Part 15 vs Part 97

Part 15 vs Part 97

Remember when calculating your total output that the FCC only allows 36dBm EIRP (4 watts)! 

Transmitted power must be configured correctly to prevent potential interference problems due to the effective isotropic radiated power exceeding the limits as defined in FCC part 15.247(i). 

As defined in FCC part 15.247(i), the power transmitted by the transmitter can only have a maximum power level of 1 watt or 30dBm. 

The antenna can only have a maximum gain of 6dBi. 

If the power at the transmitter is lowered by 1dB, the antenna gain can be increased by an additional 3dB. 

For example, if an installation reduced power at the transmitter to 29dBm, it could use an antenna having a gain of 9dBi. 

In general, for every 1dB power reduction at the transmitter from 30dBm, an installation can add 3dB gain at the antenna. 

A breakdown of transmitter versus antenna gain is as follows:

30dBm transmit - 6dBi antenna

29dBm transmit - 9dBi antenna

28dBm transmit - 12dBi antenna

27dBm transmit - 15dBi antenna

26dBm transmit - 18dBi antenna

25dBm transmit - 21dBi antenna

24dBm transmit - 24dBi antenna

23dBm transmit - 27dBi antenna

22dBm transmit - 30dBi antenna

21dBm transmit - 33dBi antenna

20dBm transmit - 36dBi antenna

Source: http://www.cpcstech.com/dbm-to-watt-conversion-information.htm