Fascinating...I've been reading how the Navy uses low frequencies to communicate with subs.

I don't think we can get a portable ULF controller box for our RC subs: The length an antenna needs to be reasonably efficient relates inversely to the wavelength it must send.

That's why one submarine communication facility in the US has an antenna over 200 km long.

(Plus, if someone started controlling RC boats with a ULF box, I'm sure the FCC would not be amused).

ULF/ELF signal bands have such penetrating power that antennae are buried in the ground; in fact, if the receiver antenna is aboveground, it picks up every little signal around, so they have to bury it to cut the noise.



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ULF can penetrate several hundred meters of seawater.

But the reach comes with definite considerations: A rate of--let's say one Herz--is one wave per second...meaning you can only communicate one bit per second ! If it your character set took eight bits to form each letter, you'd have to listen a minute and a half to receive "SURFACE NOW"

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ELF has less saltwater-penetrating reach than ULF: a few hundred feet, rather than a few hundred meters. But the signal rate is faster. ELF is used to beckon a sub to a shallower depth where it can receive a faster (shorter-wavelength) rate.