A high-gain microstrip patch-type WiMAX antenna operating at 3.5 GHz has been designed with a parasitic radiator and a raised ground plane. Antenna design has been carried out through extensive three-dimensional electromagnetic simulations. The patch antenna itself provides a realized gain of about 3.6 dB at 3.5 GHz. When a parasitic radiator is placed on top of the patch antenna, the gain increases from about 3.6 dB to about 7.4 dB. The raised ground plane further enhances the gain by about 1.5 dB. Hence the overall gain improvement is about 5.3 dB without the need of a radio-frequency amplifier.