New F.C.C. Maximum Permissible R.F. Exposure Rules for Dummies

Discussion in 'Amateur Radio News' started by W1RC, May 2, 2021 at 2:41 PM.

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  1. W1RC

    W1RC Ham Member QRZ Page

    I have posted a short article that distills all the technical, legal and bureaucratic verbiage relative to this matter down to one page explaining it in understandable terms and showing you how to calculate the numbers you will need to keep with your station documents in compliance with F.C.C. Maximum Exposure rules and requirements that now affect ALL radio amateurs.

    In reality, when all is said and done, it is merely some technical and legal housekeeping that is easier to perform than it is to explain and describe.


    Michael Crestohl, W1RC/VE2XL
    New England Amateur Radio Festival, Inc.
    aka NEAR-Fest......
    Join us for our “Grand Homecoming”
    Friday October 15th and Saturday, October 16th 2021.
    Last edited: May 2, 2021 at 2:47 PM
    KA4FIX, KA9EES, KB0MNM and 2 others like this.
  2. K4RGN

    K4RGN Premium Subscriber QRZ Page

    As the ARRL writeup at states, "This simple calculator [referring to the Lake Washington Ham Club website] applies for any distances that are greater than the near-field boundary limit." It doesn't apply within the reactive near field. Why? Every simple calculator that I've seen makes an assumption of plane waves... a very good assumption in the far field, but not in the reactive near field whose boundary in feet is 156.8 divided by frequency in MHz.

    We all want to gloss over this problem because the reactive near field is a PITA to deal with unless your antenna is very simple. How picky the FCC would be about the near field thing is anyone's guess at this point. I hope that over the next few months we will get more definitive info about it.
  3. W4PG

    W4PG Super Moderator Lifetime Member 279 Volunteer Moderator Platinum Subscriber Life Member QRZ Page

    Thank you!! Well done.
  4. WQ4G

    WQ4G Ham Member QRZ Page

    I'll get it ready, but I'm wondering when I might expect an 'FCC Station Inspection'? Perhaps, while they are here, they will help me locate some of the RFI that plagues my station....

    The ONLY time I've ever seen an actual FCC Agent was back about 1982 when I took the exam at the field office in Tampa, FL. Haven't seen one since.

    Dan WQ4G
  5. KD0YMG

    KD0YMG Ham Member QRZ Page

    That's exactly my concern.
    What I've heard is that near-field modeling is pretty dicey. I also wonder how the above statement interacts, if at all, with the wattage thresholds for exemption. This directly affects my QTH. I did what I could under the circumstances, and relied on the old exemption to figure I was OK. The Lake Washington online calculator tells me a minimum safe distance which is within the near field for 20M and 40M, but I figure the FCC has a reason for specifically calling out the near field.

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