Bonus Lesson 11/11100%
BONUS MODULE — CASE STUDY LIBRARY

Additional Case Studies

16 real-world radiated emission failures across FPGA interfaces, switch-mode power supplies, motor drives, and cable/connector issues. Pick a case study from the dropdown below to see the failing frequency, a real before/after spectrum graph, the debugging approach used to find it, the root cause, the fix, and the key takeaways — with animations showing exactly how each source emitted.

FPGA Power Supply Other / Mixed Issues
CATEGORY

Title

Failing frequency:

Problem

Debugging Approach — How the Issue Was Identified

    Root Cause

    Solution

      Result

      Before
      After

      Before/After Spectrum Plot

      Representative quasi-peak trace against the CISPR 32 Class B limit line (extended flat above 1 GHz for teaching purposes). Always verify against the actual measured data from your test lab.

      How This Source Actually Emitted

      ⚡ Emission Mechanism

      Board / Circuit Involved


      Wikimedia Commons
      Representative hardware of this type — not the actual proprietary board from the case, which is not publicly available.

      Test Environment & Antenna Used

      Semi-anechoic chamber used for EMC radiated emission testing, showing RF absorber cones lining the walls and ceiling
      Semi-Anechoic Chamber (SAC) Absorber-lined walls/ceiling and a conductive floor eliminate reflections for both retests.
      Wikimedia Commons
      Modern real-time spectrum analyzer used as an EMI test receiver
      EMI Test Receiver / Spectrum Analyzer Captured the quasi-peak trace shown in the before/after plot above.
      Wikimedia Commons

      Wikimedia Commons

      Key Takeaways

        How to Avoid This Failure — Best Practices

          Typical Equipment Used Across These Case Studies

          📡
          EMI Receiver / Spectrum Analyzer

          CISPR 16-1-1 compliant receiver with peak, quasi-peak, and average detectors.

          📶
          Loop, Log-Periodic & Horn Antennas

          Cover 9 kHz–40 GHz in overlapping bands, matched to each failure's frequency.

          🔍
          Near-Field H-Field/E-Field Probe Set

          Used on the bench to localize hot loops, splits, and coupling paths before a chamber retest.

          ⚖️
          Current Probe / Clamp

          Measures common-mode current on cables and harnesses non-invasively.

          🔄
          Turntable & Antenna Mast

          Automated 0–360° rotation and 1–4 m antenna height scan to find worst case.

          📊
          High-Bandwidth Oscilloscope

          Captures ringing, overshoot, and edge rates directly on switch nodes and clock traces.