REDUCTION in size of pifa antenna for mobile applictions

please help me regarding some questions about PIFA ANTENNA size redution as how we can reduce the size and volume of it ..............

Bend it more, use all 3 dimensions for these bends. Mold it in high dielectric material.
Any volume reduction comes at a cost. Efficiency and/or bandwidth will be reduced.

you can use series inductors and shunt capacitors to resonate it with smaller lengths of line. Like mentioned, it you do that aggressively, efficiency will suffer. There is no such thing as a free lunch

Please search for paper of Kin Lu Wong he studied difference for of PIFA antenna at more than 100 paper and he notice to miniaturization also u can find His book with title of Planar antenna that define every method clearly

thanks....... ferdows, biff44, E kafeman
it helped me a lot