Answer to Question #3392 Submitted to "Ask the Experts"

Let me start with a picture as you requested. Check out the Richard Tell Associates, Inc. website to find some photos of satellite dish facilities.

The large (about 10 feet across) round dishes in the photos receive radiofrequency (RF) signals from satellites and, of course, the process of receiving signals does not transmit any radiation at all. Some facilities also use large dishes to send RF signals to satellites. These dishes may transmit fairly powerful RF signals but only in a very well-collimated beam like a flashlight. The beam is aimed at the satellite. RF signal strengths can be large directly in front of a transmitting satellite dish, that is, within the beam. But there is very little RF signal, and no hazard to people, outside the beam being transmited from a satellite dish.

The small (two to three feet across) round dishes mounted on the tower (in the black and white photo) are microwave dishes. These dishes are used to send and receive signals to other microwave dishes located on other towers within typically a few miles distance. Because the distance is short (compared to transmitting all the way to an orbiting satellite) the microwave dishes operate at relatively low power. Like the satellite dishes, the transmitted RF signals from a microwave dish are sent in a narrow flashlight-like beam. So again, unless you are directly out in front of a microwave dish in the transmitted beam, there is no hazard to you in the nearby area.

Gary Zeman, CHP, ScD