FOOD FOR THOUGHT: Signal Strength

So here’s the amazing thing. An antenna signal starts out as about 50,000 watts, sometimes less, going up a giant metal rod. Think about the power of 5,000 CFL light bulbs. That’s a lot of power. But say you’re about 50 miles away. where you should be able to get reception with a modest size antenna. The power of that signal has shrunk to a modest .00000001 watts, in other words, to where you would need about a hundred million signals just to power an LED.

Now first of all you could think about all that lost energy through attenuation, you could think about how wasteful that is, especially since you and 90% of your friends could be getting the signal through a cable anyway. Why put that 50,000 watt broadcast tower up there? But that’s not really the amazing part. The amazing part is that a signal that’s so weak that you couldn’t even detect it if it were a light bulb can bring you HD picture and 5.1 digital sound, right out of the air.

It gets even more amazing when you realize that you can pull signals the same way from satellites 22,000 miles away that aren’t broadcasting nearly as strongly. But then again, think of the Mars rover that broadcasts with its tiny antenna and is picked up on Earth, or the probe that just soared past Pluto, so far away that we don’t even get its broadcasts for five hours. That super-weak signal travels billions of miles and yeah, a lot of it is through open space but still. It’s so weak when it gets here that it takes an antenna the size of a baseball diamond to hear it, but it is still heard.

And then think for a second about how you have to point the remote control “just right” or your TV won’t change channels. Oh, sure there are RF solutions, and that’s not the point. But it’s just a juxtaposition between the amazing feats that are all around us every day and the frankly idiotic little things that come around to bother us.

About the Author

Stuart Sweet
Stuart Sweet is the editor-in-chief of The Solid Signal Blog and a "master plumber" at Signal Group, LLC. He is the author of over 6,000 articles and longform tutorials including many posted here. Reach him by clicking on "Contact the Editor" at the bottom of this page.