Fundamental Operating Principles - RFID: Fundamentals and Applications in Contactless Smart Cards and Identification - page 29

Radio frequency
3.1.1

Microwaves
3.1.2

1 bit (EAS)
3.1

Frequency divider
3.1.3

Electromagnetic
3.1.4

Acoustomagnetic
3.1.5

RFID systems

Inductive coupling
3.2.1

Electromagnetic
backscatter
3.2.2 Full and half

duplex
3.2

Close coupling
3.2.3

n bit (memory)
electronic/
physical

Electrical coupling
3.2.4

Inductive coupling
3.3.1

Sequential
3.3

SAW
3.3.2

Figure 3.1 The allocation of the different operating principles of RFID systems into the
sections of the chapter

3.1.1 Radio frequency

The radio frequency (RF) procedure is based upon LC resonant circuits adjusted to
a defined resonant frequency f R . Early versions employed inductive resistors made
of wound enamelled copper wire with a soldered on capacitor in a plastic hous-
ing ( hard tag ). Modern systems employ coils etched between foils in the form of
stick-on labels. To ensure that the damping resistance does not become too high and
reduce the quality of the resonant circuit to an unacceptable level, the thickness of