6. Equivalent Isotropically Radiated Power (EIRP)
6.1. EIRP LIMITS
Revision 1
OneWireless Adapter Professional Installation Guide
11
May 2011
6.
Equivalent Isotropically Radiated Power (EIRP)
In radio communication systems, Equivalent Isotropically Radiated Power (EIRP) or, alternatively,
Effective Isotropic Radiated Power, is the amount of power that would have to be emitted by an isotropic
antenna (that evenly distributes power in all directions and is a theoretical construct) to produce the peak
power density observed in the direction of maximum antenna gain. EIRP can take into account the losses
in transmission line and connectors and includes the gain of the antenna. The EIRP is often stated in terms
of decibels over a reference power level that would be the power emitted by an isotropic radiator with an
equivalent signal strength. The EIRP allows making comparisons between different emitters regardless of
type, size or form. From the EIRP, and with knowledge of a real antenna's gain, it is possible to calculate
real power and field strength values.
EIRP(dBm) = Radio TX Power (dBm) – Cable Loss (dB) + Antenna Gain(dBi)
Antenna gain is expressed relative to a (theoretical) isotropic reference antenna (dBi).
6.1 EIRP LIMITS
Table 6-1 Maximum
EIRP Limits for DSSS and ISA100 Radios
Antenna
Type
Radio Usage /
Application
Freq.
(GHz)
Max. Ant.
Gain (dBi)
Agency/Country
Max. TX
Power Setting
(dBm)
1
Max.
EIRP
(dBm)
7
FCC, IC
20 22
2.5 dBi
Omni
Point to
Multi-Point
Integral 2.4
2.5
ETSI
9 12
Notes for Table 6-1:
1.
The Maximum TX Power Setting values given in
Table 6-1
represent the power produced by the Radio
circuit within the RF Module. These Maximum TX Power Setting values do not include antenna gain nor
do they include the losses caused by the enclosure, cables and connectors. When these external gains and
losses are included, then using these Maximum TX Power Setting values ensures that the OneWireless
Adapter EIRP will not exceed the maximum EIRP limits that are given in
Table 6-1
.
2.
The values in the above tables have been determined through agency certification testing.
3.
The following shall apply for antenna type, frequency range, application/usage and agency/country
compliance:
Antenna gains above the maximum values shown shall not be used.
Maximum overall radio output power shown shall not be exceeded.
Maximum EIRP values shown above shall not be exceeded.
4.
Industry Canada Compliance Statement
: This device has been designed to operate with the
antenna types listed in this document. Antenna types not included in this list are strictly prohibited for use
with this device.
