1、Designation: D 5568 08An American National StandardStandard Test Method forMeasuring Relative Complex Permittivity and RelativeMagnetic Permeability of Solid Materials at MicrowaveFrequencies Using Waveguide1This standard is issued under the fixed designation D 5568; the number immediately following
2、 the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method cov
3、ers a procedure for determiningrelative complex permittivity (relative dielectric constant andloss) and relative magnetic permeability of isotropic, reciprocal(non-gyromagnetic) solid materials. If the material is nonmag-netic, it is acceptable to use this procedure to measurepermittivity only.1.2 T
4、his measurement method is valid over a frequencyrange of approximately 100 MHz to over 20 GHz. These limitsare not exact and depend on the size of the specimen, the sizeof rectangular waveguide transmission line used as a specimenholder, and on the applicable frequency range of the networkanalyzer u
5、sed to make measurements. The practical lower andupper frequencies are limited by specimen dimension require-ments (large specimens at low frequencies and small speci-mens at high frequencies). Being a non-resonant method, theselection of any number of discrete measurement frequenciesin a measuremen
6、t band would be suitable. Use of multiplerectangular waveguide transmission line sizes are required tocover this entire frequency range (100 MHz to 20 GHz). Thistest method can also be generally applied to circular waveguidetest fixtures. The rectangular waveguide fixture is preferredover coaxial fi
7、xtures when samples have in-plane anisotropy orare difficult to manufacture precisely.1.3 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are in English units.The equations shown here assume an e+jvtharmonic timeconvention.1.4 This standard does not p
8、urport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2
9、D 1711 Terminology Relating to Electrical Insulation3. Terminology3.1 For other definitions used in this test method, refer toTerminology D 1711.3.2 Definitions:3.2.1 relative complex permittivity (relative complex dielec-tric constant), r*, nthe proportionality factor that relates theelectric field
10、 to the electric flux density, and which depends onintrinsic material properties such as molecular polarizability,charge mobility, etc.:r*5r8 jr885D0E(1)where:0= the permittivity of free space,D= the electric flux density vector, andE= the electric field vector.3.2.1.1 DiscussionIn common usage the
11、word “relative”is frequently dropped. The real part of complex relativepermittivity (r8) is often referred to as simply relative permit-tivity, permittivity or dielectric constant. The imaginary part ofcomplex relative permittivity (r88) is often referred to as theloss factor. In anisotropic media,
12、permittivity is described by athree dimensional tensor.3.2.1.2 DiscussionFor the purposes of this test method,the media is considered to be isotropic, and therefore permit-tivity is a single complex number at each frequency.3.2.2 relative complex permeability, r*, nthe proportion-ality factor that r
13、elates the magnetic flux density to the1This test method is under the jurisdiction of ASTM Committee D09 onElectrical and Electronic Insulating Materials and is the direct responsibility ofSubcommittee D09.12 on Electrical Tests.Current edition approved Dec. 15, 2008. Published January 2009. Origina
14、llyapproved in 1994. Last previous edition approved in 2001 as D 5568 01.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe A
15、STM website.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.magnetic field, and which depends on intrinsic material prop-erties such as magnetic moment, domain magneti
16、zation, etc.:r*5 r8 jr885B0H(2)where:0= the permeability of free space,B= the magnetic flux density vector, andH= the magnetic field vector.3.2.2.1 DiscussionIn common usage the word “relative”is frequently dropped. The real part of complex relativepermeability (r8) is often referred to as relative
17、permeability orsimply permeability. The imaginary part of complex relativepermeability (r9) is often referred to as the magnetic lossfactor. In anisotropic media, permeability is described by athree dimensional tensor.3.2.2.2 DiscussionFor the purposes of this test method,the media is considered to
18、be isotropic, and therefore perme-ability is a single complex number at each frequency.3.3 Definitions of Terms Specific to This Standard:3.3.1 A list of symbols specific to this test method is givenin Annex A1.3.3.2 calibration, na procedure for connecting character-ized standard devices to the tes
