Measurements using a GTEM cell above 1GHz

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Measurements using a GTEM cell above 1GHz

• Dr Tian Hong LOH

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Overview of the Presentation

• Introduction to GTEM cell
• Reason for GTEM measurement above 1GHz
• Equipment under test (EUT)
• Experimental Setup
• Experimental Results

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Overview of the Presentation

• Introduction to GTEM cell
• Reason for GTEM measurement above 1GHz
• Equipment under test (EUT)
• Experimental Setup
• Experimental Results

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Introduction Whats GTEM?

• GTEM cell Giga-Hertz Transverse Electromagnetic
  cell.
• Tapered Coaxial Transmission Line with 50 ?
  termination at both ends.

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Introduction Whats GTEM?

• Designed for use as EMC radiated emission and
  radiated immunity test facility without impact of
  the ambient electromagnetic environment.

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Introduction Whats 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 32
  horizontal to vertical cross sectional dimensions.

b
b/a 3/2
a
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Introduction Whats 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.

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Overview of the Presentation

• Introduction to GTEM cell
• Reason for GTEM measurement above 1GHz
• Equipment under test (EUT)
• Experimental Setup
• Experimental Results

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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.

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Overview of the Presentation

• Introduction to GTEM cell
• Reason for GTEM measurement above 1GHz
• Equipment under test (EUT)
• Experimental Setup
• Experimental Results

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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.

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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.

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Equipment under test (EUT)

• Small EUT (SEUT) (LWH) 23cm ? 20cm ? 11cm
  

Side 5
Side 5
Side 2
Side 2
Side 3
Side 1
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Equipment under test (EUT)

• Large EUT with complicated slots (LEUTC)
• (LWH) 12.5cm ? 48.5cm ? 48.5cm

Side 2
Side 1
Side 3
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Overview of the Presentation

• Introduction to GTEM cell
• Reason for GTEM measurement above 1GHz
• Equipment under test (EUT)
• Experimental Setup
• Experimental Results

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Experimental Setup

• Instrumentation used
• Spectrum Analyser (PSA)
• Microwave Amplifier
• Cables
• Computer System
• GTEM cell
• Foam Table
• EUT

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1
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Experimental Setup

• Instrumentation used
• Spectrum Analyser (PSA)
• Microwave Amplifier
• Cables
• Computer System
• GTEM cell
• Foam Table
• EUT

Vertical Polarisation
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Experimental Setup

• SEUT

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Experimental Setup

• SEUT

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Experimental Setup

• SEUT

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Experimental Setup

• LEUTC

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Overview of the Presentation

• Introduction to GTEM cell
• Reason for GTEM measurement above 1GHz
• Equipment under test (EUT)
• Experimental Setup
• Experimental Results

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Experimental Results

• SEUT Sensitivity --- Transverse
  displacement

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Experimental Results

• SEUT Sensitivity --- Vertical
  displacement

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Experimental Results

• SEUT E-field comparison between GTEM FAR

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Experimental Results

• LEUTC E-field comparison between GTEM FAR

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Modified Experimental Setup

• LEUTC

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Experimental results

• LEUTC E-field comparison between GTEM FAR

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Experimental results Radiation Pattern

• Radiation pattern of LEUTC in GTEM

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• Thank you for your attention.
• Any Questions?