M21
0_D
irect
ly-M
atch
ed-A
nt_V
11-R
Bt
-1
Philips Semiconductors
Proximity Antenna Training for 13.56 MHzProximity Antenna Training for 13.56 MHz
Directly matched Directly matched antennaantenna
M21
0_D
irect
ly-M
atch
ed-A
nt_V
11-R
Bt
-2
Philips Semiconductors
Directly matched antennaDirectly matched antenna
RC500RC400
(or other
Reader)EMC-Filter
Rx
Tx
Rx- Circuit
Mat
chin
gZ
=70
0
Antenna
Matching
Z=
700
Directly matched antenna
M21
0_D
irect
ly-M
atch
ed-A
nt_V
11-R
Bt
-3
Philips Semiconductors
Directly matched antennaDirectly matched antenna
3) Tuning
5) Finetuning
1) Matching
6) Receive Circuit
Requirements:
load impedance = 700!
1) Matching
2) Resonanceresonance at 13.56 MHz
2) Resonance
4) Q-factor quality factor 35
quality factor 100
4) Q-factor
M21
0_D
irect
ly-M
atch
ed-A
nt_V
11-R
Bt
-4
Philips Semiconductors
6) Receive Circuit
2) Resonance3) Tuning4) Q-factor5) Finetuning
1) Matching
Directly matched antennaDirectly matched antenna
Guideline:
• Design a coil
• Calculate the parallel capacitance
• Tune resonance and impedance
•Connect antenna to the RC500•Tune again
• Check (and adjust) the Q-factor
• Finetune resonance and impedance
• Find the values for Rx-circuit
3) Tuning4) Q-factor5) Finetuning
6) Receive Circuit
M21
0_D
irect
ly-M
atch
ed-A
nt_V
11-R
Bt
-5
Philips Semiconductors
Directly matched antennaDirectly matched antennaComplete antennaComplete antenna
AntennaCoil
M21
0_D
irect
ly-M
atch
ed-A
nt_V
11-R
Bt
-6
Philips Semiconductors
Directly matched antennaDirectly matched antennaAntenna coilAntenna coil
La
Lb
RCoil
RCoil
HnHLLL ba 2...300 HnHLLL ba 2...300
2...2.02 coilRR 2...2.02 coilRR @13.56 MHz!
L and R of the antenna coil shall be measured at 13.56 MHz (impedance analyser or L-C-R Meter).
8.1)/ln(][
][2.0 NDll
m
HL ba
8.1)/ln(
][
][2.0 NDll
m
HL ba
La+b = L: coil inductance
l: length of the conductor circular: l = 2**r (r=coil radius) square l = 4*a (a lateral length) d: diameter of the conductorN: number of turns: shape factor =1.07 for circular coils =1.54 for square coils
Estimation:
M21
0_D
irect
ly-M
atch
ed-A
nt_V
11-R
Bt
-7
Philips Semiconductors
Directly matched antennaDirectly matched antennaAntenna coilAntenna coil
0 5 10 15 20
0.5
1
1.5
0 5 10 15 20
1
2
antenna radius [cm]
antenna radius [cm]
L [µH]
N
La
Lb
RCoil
RCoil
M21
0_D
irect
ly-M
atch
ed-A
nt_V
11-R
Bt
-8
Philips Semiconductors
Directly matched antennaDirectly matched antennaSimplificationSimplification
Due to the symmetrical circuitry of the whole antenna the antenna can be simplified:
ba LL ba LL
2ant
ba
ZZZ
2ant
ba
ZZZ
M21
0_D
irect
ly-M
atch
ed-A
nt_V
11-R
Bt
-9
Philips Semiconductors
Directly matched antennaDirectly matched antennaCalculate the external resistorCalculate the external resistor
CoilLext RQ
LRRR
22
1 CoilLext R
Q
LRRR
22
1
Consider the power consumption!
Q
LRL
MIFARE Q = 35
I*CODE Q = 100General:
M21
0_D
irect
ly-M
atch
ed-A
nt_V
11-R
Bt
-10
Philips Semiconductors
Directly matched antennaDirectly matched antennaCalculate the capacitorsCalculate the capacitors
2
2
22
2
2
2
11
1
1
CR
LCCL
CLRCC ba
2
2
22
2
2
2
11
1
1
CR
LCCL
CLRCC ba
aaa
ba
ZRL
ZRLR
ZRL
CC
111
1
222
222
aaa
ba
ZRL
ZRLR
ZRL
CC
111
1
222
222
350aZwith
Remark: there is an Excel-Sheet available, that supports this calculation.
M21
0_D
irect
ly-M
atch
ed-A
nt_V
11-R
Bt
-11
Philips Semiconductors
HnHLLL ba 2...300 HnHLLL ba 2...300
2...2.02 coilRR 2...2.02 coilRR
Directly matched antennaDirectly matched antennaEstimation: Startvalues for the tuningEstimation: Startvalues for the tuning
pFCC ba 2711 pFCC ba 2711
pFpFCC ba 600...10022 pFpFCC ba 600...10022
3...3.0extR 3...3.0extR 7.1...2.0extR 7.1...2.0extR
measured
calculated
00700 jant eZ
00700 jant eZ
1
2
M21
0_D
irect
ly-M
atch
ed-A
nt_V
11-R
Bt
-12
Philips Semiconductors
Directly matched antennaDirectly matched antennaTune resonance and impedanceTune resonance and impedance
Start
tune phase to 0° ± 10° with C2
decreaseC2
no
increaseC2
yesfres>13.56MHz ?possible ?
no
Tuning OK|Z|=Zant ± 10%
phase=0° ± 10°
no
yes
Z < Zant-10%?yes
Z >Zant+10% ?increase C1 yes
decrease C1
no
00700 jant eZ
00700 jant eZ
M21
0_D
irect
ly-M
atch
ed-A
nt_V
11-R
Bt
-13
Philips Semiconductors
10 11 12 13 14 15 16 17 18 -100
-80
-60
-40
-20
0
20
40
60
80
0
500
1000
1500
2000
1500
2000
2500
3000
350013.56 MHz
f [MHz]
|Zin| [] phase [deg.]
