Look at the first 2.4GHz access point listed below your own in the RSSI list.If it's not, rerun your Scan tool physically seated next to your access point. Your personal access point should be listed nearest to the top as it's the closest one to your Mac. Click the RSSI tab so that the listing of RSSI's are in ascending order. To keep things simple, the RSSI is the signal strength of an access point. In your Wireless Diagnostics Scan Tool, you'll notice a heading called RSSI.You'll notice that most access points will be set to one of these three channels but you can still find out the best channel to choose from by seeing which channel is used the least in your area. These are the best channels to chose from when setting your channels in your router. Channel overlap is beyond the scope of this article but to keep things simple, the channels that do not suffer from channel overlap are channels 1, 6 and 11. Although the Scan may tell you which channels are least used in your area, the dirty little secret is that only 3 channels have the best connectivity due to something called 'Channel Overlap'.

The 2.4GHz Wi-Fi range is a bit more complicated.

Wait for your Airport Base Station to reboot and you're all set! The 2.4 GHz range.

Wifi channels scanner