I have a tower with a CB antenna on it and also a scantenna and TV antenna...My Question is, The tower is 4' in concrete and in the ground....in a 4' by 4' square of concrete....DO I need to ground each antenna to the tower (or will this drown out the signal) or do I just need to ground the tower from the tower leg to an 8' grounding rod or will it be fine just like it is since it's already 4' in the ground in a 4' X 4' square of concrete...I never grounded it before but for lightning purposes I'm fixing to do it if it's not too late...Anyone have any ideas?
I'm going to throw this in, I've looked everywhere and can't seem to find them but I've ordered one before so I know someone has them out there somewhere, but I'm looking for a BNC female to BNC male adapter to go on my pro 97...I looked on universal radio and on testparts and I couldn't find them either place, does anyone know where to find them at online?
Its easy to be confused by what "grounding an antenna" means. The antenna itself is always electrically isolated from the tower and any mast, mounting bracket, stand-off, etc. That is for RF-purposes it is electrically isolated -otherwise it could not radiate, it would simply drain down the tower as you suggested. However the common design of a DC-ground antenna does allow DC to pass from the antenna through the mounting systems and to earth. That's no protection system at all because lighting is predominantly at RF frequencies, and "static electricity" isn' all DC either. Just a gimmick that might spare the antenna itself from vaporizing in a direct attachment. All antennas have some kind of mounting design, and the only thing to avoid is isolating that mounting system from the tower. If you insist on using non-conductive extension materials to mount the antenna, then a bonding conductor from the antenna base-mounting fixture to the tower is required.
As mentioned above the coax shield does get bonded to the tower, and it usually happens at the feedpoint by virtue of the antenna mounting bracket (metal-to-metal contact from antenna mount where the coax connector attaches to the antenna, to the tower connection brackets). After that you have to make your own shield grounds at base of tower and building-entrance.
You asked if the concrete is a good ground. It is an excellent ground, and a 4'x4' concrete base has a hundred times more disspiation capability than three ground rods. However the 4' deep base is nowhere near deep enough to keep a majority of lightning energy from traveling horizontally outward fromn the tower base. Bad deal if this is right next to your home. Earth is a rather lousy ground in the first few feet of mostly dry soil and lighting takes a pass on shallow grounding systems because it saturates the first few feet of dirt (or concrete) so rapidly that the earth cannot hold any more energy at that immediate area. That's why the 8' deep ground rods (three at a minimum) are specified, even when a deep concrete base is present.
Finally, all tower and coax-shield gronding must bond directly to the building's AC-entrance ground rod, which should be at the same entry-point and common grounding location for all utilities entering the structure. By code-design all coax would enter the building there also, but we often enter coax at different parts of the home - at our own peril. Extensive bonding, grounding, and powerful AC surge-protection is required at both ends when coax enters a building far from the main AC entrance. It is the most difficult and expensive kind of protection design, because there are essentially two "single point grounds", one at the coax-entrance, and one at the home's AC-entrance. Lightning could have a field-day with that condition, and it takes a lot of copper to raise the odds that it won't.