Quote:
Originally Posted by Brion Toss
I think your letter assumes ideas that are not accurate. The L-bracket should make no such electrical connection, except that from the juxtaposition of dissimilar metals, if I understand it correctly.
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It isn't often I can contribute here, so I welcome the opportunity.
It depends on the particular antenna. If the VHF antenna is a 20(ish) inch vertical with no coil at the bottom it needs an RF ground at the feedpoint (mast head). The RF ground may be 3 or 4 horizontal pieces (RF) grounded to the L-bracket (itself connected through the RF connector to the coax shield) in which case Brion's answer is correct. Otherwise a solid electrical connection to the mast is necessary to provide the RF ground; this is obviously not desirable from the perspective of connecting dissimilar metals and so those antenna should be discouraged. Some antennas (end-fed 1/2 wave in particular) don't need a ground plane at all (they are inherently balanced) in which case Brion's answer is again correct.
RF grounds and conventional power grounds (AC and DC) are not the same animal. Although I haven't done it myself, there is no reason one couldn't use some appropriately sized capacitors to form the RF ground connection between L-bracket and mast. In practice one would still have to consider the metals in the capacitor leads which gets complex.
In my opinion the easiest, most flexible, and best performance antenna solution is a balanced end-fed unit. Regardless of the vocabulary that may be used in the installation instructions of the antenna it should be clear if a feedpoint ground connection is required.