Principles of Planar Near-Field Antenna Measurements

413 Pages·2007·5.33 MB·English

by  Stuart Gregson

IETELECTROMAGNETICWAVESSERIES53
Principles of Planar
Near-Field Antenna
Measurements
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Principles of Planar
Near-Field Antenna
Measurements
Stuart Gregson, John McCormick and Clive Parini
TheInstitutionofEngineeringandTechnology
PublishedbyTheInstitutionofEngineeringandTechnology,London,UnitedKingdom
©2007TheInstitutionofEngineeringandTechnology
Firstpublished2007
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BritishLibraryCataloguinginPublicationData
Gregson,Stuart
Principlesofplanarnear-fieldantennameasurements.-
(Electromagneticwavesseries;v.53)
1.Antennas(Electronics)
I.TitleII.McCormick,JohnIII.Parini,Clive
IV.InstitutionofEngineeringandTechnology
621.3’824
ISBN978-0-86341-736-8
TypesetinIndiabyNewgenImagingSystems(P)Ltd,Chennai
PrintedintheUKbyMPGBooksLtd,Bodmin,Cornwall
Contents
Preface xi
1 Introduction 1
1.1 Thephenomenaofantennacoupling 1
1.2 Characterisationviathemeasurementprocess 4
1.2.1 Freespaceradiationpattern 6
1.2.2 Polarisation 7
1.2.3 Bandwidth 8
1.3 Theorganisationofthebook 11
1.4 References 12
2 Maxwell’sequationsandelectromagneticwavepropagation 13
2.1 Electriccharge 13
2.2 TheEMfield 14
2.3 Acceleratedcharges 16
2.4 Maxwell’sequations 18
2.5 Theelectricandmagneticpotentials 24
2.5.1 Staticpotentials 24
2.5.2 Retardedpotentials 24
2.6 Theinapplicabilityofsourceexcitationasameasurement
methodology 28
2.7 Fieldequivalenceprinciple 28
2.8 CharacterisingvectorEMfields 30
2.9 Summary 33
2.10 References 33
3 Introductiontonear-fieldantennameasurements 35
3.1 Introduction 35
3.2 Antennameasurements 35
vi Principlesofplanarnear-fieldantennameasurements
3.3 Formsofnear-fieldantennameasurements 40
3.4 Planerectilinearnear-fieldantennameasurements 43
3.5 Chambers,screeningandabsorber 44
3.6 RFsubsystem 47
3.7 Roboticspositionersubsystem 52
3.8 Near-fieldprobe 56
3.9 Genericantennameasurementprocess 58
3.10 Summary 60
3.11 References 60
4 Planewavespectrumrepresentationofelectromagnetic
waves 63
4.1 Introduction 63
4.2 OverviewofthederivationofthePWS 64
4.3 SolutionofthescalarHelmholtzequation
inCartesiancoordinates 65
4.3.1 Introductiontointegraltransforms 65
4.3.2 FouriertransformsolutionofthescalarHelmholtz
equation 65
4.4 Onthechoiceofboundaryconditions 78
4.5 Operatorsubstitution(derivativeofaFouriertransform) 79
4.6 SolutionofthevectorHelmholtzequationinCartesian
coordinates 81
4.7 SolutionofthevectormagneticwaveequationinCartesian
coordinates 83
4.8 Therelationshipbetweenelectricandmagneticspectral
components 84
4.9 Thefree-spacepropagationvectork 87
4.10 Planewaveimpedance 88
4.11 Interpretationasanangularspectrumofplanewaves 90
4.12 Far-fieldantennaradiationpatterns:approximatedbytheangular
spectrum 92
4.13 Stationaryphaseevaluationofadoubleintegral 95
4.14 Coordinatefreeformofthenear-fieldtoangularspectrum
transform 101
4.15 Reductionofthecoordinatefreeformofthenear-fieldtofar-field
transformtoHuygens’principle 104
4.16 Far-fieldsfromnon-planarapertures 106
4.17 Microwaveholographicmetrology(plane-to-planetransform) 107
4.18 Far-fieldtonear-fieldtransform 108
4.19 Radiatedpowerandtheangularspectrum 112
4.20 Summaryofconventionalnear-fieldtofar-field
transform 115
4.21 References 117
Listofcontents vii
5 Measurements–practicalitiesofplanarnear-fieldantenna
measurements 119
5.1 Introduction 119
5.2 Sampling(interpolationtheory) 120
5.3 Truncation,spectralleakageandfiniteareascanerrors 121
5.4 Antenna-to-antennacoupling(transmission)formula 125
5.4.1 Attenuationofevanescentplanewavemode
coefficients 136
5.4.2 Simplescatteringmodelofanear-fieldprobeduringa
planarmeasurement 137
5.5 Evaluationoftheconventionalnear-fieldtofar-field
transform 138
5.5.1 Standardtechniquesfortheevaluationofadouble
Fourierintegral 139
5.6 Generalantennacouplingformula:arbitrarilyorientated
antennas 143
5.7 Plane-polarandplane-bipolarnear-fieldtofar-field
transform 148
5.7.1 Boundaryvaluesknowninplane-polarcoordinates 150
5.7.2 Boundaryvaluesknowninplane-bipolar
