When I erected my tower, I took a hard look at grounding. Aside from the what my PE wrote about grounding the tower itself, I looked at NEC requirements. Because lightning currents are mostly in the MF to lower HF region (about 1 to 10 MHz), I resolved to use a ground bus near the rod: (click for bigly image) The 2" x 0.032" copper strips run a foot or so to the shack ground rod. The tower and its four ground rods are to the right. A 4 AWG solid conductor bonds the rods to the electrical service ground about 50' away. This complies with NEC, and effects a reasonably low-Z path to ground. Tom W8JI (in GA) has stated that his several TALL towers each receive multiple direct lightning strikes/year. And, he has yet to suffer any significant lightning damage. He's either VERY lucky or, he's doing something right.