Here’s a short desciption of the antenna and the ground network:
There are 6 antenna towers, each 127 meters tall, with a total distance of about 2000m between tower no 1 and no 6. The six towers are oriented for best radiation towards New York, though, we have not seen any document that confirms this. The radiation pattern of the antenna is almost omnidirectional, with a slight increase in NW-SE direction and a slight dip in the NE direction.
Along the entire antenna there is a 500 meter wide ground grid and the coils at the towers 2-6 are connected to the ground grid via overhead lines, 100m out from the towers, 7 connections on each side from each coil (no connection near the coils).
At tower no 1 it is a bit different. The coil is connected to the alternator and it is the alternator that is grounded. The alternator is connected via overhead lines to the ground line in 10 points, 5 on each side. The connection points closest to the station building are roughly 100-200 meters away from the buildning so you can assume that there is no ground grid close to the station building. Instead, overhead lines have been supplemented with extra lines closest to the station, which can then be seen as an elevated ground plane that replaces the missing ground line there.
The radiant parts of the antenna are almost vertical at towers 2-5. At towers 1 and 6, the top lines that goes up/down at about 45 degrees, is giving ”useful” radiation.
Fredrik (with assistance from Ola Hernvall) / AlexanderSAQ