Xale57 responding to your question about Bermuda:
I don't have much more to say, because WBZ, WFAN, WCBS, WABC, WOR, etc. signals cross land on the path to Bermuda. WBZ and WOR are directional.
btw- WBZ is a "textbook" cardiod, with reduced effective radiated power due east out to sea. This is not a mistake, because the power is redirected west towards land, resulting in a fantastic signal for WBZ.
You can go to FCC online public inspection files and view coverage maps. These are the maps I posted earlier in this thread.
Home - FCC Public Inspection Files
Predicted AM coverage contours are seen on many internet sites. Just be aware of the signal level value of the contours you are seeing.
schmave- I heard groundwave-skywave cancellation on WWL in Pensacola Florida on a visit to the area decades ago.
It was a "pull the car over to the side of the road" moment. This is why in earlier times, some clear channel stations were focused on adjusting antenna vertical elevation pattern to minimize groundwave-skywave cancellation in communities located in the area where this can happen.
This fits in with the Franklin antenna subject, because the Franklin antenna makes gain by modifying the vertical elevation pattern.
Just like a multi bay FM antenna. That is,
these antennas are directional antennas in the vertical elevation plane.
Thus, KFBK antenna is directional in azimuth (horizontal)
and elevation (vertical). This concentration of the signal results in huge coverage, and our fascination and admiration.