[bars] RF Exposure Calculator

[William Smith]

IIRC:

Uncontrolled:  Your neighbors (or the general population), you can’t control their location, position, or actions while you are transmitting. 

Controlled: You and your family (or employees), you can control the above. “Don’t go into the backyard (or climb the tower) while I’m transmitting. “

73, Willie N1JBJ

> On Aug 7, 2021, at 10:38 AM, Joanne Dolan <dolans.family at gmail.com> wrote:
> 
> Thanks for the calculator link!
> Can anyone tell me what’s the difference between a controlled and uncontrolled environment?
> 
> Sent from my iPad
> 
>>> On Aug 6, 2021, at 1:18 AM, Bruce Anderson <w1lus at hotmail.com> wrote:
>>> 
>> 
>> We are all required to calculate the RF exposure to people from our transmissions.
>> The results should show that our antennas are located far enough from people so no one gets over exposed. 
>> Or inversely where to locate our antennas to prevent over exposing people to our transmissions.
>> The ARRL has provided a simple calculator for hams to determine this minimum safe distance.
>> 
>> http://arrl.org/rf-exposure-calculator
>> RF Exposure Calculator
>> The FCC has adopted guidelines and procedures for evaluating environmental effects of RF emissions. The new guidelines incorporate two tiers of exposure limits based on whether exposure occurs in an occupational or "controlled" situation or whether the general population is exposed or exposure is in an "uncontrolled" situation.
>> arrl.org
>> 
>> Below in a sample calculation I did for my FT 8 transmissions on 20 Meters running 100 watts to a half wave dipole.
>> 
>> The results show two feet away for myself and family is safe and 4.5 feet away is safe for Neighbors.
>> Of course, since the antenna is over 15 feet high there is no issue with this antenna and power on 20 Meters. 
>> 
>> RF Exposure Calculator
>> Parameters
>> Power at Antenna: 100 (watts)
>> Mode duty cycle: AFSK SSB (duty cycle=100%)  (FT 8)
>> Transmit duty cycle: (time transmitting)
>> You transmit for 1 minutes then receive for 1 minutes (and repeat).
>> Antenna Gain (dBi): 2.15 (1/2 wave Dipole)
>> Operating Frequency (MHz): 14.074
>> Include Effects of Ground Reflections
>> 
>> Results for a controlled environment:
>> Maximum Allowed Power Density (mw/cm2): 4.5437
>> Minimum Safe Distance (feet): 1.9897
>> Minimum Safe Distance (meters): 0.6065
>> 
>> For an uncontrolled environment:
>> Maximum Allowed Power Density (mw/cm2): 0.9087
>> Minimum Safe Distance (feet): 4.4490
>> Minimum Safe Distance (meters): 1.3561
>> 
>> Bruce
>> W1LUS
>> 
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