Total posts : 45366
No time to do a lookup right now, but there have been a number of discussions in the past about top hats. A top hat with ground radials is a very standard way of improving range in regular commercial or government installations. The NDB here at Friday Harbor Airport uses a 40′ antenna with both top hat (6 rods) and ground radials (12 @ 50′ each), gets out rock solid (the ADF receiver in the plane) for navigation purposes to about 35 miles on 25 watts.
Note: this is old technology, many here feel it was a waste of $$ to build a new one (to replace one torn down for building hangars). The new one is exactly like the old one, had to be built, wired, tested, and flopped over before the old one could be turned off and torn down….because the FCC and FAA will not authorize building or licensing ‘new’ NDB stations.
The local Ham Radio club has tentative access to the new one if no one bids a price on it, which they have a year to do. Nothing so far, so I think I can assume the club will get it to use for mountong new digital repeaters.
I am a member. If they set it up, I’ll negotiate for mounting space on it to get a microwave digital signal, hoping to send audio to other Part 15 AM installations in the middle of the island.