WiFi antennas in this section are designed to operate on the 2.4 GHz band which is a globally harmonised frequency range from 2400 to 2500 MHz, regulated by the ITU. In Australia the 2.4 GHz band is slightly narrower, operating from 2400 to 2483.5 MHz due to the spectrum allocation for time synchronisation transmitters at 2498 MHz.
WiFi devices in the 2.4 GHz band are regulated by the ACMA LIPD Class 2000 legislation, which stipulates a maximum transmit power of 4 Watts EIRP (+36 dBm). The 83.5 MHz bandwidth allows most wireless radios to operate with channel sizes of 20, 40, or 80 MHz. Engineers often voluntarily coordinate WiFi networks to operate on three non-overlapping 20 MHz channels (channels 1, 6, and 11).
Good quality 2.4 GHz antennas are those which are tuned to provide maximum efficiency at the 2400 to 2500 MHz range. Powertec offer many wideband antennas which cover this range and operate adequately, but be mindful that best performance is always using an antenna tuned only for the specific band in use.
With most WiFi radios permitting Tx powers up to about +20 dBm, the maximum antenna size within the legal limit is 16 dBi. However it is still commonplace to see 2.4 GHz antennas up to 24 dBi in size as the higher gain provides higher directivity and helps isolate the transmission from the often (very) noisy 2.4 GHz band. To make sure we don’t breach the legal limit the radio transmit power is turned down accordingly.