Navies are known to use low frequency radio to send messages to submerged subs.

adrian_b 8 hours ago | parent | next [-]

This uses the same principle, but the traditional method required immense antennas and very high power radio transmitters.

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.

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raffael_de 9 hours ago | parent | prev [-]

But isn't torpedo steering still dependent on wire?

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XorNot 6 hours ago | parent [-]

The issue is it doesn't really matter and radio isn't much benefit: you get much higher bandwidth, better reliability, immunity to ECM, and fiber-optic wires in Ukraine are over 50km long.

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.

	▲	raffael_de 5 hours ago \| parent [-]
		fair enough but afaik torpedoes aren't tethered by a fiber optic cable like drones. it's a much thicker cable that possibly contains a fiber optic cable.