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7. Equivalent Isotropically Radiated Power (EIRP)
7.1. EIRP LIMITS
7. 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).
7.1 EIRP LIMITS
Antenna
Radio Usage /
Type
Application
Point to
4 dBi Omni
Multi-
Integral
Point
Point to
8 dBi Omni
Multi-
Remote
Point
Point to
14 dBi
Multi-
Remote
Directional
Point
Point to
14 dBi
Multi-
Remote
Sectional
Point
14
SmartLine Wireless Transmitter Professional Installation Guide
Table 7-1 Maximum EIRP Limits for ISA100 Radios
Max.
Min.
Freq.
Ant.
Cable
(GHz)
Gain
Length
(dBi)
(m)
2.4
4
2.4
8
2.4
14
2.4
14
Min.
Cable
Agency/Country
Loss
(dB)
FCC, IC, ACMA,
ANATEL
Japan
0
0
ETSI, TNTC, KCC
KOC
2485-2499 MHz
FCC, IC, ACMA
Japan
1
1
ETSI, TNTC, KCC
KOC
2485-2499 MHz
FCC, IC, ACMA
Japan
1
1
ETSI, TNTC, KCC
KOC
2485-2499 MHz
1
1
Japan
Max. TX
Max.
Power
EIRP
Setting
(dBm)
1
(dBm)
16
20
10
14
12
16
20
24
12
20
7
15
8
16
19
26
6
20
10
24
2
16
13
26
10
19.9
Revision 1
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