My quest for perfect cell phone reception.

My quest for perfect cell phone reception.

My quest for perfect cell phone reception.

The latest gadgets and tech toys.
June 13 2005 5:04 PM

How To Kill a Dead Zone

My quest for perfect cell-phone reception.

Illustration by Mark Stamaty.
Click image to expand.

My cell phone and my apartment never got along. I missed calls. When calls did come through, it sounded like I was talking to a drowning robot. I wasn't about to pay one of those gigantic contract termination fees, so I did the only logical thing—I got a new apartment.

I found out recently that there's another solution, a reception-boosting device called a cellular repeater. The name explains the simple concept: A large outdoor antenna tunes into the strongest cellular signal available and repeats it on a smaller antenna wired inside. Voila, you've got five bars.

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Cellular repeaters are mostly used by businesses that want to boost signal strength inside big office buildings. But now some of these devices are being targeted specifically to the home market. They're not cheap. Spotwave Wireless, which works with business customers for several carriers, sells home units starting at $995. A smaller outfit called JDTECK, which just became an approved T-Mobile vendor, sells its most pared-down device for $365. (Cellular service providers usually have no problem with the devices, so long as they don't interfere with their cellular networks, which a Cingular spokesman told me almost never happens. The spokesman did say you should only use a repeater that's approved by your carrier.)

Do these devices really help? Can a layperson wire them? And what about the risks of installing a miniature cell tower in your apartment?

My first testing ground is a notorious dead zone in a friend's Brooklyn apartment. A T-Mobile phone by the sink never registers more than one or two bars. (Kitchens and bathrooms frequently have poor reception because they're close to building cores and shielded by layers of walls and appliances. In general, steel is the most difficult building material for cellular signals to penetrate, followed by concrete and the insulation-coated glass of office buildings. Wood and drywall pose little problem in moderation.)

Repeaters are carrier- and location-specific. A repeater tuned to, say, an 850 MHz Cingular signal is useless in boosting the reception of T-Mobile's 1900 MHz signal. Both Spotwave and JDTECK sent me repeaters calibrated for the T-Mobile spectrum in New York City, and some simple instructions. JDTECK's repeater has two components. For inside, there's a device the size of a light switch with a tiny swivel antenna. For outside, there's a simple-looking square plate of an antenna. Spotwave's kit has larger, more sophisticated-looking versions of the same equipment. The outdoor antenna looks like an alien pizza box, and the indoor one looks like its little sibling.

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The most important part of the installation is to mount the outdoor antenna in a place with good reception, ideally in the line of sight of a cell tower. Unfortunately, like most New York apartments, this one has no roof access. I manage to secure JDTECK's outdoor antenna to a window frame, but reception in the sink area improves only slightly. The window frame isn't good enough for the picky Spotwave antenna. The signal is so weak that the unit shuts itself down.

With my first experiment a failure, I set out to find an apartment with roof access and crappy reception. I find a friend's place in the West Village with a roof and so-so T-Mobile reception, at least when I lie on my side with my head nestled in the corner near the front door.

When I activate the Spotwave repeater, the reception immediately shoots up from none or one bar to between three and four bars. A five-minute conversation isn't crystal clear, but there are far fewer missing words and garbled robot noises. The JDTECK repeater works even better. I'm getting four or five bars, and the reception is clear enough for a business call—something like a 7.5 out of 10 on the clarity scale.

In short, these things actually work. But to get the full benefits, you must live somewhere with great outdoor reception and little indoor reception. If you live in an obstruction-filled city like New York, you'd best make sure you can find perfect reception on the roof before plunking down a lot of cash for a repeater.

Why does the much cheaper device do a better job? Perhaps because the more expensive one tries harder to eliminate feedback. As the costly Spotwave repeater fires up, it continually lowers the intensity of its indoor signal until its "isolation"—how much of the indoor signal is reaching the outdoor antenna—is below a certain threshold, a precaution that Spotwave says protects your cellular provider's larger network from damage. JDTECK's repeater, by contrast, only shuts down in extreme feedback situations, after which you can manually lower its power. When I tested the JDTECK device, it worked at full power and offered better coverage indoors.

And what about the health consequences of putting a signal repeater in your bedroom? Several recent studies have shown no link between brain tumors and cell-phone use. But if you're really paranoid, you might be inclined to believe another recent study that found longtime cell-phone users in rural areas were more than three times more likely to get brain tumors than urban cell-phone toters. The researchers hypothesized that this higher cancer rate results from the extra juice that rural cell phones must transmit to reach distant cell towers.

The more power your phone uses, the farther it can transmit a signal. Your cell phone continually boosts and reduces its antenna power based on signal quality. When the phone has only one bar, it will use as much as 600 milliwatts of power to amplify its weak signal. When you've got five bars, power consumption may drop to as little as 200 milliwatts. (When your phone gets a good-quality signal, its battery will exhaust much more slowly.)

Both the Spotwave and the JDTECK outdoor antennas emit large amounts of electromagnetic radiation to allow your signal to reach the closest cell tower. (Spotwave even warns users not to install the outdoor antenna where people will regularly walk in front of it.) That outdoor radiation means you'll have to use less power indoors. Since using a repeater will give your phone a stronger signal, it's likely that it will emit less energy near your head. So, if there does turn out to be a link between brain cancer and cell phones, having a miniature cell tower in your home could help reduce your exposure. But maybe you'd just be better off finding another apartment.