yep, antenna theory where you put what seems to be a short circuit across a feeder but as it’s resonant its not a short circuit ???
the bit i find a black art is propagation
it fascinates me the difference in bands and range you can achieve at not only different times of day, but as the seasons change
the biggest mystery is grey line propagation, you can get silly places when either end of the path is an hour either side of sunset
there was an article about greyline propagation in RadCom this month