[AReU] RF Safety

[W4BIN]

   Amateur Radio is basically a safe activity.  In recent years, 
however, there has been considerable discussion and concern about the 
possible hazards of electromagnetic fields (EMF), including both RF 
energy and power frequency (50-60 Hz) EMF.
   FCC regulations set limits on the maximum permissible exposure (MPE) 
allowed from the operation of radio transmitters.  Following these 
regulations, along with the use of good RF practices, will make your 
station as safe as possible.

   “RF Exposure and You” is available in PDF format for free download 
from ARRL at, 
http://www.arrl.org/files/file/Technology/RFsafetyCommittee/28RFSafety.pdf
ARRL also has an RF Safety page on its website at: 
http://www.arrl.org/RF-exposure .

The ARRL RF Safety Committee is working with the FCC to update the FCC's 
aids for following human exposure rules - OET Bulletin 65 and OET 
Bulletin 65 Supplement B for Radio Amateurs.  In addition, ARRL is 
developing tools that all hams can use to perform exposure assessments.
   Amateur Radio has been exempt from the usual precautions, 
specifically surveying for hazardous conditions caused by our stations, 
but that is about to end (May the 3rd 2023) and we must create a record 
of our calculations.

   The Report and Order can be found online in PDF format at:
https://docs.fcc.gov/public/attachments/FCC-19-126A1.pdf .

"In the RF Report and Order, the Commission anticipated that few parties 
would have to conduct reevaluations under the new rules and that such 
evaluations will be relatively straightforward," the FCC said in an 
April 2 Public Notice.  "It nevertheless adopted a 2-year period for 
parties to verify and ensure compliance under the new rules."

The Amateur Service is no longer categorically excluded from certain 
aspects of the rules, as amended, and licensees can no longer avoid 
performing an exposure assessment simply because they are transmitting 
below a given power level.

"For most amateurs, the major difference is the removal of the 
categorical exclusion for amateur radio, which means that ham station 
owners must determine if they either qualify for an exemption or must 
perform a routine environmental evaluation," said Greg Lapin, N9GL, 
chair of the ARRL RF Safety Committee and a member of the FCC 
Technological Advisory Council (TAC).

"Ham stations previously excluded from performing environmental 
evaluations will have until May 3, 2023, to perform these. After May 3, 
2021, any new stations or those modified in a way that affects RF 
exposure must comply before being put into service," Lapin said.
The ARRL Laboratory staff is available to help amateurs to make these 
determinations and, if needed, perform the necessary calculations to 
ensure their stations comply.  ARRL Laboratory Manager Ed Hare, W1RFI, 
who helped prepare ARRL's RF Exposure and You book, explained it this 
way.  "The FCC did not change any of the underlying rules applicable to 
amateur station evaluations," he said:  "The sections of the book on how 
to perform routine station evaluations are still valid and usable, 
especially the many charts of common antennas at different heights." 
Hare said ARRL Lab staff also would be available to help amateurs 
understand the rules and evaluate their stations."


   A calculator can be found at:  http://hintlink.com/power_density.htm

   You must tackle one antenna at a time, each with the same kind of 
information.
One report for each antenna,  for each band,  for each  power level. 
(if different)

   Look to the antenna manufacturer to supply you with gain information 
for each band. (web-site)  Gain must be specified in dBi, convertible 
from other expressions.

   If you can pass the requirements by specifying your maximum TPO then 
the transmission line losses need not be investigated.  On the higher 
bands most equipment can operate using FM modulation if so the peak 
power is the average power.

   You need consider only the highest frequency that you can operate on 
for each band for each maximum power level for each antenna.
If each band of a multi band-antenna has the same gain on each band, 
only the highest frequency needs to be calculated for each maximum power 
level.

   You need to put one sheet for each of your maximum power output for 
each band for each antenna into a file folder with your station's record 
(along with a copy of your station's license) kept handy and safe.

   Mobile operations below a particular power level are exempt, but 
above that level we still must conduct a study, for each antenna, power 
level and frequency band. (and the records likewise kept)

   The distance/s is measured from the closest point of the actively 
powered portion of the radiating element/s to where a person could stand.

   When any antenna is added or moved we need to remember to update our 
safety calculation information.


-- 
   Ron  W4BIN - Understanding is much better than
                                     knowing how.MX