I'm building a full-size quarter-wave 20m vertical antenna (approx. 18 feet long, plus a trio of Hustler mobile resonators at the top to add 30, 40, and 80 meters). To make the top 12-14 feet stiff enough to survive random 40-50mph (non-sustained) wind gusts from daily summer South Florida thunderstorms, I'm planning to "double up" the aluminum tubing for the portion for the top 12 feet (basically, making the element from three 6-foot 3/4" diameter tubes, joined together and strengthened on the inside with snugly-nested 5/8" tubes offset by 50% from the outer tubes).
Should the "inside" tubes firmly butt up against each other, or should I try to separate them slightly to ensure that the gap between the inside tubes is always at least as great as any gap between the inside and outside tube?
Is it OK to drill a hole through (and perpendicular to the direction of) both tubes & secure them with a stainless steel nut and bolt that passes through both sides of both tubes perpendicular to their orieintation? Or would it be better to use a pair of shorter screws that are just long enough to penetrate the outer tube and dig into the inner one, without actually bridging all the way across?
I know that with DC, providing multiple parallel paths for current to flow is generally a good thing... but from what I've read, RF is "weird", and providing multiple parallel paths for RF to flow along the same antenna isn't necessarily desirable. But, I've also gotten the impression that with HF, there are literally so many things that can unpredictably go wrong to screw things up, it's almost futile to even bother worrying about the effect of things like one long perpendicular bolt penetrating from end to end vs two.