DRAFT Recommended Practice for Measurements and ...

1/29/98 142 C95.3-1991 Revision — 2 nd Draft
10/98 Draft
2. DEFINITIONS ............................................................................................................................................................20
3. THE MEASUREMENT PROBLEMS OF RADIO FREQUENCY (RF) HAZARD DETERMINATION .......29
3.1 CHARACTERISTICS OF RF ELECTROMAGNETIC (EM) RADIATION..............................................................29
3.1.1 Parameters Determined by the Source...................................................................................................29
3.1.2 Interference Patterns.................................................................................................................................29
3.1.3 Radiation Leakage....................................................................................................................................29
3.1.4 Reactive Near Field...................................................................................................................................30
3.1.5 Passive, Parasitic or Secondary Reradiators.......................................................................................31
3.1.6 Other Considerations. ...............................................................................................................................31
3.2 SUMMARY OF THE MEASUREMENT PROBLEM...............................................................................................32
3.2.1 External Field Measurement Problems................................................................................................32
3.2.2 Problems of Time and Spatial Averaging.............................................................................................33
3.2.3 In- and Out-of-Band Interference in RF Hazard Meters, Including Cable Pickup.....................34
3.2.4 Effects of Sensor Size and Measurement Distance..............................................................................35
3.2.5 SAR and Internal Body Current Measurement Problems.................................................................36
3.2.6 Limitations on the Measurement Accuracy of the RF Energy Absorption Rate (SAR)..............36
3.2.7 Limitations in the Use of Near-Field Instrumentation.......................................................................37
4. INSTRUMENTATION..............................................................................................................................................38
4.1 INSTRUMENTATION FOR EXTERNAL FIELD MEASUREMENTS. ...................................................................38
4.1.1 RF Survey Instruments.............................................................................................................................38
4.2 DESIRABLE ELECTRICAL PERFORMANCE CHARACTERISTICS......................................................................39
4.2.1 Power Supply. .............................................................................................................................................39
4.2.2 Polarization.................................................................................................................................................40
4.2.3 Quantities and Units..................................................................................................................................40
4.2.4 Range............................................................................................................................................................40
4.2.5 Recorder Output.........................................................................................................................................40
4.2.6 Shielding......................................................................................................................................................40
4.2.7 Modulation..................................................................................................................................................41
4.2.8 Static Electricity.........................................................................................................................................41
4.2.9 Response to Other Radiation...................................................................................................................41
4.2.10 Response Time..........................................................................................................................................41
4.2.11 Special Functions....................................................................................................................................41
4.2.12 Stability......................................................................................................................................................42
4.2.13 Precision and Accuracy Considerations.............................................................................................42
4.3 DESIRABLE PHYSICAL CHARACTERISTICS.......................................................................................................42
4.3.1 PORTABILITY.....................................................................................................................................................42
4.3.2 Weight..........................................................................................................................................................42
4.3.3 Volume. ........................................................................................................................................................42
4.3.4 Dependence on Temperature, Humidity, and Pressure......................................................................43
4.3.5 Durability.....................................................................................................................................................43
4.3.6 Readability..................................................................................................................................................43
4.3.7 Ease of Adjustment....................................................................................................................................43
4.3.8 Ease of Use. .................................................................................................................................................43
4.4 INSTRUMENT TYPES FOR EXTERNAL FIELD MEASUREMENTS....................................................................43
4.4.1 Diode Rectifier-Based Instruments. .......................................................................................................43
4.4.2 Active Antenna...........................................................................................................................................45
4.4.3 Displacement Current Sensors. ...............................................................................................................45
4.4.4 Electro-Optical (Photonic) Sensors........................................................................................................46
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subject to change.