Access points – the Cisco Aironet 1600e, 2600e, 3600e Series and 1550 Series – requires the use of dual-band external antennas to make them fully functioning units. As these access points take greater advantage of the multiple-input multiple-output (MIMO) features supported under the 802.11n standard, the number of radio transceivers per frequency band has increased. Using dual-band antenna ports allows the access point to support these added transceivers while maintaining a reasonably low number of antenna connections. Each dual-band antenna can transmit or receive Wi-Fi signals in both the 2.4-GHz and 5-GHz bands simultaneously.