Update on Aug 2, 2021: the September issue of QST has a free article about Understanding the Changes to the FCC RF Exposure Rules.

The FCC has announced that rule changes detailed in a lengthy 2019 Report and Order governing RF exposure standards go into effect on May 3, 2021. The new rules do not change existing RF exposure (RFE) limits but do require that stations in all services, including amateur radio, be evaluated against existing limits, unless they are exempted. For stations already in place, that evaluation must be completed by May 3, 2023. For more information see: www.arrl.org/news/updated-radio-frequency-exposure-rules-become-effective-on-may-3

We have two ways to comply with the rules. One method involves taking measurements with the appropriate instruments. Another method is a predictive model with calculations based on antenna theory and documented properties of the transmitters and antennas at your station.

Below are some of the RF exposure calculations I created for the antennas at my station using a calculator that is available on-line. See below the table for links to sources of the information and the calculator that I used.

I also found a spreadsheet from Ham Radio School, adapted and updated it to create this spreadsheet that seems to be easier to produce calculations.

I used the most conservative estimates possible. For example, I assumed a 100 percent duty cycle on FM and entered the maximum power rating for each band from the tech specs for my radios. I chose not to calculate power losses from feedline. You might want to use a feedline power loss calculator to estimate a more accurate power level at your feed point.

Please let me know if you see any mistakes.

I used the Calculator at: hintlink.com/power_density.htm

Antenna and Calculation | Band Start | Band End |

Comet CX-333 | 70cm Band | Gain per Comet |

Average Power at the Antenna | 35 watts | 35 watts |

Antenna Gain in dBi | 9 dBi | 9 dBi |

Distance to the Area of Interest in Feet | 48 feet | 48 feet |

Distance to the Area of Interest in Meters | 14.6304 metres | 14.6304 metres |

Frequency of Operation | 420 MHz | 450 MHz |

Are Ground Reflections Calculated? | Yes | Yes |

Estimated RF Power Density | 0.0265 mW/cm2 | 0.0265 mW/cm2 |

Controlled MPE | 1.405 mW/cm2 | 1.505 mW/cm2 |

Controlled Distance to Compliance From Centre of Antenna Feet | 6.6489 feet | 6.4251 feet |

Controlled Distance to Compliance From Centre of Antenna Meters | 2.0266 metres | 1.9584 metres |

Uncontrolled MPE | 0.285 mW/cm2 | 0.305 mW/cm2 |

Uncontrolled Distance to Compliance From Centre of Antenna Feet | 14.8055 feet | 14.3052 feet |

Uncontrolled Distance to Compliance From Centre of Antenna Meters | 4.5127 metres | 4.3602 metres |

Does the Area of Interest Appear to be in Compliance? | yes | yes |

Comet CX-333 | 1.25 M Band | Gain per Comet |

Average Power at the Antenna | 70 watts | 70 watts |

Antenna Gain in dBi | 7.8 dBi | 7.8 dBi |

Distance to the Area of Interest in Feet | 48 feet | 48 feet |

Distance to the Area of Interest in Meters | 14.6304 metres | 14.6304 metres |

Frequency of Operation | 222 MHz | 225 MHz |

Are Ground Reflections Calculated? | Yes | Yes |

Estimated RF Power Density | 0.0402 mW/cm2 | 0.0402 mW/cm2 |

Controlled MPE | 1.005 mW/cm2 | 1.005 mW/cm2 |

Controlled Distance to Compliance From Centre of Antenna Feet | 9.6672 feet | 9.6672 feet |

Controlled Distance to Compliance From Centre of Antenna Meters | 2.9466 metres | 2.9466 metres |

Uncontrolled MPE | 0.205 mW/cm2 | 0.205 mW/cm2 |

Uncontrolled Distance to Compliance From Centre of Antenna Feet | 21.5547 feet | 21.5547 feet |

Uncontrolled Distance to Compliance From Centre of Antenna Meters | 6.5699 metres | 6.5699 metres |

Does the Area of Interest Appear to be in Compliance? | yes | yes |

Comet CX-333 base mounted at 48' height | 2 M Band | Gain per Comet |

Average Power at the Antenna | 50 watts | 50 watts |

Antenna Gain in dBi | 7.8 dBi | 7.8 dBi |

Distance to the Area of Interest in Feet | 48 feet | 48 feet |

Distance to the Area of Interest in Meters | 14.6304 metres | 14.6304 metres |

Frequency of Operation | 144 MHz | 148 MHz |

Are Ground Reflections Calculated? | Yes | Yes |

Estimated RF Power Density | 0.0287 mW/cm2 | 0.0287 mW/cm2 |

Controlled MPE | 1.005 mW/cm2 | 1.005 mW/cm2 |

Controlled Distance to Compliance From Centre of Antenna Feet | 8.178 feet | 8.178 feet |

