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This calculator will give you the effective power output from the transmitting antenna referenced against a hypothetical isotropic antenna, this is mostly useful for checking that you are within the relevant government regulated power limits.

Transmitter details (dBm)

The formula used to derive the EIRP is EIRP = Pt - Lc + Ga where Pt is the power of the transmitter in dBm, Lc is the loss of the connectors and cable to connect the antenna in dB and Ga is the gain of the antenna in dBi.

In New Zealand, at the time of writing the current maximums for spread spectrum devices are as follows:

Frequency Peak Power
2.4Ghz 4000mW
5.3Ghz 250mW
5.4Ghz 1000mW
5.8Ghz 4000mW

© 2009 Lincoln Reid <lincoln@osoal.org.nz>