Yeah, my basic understanding of submarine communications is that lower frequencies penetrate the water better. Lower wavelength needs a longer antenna. The system US subs use is a very low frequency from what I understand.
> TACAMO (take charge and move out) is the back up communications system to the US nuclear submarine fleet in case an attack on land based transmitters disables them. A rotating fleet of Navy E6 jets equipped with 200 KW transmitters and two 2½-mile-long trailing wire antennas (TWA) at 35,000 ft altitude to provide 24/7 coverage. Short pings are transmitted every few seconds.
Regarding "longer antenna" for submarines... -- I recently learned about this signal from https://www.sigidwiki.com/ -- which has been helpful to ID all the fun stuff you can see with RTLSDR
The cost of that must be insane - the price tag of being about the only military force on this rock capable of projecting force and delivering utter devastation 24/7/365 any place any time even if the entirety of the US got glassed.
