Wifi信號弱？放置地點有問題
Deciding where to place a Wi-Fi router at home to minimise signal blackspots is a fine art. But a physicist has attempted to tackle the problem by mathematically working out the optimum position for a router. He studied how walls and reflections affected signal strength and concluded that, as common sense might suggest, there’s just no beating the centre of a house for router location.
決定在家裏的什麼位置放置無線路由器來最大程度減少盲點是一門藝術。近來，一位物理學家最近試圖用算法來規劃處路由器的最佳位置。他研究了牆壁對WiFi信號強度的影響，得出一個似乎是顯而易見的結論：沒有比房子正中間更好的位置了。
The 'complex' research was carried out by Jason Cole, a PhD physics student at the John Adams Institute at Imperial College London. Frustrated at finding numerous Wi-Fi blackspots around his flat, Mr Cole turned to mathematics to find out how he could improve his internet connection. He found that, the waves were hindered not only by walls and closed doors but also when they went around corners. This, he says, is because the signal loses strength when it bounces off objects.
這項“複雜”的實驗由傑森·科爾，來自倫敦帝國學院約翰·亞當斯研究所的物理博士進行。在自己的公寓發現了太多WiFi信號盲點，科爾選擇採取算法提高網絡連接速度。他發現WiFi的信號流不止被牆壁和門阻擋，同樣也會在角落裏減弱。他認爲這是因爲當信號接觸物體之後會減少一些能量。
‘I found an equation which approximates the behaviour of high-frequency electromagnetic waves such as Wi-Fi, and tried to solve it by placing a virtual router in the floor plan of my flat. After crunching numbers for a few minutes I was able to generate maps of Wi-Fi signal strength inside the flat, showing poor signal near my computer.’
“我發現了一個方程式，它能計算出WiFi這類高頻電磁感應信號的運動軌跡，我在公寓地板上設置了一個虛擬路由。在測試一段時間的信號之後，我就能夠繪製出WiFi信號在公寓內強弱的圖表，發現電腦旁邊較弱的信號。”
By showing how weakened the signal can be when it moves across the flat, Mr Cole found that no matter where his router was placed at one side of the flat, there would always be blackspots elsewhere. Instead, he suggests that the only solution to ensure as few blackspots as possible is to place the router in the middle of the flat.
通過移動虛擬路由器的位置，可以看到信號強弱的變化。科爾發現無論將路由器放在公寓的哪一邊，其他地方都會有盲點。因此，他覺得儘可能減少盲點的最佳方式就是把路由器放在公寓中間。
‘There is also some reflection of the signal around corners, but engineers tell me reflections are bad too. In my case, the best position was as central as possible, preferably near open doorways. He says he hasn’t tried any physical tests of the simulation yet, but has been given suggestions by commenters on his website. There have been many other helpful comments which will no doubt improve the methodology in the future, and a surprising number of people asking for an app to test their own houses or offices, so there's plenty of work to do.’
“角落裏同樣也有信號反射，但是工程師告訴我反射很弱。因而，最佳的位置是在房間的儘可能中心位置，最好離門口近些。他說他還沒有進行任何物理實驗，但是網站上有人給出了建議。這些建議有的會爲未來的方法論提出更好的改進措施，而且令我們驚訝的是，很多人希望能有一款測試自己家裏或者辦公室裏信號強弱的app，所以我們還有很長的路要走。”
ARE WI-FI SIGNALS DANGEROUS?
Wifi信號危險嗎？
Wi-Fi signals use very low intensity radio waves. Whilst similar in wavelength to domestic microwave radiation, the intensity of Wi-Fi radiation is 100,000 times less than that of a domestic microwave oven.
Wifi信號運用的是非常低強度的無線電波，其波長與家用微波輻射相似，而其強度則比家用微波爐要弱10萬倍。
The type of radiation emitted by radio waves (Wi-Fi), visible light, microwaves and mobile phones has been shown to raise the temperature of tissue at very high levels of is called a thermal interaction, but researchers are divided as to whether the radiation we receive daily can cause damage.
由無線電波（如Wifi），可見光，微波和手機發出的輻射，在長時間照射下會使物體溫度升高。這被稱作熱互作用，但是針對這種輻射是否會對人身體產生危害，調查者們持不同意見。
The UK Health Protection Agency (HPA) has been monitoring the safety of Wi-Fi. It says people using Wi-Fi, or those in the proximity, are exposed to the radio signals it emits - and some of the transmitted energy in the signals is absorbed in their bodies.英國健康保護署曾檢測Wifi的安全性。它的調查結果稱，使用或者接近Wifi的人羣都在其輻射範圍內，而且信號中傳送的一些能量會被吸取進身體中。
However, the signals are very low power. Sitting in a Wi-Fi hotspot for a year results in receiving the same dose of radio waves as making a 20 minute mobile phone call.
然而，這些信號的能量很低。在Wifi熱點附近坐上一年所吸取的輻射，大約等於20分鐘通話所產生的無線電波。
