Naval tech researcher Spawar has figured out how to use a jet of seawater as an antenna. By squirting a measured length of saltwater through a “current-probe”, various antennae can be formed which will transmit and receive radio-waves on the UHF, VHF and HF frequencies.
Why bother? Ships have limited space for mounting antennae, and these have to be carefully positioned so they don’t interfere with one another. A seawater antenna can be set up anywhere on deck with minimum effort and gear, and uses something that is in ample supply aboard a ship – gallons and gallons of the briny deep.
To turn a squirt of saltwater into an antenna, a jet is fired through a current-probe, essentially a metal donut which uses magnetic induction to transfer the signals to the seawater. This is why it needs to be seawater – saltwater has magnetic induction properties not found in fresh water.
The frequency of the antenna is determined by the height of the water column, and several current-probes can be stacked up, with several different-length streams of water, to broadcast simultaneously on different bands. The big advantage is portability and quick setup, as you don’t need any long metal poles.
Will we see our backyard fountains turned into antennae? Probably not, but it is possible to do. And if you mix your own saltwater you can fire the stream up and enclosed plastic tube, recycling it so you can use one on dry land, although if you have to carry the tube, you may as well just carry a regular antenna. And who knows? Given the all the problems of antennagate, maybe the iPhone 5 will come with it’s own super-soaker-style aerial?
Sea Water Antenna System [Spawar via George Lazenby. Yes, that George Lazenby]
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