EXPERIMENT EMC2: EMI EMISSION FROM PCB

OBJECTIVE:

Evaluate the EMI emission from different layouts of electronic circuits and design layout guidelines for printed circuit board.

LEARNING OUTCOME:

LO3 – Evaluate the mechanism of radiated emission between electronic components.

(cognitive – evaluating, level 5)

APPARATUS:

  1. Experiment Board (EMI Radiation)
  2. DC Power Supply
  3. Spectrum Analyzer
  4. Close Field Probe

OVERVIEW:

In this experiment two different types of transmission lines, namely the microstrip transmission line and parallel line, are compared in terms of its radiation. There is a short and long line for each of the types. Thus, altogether, there are four experiments. Each time, one of these linesis used to carry a square-wave signal, and the resultant radiation is measured by a probe.

EXPERIMENT STEPS:

  1. Connect the close-field probe to the RF input of a Spectrum Analyzer.
  2. Set the Spectrum Analyser to a known state by pressing [Preset][Preset All].
  3. Select the frequency range: press [Frequency][Start Freq][60][MHz] [Stop Freq] [400][MHz].
  4. Set the Amplitude unit to dBuV.
  5. Set the DC Power Supply to 5 V and connect the supply to the experiment board. Caution: make sure the polarity is correct.
  6. Turn S1:1 of the DIP-Switch on. (The rest of the switches shall be off.) The high-frequency clock signal will be transmitted through the Long Microstrip.
  7. Place the close-field probe near to the Long Microstrip. Measure the frequency of the fundamental spectral line ([Measure][Freq Count][Count On]). Record the reading and turn off the frequency count function: [Measure][Freq Count][Count Off].
  8. Move the close-field probe slowly over the entire PCB column-by-column. Throughout the experiment, keep the close-field probe at almost the same height above the PCB.
  9. For every column, record the highest magnitudes of the fundamental and 3rd harmonic spectral lines.
  10. Repeat step 9 and 10 for signal transmission using Straight Microstrip, Parallel Line, and Long Wire by setting the DIP-Switch accordingly.

Name:
Student ID: / Major: / TE MCE EE
Date: / Table No.:

EMC2 ANSWER SHEET:

EMI EMISSION FROM PCB

Answer to Experiment Step 7

Comment on the radiation emitted by transmission lines.

Comment on the radiation levels across the board for any single type of line.

F / 3rd
LM
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F / 3rd
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Answer to Experiment Step 9