19、t ports of a network analyzer tocharacterize the measurement systems systematic errors. Theeffects of the systematic errors are then mathematically re-moved from the indicated measurements. The calibration alsoestablishes the mathematical reference plane for the measure-ment test ports.3.3.2.1 Discu
20、ssionModern network analyzers have thiscapability built in. There are a variety of calibration kits thatcan be used depending on the type of test port. The modelsused to predict the measurement response of the calibrationdevices depends on the type of calibration kit. Most calibrationkits come with
21、media that can be used to load the definitions ofthe calibration devices into the network analyzer. Calibrationkit definitions loaded into the network analyzer must match thedevices used to calibrate. Since both transmission and reflec-tion measurements are used in this standard, a two-portcalibrati
22、on is required.3.3.3 network analyzer, na system that measures thetwo-port transmission and one-port reflection characteristics ofa multiport system in its linear range and at a common inputand output frequency.3.3.3.1 DiscussionFor the purposes of this standard, thisdescription includes only those
23、systems that have a synthesizedsignal generator, and that measure the complex scatteringparameters (both magnitude and phase) in the forward andreverse directions of a two-port network (S11, S21, S12, S22).3.3.4 scattering parameter (S-parameter), Sij, na complexnumber consisting of either the refle
24、ction or transmissioncoefficient of a component at a specified set of input and outputreference planes with an incident signal on only a single port.3.3.4.1 DiscussionAs most commonly used, these coeffi-cients represent the quotient of the complex electric fieldstrength (or voltage) of a reflected o
25、r transmitted wave dividedby that of an incident wave. The subscripts i and j of a typicalcoefficient Sijrefer to the output and input ports, respectively.For example, the forward transmission coefficient S21is theratio of the transmitted wave voltage at Reference Plane 2 (Port2) divided by the inci
26、dent wave voltage measured at ReferencePlane 1 (Port 1). Similarly, the Port 1 reflection coefficient S11is the ratio of the Port 1 reflected wave voltage divided by thePort 1 incident wave voltage at reference plane 1 (Port 1).3.3.5 transverse electric (TEmn) wave, nan electromag-netic wave in whic
27、h the electric field is everywhere perpen-dicular to the direction of propagation.3.3.5.1 DiscussionThe index m is the number of half-period variations of the field along the waveguides largertransverse dimension, and n is the number of half-periodvariations of the field along the waveguides smaller
28、 transversedimension. The dominant wave in a rectangular waveguide isTE10. The electric field lines of the TE10mode are parallel tothe shorter side.3.3.6 cutoff frequency, nthe lowest frequency at whichnon-evanescent, dominant mode propagation can occur withina rectangular waveguide.4. Summary of Te
29、st Method4.1 A carefully machined test specimen is placed in anelectromagnetic waveguide transmission line and connected toa calibrated network analyzer that is used to measure theS-parameters of the transmission line-with-specimen. A speci-fied data-reduction algorithm is then used to calculate per
30、mit-tivity and permeability. If the material is nonmagnetic adifferent algorithm is used to calculate permittivity only. Errorcorrections are then applied to compensate for air gaps betweenthe specimen and the transmission line conductor surfaces.5. Significance and Use5.1 Design calculations for ra
31、dio frequency (RF), micro-wave and millimetre-wave components require the knowledgeof values of complex permittivity and permeability at operatingfrequencies. This test method is useful for evaluating smallexperimental batch or continuous production materials used inelectromagnetic applications. Use
32、 this method to determinecomplex permittivity only (in non-magnetic materials) or bothcomplex permittivity and permeability simultaneously.6. Interferences6.1 The upper limits of permittivity and permeability thatcan be measured using this test method are restricted by thetransmission line and speci
33、men geometries, which can lead tounwanted higher order waveguide modes. In addition, exces-sive electromagnetic attenuation due to a high loss factorwithin the test specimen can prevent determination of permit-tivity and permeability. No specific limits are given in thisstandard, but this test metho
34、d is practically limited to low-to-medium values of permittivity and permeability.6.2 The existence of air gaps between the test specimen andthe transmission line introduces a negative bias into measure-ments of permittivity and permeability. In this test methodcompensation for this bias is required