Controlled Distance to Compliance From Centre of Antenna Meters | 2.4927 metres | 2.4927 metres |

Uncontrolled MPE | 0.205 mW/cm2 | 0.205 mW/cm2 |

Uncontrolled Distance to Compliance From Centre of Antenna Feet | 18.2248 feet | 18.2248 feet |

Uncontrolled Distance to Compliance From Centre of Antenna Meters | 5.5549 metres | 5.5549 metres |

Does the Area of Interest Appear to be in Compliance? | yes | yes |

Radiowavz DX80PL OCF Dipole | 10 M Band | Gain estimates |

Average Power at the Antenna | 100 watts | 100 watts |

Antenna Gain in dBi | 10.77 dBi | 10.77 dBi |

Distance to the Area of Interest in Feet | 36 feet | 36 feet |

Distance to the Area of Interest in Meters | 10.9728 metres | 10.9728 metres |

Frequency of Operation | 28 MHz | 29.7 MHz |

Are Ground Reflections Calculated? | Yes | Yes |

Estimated RF Power Density | 0.2021 mW/cm2 | 0.2021 mW/cm2 |

Controlled MPE | 1.153 mW/cm2 | 1.0253 mW/cm2 |

Controlled Distance to Compliance From Centre of Antenna Feet | 15.1521 feet | 16.069 feet |

Controlled Distance to Compliance From Centre of Antenna Meters | 4.6184 metres | 4.8978 metres |

Uncontrolled MPE | 0.2346 mW/cm2 | 0.2091 mW/cm2 |

Uncontrolled Distance to Compliance From Centre of Antenna Feet | 33.8193 feet | 35.8696 feet |

Uncontrolled Distance to Compliance From Centre of Antenna Meters | 10.3081 metres | 10.933 metres |

Does the Area of Interest Appear to be in Compliance? | yes | yes |

Radiowavz DX80PL OCF Dipole | 15 M Band | Gain estimates |

Average Power at the Antenna | 100 watts | 100 watts |

Antenna Gain in dBi | 9.58 dBi | 9.58 dBi |

Distance to the Area of Interest in Feet | 36 feet | 36 feet |

Distance to the Area of Interest in Meters | 10.9728 metres | 10.9728 metres |

Frequency of Operation | 24.89 MHz | 24.99 MHz |

Are Ground Reflections Calculated? | Yes | Yes |

Estimated RF Power Density | 0.1537 mW/cm2 | 0.1537 mW/cm2 |

Controlled MPE | 1.4578 mW/cm2 | 1.4462 mW/cm2 |

Controlled Distance to Compliance From Centre of Antenna Feet | 11.7559 feet | 11.8029 feet |

Controlled Distance to Compliance From Centre of Antenna Meters | 3.5832 metres | 3.5975 metres |

Uncontrolled MPE | 0.2956 mW/cm2 | 0.2932 mW/cm2 |

Uncontrolled Distance to Compliance From Centre of Antenna Feet | 26.2251 feet | 26.3303 feet |

Uncontrolled Distance to Compliance From Centre of Antenna Meters | 7.9934 metres | 8.0255 metres |

Does the Area of Interest Appear to be in Compliance? | yes | yes |

Radiowavz DX80PL OCF Dipole | 20 M Band | Gain estimates |

Average Power at the Antenna | 100 watts | 100 watts |

Antenna Gain in dBi | 10.67 dBi | 10.67 dBi |

Distance to the Area of Interest in Feet | 36 feet | 36 feet |

Distance to the Area of Interest in Meters | 10.9728 metres | 10.9728 metres |

Frequency of Operation | 14.0 MHz | 14.350 MHz |

Are Ground Reflections Calculated? | Yes | Yes |

Estimated RF Power Density | 0.1975 mW/cm2 | 0.1975 mW/cm2 |

Controlled MPE | 4.5968 mW/cm2 | 4.3756 mW/cm2 |

Controlled Distance to Compliance From Centre of Antenna Feet | 7.5146 feet | 7.7012 feet |

Controlled Distance to Compliance From Centre of Antenna Meters | 2.2905 metres | 2.3473 metres |

