Corrected numbers for linearly segemented radials from Frank's latest NEC-4
model of one buried radial wire, compared to Reg's program.

Side by side with the NEC-4 data


This is how many dB down the current is as you move outward from the origin
of the radial.

Distance Reg NEC-4 (dB down)

1.0 m 2.5 1.3

3.5 m 8.7 4.4

5.9 m 14.9 8.7

8.5 m 21.4 10.0

9.7 m 24.4 23.8

Conclusion: the current drop along the radial is no where near as fast as
Radials3 predicts, therefore shortening the radials as much as the program
shows will increase losses significantly.

I find it VERY interesting, that at the full length of 10m, there is good
agreement between Reg's program and NEC-4.

If I were going to base my conclusions on this preliminary small sample, I
would say that Reg's program does not hold up for short radials. BL&E, W8JI
and now NEC-4 all indicate that there is no where near 20 dB of attenuation
in short radials. To confirm this isn't an odd case, a lot more runs would
need to be done with varying lengths and radial numbers...but I have to say,
it ain't lookin' good for Radials3 in terms of fairly representing the
rapidity with which currents diminish on a radial wire over its length.

Bottom Line:

For the present, the articles in QST, ARRL Handbook, Low-Band DX'ing and
W8JI's findings are the ones I would follow. The first three are all the
same study and that formula is based on BL&E. The following data are from a
spreadsheet I used to calculate the optimum length and number of radials
based on the above sources. I put the BL&E data in the spreadsheet as a
reference. The numbers are how many dB down the field strength was for a
given number and length of radials.

Brn/Lw/Ep



# Rad 0.137 wl 0.274 wl 0.411 wl
2 -4.36 -4.36 -4.05
15 -2.40 -1.93 -1.65
30 -2.40 -1.44 -0.97
60 -2.00 -0.66 -0.42
113 -2.00 -0.51 0 (Ref)


Here are a few runs for 80 meters of various numbers and lengths of radials
that should be within a dB or so of optimum (BL&E).(Based on the references
noted above) 3.7 mhz, 1/4 wave vertical. The formula is based on tip
separation at the perimeter. Too much separation increases loss, too little
wastes wire. All based on wavelenthgs, of course. I believe the maximum tip
separation recommended was .015 wavelength.

Available Wire # of Radials Length of Radials
500' 25 19.7' (not within a dB, not
enough wire)
1000' 36 27.8' (not within a dB, not
enough wire)
1500' 44 34.0'
2000' 51 39.3'
3116' 63 49.0 (should be within 0.5 dB
of BL&E Optimum)

My final setup will be 46 radials 50' long. I have 26 right now. It looks
like for 50' long radials, I should really have 63 of them, otherwise, I
could have stayed at 51 radials only 39.3' long. All this says is that I'm
not making the "most" out of the available wire I had. (which makes sense,
given I've added radials over time, and didn't have a final plan).

At this point, it looks like when copper prices drop, I need to get another
850' of wire and put in 17 more radials and I will have met the criteria for
the formula. (Be within 0.5 dB of maximum field strength according to BL*E).

If anyone wants a copy of the Excel spreadsheet, just email me and I'll send
it to you as an attachment.
Only two variables should be entered: Total length of available wire and
Frequency in Mhz. Everything else is calcuated.( I did not protect any of
the fields, so if you enter data into a calculated field, you'll have to
reload your spreadsheet from a non-messed-up one...so save a virgin copy
somewhere until you protect the appropriate cells.)

73,

....hasan, N0AN