How Wi-Fi Waves Propagate: From Physics to Practical Optimization

Have you ever wondered why the Wi-Fi signal in one room is excellent, while in another it's barely even a sliver? Or why your neighbors on the fifth floor can "steal" your signal even though you live on the second? The answer lies in the physics of propagation. radio waves, which Wi-Fi operates on. Unlike light or sound, these waves behave unpredictably: they reflect off metal, are absorbed by concrete, and can even "bend" around corners—but only under certain conditions.

In this article we will figure out exactly how Wi-Fi signal how it spreads in space, what factors influence it, and what can be done to improve coverage. You'll learn why 2.4 GHz And 5 GHz behave differently, how walls and furniture "steal" speed, and why sometimes even moving the router half a meter can radically change the situation. And also—learn to read antenna radiation patterns, to understand where exactly your router is hitting.

What are Wi-Fi waves from a physics perspective?

Wi-Fi works on the basis of electromagnetic waves radio frequency range—the same ones used in mobile communications, television, or walkie-talkies. But unlike, say, FM radio, where waves travel for kilometers, Wi-Fi is designed for short distances (usually up to 100 meters under ideal conditions). The main characteristics that determine its behavior are:

• 📡 Frequency: 2.4 GHz or 5 GHz (and in newer standards, 6 GHz). The higher the frequency, the fewer obstacles the wave can overcome, but the more data it can transmit.
• 🌊 Wavelength: for 2.4 GHz it is ~12 cm, for 5 GHz - ~6 cm. This explains why the high-frequency signal "flows" around corners worse.
• 🔄 Modulation: a way of "packing" data into a wave (e.g. OFDM in modern standards). Interference immunity depends on it.
• 📶 Transmitter power: limited by law (usually up to 100 mW for household routers), but even this is enough to “break through” a couple of walls.

It's important to understand that Wi-Fi waves are not a beam of light that travels in a straight line. They are more like waves on the water: They can bend around obstacles (diffraction), reflect off surfaces (reflection), or even overlap each other (interference), creating "dead zones." For example, if you're standing directly between your router and a metal cabinet, the signal can weaken significantly due to multipath fading - when reflected waves cancel each other out.

2.4 GHz vs. 5 GHz: Why One Signal Penetrates Walls While the Other Doesn't

The most noticeable difference between these ranges is penetrating powerWaves 2.4 GHz They are longer, so they can better bend around obstacles and pass through materials. 5 GHz, although faster, "hits" the first concrete wall. Here's a comparison chart:

But there is a nuance: Even in the 2.4 GHz band, the actual range depends on the channel width. If you use a 40 MHz channel instead of a 20 MHz channel, the signal spreads out more and may have difficulty penetrating walls, despite the lower frequency. This is one of the reasons why it is better to choose narrow channels in densely populated houses - they are less susceptible to interference.

⚠️ Note: Some countries (such as Russia) have power and channel limitations for the 5 GHz band. If your router can't see channels above 149, check your region settings in your firmware.

How Materials Affect Wi-Fi Distribution

Not all walls are equally beneficial for Wi-Fi. For example, drywall almost does not weaken the signal (losses ~3 dB), and brick or concrete They can "eat" up to 15-20 dB—this reduces the power by 10-100 times! Here's how different materials affect the signal:

• 🧱 Brick wall (15–20 cm): attenuation of ~10–15 dB. Particularly critical for 5 GHz.
• 🏗️ Concrete slab: up to 20 dB. Virtually blocks 5 GHz.
• 🪟 Glass: ~2 dB. Almost no effect, but metallized glass (for example, in offices) shields the signal.
• 🚪 Wooden door: ~3 dB. Slight attenuation.
• 🛋️ Furniture (sofa, wardrobe): ~5–10 dB. Especially if there are metal parts inside.
• 💧 Water (aquarium, person): ~20 dB at 5 GHz. The human body absorbs the signal almost like concrete!

Interesting fact: mirrors And metal surfaces (for example, a refrigerator) do not simply weaken the signal, but create multipath interferenceWaves are reflected, overlap, and in some areas the signal may disappear completely. If you have a lot of metal in your room, try moving the router or using MIMO antennas with different polarization.

Antenna Patterns: Where Your Router Is Hitting

Many people think that router antennas radiate a signal evenly in all directions, but this is not true. Each antenna has radiation pattern — a graph showing how power is distributed in space. For example:

• 📶 Omnidirectional antennas (most routers): the signal spreads in a "donut" pattern perpendicular to the antenna. If the antenna is vertical, the "donut" pattern is horizontal. This means the signal will be weaker on higher floors!
• 🎯 Directional antennas (panel, yagi): focus the signal in one direction (for example, for communication between buildings).
• 🔄 MIMO antennas: Use multiple transmitters to create "beams" that adapt to the position of the device (beamforming).

