Wireless 802.11x Spectrum
2.4 GHz band is very narrow and only supports 3 non-overlapping channels
802.11b later the 802.11g wich is compatible with the 'b' but on the same Access Point the speed slows down to the 'b' speed.
802.11n MIMO (Multiple In Multiple Out) transmission technology 2.4 or 5 GHz operation. However the vast majority use only the 2.4 GHz band due to cost considerations.
the 5.3 GHz range 8-channels
the 5.8 GHz range 4-channels; for a total of 12 non-overlapping channels.
802.11a
3 Tx- and 3 RX-antennas 300 Mbiz