73 KHz band propagation...

[Externet]

Hi.
Many years ago, found about 5cm diameter loooong steel? cables at the bottom of a bay while diving. I was told it was part of an abandoned "cable" ¿? communications system from WW2.
Were those the actual radiating elements for undersea communications, or a 'ground plane' net for a shore mounted antenna ? Or, what was their function ?

How to calculate a ferrite rod or iron rod wound antenna coil to resonate at 73 KHz, embedded in an epoxy sealed enclosure, submerged in the sea ?
A resonating capacitor to such wound coil should better be in series or in parallel to the coil for longer range ?

 

[biff44]

it is possible. those low frequency antennas were huge! They put them in the middle of the country now, where they can take up a couple square miles with the antenna grid.

It also could have been some sort of submarine detection net...submarines are big hunks of steel, and can be detected magnetically