三菱展示可将海水喷泉用作无线电天线的SeaAerial技术

说到无线电天线，大家第一时间想到的或许都是金属与电线。但如果说有人用水做出了天线，你信还是不信呢？2016年1月底，三菱电机（Mitsubishi Electric Corporation）向大家展示了通过将海水阵列喷到空气中来创建无线电收发天线的SeaAerial技术。这种设计据说是世界上首个能够接收数字地面电视广播的海水天线，适用于在海上或沿着海岸线部署。

在日常生活中，我们与之打交道的无线电频段相对强劲却很短，因而设备中的收发天线可以做到很微小。

不过随着无线电频率的变长、以及信号的衰弱，所需要的天线就长的多了，然而也这意味着打造此等规模的天线会非常昂贵、耗时、且难以搬运。

另一方面，如果可以把水当做材料，就可以轻松泵出“日内瓦大喷泉”（Geneva's Jet d'Eau）这等规模的天线了。

当需要搬动的时候，只需关阀断水，将电气组件搬到另一个地方即可。不过，为什么海水可以、纯水就不行了呢？显然，这与它们的导电能力有关。

纯水不含杂质，因此极难导电。但是海水中溶解有各种矿物离子，所以被当做是最方便、实用、完美的SeaAerial材料。

当然，海水部分并不是SeaAerial的重点。美国海军近年来对它产生了浓厚的兴趣，只是目前仍限于保持住跃出水面的喷洒装置，以免底部海水“短路”并影响到信号。

该公司称，喷嘴里面是一个用绝缘材料制成的1/4波长管，用以物理上隔绝周水和保持电路。SeaAerial设计的另一个要点是，虽然盐水可以导电、但毕竟还是比金属小很多。

换言之，海水天线的“效率”要比金属天线低得多。三菱称，通过运行计算机模拟，确定了理想的柱直径可让效率增加70%。

目前三菱正在尝试其他类型的新型天线材料（导电液体），并申请将SeaAerial作为注册商标。

[编译自：Gizmag , 来源：Mitsubishi]

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Mitsubishi's SeaAerial turns fountains into antennae

Mitsubishi's SeaAeriel could be used to create a water aerial tens of meters high, as illustrated by Geneva's Jet d"eau (Credit: Shutterstock).

When someone mentions a radio aerial, it tends to conjure up a vision of something made of steel and wire. But what about one made of water? On Thursday, the Mitsubishi Electric Corporation unveiled its SeaAerial, which uses a column of seawater sprayed into the air to create a radio transceiver antenna. Designed for use at sea or along shorelines, it's billed as the world's first seawater antenna capable of receiving digital terrestrial broadcasts.

In our day to day lives, we're used to dealing with radio frequencies that are so short and relatively strong that the transceiver antennae on our devices are correspondingly tiny. However, as radio frequencies get longer and the signals become weaker, the antenna has to be longer as well.

This fact of life means that many radio installations require very large antennae that are expensive, time consuming to build, and far from portable. On the other hand, if an antenna could be made out of water, you could have an aerial the size of Geneva's Jet d'Eau in the time it takes to fire up the pump. When it came time to move the installation, it would simply a matter of switching off the water and moving the electronics to another location.

But why seawater and not garden variety fresh water? Contrary to popular belief, pure water is a very poor conductor of electricity. It's the mineral ions dissolved in it that actually carry current, so for practical purposes, seawater works best for making a watery antenna.

The point about the SeaAerial isn't that it's aquatic. This isn't the first seawater antenna – the US Navy has taken a keen interest in the idea in recent years, but so far it's been limited by the necessity of keeping the plume-spraying apparatus out of the water to prevent the circuit from grounding in the sea and killing the signal. Mitsubishi's innovation is an insulated nozzle that transmits the radio signal to the saltwater plume. According to the company, inside the nozzle is a quarter-wavelength tube of insulated material that physically separates the plume from the surrounding water and maintains the circuit.

Another factor in the SeaAerial design is that, though saltwater can conduct electricity, it is much less conductive than metals, which translates into poor efficiency as an antenna material. Mitsubishi claims that by running computer simulations it was able to determine the ideal plume diameter – allowing for a 70 percent increase in efficiency.

Mitsubishi is currently working on other conductive and transmutative liquids as new antenna materials and has applied to register SeaAerial as a trademark.