I have what looks to be a log periodic antenna design and I'm really confused with the connection to the longest element. Take a look here: **broken link removed** It's not this antenna. It is a VHF/UHF antenna.
For the most part, there is a square boom and each "half" of an element is connected in an array like structure, a connection for one side and one for the other side with an aluminum strap.
So picture, properly spaced elements a through whatever.
(top)
element a1 or (what I might call 1/2 an element)
Bus bar a1
insulator a1
aluminum tube (Boom)
insulator a2
Buss bar a2
element a2
(bottom)
Rivet 1, goes though all of the a1's and rivet #2 goes through all of the a2 sections with no connection to the square aluminum tube.
That's fine and dandy UNTIL we get to the longest element, then things get really wierd and don't make ANY sense at all.
This is where the antenna manufacturer takes one huge 3/16 rusty rivet and connects everything together and mounts the rivet head on the bottom. The connections to element a1, Buss bar a1 and bus bara3 and element a2 is a solid connection.
I enlarged the hole in the system from 3/16 (0.1875) to 5.1 mm (0.196) almost negligible to fit a 5 mm screw.
The thing is, that connection can ground the boom based on corrosion and shear luck (OEM and my version). Me thinks that the holes in the aluminum tube should be much much larger than the rivet to avoid that connection. The grounded boom should be Earthed because it is connected to the mast.
How did I run across the possible problem? I wanted to replace the longest element because it was severely bent.
I did make a special screw to insulate the boom. Is this the right way?