Cell signal is weird. One moment you could have five bars, but walk a few feet and it drops to two. In my house, the signal downstairs is awful, but it’s perfect upstairs. There’s a lot going on with cell reception, so let’s look at some of the main factors that affect it.

Your Distance from a Cell Tower

Your cell phone communicates using radio waves, which get weaker the more atmosphere they have to move through. This means that the distance you are from a cell tower can be one of the most crucial factors. A more powerful transmitter can send the signal further, but obviously there’s a limit to how big a radio can be crammed into a modern smartphone.

According to Outside, a cell phone can theoretically reach a tower that’s 45 miles away in ideal circumstances, but because of the way cell phones work, the actual limit will be about 22 miles, even in perfect circumstances.

In a city, distance probably won’t be a massive factor, but out in the backcountry or when you’re driving between towns, it will be one of the most important ones. If you’re too far away from a tower, the only thing you can do to get better signal is move.

Any Terrain That’s in the Way

Radio waves travel in a straight line from your phone to the cell tower. If there’s something big in the way, like a hill or mountain range, the radio waves will find it impossible to reach the tower. In the place I live, one side of the main hill has great reception because you can see the tower on top. The other side of the hill has terrible reception because you can’t; instead, our phones connect to a tower about ten miles away that they can see, rather than the one less than a mile away that they can’t.

In a city, this isn’t as much of a problem because:

There are normally small radio antennas placed all over the city so the signal never has too far to go. Radio waves bounce and ricochet off buildings which helps them get around things in the way. Other wave effects like diffraction.

So while certain buildings and structures can affect signal, it won’t be as tough as in more rural areas with high terrain.

Being Inside

 

While terrain doesn’t matter as much in cities, the material between you and the cell towers certainly does. Concrete, steel, and most other building materials are great at blocking cell signals. The reason your cell reception goes when you’re in the basement is that your phone has no way to reach the tower except through concrete.

Once you are on an upper floor, your cell signal will most likely return. In this case, the strongest radio signal leaves by the windows and gets diffracted (basically, spread out in all directions) so it still reaches a tower.

If you’re inside and have poor signal, stepping out into your front garden or balcony can do a huge amount to help.

The Weather

Radio waves travel through the atmosphere, so other things travelling through the atmosphere—like raindrops, dust particles, and ionized particles—can get in the way. Your cell signal will drop if you’re in the middle of a thunderstorm, because the pouring rain and ions will interfere with it. You will almost always have better signal on a clear day than when it’s raining or foggy.

Other Users On the Network

Cell towers are only designed to handle a certain number of connections at once. Most of the time, they’ve got more than enough capacity for everyone who wants to use their phone.

If, however, you’ve noticed your signal dropping when the clock turns midnight on New Year’s Eve, or while you’re in a football stadium full of people, this is why: an unusually large number of people are putting strain on the tower.

There’s two ways this can happen. First, a normal number of people in one area can all decide to use their phones at once, like on New Year’s Eve or during emergencies. Second would be an unusually high number of people all cram into one area and use their phones normally. A cell tower near a football stadium might serve 50,000 people six days a week, but on game day it might have to serve 100,000 people.

The Speed You’re Moving

When you use your cell phone, it is both sending signals to the cell tower and receiving them back. The radio waves move incredibly quickly so this normally all happens without issue. If, however, you’re moving at speed, your constant changes in position can start to have an effect on the quality of the signal.

Once you’re travelling above about 60mph, you’ll begin to see a drop in signal. At a few hundred miles an hour, your phone will struggle to work. If you’ve ever turned your phone on before landing and noticed you didn’t start to receive notifications until you were actually on the ground, this is one of the reasons why.

Cell signal is a complex thing. There are always loads of small factors interfering with it. This is why one corner of your house might be a dead spot, but another has great signal.

Photo credit: Craig Lloyd/Flickr