I simply use a grounding clamp on the antenna mast, then run a #10 AWG copper wire to the electrical service ground. Then I route the coax from the antenna, outside the building, to a point colse to the electrical service ground. There, I install a coax grounding block, which is connected to the electrical service ground via a short piece of #10 AWG copper wire.
I avoid adding a ground rod if possible. If I do add a ground rod, I run #6 AWG copper between the new rod and the existing electrical service ground. The earth can't be counted on as a low resistance conductor, the #6 AWG 'bond' ensures that the 'antenna ground' and the rest of the house wiring ground are the same voltage even if a fault is present.
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