"You can't do it with current technology, radio waves do not penetrate water. "
They can so too.
Han, I read your post and then thought :"What the hell does the US Submarine VLF Communication Base at Learmonth, WA, do?" ...... besides make WA a nuclear target in case of war?
That's been operational for ages.
So VLF and ELF CAN communicate TO submarines while submerged, but not receive because of problems as below.
So you were Half right.
"
Very low frequency
VLF radio waves (3–30
kHz) can penetrate seawater to a depth of approximately 20 meters. Hence a submarine at shallow depth can use these frequencies. A vessel more deeply submerged might use a
buoy equipped with an antenna on a long cable. The buoy rises to a few meters below the surface, and may be small enough to remain undetected by enemy
sonar / radar.
Due to the low frequency a VLF broadcast antenna needs to be quite large. In fact, broadcasting sites are usually a few square kilometres. This prevents such antennas being installed on submarines. Submarines only carry a VLF reception aerial, and do not respond on such low frequencies. So a ground-to-submarine VLF broadcast is always a one-way broadcast, originating on the ground and received aboard the boat. If two-way communication is needed, the boat must ascend to periscope depth (just below the surface) and raise a telescopic mast antenna to communicate on higher frequencies (such as
HF,
UHF or
VHF).
Because of the narrow
bandwidth of this band, VLF radio signals cannot carry
audio (voice), and only transmit text messages at a slow data rate. VLF data transmission rates are around 300 bit/s - or about 35 8-bit
ASCII characters per second (or the equivalent of a sentence every two seconds) - a total of 450 words per minute. Simply shifting to 7-bit ASCII increases the number of transmitted characters per time unit by 14%. An additional shift to a 6-bit or a 5-bit code (such as the
baudot code) would result in speeds of more than 600 and 700 words per minute."
And then there is ELF, still only one way, but down to operating depths.
https://en.wikipedia.org/wiki/Communication_with_submarines
GZ
