Roger, I think I understand your point, that there are nonsense tower grounds with a few ohms at DC that are useless for strikes. OTOH, I think a high DC resistance to "far earth ground" is not a pro
I've measured thousands of ohms between 8 ft rods that are only a few feet apart with a Simpson 260. 73, Jim K9YC _______________________________________________ _____________________________________
Do you propose that it is not necessary to achieve the recommended 5 to 10 ohms of resistance in a tower ground system? Recommended by who and for what purpose? What is your measurement technique to
Another factor not usually considered by hams is that conduction through the ground is NOT the same as conduction through a copper wire! A copper wire has a copious supply of free electrons and will
There are measurement techniques to see how a ground behaves under lightning type impulses, but they aren't exactly portable. If you get a ground that is acceptable by the NEC for AC safety that is g
There is no such thing as "RF ground." Radial systems work by SHIELDING a vertical antenna from the lossy earth, so that the fields (and the return current) flow in low resistance copper rather than
At lightning current densities and time scales the earth ionizes and rapidly increases its conductivity. See equations by Weck and others: http://www.ipstconf.org/papers/Proc_IPST2011/11IPST109.pdf N
Note in the graphs how the effective resistance of the ground decreases as the current increases. Very interesting.. (and, of course, there's about a 3:1 difference among the various models, which I'
Author: "Roger (K8RI) on TT" <K8RI-on-TowerTalk@tm.net>
Date: Mon, 11 Jan 2016 05:57:49 -0500
My thoughts on a ground system. When you go through the calculations, my current preference is based partly on these regs, calculations and experience. "I believe" a tower of any type should be plant
correct, on the time scales and current level of lightning the ionization of the soil rules. I could see a saturation effect being possible for DC, perhaps in cases where you are using the soil retur