There are three main different types of antennas: Directional-, omnidirectional- and sector antennas. The main difference is the beamwidth.
There are essentially two different frequency bands in which a WiFi network can work with. The 2.4 GHz and the 5 GHz frequency band. The 2.4 Ghz frequency band according to IEEE802.11b/g/n is still the current standard. The 5 GHz frequency band with the IEEE802.11a/n/ac standards is a bit more susceptible to interference, but offers much more channels than the 2.4 GHz frequency band and is therefore used more and more often. In addition, extremely high data rates are possible here
The connection of various devices via WiFi has become standard, hardly anyone wants to deal with annoying cable mess. However, in order to build and maintain a stable WiFi connection, several factors must be considered. Especially in confined spaces, there are many confounding factors that can severely limit the range of about 100 meters that standard routers promise. The radio signal is mainly disturbed by obstacles such as furniture and walls and thus reduced. Metallic objects redirect the signal, so that it may not arrive at all or only greatly attenuated at the device. Although an optimal point of view of the router can increase signal strength and transmission security, bridging larger areas often can not avoid using external resources.
When is a WiFi antenna worthwhile?
Whenever you want to increase the range of the WiFi network or amplify the signal in a certain direction, you can use a WiFi antenna. Most routers are factory-equipped with an antenna and can then be upgraded with higher-quality WiFi antennas to improve range or signal strength or to align accurately. High-quality antennas can be connected to the router via a cable and thus positioned precisely. However, the cable should not be too long, because it reduces the signal strength again. Basically, there are three different types of WiFi antennas: directional antennas, omnidirectional antennas, and sector antennas. By default, most networks are 2.4GHz frequency bands, and for special networks, 5GHz can be used. The antenna must always be adjusted to the frequency band used.
2.4GHz directional antennas
A directional antenna focuses the signal and amplifies it into direction. A directional antenna is always useful when a signal is to be received at a greater distance and at a certain point, for example by a single device or a hotspot, which can further distribute the signal. The higher the dBi number of the WiFi directional antenna, the higher is its range. The size of the signal opening angle indicates how concentrated the signal is delivered. The smaller the angle, the more concentrated the signal and the stronger it will arrive at the destination. The 2.4 GHz directional antenna is used in a WiFi network with 2.4 GHz frequency band.
2.4GHz omnidirectional antennas
Unlike the directional antenna, the omnidirectional antenna sends in all directions, covering much more area. Above all, it is suitable for base stations such as a router or an access point and is usually used for these purposes. The general range of the omnidirectional antenna is given in dBi, the higher the dBi number, the higher the range. Nevertheless, even with omnidirectional antennas, it should be noted that the free-area range is significantly higher than in closed rooms or when many obstacles disturb the signal. So it may well be that the range in the different directions is different due to the particular circumstances. The 2.4 GHz omnidirectional antenna is designed for WiFi networks in the 2.4 GHz frequency band.
2.4GHz sector antennas
Sector antennas are a mixture of directional and omnidirectional antennas. The opening angle is smaller than in the omnidirectional antenna, while the signal strength is higher, but of course not as high as with a special directional antenna. It is always used when large areas are to be supplied with a WiFi signal, for example several buildings, a campsite or an event site. To obtain the 360 ° coverage of an omnidirectional antenna, several differently oriented sector antennas can be used. The range of the signal is indicated by the dBi number, the higher this is, the further the sector antenna transmits. For a standard WiFi network antennas with 2.4 GHz are used.
5GHz directional antennas
The directional antenna concentrates the signal in a certain direction and can thus reach a high range with low area coverage. 5 GHz directional antennas are used for networks in the 5 GHz frequency band, for example to establish a connection to an access point.
5GHz omnidirectional antennas
Omnidirectional antennas reach a smaller range than directional antennas, but cover larger areas and are therefore quite common for home use. In the 5 GHz frequency band, they are mainly used in office buildings, because at this frequency the susceptibility to interference but also the range is slightly lower than in the usual 2.4 GHz frequency band.
5 GHz sector antennas
Sector antennas are a useful mix of omnidirectional and directional antennas offering both good area coverage with a wide signal opening angle (up to 180 °) and good range. Especially for large and open spaces they are the best choice. 5GHz sector antennas are used for networks in the 5 GHz frequency band.