With reference to a conventional air planar inverted-F antenna this paper describes the miniaturization of the planar inverted-F antenna by dielectric loading of barium tetratitanate ceramics of very high permittivity (εr = 38, 80) at 1.8 GHz. It is found that a simple loading method can reduce the antenna size but at the cost of the antenna performance. For instance, the antenna gain becomes lower. Then a sophisticated loading approach based on a novel substrate-superstrate structure is developed to improve the antenna gain. The whole process of the gain enhancement is analyzed by using the finite difference time domain method. The simulations are excellently correlated with the experiments. They both show that the sophisticated loading technique can reduce the antenna size by four times and still maintains the comparable performance.