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:
- Experiment Board (EMI Radiation)
- DC Power Supply
- Spectrum Analyzer
- 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:
- Connect the close-field probe to the RF input of a Spectrum Analyzer.
- Set the Spectrum Analyser to a known state by pressing [Preset][Preset All].
- Select the frequency range: press [Frequency][Start Freq][60][MHz] [Stop Freq] [400][MHz].
- Set the Amplitude unit to dBuV.
- Set the DC Power Supply to 5 V and connect the supply to the experiment board. Caution: make sure the polarity is correct.
- 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.
- 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].
- 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.
- For every column, record the highest magnitudes of the fundamental and 3rd harmonic spectral lines.
- 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.
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Answer to Experiment Step 9