The speed and stability of a wireless connection directly depend on the quality of the transmitting equipment you use at home or in the office. Many users mistakenly believe that the number of antennas on a router or their external size guarantee a strong signal, but the reality is often quite different. To understand why the internet is lightning fast in one room and barely loads in another, it's important to understand the transmitter's technical specifications.
Antenna power isn't an abstract concept, but a specific physical parameter that can be measured and analyzed. In this article, we'll take a detailed look at the units of measurement, how to obtain accurate signal strength data using software, and why manufacturer-reported specifications may differ from reality.
There are several ways to obtain the necessary data: from studying documentation to using specialized software. You will learn to distinguish gain and transmitter output power, which is key to properly diagnosing coverage issues. Understanding these processes will allow you to effectively configure your network or decide on the purchase of additional equipment.
Understanding units of measurement: dBi, dBm, and Watts
Before moving on to practical measurements, it's important to clearly define what exactly we're measuring, as specifications often get confusing. There are two main parameters: the output power of the router's radio module itself and the antenna gain. Transmitter output power is typically measured in milliwatts (mW) or decibels-milliwatts (dBm).dBm). This is the energy that the device generates and supplies to the antenna.
The antenna gain is measured in dBi (decibels relative to an isotropic radiator). This parameter indicates how effectively an antenna focuses radiated energy in a specific direction. A passive antenna cannot create energy out of nothing; it merely redistributes the signal: the narrower and more directional the beam, the higher the dBi value, but the smaller the coverage angle. High gain is useful for long-distance one-way signal transmission, but can degrade coverage in a multi-story building.
⚠️ Attention: The dBi value describes only the antenna's radiation pattern geometry, not its ability to "boost" the signal like an active amplifier. Installing a high-dBi antenna (e.g., 9 dBi) on a weak router will not increase signal power, but will only change the shape of the coverage area.
A logarithmic scale is used to convert between units. For example, 20 dBm is equivalent to 100 mW, while 30 dBm is equivalent to 1000 mW (1 W). Understanding the difference between these values is critical when choosing equipment. If you see a router with 5 dBi antennas and a transmit power of 20 dBm, and another router with 2 dBi antennas and a transmit power of 27 dBm, their effective efficiency (EIRP) may be comparable despite their different external specifications.
Power conversion formula
Power in dBm = 10 * log10(Power in mW). Reverse formula: Power in mW = 10^(Power in dBm / 10).
Software methods: how to find out the power through the OS
The most accessible way to determine the current signal level and indirectly judge the transmitter's power is to use the operating system's built-in tools. However, it's important to remember that the OS displays the signal level, accepted your device (RSSI), not the power that radiates router. However, this data allows us to assess the connection quality at a specific point.
In the operating system Windows There's a hidden but extremely useful command line utility. It allows you to get a detailed report on your wireless networks. To launch it, click Win + R, enter cmd and press Enter. In the window that opens, enter the command:
netsh wlan show interfacesIn the command output, find the "Signal" line, which will display the percentage value. For more precise dBm data, you can use PowerShell. Enter the command netsh wlan show networks mode=bssidIn the list of networks, find the one you need and pay attention to the parameter SignalAlthough Windows often displays percentages, third-party utilities can provide precise values in dBm.
- 📡 Acrylic Wi-Fi Home — a free utility that shows the signal level in dBm, channels and encryption type.
- 📡 WiFi Analyzer — a popular Android app that visualizes the signal strength of all available access points.
- 📡 AirPort Utility — for iOS users (requires enabling scanner mode in the app settings).
Analysis via the router's web interface
The most accurate information about your equipment's configuration can be obtained directly from its admin panel. Manufacturers often hide technical details deep within menus, but knowing where to look can reveal the actual transmission power. To access it, use a browser and enter the router's IP address (usually 192.168.0.1 or 192.168.1.1) in the address bar.
After authorization, look for sections with the names Wireless, Wi-Fi Settings or AdvancedIn some firmwares, for example, DD-WRT or OpenWrt, the transmit power (Tx Power) can not only be viewed, but also changed. In stock firmware from TP-Link, Asus or Keenetic This information may be hidden or displayed only as a percentage of maximum power.
⚠️ Attention: Firmware interfaces are constantly updated. The layout of menu items may differ from what's described. If you can't find the power parameter, check the "Status" or "System Log" tab, where connection parameters are sometimes recorded.
