In this chapter, you learned everything you need to know about tags to be able to select the most suitable tag for a specific application and find a correct placement on the product or packaging.
First, you discovered different types of tags based on their function. Active tags have a battery and broadcast a signal into the environment, whereas passive and semi-passive tags need to be in the presence of a reader's signal in order to communicate. You also learned that active tags, although they are the most expensive type, have long read ranges and can be used with sensors, GPS, and cellular networks. Passive tags have a simpler construction and lower price, but have shorter read ranges.
In the next section, you learned about various communication techniques of passive tags. Passive tags can use either inductive coupling, which utilizes a magnetic field, or passive backscatter, which utilizes an electric field. Tags using passive backscatter can have a lot longer read ranges than the inductively coupled tags.
Hopefully you enjoyed the summary of different frequency bands and the tag performance characteristics based on their frequency. Low-frequency tags have short read ranges and slow data-transfer rates but good penetration of water and metals, and are used mainly for animal tracking or access control. High-frequency tags also have short read ranges and relatively good performance around water and metals, and are used in smart cards, smart shelves, pharma, and item-level tracking. Ultra-high-frequency tags have long read ranges and relatively high data-transfer rates but bad performance around water and liquid. They are used for product tracking throughout the supply chains, in libraries, in stores, and for inventory control. The last type of tags based on frequency are microwave tags. These are used mainly as active tags for toll collection because of their fast data-transfer rates.
After discussing the characteristics of different frequencies, I specified how the frequencies within a band differ around the world. U.S., European, and Asian frequencies are not the same; therefore, some manufacturers came up with a tag that works globally.
In the next section, you learned about EPC tag classes and their capabilities. EPC Class 0 is a read-only tag, and EPC Class 1 is a WORM tag. These classes are now called Generation 1. Generation 2 came with many improved and new features such as higher data-transfer rates for reading and writing, longer passwords, better anticollision, and dense reader mode.
After this, you discovered the components hidden behind the tag, such as the microchip and antenna. You found out how the chip can be attached to an antenna and the antenna manufacturing techniques. I also described Q factor as a measurement of a tag's efficiency.
In the section discussing tags designed for specific applications, you learned that tags can come in different types of packaging or be embedded into the product itself. There are specific tags for various types of materials, especially the materials that RF waves find difficult to penetrate or materials that detune the tag and decrease its performance.
In the following section, I discussed how to place a tag onto a product or its packaging related to the physical and chemical properties of the item, how to evaluate a correct tag placement, and which facilities can do the testing for you.
This chapter has given you a good level of knowledge about various types of tags and their applications and has equipped you with comprehensive knowledge to help you select the right tag during the design stage of your RFID system.