@kbyrd: thanks for the contribution
Here is the spec sheet for the commel 2400 card:
Can someone smarter than me interpret this: "Output power: 12~14dBm (54Mbps), 18dBm (11Mbps)
Does this mean that as is, the card provides from 12dB to 18dB of gain? That sounds pretty good to me, no? Is there any real need for another antenna for this card?