If your router is on a table and the antennas are pointed toward the ceiling, most of the signal goes up and down rather than to the sides. To ensure uniform coverage, antennas should be positioned at an angle of 45–60 degrees relative to the vertical—this way, the “donuts” cover the maximum area.

How to check your router's radiation pattern?

Many manufacturers (eg TP-Link, ASUS) publish diagrams in technical specifications. Look for files with the extension .pdf or .dbf on the official website.

Interference and jamming: why Wi-Fi slows down for no apparent reason

Even if the router is powerful and the walls are thin, the signal can drop due to interference. The main sources are:

1. Other Wi-Fi networksIn apartment buildings, 2.4 GHz channels are often overloaded. If neighbors use the same channel, speeds drop significantly.
2. Household appliances: microwaves (work on 2.4 GHz!), cordless DECT phones, baby monitors.
3. Bluetooth devices: especially headsets and speakers that are constantly “talking” to the phone.
4. Power lines and transformers: create broadband interference that “clogs down” the signal.

To reduce the impact of interference:

• 🔍 Use WiFi Analyzerto find the least loaded channel.
• 📶 Configure your router to automatic channel selection (but check if it really chooses the optimal one).
• 🔄 Turn on beamforming (if supported) - this will help the router "focus" on your devices.
• 🚫 Disable outdated standards (eg. 802.11b) in the router settings - they slow down the entire network.

⚠️ Attention: In some routers the function automatic channel selection It works poorly and may switch to busy channels. If you notice speed drops, manually lock the channel.

Practical optimization: where and how to install a router

Now that you know the theory, let's put it into practice. Here's a checklist for maximum coverage:

Additional tips:

• 🏠 In a two-story house, it is better to place the router on first floor closer to the stairs - this way the signal will be distributed more evenly across both levels.
• 🌿 Houseplants (especially large ones) can weaken the signal by 5-10 dB due to the high water content in the leaves.
• 🔌 If you use powerline adapters (Internet via electrical wiring), remember: they are also susceptible to interference from other electrical appliances.

If moving the router doesn't help, consider:

• 📡 Repeaters: a cheap solution, but reduces the speed by 2 times.
• 🔗 Mesh systems: several nodes create a single network without loss of speed (for example, Google Nest WiFi, TP-Link Deco).
• 📶 External antennas: directional antennas (eg Yagi) will help to “break through” the signal over long distances.

The Future of Wi-Fi: What's Changing with Wi-Fi 6E and 7

Modern standards Wi-Fi 6 (802.11ax) And Wi-Fi 6E are already solving many problems of past generations:

• 🆕 6 GHz band (in Wi-Fi 6E): even wider channels (up to 160 MHz) and less interference.
• 🤝 OFDMA: Allows one router to communicate with multiple devices simultaneously, reducing latency.
• 🔋 TWT (Target Wake Time): saves battery power on connected gadgets.
• 📈 1024-QAM: Increases speed by 25% compared to 256-QAM in Wi-Fi 5.

And in Wi-Fi 7 (mass implementation expected after 2026) will appear:

• 🔄 320 MHz channels in the 6 GHz range.
• 🤖 AI optimization traffic in real time.
• 🚀 Speed ​​up to 40 Gbps (theoretically).

However, even with the new standards physics of wave propagation will not change. Therefore, the principles of router placement and interference control will remain relevant.

FAQ: Frequently Asked Questions about Wi-Fi Distribution

Can a Wi-Fi signal pass through a mirror?

A mirror with a metallic coating (aluminum, silver) almost completely reflects Wi-Fi waves, creating a "dead zone" behind it. If the mirror is large, the signal can be weakened by 10-20 dB. Solution: Move the router or use a directional antenna to bypass the reflection.

Why does Wi-Fi work better at night?

During the day, hundreds of devices (routers, microwaves, Bluetooth headsets) operate simultaneously in apartment buildings, creating interference. At night, some of them turn off, resulting in cleaner air. This also affects DFIR (Dynamic Frequency Selection) is a mechanism that automatically reduces power on busy channels.

Is it true that an aquarium makes Wi-Fi worse?

Yes. Water strongly absorbs radio waves, especially in the 5 GHz band. A large aquarium (100 liters or more) can weaken the signal by 10-15 dB. If your router is located near the aquarium, try moving it or using the 2.4 GHz band (it's less susceptible to absorption).

How can I check what's blocking my Wi-Fi?

Use network analysis applications:

• WiFi Analyzer (Android) - shows channel load.
• NetSpot (macOS/Windows) — creates a heat map of the signal.
• inSSIDer - analyzes interference from other devices.

If you see that neighboring networks are taking up your channel, change it in the router settings (section Wireless → Channel).

Why does Wi-Fi work worse on the balcony than in the room?

Most likely, the balcony is separated by a double-glazed window metallized coating (energy-saving or tinted glass). It shields the signal almost like foil. Solutions:

• Check if there is a metal film on the glass (hold a magnet).
• Move the router closer to the balcony or use external antenna.
• Set up beamforming in the router so that it “aims” at the balcony.