Q Bernard, K8LIX, asks, “The Dovetron stealth antenna uses house wiring as part of the radiating system. I live in a condo with neighbors on both sides. If I use it with my 150-W transmitter, what kind of measurements will I have to make in order to satisfy the FCC RF safety requirements?”
A You can make the same calculations for this as for any antenna. Unless you and your neighbors are on the same circuit, you can probably safely assume that all of the wiring in your unit could be radiating. These types of antennas are not very efficient, so a calculation assuming 0-dBi gain is probably reasonable.
At 150 W, with a 40% duty factor and 67% on/off operating times, you have 40 W of average power for the purposes of the safety calculation. Your neighbors would need to be the following distances from any part of your residential electrical wiring:
28 MHz: 6.2 feet
14 MHz: 3.1 feet
7 MHz: 1.5 feet
Assuming the same conditions and 100% on/off time (in 6 minutes), you and your family would have to be:
28 MHz: 3.4 feet
14 MHz: 1.7 feet
7 MHz: 0.8 feet
From QST July 2000
