Navies are known to use low frequency radio to send messages to submerged subs.
Such antennas and transmitters cannot be installed in a small submarine.
Here a new kind of antenna is used, which is efficient under water even at small dimensions, so it can be installed in small submarines, for communication at distances of up to a few hundred meter.
The exact application for this is autonomous underwater vehicles where what you would like to do is communicate quickly and without a tether in arbitrary scenarios - i.e. think a bunch of autonomous vehicles which might need to relay a message or communicate with dropped assets. Using radio in those scenarios solves the problem of a consumable (the wire), and also the problems associated with sonar like fouling of the array.
The point is a very thin wire had a surprisingly long range - versus this system which has a very low bitrate much past 1km.
For an active weapons system it's just not a great choice when you already have the wires and they work.
But for sensors or vehicle meshing, where you can't lay wires in advance? Potentially huge.