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Author Topic: Terminating Radial Ends with Nails  (Read 955 times)
K0BG
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« Reply #15 on: April 01, 2009, 10:06:13 AM »

I can't attest to the nails increasing the effectiveness of the radials, but gutter nails work fairly well to "stake" down the ends when you're laying they out.

Alan, KØBG
www.k0bg.com
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KJ4DIS
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« Reply #16 on: April 01, 2009, 11:45:46 AM »

Sevick's radials were laying on the ground and were terminated in "large nails" for mechanical reasons. His soil is classified as average to slightly above average in conductivity. He ran tests to determine if the length of the spike had any effect on the antenna efficiency (i.e., ground resistance). He used 1/4 wave verticals for 20m and 40 m. The radials were 4 and 8 ft long (1/16th wavelength). His graph indicates an efficiency of 50% at 20m with four 4ft radials with no termination. The efficiency increased to about 62% with 6 inch spikes, about 65% with 12 inch spikes, and about 68% with 18 inch spikes. Similar increases were shown for 40m and eight 8ft radials.
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K5DVW
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« Reply #17 on: April 01, 2009, 12:33:08 PM »

That seem overly optimistic. I dont know what he means by efficiency or how he measured ground loss, but 50% system efficiency with only 4 radials at 1/16 wavelength seems WAY too good based on data I've seen.

Field strength in the far field would have been a better way to catagorize this than effiency.
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AA4PB
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« Reply #18 on: April 01, 2009, 12:46:04 PM »

With a 4-foot radial a 12-inch spike increases the total length by 25%! I wonder what would have happened if the spikes were just layed on the ground like the wire in lieu of being driven into the ground or if the radials were just increased to 5-foot.

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W4VR
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« Reply #19 on: April 01, 2009, 01:14:07 PM »

LaPort does say in his book that with short radials adding ground rods at the far end of each radial increases efficiency, but this is at AM broadcast frequencies.  As LaPort states, and you may want to try this simple test, "If the radials are of optimal length, sufficient to have zero current as one approaches the end of the wires, there is no need to add ground rods.  The test for the desirability of ground rods, is to drive one ground rod, connect one of the radials to it, and measure the current distribution along the wire up to the end.  If it is evident that any appreciable current exists at the end of the wire in using the ground rod, their desirablility may be indicated.  The same applies to the use of a circular bonding wire around the periphery of the system.  It is only when the lengths of the radials are insufficient that there is justification for using peripheral bonding and ground rods."
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