How close can your cell phone be to the booster’s indoor antenna?

A typical outdoor cellular antenna.

If you get a cellular signal booster, you want it to work its best. After all you got the booster in order to improve cell service indoors, right? While cell boosters aren’t incredibly expensive, they also aren’t incredibly cheap and you want to get the best service for your money.

How distance relates to cell service

All radio waves use something called the “rule of squares” to give you an idea of signal power. It’s a simple idea: as you double the distance from the antenna, you cut the power by 3/4. It doesn’t matter what measurement unit you use, it always holds up. The signal received at the phone, if it’s 10 feet away, will be only one quarter (6dB less, roughly) what the signal is at 5 feet.

So, ideally to get the best signal at your phone, you’ll want the phone to be fairly close to the booster’s indoor antenna. Generally home systems will only provide enough boost for about 25 feet from the antenna, but that number really depends on factors like the construction of your home and how much signal there was to work with outside. Sometimes you get a lot more distance out of a booster. Occasionally you get a lot less.

Is it possible to get too close?

Technically, yes. In most cases with radio reception, you should be at least one full wavelength away from the antenna. In the case of cell phones, that means you should be about four inches from the antenna at least. That’s a rough number and doesn’t take into account every frequency, but it’s a good guideline.

You may be asking yourself though, what about those in-car boosters where you put the phone right on the cradle and the cradle has the indoor antenna built-in? That’s a great observation. It would actually be more effective in many cases to have more separation between the built-in antenna and the phone but that would make the cradle chunkier. Older cradle boosters were very chunky and this made them unattractive to customers. So, the current generation of boosters puts the indoor antenna right up against the phone and cranks up the broadcast power to the highest legal limit to compensate.

For in-home use, however, it’s a good idea to be at least four inches from the indoor antenna. That’s usually not hard since the indoor antennas are generally mounted on the ceiling. Four inches isn’t a lot to ask in those cases.

While you will lose some signal strength going from, say, four inches away to two feet away, it won’t be enough to really limit the effectiveness of the booster. In-home boosters are designed to boost the signal up to 10,000,000 times to allow you to get a reasonable distance away from them.

Looking for a cellular signal booster?

If you’re looking to improve cell service in your home or office, look no further than the great selection of products you’ll find at Solid Signal. There are boosters for everything from small cars to 100,000 square foot warehouses, all at the best prices on the web. You’ll find all the top brands, and all the free tech support you need by calling 888-233-7563!

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 8,000 articles and longform tutorials including many posted here. Reach him by clicking on "Contact the Editor" at the bottom of this page.