have the same problem as some one else with debian squeeze earlier a while ago. I get the same message as below

my-comp:/home/myuser# iwconfig
lo no wireless extensions

eth0 no wireless extensions

wmaster0 no wireless extensions

wlan0 IEEE 802.11bg ESSID: ""
Mode: Managed Frequency:2.437Ghz Access Point: Not-Associated
Tx-Power=27 dBm
Retry min limit:7 RTS thrff Fragment thrff
Encryption keyff
Power Managementff
Link Quality:0 Signal level:0 Noise level:0
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:0 Missed beacon:0

pan0 no wireless extensions

There were several suggestions on adding contrib non-free and similar sopurce lists and doing an update. Another suggestion was to apt get firmware:ath9

did all that and still no luck. Any suggestions?

Which kernel are you running? It must be 2.6.29 or newer, then you can use the builtin ath9k module.

Secondly, check this.
http://wiki.debian.org/ath9k

Thanks. Yes the kernel is the same. I already tried the procedure outlined in the link you posted. I was on that link before and followed the procedure. May be I will try that again and check my steps. will post the result here. Thanks again