Have you tried installing the free atheros-firmware package? Or does it not work even then?

I found: http://wireless.kernel.org/en/users/Drivers/ath9k_htc It says: ath9k_htc provides hardware support for Atheros AR9001 and AR9002 family hardware. But the driver is part of wireless-testing and the newer, properly versioned firmware is at: http://wireless.kernel.org/download/htc_fw/. So I downloaded htc_7010.fw and htc_9271.fw and placed them in /lib/firmware, but I don't know what to do next.

I'm afraid that firmware is non-free, so it won't work with Trisquel, as the driver probably isn't installed either, due to its dependency on that firmware. You would have to compile the driver somehow.

I feel your pain, as I just bought one of these, hoping it would be v2, but it came as v3.1. Where can we find v2 ?? :(

In case anyone reading this is curious, I got this card from NewEgg, which didn't list the version number. I don't suggest taking that risk.

Now the default Linux-libre 3.2.0-45-generic includes the ability to load the firmware needed for these devices. The firmware itself is still needed and pre-compiled .fw files are available for download at http://jxself.org/ath9k-htc/ (drop them into /lib/firmware) but eventually that won't be necessary either once it gets packaged and included in the Trisquel repositories.