Thank you vfone and jiripolivka! Your answers were what i needed to get a good google direction
In addition, i have another "brilliant" question: is it possible to use a PIFA antenna inside a mobile device with a metal (steel) casing (housing), and use the casing as a ground plane (or not, the important issue is that the device receives/transmits a solid signal)?
Now, i am aware that there is a lot of antenna theory behind the answer, but basically i would like to know if it is a feasible technology used today? (just a simple answer