[TowerTalk] Tower grounds
jimlux at earthlink.net
Wed Jun 13 08:02:13 PDT 2012
On 6/13/12 7:46 AM, John Langdon wrote:
> I favor the strap over wire for lighting because of the larger surface area
> bang for the buck.
but surface area doesn't buy you anything for lightning or electrical
safety grounds. increasing surface area doesn't markedly reduce the
inductance. All it does is decrease the AC resistance (skin effect and
all that). And if you're in a corrosion prone environment, more surface
area is worse.
For transient protection, it's inductance that's important, not resistance.
For vertical antenna ground fields, AC resistance is important.
If you're building a AM (or topband) vertical antenna, then using strap
makes sense: kill two birds with one stone..
Or, if strap is mechanically more convenient. I'd rather drill holes
and bolt 1/16"x1" copper bar than the same cross section round wire.
> Also, there are really three grounds to consider: lightning, radio, and
> legal/building code ground.
> 73 John N5CQ
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