coordinates 151
5.8 Regularazimuthoverelevationandelevationoverazimuth
coordinatesystems 156
5.9 Polarisationbasisandantennameasurements 159
5.9.1 Cartesianpolarisationbasis–LudwigI 159
5.9.2 Polarsphericalpolarisationbasis 160
5.9.3 Azimuthoverelevationbasis–LudwigII 161
5.9.4 Copolarandcross-polarpolarisation
basis–LudwigIII 163
5.9.5 Circularpolarisationbasis–RHCPandLHCP 165
5.10 Overviewofantennaalignmentcorrections 169
5.10.1 Scalarrotationoffar-fieldantennapatterns 169
5.10.2 Vectorrotationoffar-fieldantennapatterns 171
5.10.4 Rotationofcopolarpolarisationbasis–generalized
LudwigIII 173
5.10.5 Generalizedcompoundvectorrotationoffar-field
antennapatterns 174
5.11 Briefdescriptionofnear-fieldcoordinatesystems 175
5.11.1 Rangefixedsystem 176
5.11.2 Antennamechanicalsystem 177
5.11.3 Antennaelectricalsystem 178
5.11.4 Far-fieldazimuthandelevationcoordinates 178
5.11.5 LudwigIIIcopolarandcross-polardefinition 178
5.11.6 Probealignmentdefinition(SPP) 178
5.11.7 Generalvectorrotationofantennaradiationpatterns 179
viii Principlesofplanarnear-fieldantennameasurements
5.12 Directivityandgain 180
5.12.1 Directivity 180
5.12.2 Gain–bysubstitutionmethod 181
5.12.3 Gain-transfer(gain-comparison)method 182
5.13 Calculatingthepeakofapattern 183
5.13.1 Peakbypolynomialfit 183
5.13.2 Peakbycentroid 185
5.14 Summary 186
5.15 References 187
6 Probepatterncharacterisation 189
6.1 Introduction 189
6.2 Effectoftheprobepatternonfar-fielddata 189
6.3 Desirablecharacteristicsofanear-fieldprobe 191
6.4 Acquisitionofquasifar-fieldprobepattern 193
6.4.1 Samplingscheme 194
6.4.2 Electronicsystemdrift(tie-scancorrection) 197
6.4.3 Channel-balancecorrection 198
6.4.4 Assessmentofchambermultiplereflections 200
6.4.5 Correctionforrotaryerrors 202
6.4.6 Re-tabulationofprobevectorpatternfunction 205
6.4.7 Alternateinterpolationformula 209
6.4.8 Truefar-fieldprobepattern 211
6.5 Finiteelementmodelofopen-endedrectangularwaveguide
probe 213
6.6 Probedisplacementcorrection 217
6.7 Channel-balancecorrection 217
6.8 References 218
7 Computationalelectromagneticmodelofaplanarnear-field
measurementprocess 219
7.1 Introduction 219
7.2 Methodofsub-apertures 220
7.3 Aperturesetinaninfiniteperfectlyconductinggroundplane 223
7.3.1 Planewavespectrumantenna–antennacoupling
formula 225
7.4 VectorHuygens’method 227
7.5 Kirchhoff–Huygens’method 229
7.6 Generalizedtechniqueforthesimulationofnear-fieldantenna
measurements 233
7.6.1 Mutualcouplingandthereactiontheorem 234
7.7 Near-fieldmeasurementsimulation 237
7.8 Reactiontheorem 239
7.8.1 Lorentzreciprocitytheorem(fieldreciprocity
theorem) 240
Listofcontents ix
7.8.2 Generalizedreactiontheorem 244
7.8.3 Mutualimpedanceandthereactiontheorem 247
7.9 Summary 247
7.10 References 248
8 Antennameasurementanalysisandassessment 249
8.1 Introduction 249
8.2 Theestablishmentofthemeasurefromthemeasurement
results 249
8.2.1 Measurementerrors 250
8.2.2 Thesourcesofmeasurementambiguityanderror 253
8.2.3 Theexaminationofmeasurementresultdatatoestablish
themeasure 256
8.3 Measurementerrorbudgets 259
8.3.1 Applicabilityofmodellingerrorsources 259
8.3.2 Theempiricalapproachtoerrorbudgets 260
8.4 Quantitativemeasuresofcorrespondencebetweendatasets 261
8.4.1 Therequirementformeasuresofcorrespondence 261
8.5 Comparisontechniques 263
8.5.1 Examplesofconventionaldatasetcomparison
techniques 263
8.5.2 Noveldatacomparisontechniques 267
8.6 Summary 282
8.7 References 283
9 Advancedplanarnear-fieldantennameasurements 285
9.1 Introduction 285
9.2 Activealignmentcorrection 285
9.2.1 Acquisitionofalignmentdatainaplanarnear-field
facility 287
9.2.2 Acquisitionofmechanicalalignmentdatainaplanar
near-fieldfacility 289
9.2.3 Exampleoftheapplicationofactivealignment
correction 291
9.3 Amplitudeonlyplanarnear-fieldmeasurements 296
9.3.1 PTPphaseretrievalalgorithm 297
9.3.2 PTPphaseretrievalalgorithm–withaperture
constraint 301
9.4 Efficientpositioncorrectionalgorithms,in-planeandz−plane
corrections 303
9.4.1 Taylorseriesexpansion 305
9.4.2 K-correctionmethod 311
9.5 Partialscantechniques 315
9.5.1 Auxiliarytranslation 315
9.5.2 RotationsoftheAUTaboutthez-axis 319