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Shelley Begley Application Development Engineer Agilent Technologies

Electromagnetic Properties of Materials: Characterization at Microwave Frequencies and Beyond. Shelley Begley Application Development Engineer Agilent Technologies. Agenda. Definitions Measurement Techniques Coaxial Probe Transmission Line Free-Space Resonant Cavity Summary.

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Shelley Begley Application Development Engineer Agilent Technologies

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  1. Electromagnetic Properties of Materials: Characterization at Microwave Frequencies and Beyond Shelley BegleyApplication Development EngineerAgilent Technologies

  2. Agenda • DefinitionsMeasurement Techniques Coaxial Probe Transmission Line Free-Space Resonant Cavity Summary

  3. Definitions Loss Tangent? • Permittivity is a physical quantity that describes how an electric field affects and is affected by a dielectric medium and is determined by the ability of a material to polarize in response to an applied electric field, and thereby to cancel, partially, the field inside the material. Permittivity relates therefore to a material's ability to transmit (or "permit") an electric field…The permittivity of a material is usually given relative to that of vacuum, as a relative permittivity, (also called dielectric constant in some cases)….- Wikipedia Dissipation Factor? Permittivity! Dielectric Constant? Permeability!

  4. Permittivity and Permeability Definitions Permittivity (Dielectric Constant) • interaction of a material in the presence of an external electric field.

  5. Permittivity and Permeability Definitions Permittivity (Dielectric Constant) • interaction of a material in the presence of an external electric field.

  6. Permittivity and Permeability Definitions Permeability Permittivity (Dielectric Constant) • interaction of a material in the presence of an external electric field. interaction of a material in the presence of an external magnetic field.

  7. Permittivity and Permeability Definitions Permeability Permittivity (Dielectric Constant) • interaction of a material in the presence of an external electric field. interaction of a material in the presence of an external magnetic field. Complex but not Constant!

  8. Electromagnetic Field Interaction STORAGE Magnetic Electric Fields Fields Permeability Permittivity MUT STORAGE

  9. Electromagnetic Field Interaction STORAGE Magnetic Electric Fields Fields LOSS Permeability Permittivity MUT STORAGE LOSS

  10. Quality Factor Dissipation Factor Loss Tangent

  11. Water at 20o C 100 10 most energy is lost at 1/t 1 1 10 100 f, GHz Relaxation Constant t • t= Time required for 1/e of an aligned system to return to equilibrium or random state, in seconds.

  12. Techniques Coaxial Probe Transmission LIne Resonant Cavity Free Space

  13. Which Technique is Best? It Depends…

  14. Which Technique is Best? It Depends… on • Frequency of interest • Expected value of er and mr • Required measurement accuracy

  15. Which Technique is Best? It Depends… on • Frequency of interest • Expected value of er and mr • Required measurement accuracy • Material properties (i.e., homogeneous, isotropic) • Form of material (i.e., liquid, powder, solid, sheet) • Sample size restrictions

  16. Which Technique is Best? It Depends… on • Frequency of interest • Expected value of er and mr • Required measurement accuracy • Material properties (i.e., homogeneous, isotropic) • Form of material (i.e., liquid, powder, solid, sheet) • Sample size restrictions • Destructive or non-destructive • Contacting or non-contacting • Temperature

  17. Measurement Techniques vs. Frequency and Material Loss Loss High Coaxial Probe Transmission line Medium Free Space Resonant Cavity Low Frequency 50 MHz 5 GHz 20 GHz 60 GHz 40 GHz 500+ GHz RF Low frequency Millimeter-wave Microwave

  18. Measurement Techniques vs. Frequency and Material Loss Loss High Coaxial Probe Medium Low Frequency 50 MHz 5 GHz 20 GHz 60 GHz 40 GHz 500+ GHz RF Low frequency Millimeter-wave Microwave

  19. Measurement Techniques vs. Frequency and Material Loss Loss High Coaxial Probe Medium Low Frequency 50 MHz 5 GHz 20 GHz 60 GHz 40 GHz 500+ GHz RF Low frequency Millimeter-wave Microwave

  20. Measurement Techniques vs. Frequency and Material Loss Loss High Coaxial Probe Transmission line Medium Free Space Low Frequency 50 MHz 5 GHz 20 GHz 60 GHz 40 GHz 500+ GHz RF Low frequency Millimeter-wave Microwave

  21. Measurement Techniques vs. Frequency and Material Loss Loss High Coaxial Probe Transmission line Medium Free Space Low Frequency 50 MHz 5 GHz 20 GHz 60 GHz 40 GHz 500+ GHz RF Low frequency Millimeter-wave Microwave

