WiFi Frequencies and Standards

Wireless Local Area Network (WiFi, Wi-Fi, Wireless LAN, or W-LAN) refers to a local wireless network, usually based on the IEEE 802.11 family of standards.

Wireless communication is on the rise. Particularly in the private sector, its use has grown significantly in recent years. Nearly every internet provider offers customers a free WiFi router upon signing a contract. Hotels and campgrounds provide visitors with internet access via their internal WiFi networks. Cafes and restaurants offer internet access through so-called "HotSpot" systems.

Currently, there are several different WiFi standards based on IEEE 802.11, each with manufacturer-specific extensions (such as Turbo Mode or Range eXtend). To keep this explanation clear and understandable, we will focus initially on two groups: WiFi networks following IEEE standards in the 2.4 GHz (2400 MHz to 2485 MHz) frequency band and WiFi networks in the 5 GHz (5150 MHz to 5725 MHz) frequency band.

What does this mean? What is the difference? What should be considered?

The two groups mainly differ in the frequency band used. In both private applications and public WiFi networks (Hot-Spots), 2.4 GHz networks are typically used. In contrast, 5 GHz networks are more commonly used for long-distance directional links in commercial settings. However, the use of 5 GHz networks in public and private WiFi applications is increasing significantly with the introduction of the 802.11ac standard. Devices designed for the 2.4 GHz frequency band cannot communicate via WiFi with devices exclusively designed for the 5 GHz band. The same applies to accessories. An antenna designed for the 2.4 GHz band cannot be used with a device operating in the 5 GHz band.

Please ensure before purchasing antennas or accessories whether you are operating a 2.4 GHz, a 5 GHz, or a dual-band network, or whether the network you intend to connect to uses one of these bands.

Details

2.4 GHz:
The 2.4 GHz frequency band includes the standards IEEE 802.11b (up to 11 Mbps), IEEE 802.11g (up to 54 Mbps), and the newer IEEE 802.11n standard with data rates of up to 300 Mbps. These three standards use the same frequencies and are compatible. The same antennas can be used for different standards. In private WiFi applications, the 2.4 GHz frequency band is predominantly used. Most commonly available WiFi routers, access points, PC cards, USB sticks, etc., operate exclusively in this band or are dual-band capable, supporting both frequency bands. Due to its widespread use, hardware and accessories are very affordable. The main problem in the 2.4 GHz frequency band is the limited number of available channels. In Europe, there are 13 channels available, but only 3 are non-overlapping at 20 MHz channel width, or 2 at 40 MHz channel width. In densely populated areas, you often find a large number of WiFi networks in a small space. Additionally, other devices (such as Bluetooth and baby monitors) also use this frequency band, causing interference and disruptions.

5 GHz:
The 5 GHz frequency band includes the standards IEEE 802.11a, IEEE 802.11n, and IEEE 802.11ac and is often used for professional directional links in commercial settings, such as large corporate networks or site interconnections. Due to its less widespread use, components are comparatively more expensive. The clear advantage is that the frequency band is much larger and offers significantly more non-overlapping channels. Higher transmission power is also allowed. The downside is that EU regulations are stricter in this frequency band, and indoor range is significantly lower.

Wavelength:
The higher the frequency, the shorter the wavelength. As a result, WiFi in the 5 GHz range is less affected by obstacles due to the higher frequency. However, the shorter wavelength also has disadvantages: the attenuation caused by air increases with decreasing wavelength. Therefore, WiFi in the 5 GHz range has a significantly shorter range than 2.4 GHz WiFi at the same transmission power. This could make 5 GHz WiFi unsuitable for directional applications, but there’s a workaround: increased allowable transmission power.

Allowed Transmission Power:
In the 2.4 GHz band, the maximum transmission power allowed by law is 100 milliwatts (mW), equivalent to 20 dBm.

In the 5 GHz band, the law allows a maximum transmission power of 1000 milliwatts (mW) under certain conditions.

Range:
Due to lower air attenuation, 100 mW with suitable directional antennas in the 2.4 GHz band can cover significant distances. Under ideal terrain conditions, maximum ranges of 12 to 15 km may be possible, though bandwidth at these distances is very low (approximately 1 Mbps).

In the 5 GHz band, higher air attenuation results in only slightly greater range compared to 2.4 GHz under ideal conditions. However, other transmission techniques under IEEE 802.11a enable significantly higher bandwidths (between 12 and 36 Mbps).

Terrain:
If the terrain is open, with few or no trees, and both antennas are elevated on hills, buildings, or masts, ideal conditions can be assumed.

If the terrain is flat, hilly, and tree-covered, conditions are challenging. Ensuring a line of sight with a clear Fresnel zone between antennas can make finding suitable antenna locations more difficult.