Reviewing Wireless Basics
Antennas
Directional 
Isotropic
Omnidirectional
Antennas transmit and receive signals in all directions at the same time.
Transmits in a single direction and receives signals back from the same direction
A theoretical concept where an antenna has a perfect three-dimensional radiation pattern of 360 degrees vertically and horizontally.
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)
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
identifies the gain of an antenna compared with a type of dipole antenna
Decibels-milliwatt (dBm)
higher dBd numbers indicate the antenna can transmit and receive over greater distances.
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.
cannot be modify without changing its physical properties.
cannot be modify without changing its physical properties.
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.