AR9287
This chip was released in 2010, so it is quite old.
2.4GHz band
The Atheros AR9287 is a highly integrated single-chip solution for 2.4 GHz 802.11n-ready WLANs to enable high-performance 2x2 MIMO configurations for applications demanding robust link quality and maximum throughputand range.
https://gyazo.com/94f9418acbd212a4aa0cddddbfbf2c34 http://datasheet.jp/pdf/943104/AR9287.html