Effective Isotropic Radiated Power

The [ACMA] had previously defined two [EIRP] limits in the 2.4 GHz [ISM] 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].

For [802.11]/[802.11b] applications, this means [Channels] 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)

EIRP = 15 + 24 - 3 = 36 dBm

This system is right on the legal limit of +36dBm (4W) EIRP.