Figure 3: Transmit spectrum mask for 802.11b Transmit spectrum mask FIGURE 2b Transmit spectral mask for a 20 MHz 802.11n transmission in 5 GHz band and transmit spectral mask for 802.11ac 0 dBr –30 dBr fc –22 MHz fc –11 MHz fc fc +11 MHz fc +22 MHz 1450-04 Regulations for the use of unlicensed spectrum 8