[bars] RF Exposure Calculator

[Marla A. Wallace]

Yes, thanks.  The calculator says I need to move my antenna a tad further from the rig when I check into the Wednesday night net.  Or reduce power, which I can do for the Westford repeater (though not for Billerica).

Me ke aloha
-- Marla

On August 6, 2021, at 06:38, William Smith <w_smith at compusmiths.com> wrote:

Very nice, Bruce, thanks for the pointer!


73, Willie N1JBJ


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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