Uncontrolled MPE | 0.9234 mW/cm2 | 0.8791 mW/cm2 |

Uncontrolled Distance to Compliance From Centre of Antenna Feet | 16.7414 feet | 17.1587 feet |

Uncontrolled Distance to Compliance From Centre of Antenna Meters | 5.1028 metres | 5.23 metres |

Does the Area of Interest Appear to be in Compliance? | yes | yes |

Radiowavz DX80PL OCF Dipole | 30 M Band | Gain estimates |

Average Power at the Antenna | 100 watts | 100 watts |

Antenna Gain in dBi | 7.34 dBi | 7.34 dBi |

Distance to the Area of Interest in Feet | 36 feet | 36 feet |

Distance to the Area of Interest in Meters | 10.9728 metres | 10.9728 metres |

Frequency of Operation | 10.1 MHz | 10.150 MHz |

Are Ground Reflections Calculated? | Yes | Yes |

Estimated RF Power Density | 0.0918 mW/cm2 | 0.0918 mW/cm2 |

Controlled MPE | 8.8277 mW/cm2 | 8.741 mW/cm2 |

Controlled Distance to Compliance From Centre of Antenna Feet | 3.7203 feet | 3.7385 feet |

Controlled Distance to Compliance From Centre of Antenna Meters | 1.1339 metres | 1.1395 metres |

Uncontrolled MPE | 1.7695 mW/cm2 | 1.7522 mW/cm2 |

Uncontrolled Distance to Compliance From Centre of Antenna Feet | 8.257 feet | 8.2976 feet |

Uncontrolled Distance to Compliance From Centre of Antenna Meters | 2.5167 metres | 2.5291 metres |

Does the Area of Interest Appear to be in Compliance? | yes | yes |

Radiowavz DX80PL OCF Dipole | 40 M Band | Gain estimates |

Average Power at the Antenna | 100 watts | 100 watts |

Antenna Gain in dBi | 6.11 dBi | 6.11 dBi |

Distance to the Area of Interest in Feet | 36 feet | 36 feet |

Distance to the Area of Interest in Meters | 10.9728 metres | 10.9728 metres |

Frequency of Operation | 7 MHz | 7.3 MHz |

Are Ground Reflections Calculated? | Yes | Yes |

Estimated RF Power Density | 0.0691 mW/cm2 | 0.0691 mW/cm2 |

Controlled MPE | 18.3723 mW/cm2 | 16.8937 mW/cm2 |

Controlled Distance to Compliance From Centre of Antenna Feet | 2.2579 feet | 2.3525 feet |

Controlled Distance to Compliance From Centre of Antenna Meters | 0.6882 metres | 0.717 metres |

Uncontrolled MPE | 3.6785 mW/cm2 | 3.3827 mW/cm2 |

Uncontrolled Distance to Compliance From Centre of Antenna Feet | 4.987 feet | 5.1986 feet |

Uncontrolled Distance to Compliance From Centre of Antenna Meters | 1.52 metres | 1.5845 metres |

Does the Area of Interest Appear to be in Compliance? | yes | yes |

Radiowavz DX80PL OCF Dipole | 80 M Band | Gain estimates |

Average Power at the Antenna | 100 watts | 100 watts |

Antenna Gain in dBi | 4.94 dBi | 4.94 dBi |

Distance to the Area of Interest in Feet | 36 feet | 36 feet |

Distance to the Area of Interest in Meters | 10.9728 metres | 10.9728 metres |

Frequency of Operation | 3.5 MHz | 4.0 MHz |

Are Ground Reflections Calculated? | Yes | Yes |

Estimated RF Power Density | 0.0528 mW/cm2 | 0.0528 mW/cm2 |

Controlled MPE | 73.4744 mW/cm2 | 56.255 mW/cm2 |

Controlled Distance to Compliance From Centre of Antenna Feet | 1.0148 feet | 1.1527 feet |

Controlled Distance to Compliance From Centre of Antenna Meters | 0.3093 metres | 0.3513 metres |

Uncontrolled MPE | 14.6989 mW/cm2 | 11.255 mW/cm2 |

Uncontrolled Distance to Compliance From Centre of Antenna Feet | 2.2074 feet | 2.5156 feet |

Uncontrolled Distance to Compliance From Centre of Antenna Meters | 0.6728 metres | 0.7668 metres |

Does the Area of Interest Appear to be in Compliance? | yes | yes |