Grounding of Nearson SG104N-915 antenna

Where should I attach the grounding wire when installing this antenna on a fiberglass mast? The top U-bolt clamping it to the mast looks like a convenient spot, as it offers a place that ground connector could slip under locking washer and it adjoins the base.

Would this be a sufficient ground, or do I need to insert a coaxial lightning arrestor? The antenna will be mounted a couple of feet over my roof in Denver, Colorado. As my transmitter will be getting only 26dBm (~400 mw ) to the antenna, I am tempted to avoid inserting additional loss into the feed, if safe.

I claim no specific expertise in such matters, but a purpose-built lightning arrestor would seem prudent if you’re in a high-risk area. If your link budget is thin enough that you’re skating on the margins without it, variability in prevailing RF conditions would seem likely to give you spotty results regardless.

This said, a both/and solution might be worth considering if you’re at substantial risk for a direct strike. Lighting usually starts a half mile or better upward, so six inches at the end of the journey 'aint gonna make a lot of difference, and a puny gas tube arrestor isn’t going to keep nasties from getting at your gear in that case either. But I’d personally rather buy a new radio than have to deal with an insurance claim on a new house…