翻译练习：Electricity Can Be Transmitted Through The Air(2)

无线微波电力传输

The aim is to transmit the power as a narrow beam of microwaves. That will overcome the two fundamental flaws in Tesla's plan. One was how to charge people for electricity they can simply scoop from the air. The other was the need to overcome the law of radiative propagation, which states that the strength of a signal is inversely proportional to the square of the distance it has travelled from the transmitter. The upshot is that a signal's strength falls sharply even over short distances. Transmitting power in a tight beam, instead of radiating it in all directions, helps minimise the issue.

目标是发射微波窄能量束来传输电力。这样能解决特斯拉计划中两个基本缺点。一个缺点是既然人们可以简单的白嫖空气中的电力，那如何收费？另一个缺点则是克服辐射传输的规律，即信号强度与其传输距离的平方成反比。这会导致即使只传输了一小段距离也会导致信号急速减弱。用密集的波束来传输电力，而不是向所有方向发射，有助于最小化这个问题。

无线电力能量束

Power-beaming, as Emrod's process is known, has been tried before, but mainly for military applications, or for use in outer space. In 1975 NASA, America's space agency, used microwaves to send 34kW of electricity a distance of 1.6km - a record that still stands. It has never, though, been developed for commercial use.

埃姆罗德这项技术被称为“无线电力能量束”，以前就有人试过，不过主要是用于军事或外太空。1975年美国空间机构NASA利用微波把34千瓦电力传输了1.6千米——到目前仍然是世界记录。从来没有以商业应用为目的开发这项技术。

中继设备传输微波电力

Emrod's operation will begin cautiously. It will start by transmitting what Greg Kushnir, the firm's founder, describes as "a few kilowatts" over 1.8km. It will then gradually increase both power and distance. The crucial variable is the efficiency with which it can be done. According to Mr Kushnir, this is currently around 60%. That, he reckons, is already good enough to make power-beaming commercially viable in some circumstances, such as reaching remote areas without spending money on costly lines. But, to improve matters, Emrod has two other tricks up its sleeve. One is to employ relays. The other is to spice up the receivers with so-called metamaterials.

埃姆罗德的业务将会非常小心地开展。用公司创始人格雷格库什尼尔的话说，先把“几千瓦”的电力传输超过1.8千米。再逐步提升功率和距离。关键变量是完成传输的效率。据库什尼尔先生表示，目前传输效率约为60%。他评价认为，这已经非常棒了，已经可以在一些环境下进行无线电力能量束的商业化了。比如向偏远地区传输电力而不需要花钱建设昂贵的输电线。不过，为了获得更好的效果，埃姆罗德还有两个锦囊妙计。一个是使用中继设备。另一个是在接收器中加入他们叫做超材料的材料。