RFID : (radio frequency identification) is a small circuit, with a small antenna, that when receiving energy via a radio signal from an outer emitter (a “measurer”) responds as well with a signal, indicating its state and position.

In the simplest terms an RFID system consists of a tag (transponder) and a reader (interrogator). The technology of RFID deals with the remote collection of information stored on a tag using radio frequency communications. Information stored on the tag can range from as little as an identification number, to kilo-bytes of data written to and read from the tag, to dynamic information maintained on the tag, such as temperature histories. The information from the tag/reader combination is either presented to a human operator typically using a hand-held device with a alpha-numeric display or a host computer which automatically manages the information.

Critical performance variables in an RFID system involve the range at which communication can be maintained, the size of the information space contained on the tag, the rate at which the communication with the tag can take place, the physical size of the tag, the ability of the system to “simultaneously” communication with multiple tags, and the robustness of the communication with respect to interference due to material in the path between the reader and the tag. Several factors determine the level of performance that can be achieved in these variable. The factors include the legal/regulatory emmission levels allowed in the country of use, whether or not a battery is included in the tag to assist its communication back to the reader, and the frequency of the RF carrier used to transport the information between the tag and the reader.

A basic RFID system consist of three components:

·          An antenna or coil

·          A transceiver (with decoder)

·          A transponder (RF tag) electronically programmed with unique information

RFID tags come in a wide variety of shapes and sizes. Animal tracking tags, inserted beneath the skin, can be as small as a pencil lead in diameter and one-half inch in length. Tags can be screw-shaped to identify trees or wooden items, or credit-card shaped for use in access applications. The anti-theft hard plastic tags attached to merchandise in stores are RFID tags. In addition, heavy-duty 5- by 4- by 2-inch rectangular transponders used to track intermodal containers or heavy machinery, trucks, and railroad cars for maintenance and tracking applications are RFID tags.

Passive RFID tags operate without a separate external power source and obtain operating power generated from the reader. Passive tags are consequently much lighter than active tags, less expensive, and offer a virtually unlimited operational lifetime. The trade off is that they have shorter read ranges than active tags and require a higher-powered reader. Read-only tags are typically passive and are programmed with a unique set of data (usually 32 to 128 bits) that cannot be modified. Read-only tags most often operate as a license plate into a database, in the same way as linear barcodes reference a database containing modifiable product-specific information.

Developments in RFID technology continue to yield larger memory capacities, wider reading ranges, and faster processing. It is highly unlikely that the technology will ultimately replace barcode — even with the inevitable reduction in raw materials coupled with economies of scale, the integrated circuit in an RF tag will never be as cost-effective as a barcode label.  However, RFID will continue to grow in its established niches where barcode or other optical technologies are not effective. If some standards commonality is achieved – whereby RFID equipment from different manufacturers can be used interchangeably – the market will very likely grow exponentially.

cited from the documents downloaded from the internet

人说开卷有益，从某种角度上来说，在经过指导之后开卷才可谓真正的有益。如果盲目的满篇乱抓，有时候反倒不要看算了！所以，这里给大家介绍几本有关RFID的书籍—-大部分都是英文的，可不要头大哦！

1、《射频识别（RFID ）技术》 陈大才编译        电子工业出版社

这本书是翻译自德国人Klaus的书，内容不错，在国内的书中算是上上等，值得一读，但是翻译的内容还是少数，并不能给出RFID系统的全貌，建议读英文版的以下几本！

2、RFID for Dummies     Patrick J. Sweeney      Wiley Publishing,Inc. 

××for Dummies是一系列的书，封面都长相一样，是对相关技术的入门级书（觉得还是很有深度的），介绍了有关RFID的很多方面，诸如入门知识，技术原理，应用需求以及制造商信息。是一本较为全面的入门级读物！想要大概了解，就硬着头皮看吧！！呵呵：）

3、RFID Handbook: Fundamentals and Applications in Contactless Smart Cards and Identification, Second Edition 

这本其实是1中提到的中文翻译书的原版，但是内容详尽很多，包括标签、读写器，软件、硬件，数据编码信息等内容，图表很多，理解容易，是不可多得的一本好书（可惜，没看得很详细）

4、Is Your Cat Infected with a Computer Virus?

一篇论文，内容大体是说RFID技术本身存在隐患，是不那么安全的等等（没怎么好好看：）

5、RFID: READ MY CHIPS!        2004

算是一本老书了吧！里面讲了发展现状、展望、EPC网络结构、案例介绍、市场分析等。从总体上分析了整个产业链。是一本产业刚刚兴起时的分析报告性质的书！

6、RFID Sourcebook                 作者Sandip Lahiri           出版社 Prentice Hall PTR   2005

介绍了技术优势、局限性、应用领域、与条型码的区别、解决方案、协议介绍等等内容。从总体上把握RFID技术本身，内容详尽

7、RFID Field Guide: Deploying Radio Frequency Identification Systems 作者Bhuptani Manish 和Moradpour Shahram 出版社Prentice Hall PTR

内容分为三部分：1、什么是RFID；2、如何开发RFID；3、先行知识（协议、发展趋势等）其中介绍了RFID中间件，较为详细！

还有几本，好久没看过了，都淡忘了，今天就到这儿，赶明儿我再看看再说！有需要的话，给我你的email，我抽空给发过去！

Wireless personal mobile and cellular communications are expected to be one of the hottest growth areas of the 2000s and beyond. They have enjoyed the fastest growth rate in the telecommunications industry. Thanks to the satellite systems, wireless personal voice and data communications can be transmitted from any part of the earth to another using a simple, hand-held device. These future systems will provide data and voice communications to anywhere in the world, using a combination of wireless telephones, wireless modems, terrestrial cellular telephones and satellites. The use of wireless remote sensing, remote identification, direct broadcast, global navigation, and compact sensors has also gained popularity in the past decade. Wireless communications and wireless sensors have become a part of a consumer’s daily life.     Communication through the air means wireless! All of these wireless systems consist of a radio frequency (RF) or microwave front end. Without the RF-end, no radio-frequency wave or microwave can be send to the air. Where there’s wireless there’s the RF or microwave end in the communication system!

     虽说学无所成，但是在老师的点拨下，确是对这门技术有了一定的理解和认识，这里将点点滴滴记录下我平日里学习研究的一些心得，倒也算是对3年研究生生活的缅怀和交代。

      可是说些什么呢，这里却不知如何下手……思考思考