dBm, dBi and mW - Briefly explained
In our product descriptions, you will often encounter terms like dBi, dBm, mW, or Watt. Below is a brief explanation of these terms to help you understand their meaning:
In wireless technology (including WiFi components), various units are used to measure performance, such as transmission power or gain of individual components. As a general rule: the higher the value (regardless of whether it’s dBi, dBm, or mW), the greater the transmission power or gain of the component.
Milliwatt (mW):
This unit measures the transmission power of active WiFi components (e.g., WiFi routers, access points, USB adapters). Typical WiFi components operate with a transmission power of 50-100 mW. Since WiFi components work with relatively low transmission power, the unit used is milliwatts rather than watts.
| 1 mW | = | 0.001 Watt |
| 100 mW | = | 0.1 Watt |
| 1000 mW | = | 1 Watt |
Decibel (dB):
Decibel is a logarithmic measurement used for simplified calculations of power, attenuation, and amplification in interconnected components and systems. For example, the attenuation (power loss) of antenna cables or connections is expressed in dB. To calculate the total power of a system, the individual dB values are added or subtracted.
Decibel Milliwatt (dBm):
dBm is an absolute measure of power relative to one milliwatt. This unit can also be used to indicate the transmission power of a WiFi component. As mentioned earlier, typical WiFi components operate with a transmission power of 50-100 mW, equivalent to 17-20 dBm.
| 0 dBm | = | 1 mW |
| 17 dBm | = | 50 mW |
| 20 dBm | = | 100 mW |
Antenna Gain (dBi):
The gain of an antenna is measured in dBi. dBi is a relative measure compared to an isotropic radiator (a lossless point source emitting power equally in all directions, with a gain of 0 dBi). By concentrating the signal through an antenna, the power is no longer distributed equally in all directions but is focused in specific directions defined by the antenna's beamwidth. This focusing increases the gain relative to an isotropic radiator.
What is the maximum allowable transmission power for a WiFi device?
In accordance with German regulations, the effective radiated power (including antenna gain) of a WiFi device must not exceed 20 dBm or 100 mW.