Downloaded and installed the driver
Happy now with my device, and using it now.
---- SOLVED ----
Now I have bought and replaced the internal wireless in the Dell E6420:
lspci -nn
02:00.0 Network controller [0280]: Atheros Communications Inc. AR9285 Wireless Network Adapator (PCI-Express) [168c:002b] (rev 01)
I checked all the BIOS settings, they are ok, but it doesn't light up .. and in Mavericks, it is not a detected item. Sounds like I am not bringing up the wireless on the kernel boot (and I cannot actually see a wireless in the dmesg as well).
May I ask what am I missing ??
Thanks.