Pay attention to the region set in the settings. Transmission power is regulated by law: the limits differ in the US and Europe. If your router is locked to a region with low limits, you won't be able to get the most out of it, even if the hardware allows it. Changing the region code is a popular but risky way to increase power, which can lead to unstable operation or violation of radio regulations.
Using specialized software for Android and iOS
Mobile devices are excellent tools for measuring signal strength, as we use them in places where internet is needed. There are many Android apps that provide access to raw Wi-Fi chip data. One of the best is WiFi Analyzer (open source)It shows a real-time signal strength graph in dBm units.
On iOS devices, the situation is more complicated due to the closed nature of the system. Apple restricts apps' access to Wi-Fi module data in the background. However, the utility AirPort Utility Apple's app allows you to enable scanner mode. To do this, go to iOS Settings, find AirPort Utility, and turn on the "Wi-Fi Scanner" toggle switch. After launching the app and tapping "Scan," you'll see a list of networks with their RSSI signal strength.
The resulting values should be interpreted correctly. Signal strength in dBm is a negative number. The closer it is to zero, the better the signal. For example, -40 dBm is an excellent signal (you're close to the router), -70 dBm is borderline, and -90 dBm is practically nonexistent. A difference of 3 dBm means a twofold change in signal strength.
Table of correspondence between signal levels and connection quality
To make it easier for you to navigate the resulting figures, we've compiled a summary table. It will help you quickly assess the status of your network without extensive technical knowledge. Keep in mind that these values are for the standard 2.4 GHz band; in the 5 GHz band, signal attenuation is faster, and the values may be slightly lower for the same distance.
| Signal level (dBm) | Signal quality | Expected speed | Recommendations |
|---|---|---|---|
| -30 ... -50 | Great | Maximum | Ideal for 4K video and gaming |
| -50 ... -60 | Good | High | Stable operation of all services |
| -60 ... -70 | Average | Normal | Speed drops are possible |
| -70 ... -80 | Short | Low | Web surfing only, video may be slow |
| -80 ... -90 | Critical | Unstable | A repeater or router replacement is required. |
Factors Affecting Actual Signal Strength
Even if you've determined that your antenna's power is high, the signal may still be weak in practice. This is due to a variety of external factors. Wall materials play a huge role: concrete with reinforcement, mirrors, and metal shield the signal almost completely. Water also absorbs radio waves, so large aquariums or heating pipes can act as a barrier.
The second important factor is interference. In apartment buildings, the airwaves are clogged with signals from neighboring routers, especially in the 2.4 GHz band. This creates a "mess" that reduces the effective signal strength. Switching to a clear channel or upgrading to 5 GHz often solves the problem better than purchasing a powerful antenna.
- 🏠 Router location: The higher and more centrally located in the apartment, the better. Don't hide the device in a closet.
- 📶 Antenna orientation: For omnidirectional coverage, the antennas should be vertical. To transmit the signal to the floor above or below, one antenna can be placed horizontally.
- 🔌 Cables and adapters: Using long antenna extension cables or low-quality adapters can result in a loss of up to 50% power.
☑️ Checking signal reception conditions
Frequently Asked Questions (FAQ)
Is it possible to increase the antenna power programmatically?
It's impossible to increase the antenna's physical gain (dBi) via software—it's a hardware characteristic. However, you can increase the transmitter power (Tx Power) in the router settings if the firmware allows it. Be careful: this may cause the device to overheat or violate regulations.
Why does a router with 4 antennas perform worse than one with 2?
The number of antennas does not always equal power. Additional antennas are often used for MIMO technology (transmitting multiple data streams simultaneously) or for different bands (2.4 and 5 GHz). Two high-quality, high-gain antennas can perform better than four cheap ones.
How to check antenna strength on an iPhone?
You can't directly view the signal strength in dBm on an iPhone using standard tools. Use the AirPort Utility app with the Wi-Fi scanner enabled in iOS settings. The RSSI value in the network list will show the signal strength, where -50 is better than -80.
Does replacing an antenna affect internet speed?
Replacing the standard antenna with a more powerful one (with a higher dBi) or a directional one can significantly improve connection stability and speed in "dead zones" if the problem is a weak signal, and not the provider's channel.