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21 November 2009

Answer to Question #7243 Submitted to "Ask the Experts"

Category: Microwaves, Radar, and Radiofrequency — Satellite Dishes

The following question was answered by an expert in the appropriate field:

My neighbor has a satellite dish that is six feet from from my house and about eight feet above ground and is aimed directly at my house. Since the dish has been up, I have a high-frequency sound all through my house. It's sort of like ringing in the ear but a lot higher. I know that the dish is a receiver—does my neighbor have the dish too close to me and, if so, what would be the dangers and laws on this?

You are correct, most satellite dishes receive weak signals; they do not generate high-intensity electromagnetic waves. And yes, there are government standards to protect the public. Microwave emissions from such transmitting sites must be below a certain level, while higher levels must be restricted, usually with fencing or distance, by using a tower. These restrictive emission levels are usually at the point of nearest public access, but the effect of additional distance greatly reduces these levels.

Microwave radiation, the type emitted from radar, is also similar to the type used by cell phones. Microwave radiation's primary mode of biological interaction is heating, unlike ionizing radiation (x rays, radioactivity). Microwave ovens use high amounts of microwave radiation, but these ovens must have two safety interlocks to operate safely and protect the public, and the external emissions, like cell phones and radar emissions, are extremely low and very safe.

The high-frequency sound you refer to should not be associated with a satellite dish and is probably not hazardous unless of very high intensity. But without any additional information, it is difficult to determine what the source of this high-frequency sound is.

For additional information on radiofrequency (RF) radiation, I refer you to the Health Physics Society's Q and A section that addresses microwave radiation along with other electromagnetic radiations. Embedded in some of these answers are additional links to other Web sites with useful information.

In addition to these regulatory safety standards, there continues to be a lack of credible scientific evidence to show that such emissions pose a safety issue for the public.

Orhan H Suleiman, MS, PhD

Answer posted on 8 April 2008. The information and material posted on this Web site is intended as general reference information only. Specific facts and circumstances may alter the concepts and applications of materials and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice specific to whatever facts and circumstances are presented in any given situation. Answers are correct at the time they are posted on the Web site. Be advised that over time, some requirements could change, new data could be made available, or Internet links could change. For answers that have been posted for several months or longer, please check the current status of the posted information prior to using the responses for specific applications.