Here's yet another resource that was posted a week ago if anyone's interested. Part of it makes a case for radials at the tower and ground rods at the shack, with the reasoning that lightning striking a tower will radiate horizontally when it strikes the earth. R56 seems to support this method, but it's probably way overkill for most locations, and I'm not sure if it's helpful for anything other than a direct strike.
I’m not sure where the idea of radials only comes from. R56 shows rods along a conductor ring surrounding a tower, and at intervals along the radials, and on the bonding conductor back to the shack. Also structure lightning protection systems per NEC use rods in a similar way.
I’m not sure if that’s what he meant, but you’re right, every lightning protection radial installation I see involves rods as well, and maybe a ring. I’m guessing they all contribute, but the radials are doing the heavy lifting.
I’m not sure about that. Lightning spectrum is kHz to UHF but most of the energy is 1 MHz and below so skin depth would be large, plus soil constants range all over the place. It may be that the higher frequency components are more at the surface where the radials dissipate the energy into the soil, while lower frequency components are dissipated by the rods into the soil along their length. I’ll try to find some information on it.
