Monday, September 11, 2017

The selection and use of access points affect the performance of the network and availability. The signal strength or amount of energy emitted by an antenna must be related to the type of antenna and the transmission specifications of the access point. The length of the cable increases the attenuation or signal loss and must be minimized. Each type of antenna has a certain horizontal and vertical beamwidth. The type of antenna, amplification, cable length, number and mounting are all the basis for the project. For example, a high-gain directional antenna, no external cable mounted at the right height, provides the best performance for heavily disturbed outdoor use.

The wireless cover cell in the internal implementations can be expanded with external antennas that connect to connectors at the access points. Most antennas can be mounted on the ceiling or the wall, and external antennas usually use a mast to raise the height for the viewing angle.

Effective isotropic radial energy = transmit power (dBm) + gain (dB) - cable loss (dB)

Omni directional

image from Terapeak

The omni directional antenna sends a 360 degree horizontal radiation pattern and a vertical pattern of 50 to 70 degrees from the source. It is a multi-homing antenna that sends signals to various nearby customers, thus fading a multipath that is minimized with antenna diversity. The gain values ​​with 2.4 GHz antenna range from 2.2 dBi to 12 dBi. Some Cisco Access Points have an integrated omni directional dipole antenna or "rubber ducky" that is standard on any device.


image from Importitall

The directional antenna sends a focused radiation pattern that connects to an external antenna. The purpose of the antenna is to transfer traffic between antennas and not to use the location of multiple devices. The dish has the highest profit factor and the narrowest beam beam, while the patch antenna has the lowest gain and widest radius. Reinforcement values ​​with 2.4 GHz antennas range from 6 dBi to 21 dBi. Most antennas of this group are implemented in buildings with a lot of signal damping, such as manufacturing, bearings and structures with many steel, concrete, angles, etc. projects.


image from Friends Shop

The diversity antenna implements a dual antenna at the access point that receives signals in both. The access point determines which antenna wins the best and transmits on this antenna. Diversity antennas are designed with omnidirectional, directional or dipolar styles. Multipath fading occurs in buildings that have a lot of signal reflection.

External antenna

image from YouTube

Some Cisco Access Points, like the 1200 Series, have connectors for an external antenna. The external antenna with a specified coaxial cable of 3 to 100 feet allows the antenna to be placed in the ideal position. Minimizing cable length reduces signal attenuation for transmission. The company could use a repeater as a solution with an 1100 access point, which does not support an external antenna.Building materials and structural designs contribute to the damping of the signal.

* Madeira

* Concrete

* Reinforced concrete

* Steel

Mount the antenna

image from Solwise

Access points should be mounted on the ceiling, if possible at least 17 to 19 feet high, optimizing the width of the horizontal and vertical radius. In some cases, the access points must be mounted on the wall. Antenna assembly is important and must be implemented with instructions from the hardware installation manual.

Installation on the outer bridge

image from Hotspot management Software

Companies have implemented many Cisco Wireless Bridges that connect buildings to a campus network. External antennas handle environmental problems and longer distances, requiring higher antennas. Distances can range from 250 to 500 feet or more with higher power bridges, good antenna mounting and repeater implementation.

The peer-to-peer topology has been widely implemented with external wireless implementations. The root or root access point in a multi-point topology is occupied by traffic from multiple bridges or access points without roots. The radio stations have a point-to-point connection with the hub office and the hub office has a multipoint connection with all radio offices. The office hub will implement an omni directional wide-beam antenna while the radio offices use a directional antenna.

The default internal access point projects do not have any directional antennas. Most will perform omni directional antennas and use directional antennas, if necessary as a means of addressing distances. External implementations largely mean greater distances and environmental issues, so that targeting antennas make an effective selection.


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