could
develop a model, which will probably be close enough.

73,

Frank