This book is devoted to the specific problems of electromagnetic field (EMF) measurements in the near field and to the analysis of the main factors which impede accuracy in these measurements. It focuses on careful and accurate design of systems to measure in the near field based on a thorough understanding of the fundamental engineering principles and on an analysis of the likely system errors.

Beginning with a short introduction to electromagnetic fields with an emphasis on the near field, it them presents methods of EMF measurements in near field conditions. It details the factors limiting measurement accuracy including internal ones (thermal stability, frequency response, dynamic characteristics, susceptibility) and external ones (field integration, mutual couplings between a probe and primary and secondary EMF sources, directional pattern deformations).

It continues with a discussion on how to gauge the parameters declared by an EMF meter manufacturer and simple methods for testing these parameters. It also details how designers of measuring equipment can reconsider the near field when designing and testing, as well as how users can exploit the knowledge within the book to ensure their tests and results contain the most accurate measurements possible.

Electromagnetic Measurements in the Near Field is addressed to a wide range of specialists in biology, medicine, labor safety, environmental protection, metrologists, EMF meter designers, testers and users, and even for those who must make legal decisions on the grounds of measurement results interpretation.

1. Introduction

2. The Near Field and the Far Field
2.1 An EMF Generated by a System of Currents
2.2 The Far Field and the Near Field
2.3 EMF from Simple Radiating Structures

3. EMF Measurement Methods
3.1 E, H, and S Measurement
3.2 Temperature Rise Measurements
3.3 SAR Measurement
3.4 Current Measurements

4. Electric Field Measurement
4.1 Field Averaging by a Measuring Antenna
4.2 Influence of Fields from Beyond a Probe Measuring Band
4.3 Mutual Interaction of the Measuring Antenna and the Field Source
4.4 Changes in the Probes’ Directional Pattern
4.5 E-Field Probe Comparison
4.6 Comments and Conclusions

5. Magnetic Field Measurement
5.1 The Sizes of the Measuring Antenna
5.2 Frequency Response of the Magnetic Field Probe
5.3 Directional Pattern Alterations
5.4 Measurement Accuracy vs. Antenna Distance to Radiation Source
5.5 Magnetic Field Probe with a Loop Working above its Self-Resonant Frequency
5.6 Conclusions and Comments

6. Power Density Measurement
6.1 Power Density Measurement Methods
6.2 Power Density Measurement Using the Antenna Effect
6.3 Conclusions and Comments

7. Directional Pattern Synthesis
7.1 A Probe Composed of Linearly Dependent Elements
7.2 Spherical Radiation Pattern of an E/H Probe
7.3 A Probe Composed of Three Mutually Perpendicular Dipoles
7.4 Conclusions and Comments

8. Other Factors Limiting Measurement Accuracy
8.1 Thermal Stability of a Field Meter
8.2 The Dynamic Characteristics of the Detector
8.3 Measured Field Deformations
8.4 Susceptibility of the Meter to External EMF
8.5 Resonant Phenomena
8.6 Human Factor
8.7 Uncertainty Budget

9. Photonic EMF Measurements
9.1 The Photonic EMF Probe
9.2 Frequency Response of the Probe
9.3 Sensitivity of the Photonic Probe
9.4 Magnetic Field Photonic Probe
9.5 Detector Linearity
9.6 Synthesis of the Spherical Directional Pattern
9.7 The “Future Meter”

10. Final Comments

Pawel Bienkowski, Ph.D., is affiliated with the EM Environment Protection Lab at the Technical University of Wroclaw where he researches electromagnetic compatibility and electromagnetic field measurements and standards. He was born in Wroclaw in 1968 and is the author or co-author of over 100 publications and symposia presentations and over 20 patents.

Hubert Trzaska is a Professor in the EM Environment Protection Lab at the Technical University of Wroclaw, Poland where he is involved in researching electromagnetic field measurements and standards. He was born in 1939 in Wilno, Poland (presently Vilnius, Lithuania). After World War II he was deported to Wroclaw, Poland (formerly Breslau, Germany). He is a Charter Member of the Bioelectromagnetic Society and is author or co-author of over 300 publications and symposia presentations and over 50 patents.