I already saw that link. There is no information about antennas in any of that online stuff.
There are some pictures of those old flat wire coil antennas on a flat board the old 1940s radios had those antennas to receive, what about the transmitter did they use the same FLAT coil pancake antenna. The pictures all look like a Tesla Coil power supply circuit without the primary & secondary coils. I figured out from looking at the pictures they are basically an old Model T ignition coil wired so the telegraph key turns the coil on/off.
I am surprised those CW transmitters had a range of 30 miles.
Another interesting thing, when the spark gap gets hot it will not transmit, the spark gaps had to be kept cool with a fan, then rotary sparks gaps were invented. LOL. the rotary spark gap was advancing technology.
Just think about how primitive technology was then, enamel coated copper wire had not been invented yet. Someone learned how to make carbon rods to make better spark gaps. It is hard for me to imagine how primitive ALL technology was in those days. Every thing was made with brass and cast iron, very primitive steel had just been invented.
All technology is limited by other technology they all need to advance at the same rate.