1. Chapter 6. Tag implementation
Ph.D Chang-Duk Jung

2. Interaction between tags and interrogators

3. Tag selection and implementation
depends on four key performance areas:
Communication link margin : Measures how efficiently each tag uses RF power
Distance performance : Measures the maximum distance at which you can successfully read a tag
Read rate performance : Measures whether a tag can be successfully read while moving at varying speeds
Orientation sensitivity : Measures how the tag’s orientation affects readability when the tag is attached to different materials
depends on the type of reader that you are using :
Read range - Reading volume geometry
Tag size and geometry - Tag velocity
Number of tags - Anti-collision strategy
Operating power level - Operating frequency

4. Communication link margin
Refers to the amount of power the tag extracts from the RF signal before the reader-tag communication weakens
Used to calculate the distance between the tag and reader antenna

5. Relationship between frequency and read range
Low frequency (LF)
Tags operate at 125 KHz, and have a range between 3 feet and 4 feet
High frequency (HF)
Tags operate at MHz, and have a range between 3 feet and 6 feet
Ultra-high frequency (UHF)
Tags operate in the range of 400 MHz and 1 GHz (depending on the geographical location), and have a range of nearly 7 feet
Microwave frequency
Tags operate in the range of 2.35 GHz and 2.45 GHz

6. Factors affecting tag performance
Tag sensitivity
Tag size
Tag shape
Number of tag antennas
Speed
Tight tag stacking
Interference
Materials to which the tags are attached

7. IC performance Chip memory Power circuitry Impedance mismatch
Impedance alteration
Collision-free channels

8. Effects of operating frequency
The choice of operating frequency affects
Reading distance
Interference with other radio systems
Communication data speed
Antenna size
Low frequency RFID systems use passive tags
High- and ultra-high frequency systems operate with active tags

9. Packaging material
The four principal effects that a material can have on a tag are:
Absorption
Reflection/refraction
Dielectric effects
Multipath

10. Packaging design considerations
Variations in package dimensions can change signal propagation
Air pockets help the tag use more RF energy to increase its power
Altering the processing and composition of the existing packaging material can improve tag performance
Changing the chemical formula of a product can enhance RFID compatibility

11. Tag and antenna orientation

12. Tag sensitivity map

13. Polarization
continued

14. Polarization( con’t )

15. Polarization & tag orientation
continued

16. Polarization & tag orientation, continued

17. Substrate
A substrate that contains a metal antenna and an IC is known as an inlay
Substrates are either rigid or flexible

18. Media selection for tags
The common RFID-enabled media configurations:
Pressure-sensitive labels
RFID-enabled tickets
Tie-on tags

19. Adhesive selection for tags
Effective tag adhesives depend on
Ease of initial adhesion
Settling time
Ultimate bond strength
Environmental stability
Resistance to deterioration over time
Two basic adhesive families
Acrylic adhesives
Rubber-based adhesives

20. Movement of tags

21. Tag stacking You can resolve tag stacking by
Placing tags farther apart from each other
Placing tags in an alignment where they cause the least amount of interference

22. Tag placement

23. Unit summary The interaction between tags and interrogators
The factors affecting tag performance and the effects of packaging materials on a tag
Tag orientation and placement, the movement of tags, and the issues caused by tag stacking

24. Review questions How would you define a link margin?
Why should you be concerned about antenna polarization?
What type of tag can be read through human or animal skin and why?
What is the purpose of an IC chip in the tag?
Explain how the link margin influences the performance of an RFID