  22. Measurement Techniques vs. Frequency and Material Loss Loss High Coaxial Probe Transmission line Medium Free Space Resonant Cavity Low Frequency 50 MHz 5 GHz 20 GHz 60 GHz 40 GHz 500+ GHz RF Low frequency Millimeter-wave Microwave

  23. Coaxial Probe System Computer (Optional for PNA or ENA-C) Network Analyzer (or E4991A Impedance Analyzer) GP-IB, LAN or USB 85070E Dielectric Probe 85070E Software (included in kit) Calibration is required

  24. Reflection (S ) 11 Coaxial Probe • Material assumptions: • effectively infinite thickness • non-magnetic • isotropic • homogeneous • no air gaps or bubbles er

  25. Three Probe Designs • High Temperature Probe • 0.200 – 20GHz (low end 0.01GHz with impedance analyzer) • Withstands -40 to 200 degrees C • Survives corrosive chemicals • Flanged design allows measuring flat surfaced solids.

  26. Three Probe Designs • Slim Form Probe • 0.500 – 50GHz • Low cost consumable design • Fits in tight spaces, smaller sample sizes • For liquids and soft semi-solids only

  27. Three Probe Designs • Performance Probe • Combines rugged high temperature performance with high frequency performance, all in one slim design. • 0.500 – 50GHz • Withstands -40 to 200 degrees C • Hermetically sealed on both ends, OK for autoclave • Food grade stainless steel

  28. Coaxial Probe Example Data

  29. Coaxial Probe Example Data

  30. Coaxial Probe Example Data

  31. Martini Meter! Infometrix, Inc.

  32. Transmission Line System Computer (Optional for PNA or ENA-C) Network Analyzer GP-IB, LAN or USB 85071E Materials Measurement Software Sample holder connected between coax cables Calibration is required

  33. Coaxial Waveguide Transmission Line Sample Holders

  34. l Transmission Reflection (S ) (S ) 21 11 Transmission Line • Material assumptions: • sample fills fixture cross section • no air gaps at fixture walls • flat faces, perpendicular to long axis • Known thickness > 20/360 λ er andmr

  35. Transmission models in the 85071E Software

  36. Reflection models in the 85071E Software

  37. Transmission Example Data

  38. Transmission Example Data

  39. Network Analyzer Sample holder fixtured between two antennae Transmission Free-Space System Computer (Optional for PNA or ENA-C) GP-IB, LAN or USB 85071E Materials Measurement Software Calibration is required

  40. Non-Contacting method for High or Low Temperature Tests. Free Space with Furnace

  41. l Transmission Reflection (S21 ) (S11 ) Transmission Free-Space • Material assumptions: • Flat parallel faced samples • Sample in non-reactive region • Beam spot is contained in sample • Known thickness > 20/360 λ er andmr

  42. Free Space Example Data

  43. Free Space Example Data

  44. Resonant Cavity System Computer (Optional for PNA or ENA-C) Network Analyzer GP-IB or LAN Resonant Cavity Software Resonant Cavity with sample connected between ports. No calibration required

  45. Resonant Cavity Fixtures ASTM 2520 Waveguide Resonators Agilent Split Cylinder Resonator IPC TM-650-2.5.5.5.13 Split Post Dielectric Resonators from QWED

  46. Resonant Cavity Technique empty cavity fc = Resonant Frequency of Empty Cavity fs = Resonant Frequency of Filled Cavity Qc = Q of Empty Cavity Qs = Q of Filled Cavity Vs = Volume of Empty Cavity Vc = Volume of Sample Q c S21 f f c ASTM 2520

  47. Resonant Cavity Technique empty cavity fc = Resonant Frequency of Empty Cavity fs = Resonant Frequency of Filled Cavity Qc = Q of Empty Cavity Qs = Q of Filled Cavity Vs = Volume of Empty Cavity Vc = Volume of Sample sample inserted Q c Q s S21 f f f s c ASTM 2520

  48. Resonant Cavity Technique empty cavity fc = Resonant Frequency of Empty Cavity fs = Resonant Frequency of Filled Cavity Qc = Q of Empty Cavity Qs = Q of Filled Cavity Vs = Volume of Empty Cavity Vc = Volume of Sample sample inserted Q c Q s S21 f f f s c ASTM 2520

  49. Resonant Cavity Technique empty cavity fc = Resonant Frequency of Empty Cavity fs = Resonant Frequency of Filled Cavity Qc = Q of Empty Cavity Qs = Q of Filled Cavity Vs = Volume of Empty Cavity Vc = Volume of Sample sample inserted Q c Q s S21 f f f s c ASTM 2520

  50. Resonant Cavity Example Data

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