Introduction to Wireless Antennas
Wireless antennas are elements of a radio communications system that radiate and/or collect radiofrequency energy. They are usually connected using a low-loss coaxial cable to a power amplifier, splitter, and filter or directly to wireless devices. For outdoor usage, wireless antennas are often attached via mounting clamps to a mast or the side of a building via mounting brackets. Wireless Antennas used indoors are typically ceiling-mounted or wall-mounted.
A wireless antenna is also an important element of APs. Business-class APs use external wireless antennas for better results. Cisco uses different types of antennas with 802.11 APs. The type of antenna depends on deployment conditions, layout, and distance coverage. APs can be used. The figure below illustrates the general type of Wireless Antennas.
Omni Directional Wi-Fi Antennas
Omnidirectional antennas cover 360-degree areas and are better for open areas such as hallways, conference rooms, and outdoor areas. This type of antenna sends out and receives signals from all directions.
Omnidirectional antennas are commonly used on Wi-Fi routers and mobile adapters that support connections from several directions. Wi-Fi devices and APs usually use basic dipole antennas of the rubber duck design. These antennas usually have again between 2 and 9 dBi.
Directional Wi-Fi Antennas
Directional antennas spot the lobs in a specific direction and provide better gain. A directional Wi-Fi Antenna enhances the signal strength while receiving and transmitting.
The drawback of the directional antenna is that it sends and receives strong signals only in one direction and less signal strength in all other directions. Directional antennas are usually used to extend the range of a Wi-Fi network into hard-to-reach areas of buildings or in situations where 360-degree coverage is not required.
Yagi antennas
Yagi antenna is used for long-distance communication. A Yagi antenna is another directional radio antenna used for long-distance Wi-Fi networking in a specific direction. These antennas are extremely high gain used with outdoor APs to extend the gain up to 12 dBi or higher.
MIMO technology increases wireless bandwidth. The IEEE 802.11n/ac/ad standard uses MIMO technology, which uses several antennas to send and receive more data than possible using a single antenna.
Four antennas can increase throughput. All wireless routers are not the same. For example, 802.11n routers have a capacity of 150 Mbps using one Wi-Fi radio with one antenna. We can get more data using more than one radio and antenna in parallel. We can add more radios to the network in parallel. Each radio will increase the 150 Mbps data speed into the router.
