Tech

Presentation explains latest RF

exposure regulations

Dan Romanchik, KB6NU On Tuesday, April 27, Dan, W1DAN, ARRL Eastern Massachusetts Section Technical Coordinator, gave a Zoom presentation on the latest FCC regulations on RF exposure evaluation. These are spelled out in FCC-1926A1, “Proposed Changes in the Commission’s Rules Regarding Human Exposure to Radiofrequency Electromagnetic Fields; Reassessment of Federal Communications Commission Radiofrequency Exposure Limits and Policies.” The document is as long as the title might suggest—159 pages—but W1DAN boiled it down, focusing on what these changes mean for radio amateurs. A recording of the presentation can be viewed by going to https://drive.google.com/drive/folders/1_qIGZhHyM rha-axJt87Dcu0UZuJO0t8F. After explaining how RF exposure can be harmful, Dan explained how the rules are changing: The biggest change, he notes, is that amateur radio’s categorical exclusion has been eliminated. What this means is that now every radio amateur will have to perform an RF exposure evaluation of their stations. This now includes mobile and portable stations, including HTs, SOTA/POTA stations, and Field Day and special event stations. He noted that you must be able to prove that your station is safe. This includes not only performing the evaluation, but also documenting these evaluations, should this data be requested by FCC personnel. One thing that’s not changing are the maximum permissible exposure (MPE) limits. These are spelled out in FCC OET Bulletin 65, “Evaluating Compliance with FCC Guidelines for Human Exposure to Radiofrequency Electromagnetic Fields.” The FCC published this document in August 1997, but it’s still the Bible when it comes to RF exposure. If you don’t have a copy, or have never taken a look at it, you really should do so. Be careful, though, when reading it. It contains a table (Table 1 on p. 21) that contains a list of output powers at various frequencies. If your station exceeded those limits, then you were required to perform an RF evaluation. Now, however, all amateurs (and other radio services, for that matter) must perform RF exposure evaluations if their output power exceeds 1 mW. We are no longer categorically excluded from performing these evaluations. OET Bulletin 65 goes on to give guidance on how to calculate or measure exposure levels. Explaining how to do this is outside the scope of this article, but again, you’ll want to refer to the bulletin for more information. Besides the elimination of the categorical exclusion for amateur radio stations, what else is new is the dates on which amateur radio stations must perform evaluations. They are:  May 3, 2021(!!) for new and modified stations  May 3, 2023 for stations that complied under the old rules. Having said all that, the ARRL’s RF Exposure page has a lot of resources to help you understand this topic and perform your own RF exposure evaluations:  An RF-exposure FAQ to help hams understand the new rules.  “Learning to Live with RF Safety,” QST March 2009 pp. 70-71.  RF Safety at Field Day QST June 1999, pp. 48-51. A case study of Field Day with NSRC in a public park  RF Exposure Station Evaluation and Exemption Worksheets  RF Exposure and You. This 8 Mbyte PDF file contains the text of the entire book by Ed Hare, W1RFI.  Chapter 5 References needed for filling out worksheet. The page also has links to FCC web pages with information on RF exposure. I’m sure we’ll all be hearing more about this in the days ahead. Hopefully, someone will come out with a simple way to do the modeling or make the calculations. As always, play safe. The post appeared first on KB6NU's Ham Radio Blog.