Although I've never had one apart, I believe the cap is attached to the radiating element. Also, I have never seen any fiberglass collinear antenna survive a direct hit. I have, however, seen folded dipole arrays survive a lightning strike.
Chuck WB2EDV ----- Original Message ----- From: "Doug Rehman" <d...@k4ac.com> To: <Repeater-Builder@yahoogroups.com> Sent: Monday, November 02, 2009 5:45 PM Subject: [Repeater-Builder] Lightning Rod (Bolt)? > Looking at some DB Products fiberglass radome antennas, they all have a > metal protrusion on the top cap; it looks like bronze perhaps. I presume > that it is some form of lightning mitigation device. Is this just a piece > of > metal in the cap, unattached to the internal antenna element? > > I'm curious as I need to mount a Maxrad 900 MHz antenna on top of a long > mast on the top of a tower. The tower takes a lightning hit about once a > year. The Maxrad is in PVC tubing and it'd probably be simple to add a > stainless bolt to the top of the antenna if it would do any good. > > The previous 3 antennas on top were Comet GP-15's. They have a thin metal > cap on the top of the radome. The first one took a pretty significant hit, > melting part of the cap and making a mess out of the antenna. The second > one > took a lesser hit, heating the element enough that it burned thru the > radome. The third strike was even less, just discoloring the fiberglass on > the top 8" of the radome. > > I know that I'd be better off with a DB Products antenna, but their weight > likely well exceeds the mast capability for a top antenna (where it needs > to > be). > > Thoughts??? > > Thanks, > DOUG > K4AC > > > > > > ------------------------------------ > > > > Yahoo! Groups Links > > > >
