RFID技术基于明确的科学原理。 标签收集电磁场中无线电波的投射能量。 然后标签使用一种叫做的技术反射一个改变的信号
back-scatter which the antennas receive. Because it is a science, it is often assumed that an expert can accurately predict both the read performance of a tag on any item and the distance it can be read from, just by looking at the system. Unfortunately, reality is much more complex, making RFID operation seem like black magic. In most
环境，RFID产生奇怪的结果。 - 经常反直觉。 通常情况下，一旦调查结果，结果就会变得有意义，但它很少是你最初期望的结果。
感谢RR Donnelley＆Sons Co.向我们发送他们的Custom Wave RFID标签样品。 现在大家都知道RR Donnelley的定制天线打印吗？ （你不是吗？你应该。 在RFID Journal中查看这篇关于它们的文章！)
Why is there such a significant difference in read range between the two environments if we are using the same reader and the same tags? Most likely the answer is due to reflection of RF energy. The diagram below shows the environment in our warehouse which we tested. The tags were being read down a corridor bordered by pallets of paper products. The image shows how the RF field might be reflected to improve our range.
The warehouse test diagram illustrates a reader with energy reflected down the corridor. Only a small amount of the energy output from the reader is able to escape through space between the pallets and up into space above the pallets. In this warehouse trial, the tag was able to be read from further away because there was more RF energy available to power the tag than there would have been in the open. Additionally, the large metal door behind the tag could have reflected energy back towards the tag, which would give the tag a double dose of RF energy.
Outside, most of the RF energy that was not oriented directly at the tag was lost because it escaped into space. The RF energy around the tag was weaker and it could not power the tag at the longer distances.
反射不仅会改变您阅读标签的能力，还会创建奇怪的标签阅读情境。 在外部测试期间，我们发现我们认为CW-100-05U7在4米处的最大读取范围。 在4.5米，我们无法读取标签。 但是，在5米时，读者再次找到了标签。 为什么读者可以从5仪表读取读数而不读取4.5仪表？ 当然答案是反思。 下图显示了我们看到的现象。
Passive UHF tags are dormant until they are powered by enough energy to send a response. In the example above, the RF energy is powerful enough to read a tag anywhere in the first area without any reflection. Then there is a small gap between fields. There is likely energy in the gap between the blue areas, but it is not enough to power the tag. In the small blue areas to the right of the large oval, the RF energy is enhanced via reflected RF waves increasing the energy available to the tags. In this situation, it may have reflected from the ground or nearby vehicles, as shown in the image below.
Testing is critical as it is almost impossible to consider all factors which you may see in your actual environment. More than focusing solely on the tag and reader, consider the places where the field will be at its weakest and adjust the tag or antenna locations if possible.
您可以在下面看到有关其如何运作的视频。 LED板显示，显示Telaeris UHF传感器的场强。
RF reflection is one of many aspects of an RFID system to consider. For more information on RFID systems please contact email@example.com。 有关Custom Wave RFID标签的更多信息，请访问他们的网站 http://www.rrdonnelley.com/printed-electronics/customwave/.
Note: Handheld RFID readers are not usually the best solution for long distance scanning. Fixed readers and antennas will typically provide a longer read range as the readers project more RF energy.