The 5 GHz WiFi band can be difficult to understand due to the many rules and regulations that govern the operation of its transmitters. While the WiFi user is none the wiser, when it comes to designing 5 GHz wireless networks close attention needs to be paid.
The 5 GHz band is a very wide set of frequencies running from 5150 to 5850 MHz, comprising five subsets of frequencies each with its own rules. Most countries like Australia have tried their best to harmonise spectrum planning with the United States FCC, who follow a separate but similar set of rules known as the U-NII which divides up this massive 700 MHz band also into five segments. The rules are challenging due to the splitting of some frequencies into indoor-only and others outdoor-only, and the sharing of the mid-5 GHz band with civilian radar services.
Choosing the right 5 GHz antenna is very much application-specific. With a 700 MHz wide frequency range it pays to consider whether an antenna covering the full band is required or not. Simple terminal and M2M 5 GHz antennas are quite easy to design to cover the full band, but this is much more challenging with high gain antennas such as patch array, grid and dish parabolic antennas.