This is a great question. We have mentioned “dual band amplifiers” in the past. When we talk about dual band we are generally referring to an amplifier. This means the amplifier is built to amplify/enhance signals for both the 800 MHz cellular or the 1900 MHz PCS frequencies. There are other aspects of wireless that relate to dual band:
In Wi-Fi wireless networking, dual band is the capability to transmit on the 5 GHz band of 802.11a and also the 2.4 GHz band used by 802.11b, 802.11g, and 802.11n. Unlike ordinary Wi-Fi equipment that only supports one signal band, dual-band gear contain two different types of wireless radios that can support connections on both 2.4 GHz and 5 GHz links.
Dual-band Wi-Fi is a feature of some wireless routers and network adapters. Some cellular phones also utilize a kind of dual band communications, separate from Wi-Fi.
Unlike ordinary routers that only support one wireless signal band, dual-band routers contain two different types of wireless radios. When first introduced many years ago, dual-band routers supported both 802.11a and 802.11b and were designed for business networks that used a mix of both types of Wi-Fi clients.
Some newer 802.11n Wi-Fi routers also allow simultaneous dual band communication with both 2.4 GHz and 5 GHz clients. By supplying a separate bandwidth or each of the two types of links, these routers provide maximum flexibility in setting up a home network. For example, older 802.11b/g clients can be set to run on the 2.4 GHz side of a simultaneous dual-band router without impacting the performance of 802.11n clients running at 5 GHz.
Like dual band wireless network equipment, some cell phones also use two bands for wireless communications. So-called dual-band phones typically utilize GPRS or EDGE data services on either 0.85/0.9 GHz or 1.9 GHz radio frequencies. Unlike Wi-Fi, cellular networks sometimes support tri band (three) or quad band (four) types of transmission. Phone that support multiple bands can connect to different types of cellular networks, helpful while roaming or traveling. Cell phones do not support simultaneous dual band connections.