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Why a router has two WiFi bands and how they work

If you look at your WiFi router, you’ll likely see that it has two communication bands: 5 GHz and 2.4 GHz. Why are there two different signals for your WiFi router instead of just one? We’ll break down what both signals are there to do, and why more are coming in the future.
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Turns out technology is a lot like evolution. Things change not to fit some idea of perfection, but to fit the needs and requirements at the time.

Why So Many WiFi Channels?

Take a look at your WiFi router, whether it’s the one that came from your cable company or internet service provider or the one you bought for your company. If you check out the settings, you’ll notice that most WiFi router list two frequencies, usually 2.4 GHz and 5 GHz. Why waste time on two different frequencies?

First, let’s explain frequency. Light has a constant speed. It’s been about a hundred years since Einstein came along and revealed the discovery that no matter what’s going on, light is always going at the same speed of about 190,000 miles in a second. Not bad for a little speck of energy.

But light isn’t like a bunch of little bullets whizzing through the air until they hit your eye — it’s more like waves traveling through the vacuum. (Turns out — light does both. It gets into a lot of weird timey-whimey stuff.)

Light has both a speed (186,282 miles per second) and a frequency, the way that it moves up and down. It turns out while the speed doesn’t change, the fact that the frequency can tell you how much energy is in the light wave.

So those frequencies, the way light moves up and down, actually matters when it comes to signals. Radio waves and microwaves are really light. The same stuff you see when the sun comes through your window at 5 AM in the morning, hits you in the eyes and makes you regret you were ever born. But unlike sunlight, you can’t see radio waves with the naked eye.

Which lead to the big question: what frequency to use? Two competing ideas came out: 2.4 GHz or 5 GHz.

2.4GHz vs 5GHz WiFi

Frequency use in most countries is regulated — this is to prevent someone from setting up a transmitter that blocks radio signals and telephones from working. It’s why Christian Slater’s movie Pump Up the Volume shows the dangers of rogue pirate radio stations. Just gets those teenagers with their rock and roll in trouble.

So when engineers looked over the available spectrum, two candidates came to the front — 5 GHz and 2.4 GHz. As explained earlier, light does weird things, but one thing to know is the higher the frequency, the more waves in the same space, which means the higher the data.

Here’s an idea of how those waves would look if you could see them. 5 GHz has shorter waves (more waves in the same area) than 2.4 GHz:

WiFi channels waves
WiFi channels waves

Different things happen because of frequencies. At 5 GHz, more data can be carried, because there are more ups and downs (which the computer represents as 1’s and 0’s). But the problem is it’s harder for higher frequency light to go as far. With those increased waves, it can be harder to move through solid objects like walls, and the energy dissipates faster with high-frequency signals versus lower frequency ones.

At 2.4 GHz, not as much information can be transmitted, but because it’s not as high energy, it can go further before the signal degrades.

Frequency Data Speed Distance
5 GHz High speed Low Distance
2.4 GHz Low speed High Distance

Go back to when WiFi was first being invented, engineers had to decide what to do. Did they want a lot of data, or did they want a lot of range?

Two standards
Two standards

Turns out — the answer was “yes.” Two standards were created — a and b. A would use the 5 GHz frequency, and B would use 2.4 GHz. Problem solved! Everybody is Happy! Some routers were made to only support one of these two standards, but over time manufacturers developed routers that could support both networks.

This plays out later on when new WiFi standards were made to be backwards compatible with A or B (such as how 802.11g networks are backwards compatible with 802.11b which uses 2.4 GHz).

WiFi Frequency Band Breakdown

It’s not enough that there are multiple frequencies, but there are also multiple WiFi bands also known as WiFi channels. Really, a channel is a segment range of the frequency. This way there can be multiple devices on the same frequency, but keep to their section.

It’s like lanes on a freeway — it’s one freeway, but cars keep to their own lane, and drifting back and forth is discouraged. WiFi does the same. In the 2.4 GHz frequency, there are 14 different channels, listed as 1 through 14. Channel 1 uses the frequencies 2.401 GHz through 2.423 GHz, and Channel 14 ranges from 2.473 GHz to 2.495 GHz. 5 GHz channels break down the same way only some signals are designated as “indoor” versus “outdoor.”

What this means for you is if there are too many devices sitting on one channel, you can set your router and devices to use another. Maybe your neighbor is using 2.4 GHz and has their devices all on Channel 7. To keep your network working well, it might be a good idea to put your devices and WiFi network on Channel 11. This way there is a lot of crosstalk crowding the signal.

How to know if channels are a problem? The best way is through a network analyzer tool like NetSpot. NetSpot has the capacity to list what channels are being used by different networks detectable by your devices.

NetSpot — network analyzer tool
NetSpot — network analyzer tool

It features other tools that can be used to track how signal strength changes from location to location, what networks are doing, and can be used to find rogue networks or determine the best places to put routers or repeaters on your network.

Either way, you look at it, knowing about the WiFi signals and channels being used by not just your network, but the networks within range of your building with NetSpot will help reduce issues and increase the communication range and speed.

WiFi Frequency: The Future

So we’re stuck in this “either one frequency or the other” situation in the world? Turns out it might be a good thing in the long run. New standards such as WiFi 6 or 802.11 ax will use both frequencies at the same time, doubling the amount of data that can be transmitted over the network. New frequencies in the 1 GHz and 7 GHz range are planned to be used as well, which will increase the amount of data transmitted over time.

The original two frequencies were selected as a compromise between the physical range of the network, and how quickly to transmit data. As new technologies have been developed to increase the sensitivity of antennae, and allow them to detect multiple frequencies using fractal technologies, the ability of WiFi networks to grow will only be increased.

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Don’t be stuck with slow networks and poor performance. As we mentioned earlier, make sure you know what’s going on with your WiFi network with a network analyzer tool like NetSpot. You shouldn’t have to wonder what’s going on in your network, why your WiFi is slow or loses connections. Instead of just buying a new router and hoping for the best, know what’s happening.

What frequencies and channels your network is using, and what the networks around you are doing. A wise cartoon show once taught that “Knowing is half the battle”, and using a tool like NetSpot can help you attain that knowledge.
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Read next in All about Wi-Fi

If you want to dive deeper into this Wi-Fi thing, check out the following articles about Wi-Fi security, the best apps for wireless networking, inflight WiFi, etc.
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