Hi yelling_softly,
If you are looking to configure one system I would suggest going in the same Advanced Tab then Wireless Mode and selecting 802.11a only.
If you are looking to deploy several systems, in order to do that I would recommend creating a profile for your wireless network and including that option on the adapter settings in the profile, the following link will provide information on how to create a profile, remember you will need to select the options according to your needs: