DRAFT Recommended Practice for Measurements and ...

1/29/98 143 C95.3-1991 Revision — 2 nd Draft
10/98 Draft
4.4.5 Thermocouple.............................................................................................................................................46
4.4.6 Shaped Frequency Response...................................................................................................................47
4.4.7 Combined Electric and Magnetic Field Probes..................................................................................47
4.4.8 Personnel monitors...................................................................................................................................48
4.4.9 Human equivalent antenna.....................................................................................................................49
4.5 CALIBRATION OF EXTERNAL FIELD MEASURING INSTRUMENTS...............................................................49
4.5.1 Free-Space Standard-Field Method......................................................................................................49
4.5.2 Calibrations Using Rectangular Waveguides. ...................................................................................54
4.5.3 Calibrations Using TEM Cells................................................................................................................56
4.5.4 Magnetic Field Generators Using Coils. ..............................................................................................59
4.5.5 Standard-Probe Method...........................................................................................................................60
4.5.6 Evaluation of Field Survey Instruments. ..............................................................................................61
4.5.7 Practical Measurement Accuracy. ........................................................................................................62
4.6 INSTRUMENTS FOR MEASURING INTERNAL FIELDS AND SAR....................................................................63
4.6.1 Implantable E-Field Probes for SAR Measurements.........................................................................63
4.6.2 Calibrating induced current meters......................................................................................................63
4.7 CALIBRATION OF SAR INSTRUMENTS..............................................................................................................65
4.7.1 Implantable E-field Probe Calibration Techniques...........................................................................65
5. MEASUREMENT OF POTENTIALLY HAZARDOUS EXPOSURE FIELDS.................................................68
5.1 PRELIMINARY CONSIDERATIONS.......................................................................................................................68
5.1.1 Source and Propagation Characteristics.............................................................................................68
5.1.2 Estimate of Expected Field Strength....................................................................................................69
5.1.3 Determination of Type of Instrument Required..................................................................................70
5.2 SAFETY PRECAUTIONS.......................................................................................................................................70
5.2.1 Hazards Not Directly Associated with the Survey..............................................................................71
5.2.2 Precautions During the Survey Process................................................................................................72
5.3 MEASUREMENT PROCEDURES FOR EXTERNAL FIELDS.................................................................................74
5.3.1 General Considerations...........................................................................................................................74
5.3.2 Far-Field, Single-Source Conditions. ..................................................................................................74
5.3.3 Far-Field, Complex Sources. .................................................................................................................75
5.3.4 Near Fields.................................................................................................................................................76
5.3.5 External Field-Measurement Instrumentation—Usage Considerations......................................76
5.3.6 Interaction of RF Hazard Probes with Nearby Passive Scattering Objects (Reradiators) and
Active Radiators...................................................................................................................................................78
5.4 INDUCED BODY CURRENT AND CONTACT CURRENT MEASUREMENTS....................................................84
5.4.1 Induced Body Current..............................................................................................................................84
5.4.2 Contact Current.........................................................................................................................................86
5.5 INTERNAL FIELD MEASUREMENT PROCEDURES (SAR)...............................................................................86
5.5.1 Temperature Probes for SAR Measurement........................................................................................86
5.5.2. SAR Measurement with Miniature Electric-Field Probes..............................................................90
FORMULATIONS:.........................................................................................................................................................91
5.5.3 Calorimetric Determination of the Whole-Body Average SAR......................................................94
5.6 HAZARD ASSESSMENT; ESTIMATION OF INTERNAL SAR FROM EXTERNAL-EXPOSURE FIELD
MEASUREMENT DATA..............................................................................................................................................95
5.6.1 General........................................................................................................................................................95
5.6.2 Enhanced or Reduced SAR in Personnel in Close Proximity to Passive Reradiators or Active
Radiators. ..............................................................................................................................................................95
5.6.3 Using Near-Field Survey Data to Assess Potentially Excessive SAR in Exposed Personnel...97
APPENDIXES .................................................................................................................................................................99
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subject to change.