How TO CHOOSE ANTENNA FOR CC2541

hi all.

             As i am going to do BIOMETRIC USB MASS STORAGE APPLICATION (authentication) PURPOSE . I need BLUETOOTH CHIP for my project to interface with my MCU.

  so I choose chip CC2541 (BLUETOOTH CHIP) . in that chip it doesn't contain in-build antenna . So how i can build the antenna externally &  how can i choose for this chip? please clarify ?

 thanks.