Guidelines for designing PIFA antenna

Is there any guidelines/techniques/method for designing PIFA antenna? How does the dimension/shape relates to the resonant frequency and bandwidth?

Thanks.

http://www.qsl.net/va3iul/Antenna/PI..._F_Antenna.pdf

it is very good

hope more guys to talk about your experiences . i am very concern it.

hi.. i'm doing dual band PIFA for my project...
but currently having problem with the simulation...
help me pls~~~