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Effective Isotropic Radiated Power
The ACMA [1] had previously defined two EIRP [2] limits in the 2.4
GHz ISM [3] band, but has revised the rules now into one limit.
Between the ranges of 2400 MHz to 2483.5 MHz, the limit is a maximum
of 4 W (watts) EIRP [4].
For 802.11 [5]/802.11b [6] applications, this means Channels [7] 1
through 13 have a maximum limit of 4 watts EIRP
EIRP CALCULATION
EIRP = Tx power x Antenna Gain / Feedline Loss
OR
EIRP = Tx (dBm) + Antenna Gain (dB) - Feedline Loss (dB)
e.g. 30 mW WLAN card into a 24 dBi dish with 3dB coax and connector
loss
30 mW = 15 dBm (from PowerAndGainToDecibels [8])
EIRP = 15 + 24 - 3 = 36 dBm
This system is right on the legal limit of +36dBm (4W) EIRP.
Links:
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[1] http://melbournewireless.org.au/?ACMA
[2] http://melbournewireless.org.au/?EIRP
[3] http://melbournewireless.org.au/?ISM
[4] http://melbournewireless.org.au/?EIRP
[5] http://melbournewireless.org.au/?802.11
[6] http://melbournewireless.org.au/?802.11b
[7] http://melbournewireless.org.au/?Channels
[8] http://melbournewireless.org.au/?PowerAndGainToDecibels
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