You are allowed up to 30 dBm or 1 watt of Transmitter Power Output (TPO) with a 6 dBi antenna or 36 dBm or 4 watts Effective Radiated Power over an isotropic antenna (EIRP). The TPO needs to be reduced 1 dB for every dB of antenna gain over 6 dBi. This simplifies it somewhat: Max Antenna Input Power...