Hello Kristen,

In case you didnt catch the error on the page currently (as of 3:39PM today)

linked to for a calculator on the ARRL.ORG site - the first line asks for power in

ERP ( as opposed to PEP) and then asks for antenna gain.... and it has been

like that for years.

The new FAQ links to http://www.lakewashingtonhamclub.org/resources/rf-exposure-calculator/

which is better, but it contains no mention of whether ground gain is required. Even though there is a radio button for ground gain. , Even for verticals ground gain is needed since it gives the worse case scenario for exposure.

This is where a lot of people also get mis-led since the calculation, from OET65B gives the worse case and not a technically correct value. This worse case takes into account local reflectors that would increase the field from verticals; while there is no "ground gain" from a vertical it does in this manner account for random nearby reflecting conductors that would increase the field. (The details of this can be found in equations (4) through (8) in the OET65B publication).

If you "pass" that calculation then no further evaluation is needed. If you do not "pass" then a more careful analysis for the evaluation is required; such as EZNEC modeling, etc. Explaining that the ground gain is important for the correct use of the calculator for determination of whether an more indepth evaluation is required. Detail such as these should be explained somewhere but those explanations are lacking on the calculator-site that is linked in the FAQ.

The equation for the calculator is simple, and I agree that we should have an online

calculator the quality of which we control since without a lot of critical explanation, since without explanation, the the calculated results are at odds with what a trained engineer will expect. I also strongly agree that better and more in depth explanations are needed such as articles in QST, webpage resource papers, and online calculators.

73, Kermit Carlson W9XA

ARRL Central Division Director

ARRL EMC Committee Chairman

On Monday, April 26, 2021, 1:55:45 PM CDT, Kristen A. McIntyre <kristen@alum.mit.edu> wrote:

A third party calculator page is linked from this ARRL page. I’ve been referring people to that link.

http://www.arrl.org/rf-exposure

http://hintlink.com/power_density.htm

It’s hard to find, though, and doesn’t give a go/no-go result. An ARRL version of this should be prominently displayed right at the top. I received complaints that the recent ARRL Letter article didn’t point directly to a calculator.

Sent from my iPad

On Apr 26, 2021, at 10:55 AM, Michael Ritz <w7vo@comcast.net> wrote:

I'm already getting requests to do Zoom presentations on the new/old RF Exposure rules. The more we can get out there, the better.

That said, a special webpage (that we host and have control over) where members can input the variables and spit out a "COMPLY" or "NO COMPLY" report would be best. Another member benefit!

I never received an answer as to whether or not the ARRL is considering an update and re-publish on the RF Exposure book. I have the old one on order from e-Bay and it will be here this week.

73;

Mike

W7VO

On 04/26/2021 9:04 AM Dale Williams <dale.wms1@frontier.com> wrote:

In service to our members, we posted a FAQ cover note and link on the Great Lakes Div web page on Sunday.

73,

Dale WA8EFK

On 4/26/2021 11:36 AM, John Robert Stratton wrote:
All

    Kermit, good work.

    This FAQ needs to be provided to all Members. A special ARRL newsletter should be prepared and sent to the Membership that addresses this issue; it should either include this FAQ in its entirety and/or contain a link to an URL where the PDF can be read and downloaded.

    All the Directors need a version of this FAQ as a PDF (preferably, fancied up) that can be provided to our SMs and Club Coordinators for distribution to the Section websites and for dissemination to Clubs for inclusion in their newsletters and/or on their websites.

    This topic is hot amongst the Members and the lack of understanding and the rumors (mostly wrong) need to be addressed sooner rather than later.

_______________________________________

John Robert Stratton

N5AUS

Director

West Gulf Division

Office:             512-445-6262

Cell:                512-426-2028

P.O. Box 2232

Austin, Texas 78768-2232

_______________________________________

______________________________________

On 4/25/21 12:50 PM, Kermit Carlson via arrl-odv wrote:
Greetings All,

     Please find attached the PDF of the RF Exposure

Frequently Asked Questions (Version 1.3).   Ed Hare

and the ARRL Laboratory are the authors of this

document with technical advice from Dr. Greg Lapin, N9GL,

and the RF Safety Committee. My thanks to the Executive

Committee for their contribution to the editorial process

of this document.

    This PDF version 1.3 is suitable for distribution. Any questions

or suggestion for future inclusion in the FAQ should be directed

to the ARRL Laboratory by email at tis@arrl.org. One of the ARRL

Laboratory engineers will respond to comments by email.

     The responsibility for updates to this living-breathing document

will now pass the ARRL Laboratory staff under the direction of

Ed Hare, W1RFI; and the the RF Safety Committee under the

lead of Dr. Greg Lapin, N9GL.    As ARRL members, we are indeed

very fortunate to have such a great assemblage of truly gifted

authorities in the field of RF Engineering.

    Please be aware that updates might be very common as

details come into better focus as the discussions between the FCC

and the ARRL develop clarifications and recommendations.

     Thanks again to Ed Hare, W1RFI, for the authorship of this FAQ.

73,

    Kermit Carlson W9XA

    ARRL EMC Committee Chair
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