The Effective Isotropic Radiated Power (EIRP) of a transmitter is the power
that the transmitter appears to have if the transmitter were an isotropic
radiator. This means that the antenna radiates equally in all directions. By
virtue of the gain of a radio antenna or dish, a beam is formed that
preferentially transmits the energy in one direction. The EIRP is estimated by
adding the gain of the antenna and the transmitter power of the radio.
EIRP = transmitter power + antenna gain – cable loss
When using radio equipment, there are limits on the output of the system.
These limits are given as EIRP, and must not be exceeded. Different countries
will have different standards. Check with authorities in the country of
installation to determine maximum EIRP.
The output of the radio will be
measured in dBm (decibels per milliwatt). Figure
shows a table
that lists the dBm ratings for the various output levels available with the
Cisco Aironet Wireless equipment and the resulting EIRP when used with a 6 dBi
patch antenna.
The output of the radio will be measured in decibels per
milliwatt (dBm). The standards are different for specific point-to-point
systems. However, this course is focused on WLANs that would be considered
point-to-multipoint solutions, so the maximum EIRP allowed must not exceed 36
dBm and the maximum gain on an antenna must not exceed 16 dBi (for the United
States) unless installed by a professional installer
.
The maximum EIRP allowed for a 2.4 GHz device in France, Singapore, Israel,
Mexico, and ETSI is 20 dBm. The standards are different for specific
point-to-point systems. However, this course is focused on WLANs that would be
considered point-to-multipoint solutions, so the maximum EIRP allowed must not
exceed 36 dBm. Also, the maximum gain on an antenna must not exceed 16 dBi in
the United States, unless installed by a professional installer.