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Measurements using a GTEM cell above 1GHz

Measurements using a GTEM cell above 1GHz. Dr Tian Hong LOH. Overview of the Presentation. Introduction to GTEM cell Reason for GTEM measurement above 1GHz Equipment under test (EUT) Experimental Setup Experimental Results. Overview of the Presentation. Introduction to GTEM cell

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Measurements using a GTEM cell above 1GHz

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  1. Measurements using a GTEM cell above 1GHz Dr Tian Hong LOH

  2. Overview of the Presentation • Introduction to GTEM cell • Reason for GTEM measurement above 1GHz • Equipment under test (EUT) • Experimental Setup • Experimental Results

  3. Overview of the Presentation • Introduction to GTEM cell • Reason for GTEM measurement above 1GHz • Equipment under test (EUT) • Experimental Setup • Experimental Results

  4. Introduction: What’s GTEM? • GTEM cell – Giga-Hertz Transverse Electromagnetic cell. • Tapered Coaxial Transmission Line with 50  termination at both ends.

  5. Introduction: What’s GTEM? • Designed for use as EMC radiated emission and radiated immunity test facility without impact of the ambient electromagnetic environment.

  6. Introduction: What’s GTEM? • At the input, a normal 50 coaxial line is physically transformed to a rectangular cross section. • The cross sectional dimensions are a ratio of 3:2 horizontal to vertical cross sectional dimensions. b b/a = 3/2 a

  7. Introduction: What’s GTEM? • The centre conductor – septum, is a flat and wide conductor that will produce a uniform electrical field distribution underneath it which form a test volume for testing the EUT.

  8. Overview of the Presentation • Introduction to GTEM cell • Reason for GTEM measurement above 1GHz • Equipment under test (EUT) • Experimental Setup • Experimental Results

  9. Reason for GTEM measurement above 1GHz • The use of GTEM cell above 1GHz is still novel to product manufacturers. • Increasing clock speed of computer processors. • The need to measure the wave structure and to understand potential limitations in the use of the cell at higher frequencies.

  10. Overview of the Presentation • Introduction to GTEM cell • Reason for GTEM measurement above 1GHz • Equipment under test (EUT) • Experimental Setup • Experimental Results

  11. Equipment under test (EUT) • Dummy device that is commissioned resembling typical products. • Consists of monocone antenna as radiating source mounted on the inside of a metal box.

  12. Equipment under test (EUT) • Power by a battery operated York EMC Services CGE01 comb generator with 100MHz harmonic spacing. • Fundamental signal of 100MHz. • Measurable E-field from EUT up to 15GHz.

  13. Equipment under test (EUT) • Small EUT (SEUT): [ (L:W:H) = 23cm  20cm  11cm ] Side 5 Side 5 Side 2 Side 2 Side 3 Side 1

  14. Equipment under test (EUT) • Large EUT with complicated slots (LEUTC): [ (L:W:H) = 12.5cm  48.5cm  48.5cm ] Side 2 Side 1 Side 3

  15. Overview of the Presentation • Introduction to GTEM cell • Reason for GTEM measurement above 1GHz • Equipment under test (EUT) • Experimental Setup • Experimental Results

  16. Experimental Setup • Instrumentation used: • Spectrum Analyser (PSA) • Microwave Amplifier • Cables • Computer System • GTEM cell • Foam Table • EUT 5 2 1 4 3

  17. Experimental Setup • Instrumentation used: • Spectrum Analyser (PSA) • Microwave Amplifier • Cables • Computer System • GTEM cell • Foam Table • EUT Vertical Polarisation 5 7 6

  18. 1620mm 1750mm 1 645mm 590mm 535mm 450mm Experimental Setup • SEUT:

  19. 1620mm 1120mm 1750mm 1 2 645mm 538mm 590mm 483mm 535mm 450mm 3mm Experimental Setup • SEUT:

  20. 1620mm 1120mm 1750mm 1 2 820mm 3 645mm 538mm 425mm 590mm 255mm 483mm 535mm 370mm 450mm 3mm 60mm Experimental Setup • SEUT:

  21. 1620mm 125mm 1750mm 485mm 777.5mm 85mm 535mm 450mm Experimental Setup • LEUTC:

  22. Overview of the Presentation • Introduction to GTEM cell • Reason for GTEM measurement above 1GHz • Equipment under test (EUT) • Experimental Setup • Experimental Results

  23. Experimental Results • SEUT: Sensitivity --- Transverse displacement

  24. Experimental Results • SEUT: Sensitivity --- Vertical displacement

  25. Experimental Results • SEUT: E-field comparison between GTEM & FAR

  26. Experimental Results • LEUTC: E-field comparison between GTEM & FAR

  27. 1620mm 125mm 1750mm Stepper Motor 485mm 777.5mm 85mm 535mm 450mm Modified Experimental Setup • LEUTC:

  28. Experimental results • LEUTC: E-field comparison between GTEM & FAR

  29. Experimental results: Radiation Pattern • Radiation pattern of LEUTC in GTEM:

  30. Thank you for your attention. Any Questions?

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