It's likely that even if it has no external antenna jack, you can disassemble it and add one. Apparently you can buy antennas for your model.
If you don't want to buy an antenna or modify your card, you can try making a parabolic dish antenna and putting your card at the focus. A metal screen bent into the appropriate shape or a metal or metal-covered bowl from second-hand store might do the trick. Instructables has many guides for WiFi antennas that could be helpful.
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If you don't want to buy an antenna or modify your card, you can try making a parabolic dish antenna and putting your card at the focus. A metal screen bent into the appropriate shape or a metal or metal-covered bowl from second-hand store might do the trick. Instructables has many guides for WiFi antennas that could be helpful.