Any new knowledge usually goes through three stages: 1. "Nonsense!" 2. "And if really …" 3. "Who doesn't know that!"
Reliable and high-quality radio communication plays an important role in ensuring the safety of navigation and for the successful conduct of hostilities. A group of specialists from the scientific division of System Center Pacific, Space and Naval Warfare (SPAWAR), engaged in research in the field of radio communications, radar, meteorology and oceanography in the interests of the US Navy, proposed an original solution to the problem of congestion of ships with communication systems.
The radio-electronic equipment of a modern combat ship of the "Arlie Burke" type includes about 80 antennas for various purposes. Receiving and transmitting devices create numerous mutual interference during operation - engineers required special studies to determine the scheme of their rational placement. In addition, conventional ship antennas have a number of disadvantages - they are bulky, heavy, easily vulnerable in battle and during a storm, they require high masts, which increases the ship's radar signature. At any given time, at least half of these antennas are turned off and not used, hence the conclusion that it is necessary to create foldable structures suggests itself.
In 2007, SPAWAR specialists developed a technology that uses electrical conductivity and magnetic induction of metal salts contained in sea water to receive and transmit radio waves. Indeed, if sea water is a good electrical conductor, then why is a liquid jet not capable of replacing a traditional metal antenna? An absolutely ingenious and simple invention.
From theory to practice, there was only one step: with the help of a water pump, the researchers assembled a primitive fountain - a device spewing a stream of seawater through an inductor connected to a portable transmitter. There is plenty of water outside the ship, so no one will experience a shortage of this consumable. Signals are transmitted and received from the "water antenna" by means of conventional electromagnetic induction. And no nanotechnology!
The jet height determines the frequency to which the antenna is tuned. For example, UHF radio waves require a fountain about 2 feet (0.6 meters) high, and VHF 6 feet. To receive HF waves, you will need an 80 foot column of water (24 meters!). Such a jet is capable of receiving and transmitting signals in the range from 2 to 400 MHz. The section of the jet determines the width of the channel (i.e. transmission of more voluminous data, for example, video will require a thicker jet of water). The entire system fits in one hand. With its help, SPAWAR researchers were able to receive a clear signal at a distance of several tens of kilometers.
The advantage of such "water antennas" is the minimum space required for their installation. The antennas can be easily modified for use at any frequency by installing additional collector coils and spray nozzles. The water antenna can be formed at a minimal cost - the device consumes less power than a table lamp.
Unlike standard metal antennas, all elements of the water antenna are practically weightless and easy to dismantle. The parameters of the water columns can be constantly changed depending on the types of antennas currently in use. According to SPAWAR experts, ten such antennas can replace 80 traditional ones. In addition, the reflective effect of sea water is less than that of metal, and if the ship needs maximum stealth, the commander just needs to give the order to simply remove all the water pillars.
At the same time, before introducing their invention into real life, researchers will have to solve a number of difficult problems.
For example, a water antenna is extremely vulnerable to gusts of wind - the energy of the jet to the top decreases to zero, and then even a weak wind will tear the antenna's canvas and, as a result, completely spoil its resonance characteristic.
SPAWAR scientists have again found an original solution: it is enough to enclose a stream of water in a plastic pipe with a closed top. This will not only prevent the harmful effects of wind and preserve all the properties of the "water antenna", but will also allow the same volume of water to be used repeatedly (the researchers believe that their technology can be used on land, replacing the protruding branches of the antennas with beautiful fountains). As for placing water in a plastic tube, the idea of SPAWAR is not new - such antenna options exist when a tape is placed in a flexible plastic shell, self-twisting under air or drive pressure, like a tape in a tape measure.
Also, it still remains unclear what is the gain of water antennas. Due to not the best conductivity of the "water column", the efficiency is likely to suffer, and out-of-band emissions are possible.
The principle of a water antenna is so stupid and simple that it is simply hard to believe that no one has guessed before. The SPAWAR pranksters must have spied this beautiful idea from the whales: according to some reports, the whales put out fountains to send each other SMS messages. I somehow communicated with them - they say the signal is weak, only 2 strips …
