Join Date: Mar 2006
Location: New England
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There are quite a few 802.11g cards that allow the use of external antennas. Another important feature to look for is a card capable of 200 mW transmission. Most cards use a 100 mW radio, but there are several that have 200 mW radios instead.
For antenna design, a good cheap antenna is the "Pringles Cantenna" which can be made for under $10.