The Atheros AR9280 was seen as a genuine AirPort-card by OSX...
...in 10.6 Snow Leopard
...and in 10.7 Lion it could even do AirDrop...
...until 10.7.3 that is...
10.7.3 for some mysterious reason lost it's ability to detect the AR9280 at all...
...the AirPort-icon in the menubar is blank, and it lists "no compatible hardware"...
Oddly, when restarting the Mac mini in 'Rescue mode' (pressing Apple(CMD)+R during startup), AirPort instantly connects using that same AR9280 card... ???!!
...but that doesn't last if you start up 10.7.3 the normal way.
So... after a lot of fiddling around I found the solution is quite easy :
1- reinstall the IO8211Family.kext from 10.6 Snow Leopard and reboot
if you only need WiFi-connection, that will do, but...
...if you also want to use AirDrop, you need to do step 2 also :
2- only after doing step 1, you will be able to successfully reinstall the IO8211Family.kext from 10.7.2 (the previous version of Lion)
It is mind boggling why this works (but it does) because :
- directly reinstalling the IO8211Family.kext from 10.7.2 onto the version in 10.7.3 doesn't work - for some reason you need to downgrade to the Snow Leopard version first...
- the IO8211.kext from 10.7.3 appears to be exactly the same as the one from 10.7.2 ; they have the same version number (4.1.2) and have been created and modified at the exact same date...
You might want to use the special .kext-installer ; you can find it here :
http://cvad-mac.narod2.ru/Kext_Utility