Zant
phase
Directly matched antennaDirectly matched antennaTune resonance and impedanceTune resonance and impedance
M21
0_D
irect
ly-M
atch
ed-A
nt_V
11-R
Bt
-14
Philips Semiconductors
• Design a coil
• Calculate the parallel capacitance
• Tune resonance and impedance
•Connect antenna to the RC500•Tune again
• Check (and adjust) the Q-factor
• Finetune resonance and impedance
• Find the values for Rx-circuit
Directly matched antennaDirectly matched antennaConnect Antenna to the RC500Connect Antenna to the RC500
Guideline:
M21
0_D
irect
ly-M
atch
ed-A
nt_V
11-R
Bt
-15
Philips Semiconductors
Directly matched antennaDirectly matched antennaTune resonance and impedanceTune resonance and impedance
C1a
C1b
C2b
C2a
Matching Circuit
C
Antenna
La
Lb
R
R
distance increased ?
yes
no
no Cis added
yes
decrease C2
Find dmax
Add C C < 10 pF
Start
Find dmax
remove C add 2* C to C2aadd 2* C to C2b
no
M21
0_D
irect
ly-M
atch
ed-A
nt_V
11-R
Bt
-16
Philips Semiconductors
PHILIPS
A
Channel A:500mV/DIV
Timebase:1µs/DIV
2.5µs
95%
Reader
send request command
Directly matched antennaDirectly matched antennaChecking the Q-FactorChecking the Q-Factor
“Antenna Loop”
M21
0_D
irect
ly-M
atch
ed-A
nt_V
11-R
Bt
-17
Philips Semiconductors
Directly matched antennaDirectly matched antennaRC500 Serial Signal SwitchRC500 Serial Signal Switch
Man
chester
Deco
der
SerialData
IN CarrierDemodulator Rx Pin 29
SubcarrierDemodulator
Serial Data OUT
Miller CoderEnvelope
Modulator Driver Tx
Digital Test Signal
0123
ModulatorSource Switch
7 6 5 4 3 2 1 0
MFoutSelect Switch
SubcarrierDemodulator
RFU
0 1
Mfin Pin3
Mfout Pin 4
Manchesterw. Subcarrier
Transmit NRZ
Envelope
0123
DecoderSource Switch
Manchester OUT
M21
0_D
irect
ly-M
atch
ed-A
nt_V
11-R
Bt
-18
Philips Semiconductors
Directly matched antennaDirectly matched antennaChecking the Q-FactorChecking the Q-Factor
time in msec
Pin 4 (3): Transmit NRZ 2V/Dev.
Pin 4 (2): Envelope2V/Dev.
RFOut 0.5V/Div.
RC500 test signals
M21
0_D
irect
ly-M
atch
ed-A
nt_V
11-R
Bt
-19
Philips Semiconductors
Directly matched antennaDirectly matched antennaCheckCheck
• Design a coil
• Calculate the parallel capacitance
• Tune resonance and impedance
•Connect antenna to the RC500•Tune resonance and impedance
• Check (and adjust) the Q-factor
• Finetune resonance and impedance
• Find the values for Rx-circuit
Guideline:
M21
0_D
irect
ly-M
atch
ed-A
nt_V
11-R
Bt
-20
Philips Semiconductors
Reader
send request command
Directly matched antennaDirectly matched antennaCheck the cards answerCheck the cards answer
kR 2.21 kR 2.21
Startvalue:
Insert RX-CircuitryInsert RX-Circuitry
Check the card’s answer with oscilloscope (trigger on Pin 4, Envelope)
Check the card’s answer with oscilloscope (trigger on Pin 4, Envelope)
Get the max. operating distanceGet the max. operating distance
Check the received signal at the RC500 (Pin 4, Manchester)
Check the received signal at the RC500 (Pin 4, Manchester)
Adjust R1 (valid Manchester at min. and max operating distance)
Adjust R1 (valid Manchester at min. and max operating distance)
“Antenna-Loop”
Attention: Input voltage at Pin 29 (Rx) shall not exceed ± 1.5V!
M21
0_D
irect
ly-M
atch
ed-A
nt_V
11-R
Bt
-21
Philips Semiconductors
Directly matched antennaDirectly matched antennaChecking the Q-FactorChecking the Q-Factor
time in msec
Pin 4 (5): Manchester 2V/Dev.
Pin 4 (4): Manchester with Subcarrier2V/Dev.
RFOut 1V/Dev.
RC500 test signals
M21
0_D
irect
ly-M
atch
ed-A
nt_V
11-R
Bt
-22
Philips Semiconductors
6) Receive Circuit
2) Resonance3) Tuning4) Q-factor5) Finetuning
1) Matching • Design a coil
• Calculate the parallel capacitance
• Tune resonance and impedance
•Connect antenna to the RC500•Tune resonance and impedance
• Check (and adjust) the Q-factor
• Finetune resonance and impedance
• Find the values for Rx-circuit
3) Tuning4) Q-factor5) Finetuning
6) Receive Circuit
Directly matched antennaDirectly matched antennaSummarySummary