Materials Measurement Phil Bartley Shelley Begley

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Permittivity and Permeability DefinitionsPermittivity(Dielectric Constant)κ =εε0'r= ε = ε −"rinteraction of a material in thepresence of an external electricfield.rjεPermeabilityµ ' "µ = = µ r − jµ rµ0interaction of a material inthe presence of an externalmagnetic field.Permittivity (e), also called dielectric constant, describes the interaction of a materialwith an electric field. Dielectric constant (k) is equivalent to relative permittivity (e r )or the absolute permittivity (e) relative to the permittivity of free space (e 0 ). The realpart of permittivity (e r ’) is a measure of how much energy from an external electricfield is stored in a material. The imaginary part of permittivity (e r ”) is called the lossfactor and is a measure of how dissipative or lossy a material is to an external electricfield.Its fundamental dimensions are T 2 Q 2 M -1 L -3 where T, Q, M and L are time, charge,mass and length respectively. Normally this is expressed as farad per meter(capacitance per distance).Dielectric “Constant” is not constant over frequency or temperature!The complex permeability (µ) consists of a real part µ’) that represents the energystorage and a an imaginary part (µ“) that represents the energy loss term. Relativepermeability (µ r) is the absolute permeability (µ) relative to the permeability of freespace (µ 0). Some materials such as iron (ferrites), cobalt, nickel and their alloys haveappreciable magnetic properties; however, many materials are non-magnetic. Allmaterials, on the other hand, have dielectric properties.8
Electromagnetic Field InteractionElectricFieldsPermittivityr'rε = ε −jε"rDielectric ConstantSTORAGELOSSMUTSTORAGELOSSMagneticFieldsPermeability'r"rµ r = µ − jµWhen electric and magnetic fields pass through a material, each can interact withthat material in two ways:Storage: Energy may be exchanged between the field and the material, in a bidirectional(lossless) mannerLoss: Energy may be permanently lost from the field, and absorbed in the material(usually as heat)The electric interactions are quantified by permittivity (e r ), also called dielectricconstant (k). The magnetic properties are described by permeability (m r ). These arecomplex numbers with real and imaginary parts:♦Real Part: Represents storage term; denoted with ‘♦Imaginary Part: represents loss term; denoted with “.This presentation focuses on permittivity, since most of the common materials arecompletely non-magnetic.9
Page 3: Extremely Diverse Applications“Ma
Page 6 and 7: Maxwell’s Equations∇× E=−∂
Page 10 and 11: Definition of Dielectric Constant o
Page 12 and 13: Dielectric MechanismsIonic Polariza
Page 14 and 15: Consider Dipole RotationRandom Orie
Page 16 and 17: Electric Field Changed DirectionEDi
Page 18 and 19: Small and Large MoleculesMany mater
Page 20 and 21: ε rε' '',r6040Debye Relaxation fo
Page 22 and 23: Cole-Cole Plot Explanation"ε r3020
Page 24 and 25: Other Empirical ModelsταβOnly fe
Page 26 and 27: Dielectric Properties (at 3 GHz)100
Page 28 and 29: Which Technique is Best? Frequency
Page 30 and 31: Impedance Analyzers and FixturesHer
Page 32 and 33: Measurement Techniques that use a V
Page 34 and 35: Transmission LineMaterial assumptio
Page 36 and 37: Transmission Algorithms in 85071EOp
Page 38 and 39: Problems with N-R Model• This set
Page 40 and 41: NIST Model• Technique uses all fo
Page 42 and 43: Transmission (Fast) Model• This t
Page 44 and 45: Weakness of both the NIST and Trans
Page 46 and 47: Transmission Line Measurement Error
Page 48 and 49: Typical Errors Caused By Air GapsPe
Page 50 and 51: Transmission Line Technique Summary
Page 52 and 53: Non-Contacting method for High or L
Page 54 and 55: 40 - 60GHz Free Space System54
Page 56 and 57: Free Space W-band SystemHere is a p
Page 58 and 59:
Free Space Quasi-Optical SystemHere
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Before a Measurement Can be Made…
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TRL CalibrationThruReflectMove the
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Gated Reflect Line (GRL) Calibratio
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MUT and GRL Error AdaptersAfter 2-P
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MUT and GRL Error AdaptersAfter O11
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GRL Thru Standard (Air)A 11 =A 22 =
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QO System SchematicAdditional infor
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Measurement Results0.03Imaginary pa
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Measurement with NRL Arch andoption
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Free Space LabWith u-band calibrati
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Materials Measurement Phil Bartley Shelley Begley

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