Do You Really Know the RF Environment?

That's a question we all are asking ourselves especially as new radio services and wireless LANs and applications are coming on board. If we really need to know the answer, how in the world will you attack a measurement program of this RF environment? Well, we have a start with IEEE Standard 473 on EM Site Surveying. This has been around for over 20 years. But it is time to update it using modern instrumentation, measurement techniques, and statistical data processing and storage. If this is your bag, please read on as we are now launching a revision of the document and need your help.

Your Personal Invitation to join... IEEE WG 473
Revision of IEEE Recommended Practice for an Electromagnetic Site Survey (10 kHz to 40 GHz)

By Elya B. Joffe, Working Group 473 Chairman

I. IEEE Standard 473: 1991 at a Glance

IEEE STD 473 describes a systematic approach for performing an EM site survey, commencing from preparation of the planning of the test until completion, data analysis and documentation of the measurement results. The Standard outlines procedures and information regarding the methods for conducting EM site surveys particularly for EMR bio-effects and equipment effects applications.

II. The Revision is Under Way

IEEE approved a PAR for the revision of IEEE Standard 473 and a Working Group has been formed. The Working Group held its first meeting in Montreal, during the 2001 IEEE International Symposium on EMC.

The main objectives of this effort are to expand the coverage of the Standard from 10 GHz to 40 GHz and update measurement techniques to reflect current state of the art and technology.

Membership of the Working Group includes members from the original committee who wrote the first issue of IEEE Standard 473, who provide their insight as to the original considerations on the development of the Standard as well as new members from a broad spectrum of activities, users and equipment manufacturers alike.

III. Why the Need for Revision?

The current Standard extensively covers a broad spectrum of considerations in conducting EM site surveys, however, a detailed review indicates that an extensive revision is necessary.

The proposed revision will:

1) Expand the current scope of the Standard, including the characterization of the performance of an existing or planned electronic system as well as for the evaluation of the expected human exposure to EMF, due to emitters on site, to incorporate methods and considerations in conducting electromagnetic site surveys for the purpose of RF compatibility and collocation purposes Ð a field requiring a major revision and extension of measurement techniques and considerations! This expansion requires that specific parameters such as modulation waveforms, signal bandwidth, spectral distribution, signal waveform characteristics, field polarization, etc, be measured. The existing Standard addresses these parameters only to a limited extent.

Due to recent changes in frequency allocations, the upper frequency range needs to be extended from the current 10 GHz to 40 GHz.

2) Update and incorporate the usage of modern test and measurement equipment and procedures. These include not only the usage of similar test methods with modern test equipment, but also the consideration of brand new measurement techniques and approaches, even to incorporate time domain considerations and statistical methods in spectral analysis for pulsed RF emitters (e.g. radars).
Special consideration of new measurement technologies and techniques, enabling one to make the most of available test equipment, are going to be developed. These include the application of modern detector type, digital measurement equipment providing measurement and processing capabilities never before used, etc.

3) Incorporate statistical techniques and measurement uncertainty considerations into the Standard. This is of utmost importance, especially due to the expanded applications of the Standard.

Measurement of EMF for HERP (Hazard of EM Fields to Personnel) requires not only a qualitative knowledge of the EME, but rather a high level of certainty and confidence in the measurement results. This turns out to be one of the most important items under consideration in the development of the Standard.

4) Discuss post-survey data processing, keeping in mind the various applications of the Standard, each requiring different processing approaches and analysis. Since no project is complete until the paperwork is done, survey documentation outlines and structure are also developed.

5) Update the database; this, of course, is performed to incorporate updated bibliography and references to be applied especially in the informative appendices added to the Standard.

IV. New Outline, New Topics

Following almost six months of hard work, the Working Group has developed a new, revised outline of the Standard, reflecting the major update of the document, both in concept, in techniques and in technology.

Beginning from a revised and well-structured approach to the very planning of the site survey, the document leads the reader through detailed recommended procedures for actually conducting the survey, and reporting its results after due analysis and predictions, according to application.

The following is a high-level outline of the proposed Standard, which forms the basis for work in the months and years to come. It may give some fair idea on the topics and scope of the revised Standard:

1. Introduction
2. Definitions and Acronyms
3. References
4. Electromagnetic Environment
5. Survey Planning
6. Site Survey Procedures
7. Measurement Equipment
8. Detector Functions
9. Measurement Uncertainty and Errors
10. Data Handling, Reporting and Documentation

Appendices

Appendix A: Derivation of External Noise Figure (Fa) for Several Types of Antennae
Appendix B: Summary of Permissible Human Exposure Limits to RF Fields
Appendix C: Bibliography

V. Call for Volunteers

Would you be interested in being involved in this activity? If you are:

• Involved in RF site studies
• Experienced in running "on site" RF measurements
• Familiar with statistical analysis techniques
• Or simply have interest in this field

and would like to contribute to this activity, WE NEED YOU!

The working group is seeking technical expert volunteers to join.

Geographical location is NOT an issue. This Working Groups spans over more than 10 time zones, but thanks to technology, particularly the Internet, communication is easier than ever. Members span from the US and Canada all the way to Israel (home of the undersigned WG Chair).

The Working Group does plan to hold at least two meetings a year, one of them in conjunction with the IEEE EMC International Symposium, where attendance is recommended, but event technical contributions and e-mail communications keep you in touch.

If all of the above has encouraged you to seek new horizons for channeling your experience, your knowledge and your willingness to contribute to the benefit of the EMC Society, please do not hesitate to let us know.

Our goal is to prepare a useful, up-to-date Standard. Would you like to be a part of it?

For further information, please contact Elya B. Joffe, WG 473 Chairman, at: eb.joffe@ ieee.org EMC