How do I find out what wireless card my Mac has?

Solution 1:

 -> About This Mac -> More Info... -> System Report... 

Under the Network Heading, click Wi-Fi, and find Interfaces: on the right side of the window. You will find your card type, firmware version, MAC address, etc.

The route for older MacBook Pro running OSX 10.5, 10.6...

 -> About This Mac -> More Info... -> Under "Network" choose "Airport"

Scroll down to: "Interfaces" "en1" "Card Type"

Solution 2:

Using the command line:

ioreg -r -n ARPT

The line starting with IOName will have a value of pciVVVV,DDDD Where VVVV is the vendor ID and DDDD the device ID.

For example:

"IOName" = "pci14e4,43ba"

If you google those you'll find the corresponding vendor and model. The one from my example is Broadcom BCM43602.