There are a lot of books out with good information on designing and testing patch (printed
circuit) antennas, particularly for data communications. You can look at places like Amazon.com.
Kirt has a good list on RF Cafe where (he claims) the ones listed are 4-star rating or above. Of course,
ratings can be slewed by biased reviewers, but in general they are probably pretty reliable.
You should check them out. Most are
around $120, but get free shipping, and that's a small price to pay for taking the guesswork out of your