35、, and to do so requiresknowledge of the air gap sizes. Air gap sizes are estimatedfrom dimensional measurements of the specimen and theD5568082specimen holder, which can be measured with micrometers,feeler gauges, or other precision instruments. Several differenterror correction models have been dev
36、eloped, and a frequencyindependent series capacitor model is described in Annex A2.Air gap corrections are only approximate and therefore this testmethod is practically limited to low-to-medium values ofpermittivity and permeability.7. Apparatus7.1 Experimental Test FixtureThe test fixture includes
37、aspecimen holder connected to a network analyzer, as shown inFig. 1.7.2 Network AnalyzerThe network analyzer needs a full2-port test set that can measure transmission and reflectionscattering parameters. Use a network analyzer that has asynthesized signal generator in order to ensure good frequencys
38、tability and signal purity.7.3 Waveguide Calibration KitTo define Port 1 and Port 2measurement reference planes, calibration of the waveguidetest fixture is required. A calibration kit consists of well-characterized standard devices and mathematical models ofthose devices. Use a through-reflect-line
39、 (TRL), an open-short-load-through (OSLT), or any other calibration kit that yieldssimilar calibration quality to calibrate the waveguide testfixture.7.4 Specimen Holder:7.4.1 Because parameters such as specimen holder lengthand cross-sectional dimensions are of critical importance to thecalculation
40、 of permittivity and permeability, carefully measureand characterize the physical dimensions of the specimenholder.7.4.2 If a separate length of transmission line is used to holdthe specimen, ensure that that empty length of line is also inplace during calibration of the specimen holder.7.4.3 The th
41、eoretical model used for this test methodassumes that only the dominant mode of propagation exists(TE10for rectangular waveguide or TE11for circularwaveguide). The existence of higher-order modes restricts themeasurable bandwidth for a given waveguide test fixture.7.4.4 Be sure that the specimen hol
42、der dimensions arewithin proper tolerances for the waveguide transmission linesize in use. For an X-band rectangular waveguide transmissionline the dimensions of the inner opening are denoted by “a” thewidth and “b” the height. Proper tolerances are then:X-band waveguide width:a 5 22.86 6 0.10 mm 0.
43、900 6 0.004 in.! (3)X-band waveguide height:b 5 10.16 6 0.10 mm 0.900 6 0.004 in.! (4)7.4.4.1 Dimensions and tolerances of other standardwaveguides are in the appropriate manufacturers specifica-tions and U.S. military specifications.38. Test Specimen8.1 Make the test specimen long enough to ensure
44、goodalignment inside the holder. Also, make the test specimen longenough to ensure that the phase shift through the specimen ismuch greater than the phase measurement uncertainty of thenetwork analyzer at the lowest measurement frequency. If aspecimen is expected to have low loss, sufficient length
45、is alsorequired to ensure accurate determination of the loss factor.Finally, for high loss specimens, the specimen length cannot beso long that high insertion loss prevents material propertyinversion.8.2 Accurately machine the specimen so that its dimensionsminimize the air gap that exists between t
46、he conductor surfacesand the specimen. In this respect, measure the specimenholders dimensions in order to specify the tightest tolerancespossible for specimen preparation. Keep physical variations of3MIL-DTL-85/1F, 20 November 1998.FIG. 1 Diagram of Experimental FixtureD5568083specimen dimensions a
47、s small as is practicable and includespecimen dimensions and uncertainties in the report.9. Preparation of Apparatus9.1 Inspect Network Analyzer Test PortsInsure that therecession of both test ports center conductor shoulder behindthe outer conductor mating plane meets the minimum specifi-cations. R
48、efer to network analyzer manufacturers documenta-tion to provide connector specifications.9.2 Flexing and Tightening Cables and ConnectorsCableflexing and improperly tightened connectors introduce phaseand magnitude errors into S-parameter data. For this reason,bend the test cables as little as poss
49、ible, and under nocircumstances bend the test cables smaller than the manufac-turers minimum recommended radius. Use of phase-stablecables is highly recommended. Insofar as possible, return thenetwork analyzer cables to the same position during measure-ment of calibration standards and specimen. Use a torquewrench with the manufacturers recommended torque totighten connectors.9.3 Inspect and Clean Specimen, Specimen Holder, andConnectorsIf contamination is a concern, handle specimenswith laboratory gloves. Clean specimens, co
