1 Use an electronic microchip with data storage capacity of up to a few kilobytes Data-carrying device : Data transfer between the transponder and a reader.

1

• Use an electronic microchip with data storage capacity of up to a few kilobytes

Data-carrying device : Data transfer between the transponder and a reader

Full Duplex(FDX)

Half Duplex(HDX)

Transponder Reader

HDX

FDX

• < 30MHz• Load modulation • Simple circuitry• Harmonic Procedure

Similar to the modulated

cross-section procedure in

radar technology

• Sub-harmonic Procedure

Sequential System(SEQ)

2

• Down link : data transfer from the reader to the transponder

3

Power supply to passive transponders

Reader

Transponder

Magnetic field H

Rectification

DC Power Generation

weak transformer-type coupling

Resonance Capacitor

Resonance

Capacitor

135 kHz Typical 100-1000 windings

13.56MHz Typical 3-10 windings

trimming cap. to compensate for resonance frequency manufacturing tolerances

4

Different designs of inductively coupled transponders. The photo shows half finished transponders, i.e. transponders before injection into a plastic housing (reproduced by permission of AmaTech GmbH & Co. KG, D-Pfronten)

5

Reader for inductively coupled transponder in the frequency range <135 kHz

with integral antenna (reproduced by permission of easy-key System, micron, Halbergmoos)

6

: transponderreader

Load modulation

Binary Code Signal, subcarrier freq. (fs)

TransponderMagnetic field H

signal Modulation

product by load modulation with

subcarrierGeneration of load modulation in the transponder by switching the drain-source resistance of an FET on the chip.

7

Example : circuit-load modulation with subcarrier

13.56MHz

Subcarrier(212 kHz)

/64Divider

NAND

Full-wave

Rectifier

SW w.r.t output of IC3a

Q : TP 가 Reader 기로 너무 가까이 가면 ?

8

Example : Subharmonic Procedure

128 kHz

64 kHz

Subcarrier (64 kHz)

128 kHz

Basic circuit of a transponder with subharmonic back frequency

9

Long-range systemsRFID systems in which the gap between reader and transponder is greater than 1m

UHF frequencies :868 MHz (Europe), 915MHz (USA)908.5~914MHz (Korea)

Microwave frequencies :2.5GHz, 5.8GHz

Short Wavelength

ANT size & Efficiency

Q : RFID 의 인식거리를 넓히고자 한다 . 사용 주파수와 인식거리와의 관계는 ?

Free space path loss

Free space path loss aF at different frequencies and distances.

the transponder’s antenna gain : 1.64 (dipole),

the reader’s antenna gain : 1 (isotropic)

10

antenna

Lithium batteries

Active transponder for the frequency range 2.45 GHz.

11

reflection cross-sectionThe efficiency with which an object reflects electromagnetic waves.

Operating principle of a backscatter transponder.

The impedance of the chip is ‘modulated’ by switching the chip’s FET

12

2 Full and Half Duplex Procedure

ranges between 0.1 cm and a maximum of 1 cm. Close coupling systems

Close coupling transponder in an insertion reader with magnetic coupling coils

• frequency range : 1-10MHz• Efficiency : Very good

The mechanical and electrical parameters of contactless close coupling chip cards standard, ISO 10536

13

Magnetic Coupling

Capacitive Coupling

Load Modulation in close coupling systems

Plate capacitors are constructed from coupling surfaces isolated from one another.

Capacitive coupling in close coupling systems

ElectricalField E

Reader’s coupling surface

Transponder’s coupling surface

: transponderreader

14

Capacitive coupling

An electrically coupled system

1m 의 거리에서 전극 크기 a×b=4.5cm×7cm

( 스마트 카드에 대응하는 형태 ) 를 갖는 트랜스폰더 읽기를 위해 필요한 전극 전압 (f=125kHz)

15

2 Full and Half Duplex Procedure

Equivalent circuit diagram of an electrically coupled RFID system

3.2.5 Data Transfer : Reader Transponder

• ASK: amplitude shift keying• FSK: frequency shift keying• PSK: phase shift keying

Because of the simplicity of demodulation, the majority of systems use ASK modulation.

: transponderreader