This paper proposes a novel triple-layer partially reflecting surface (PRS) for designing a highly directive antenna. The proposed PRS design has 54% improvement in impedance bandwidth with existing design. The design has multiple cavities, optimized for improved gain and bandwidth performance. The PRS arrays are printed on the dielectric substrate, placed above the ground plane at a height of approximately half wavelength. The reference square microstrip patch antenna operating at a frequency of 5.8 GHz with a gain of 3.77 dBi is enhanced to 13.54 dBi. The measured S11 of the fabricated prototype is −22.12 dB with a VSWR of 1.17 : 1. Measured 3 dB gain bandwidth of the antenna is 390 MHz which is an improvement of 50% compared with the reference antenna. This highly directive antenna is suitable for WiMAX wireless application.