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Reviewing Wireless Basics (Antennas (Dipole (Is an actual antenna, Some…
Reviewing Wireless Basics
Antennas
Directional
Transmits in a single direction and receives signals back from the same direction
Isotropic
A theoretical concept where an antenna has a perfect three-dimensional radiation pattern of 360 degrees vertically and horizontally.
Omnidirectional
Antennas transmit and receive signals in all directions at the same time.
Dipole
Is an actual antenna
Some variations of a dipole antenna, such as a folded dipole and half-wave dipole, increase the power gain and overall covered area of the antenna.
Most omnidirectional antennas used in wireless networks are a type of dipole antenna.
Yagi.
A common type of directional antenna.
Yagi antennas typically use a dipole, folded dipole, or half-wave dipole
Antenna Power
Decibels-dipole (dBd)
identifies the gain of an antenna compared with a type of dipole antenna
higher dBd numbers indicate the antenna can transmit and receive over greater distances.
cannot be modify without changing its physical properties.
Decibels-isotropic (dBi)
Gain of an antenna
Commonly used with omnidirectional antennas.
Higher numbers indicate the antenna can transmit and receive over greater distances
It references an isotropic antenna that can theoretically transmit the signal equally in all directions
cannot be modify without changing its physical properties.
Decibels-milliwatt (dBm)
Higher numbers indicate the WAP transmits the signal over a greater distance.
identifies the power level of the WAP and refers to the power ratio in decibels referenced to one milliwatt.
Wireless Footprint
Area of coverage provided by a WAP or group of WAPs
wireless coverage
WAPs 1, 3, 5, and 6 are all uniform
WAP 4 has a larger footprint
Higher power level
WAP 2 has a smaller footprint
lower power level
wireless site survey
process of examining the wireless environment to identify potential issues
periodically repeat the site survey to verify the environment hasn’t changed and to detect potential security issues.
