Chapter 4: Tags

RFID+ Exam Objectives Covered in this Chapter:

ü	4.1 Classify tag types 4.1.1 Select the RFID tag best suited for a specific use case 4.1.1.1 Pros and cons of tag types 4.1.1.2 Tag performance 4.1.1.2.1 Tag antenna to region/frequency 4.1.2 Identify inductively coupled tags vs. back-scatter 4.1.3 Identify the differences between active and passive
ü	4.2 Given a scenario, select the optimal locations for an RFID tag to be placed on an item 4.2.1 Evaluate media and adhesive selection for tags 4.2.2 Tag orientation and location 4.2.2.1 Tag sticking (shadowing) 4.2.3 Package contents 4.2.4 Packaging 4.2.4.1 Items 4.2.4.2 Tags 4.2.4.3 Labels 4.2.4.4 Inserts 4.2.5 Liquids 4.2.6 Metal 4.2.7 Polarization

When I wrote RFID For Dummies a couple of years ago, there were only a handful of ultra-high-frequency (UHF) tags and about the same number of high-frequency (HF) tags. Now it seems like someone added water and plenty of fertilizer to the tag farm because there are dozens of tag types for all sorts of applications. As the industry grows, more and more choices will become available, so knowing the basics will be critical to selecting the right tag.

This chapter will teach you everything you need to know about tags and their characteristics, capabilities, and applications. This knowledge will be tremendously helpful in the designing stage of your radio frequency identification (RFID) system, when you will have to make the right tag selections based on the customer's needs and the desired performance of your system.

I'll also introduce you to various tag types-active, passive, and semi-passive tags-and discuss their functions, capabilities, and applications. Then I'll dive into communication methods that various types of tags use to receive interrogation signals from the reader and to respond.

In the middle of the chapter, you will learn about four primary frequency bands that are used for RFID systems and the function and application of tags operating within the specific bands. You will also discover that different frequencies within one band are used around the world, which can create challenges in an international supply chain. However, I'll show you how the differences can be overcome with clever tag design.

Finally, you will learn about tag construction, including techniques used to attach the chip to the antenna and methods of antenna manufacturing. You will also discover and evaluate tags intended for specific applications, explore the various types of tag packaging, and learn how to solve problems with materials and products that are not RF friendly. The latter can be done by using material-specific tags or by finding the correct placement on a product or its packaging and carefully testing this placement. You will learn that you can do this yourself or use various RFID testing facilities.