Electromagnetic Compatibility Tests

1
Electromagnetic Compatibility Tests

• Preliminary results

2
Aims

• Compare electromagnetic noise coupling (pickup)
  between twisted wire pair (TWP) and FPC tracks
• Determine if twisted pair emulator pattern is
  effective

3
Test Details

• 2 kinds of test
• TEM simulates radiation from outside car
• Cable Tester simulates crosstalk (wire to wire
  radiation)
• 2 kinds of electromagnetic noise
• CM (common mode)
• DM (differential mode)

4
Cable Tester at ETS
5
Test Details

• Frequency range 200kHz to 1GHz
• Usual automotive range 10kHz to 500MHz/1GHz
• Sample configuration representative of CANbus
  circuit

6
Samples

• BMW twisted wire pair
• FPC straight track
• FPC twisted pair emulator (TPE)

7
Results- TEM

• All tests complete 200kHz to 1 GHz
• CM No difference between samples over whole
  frequency range
• DM No difference between samples over whole
  frequency range

8
Preliminary Results - Cable Tester

• FPC straight track and FPC twisted pair emulator
  completed 200kHZ to 20 MHz
• CM

9
Preliminary Results - Cable Tester

• DM

10
Cable Test 200kHz to 1MHz
11
straight
tpe
Cable Test DM 1MHz to 20MHz
12
Discussion

• TEM no difference noise coupling between twisted
  wire pair and FPC straight - why?
• Expect difference in DM noise flt30MHz gt Cable
  Tester results encouraging
• DM measurement method may need improving

13
Further Work

• Repeat Cable Tester results with improved DM
  measurement method
• More tests
• Samples with shields
• Plated through hole samples