In this paper, a wideband, high -gain, and compact design of an aperture antenna has been proposed. In the proposed antenna, a patch type Frequency Selective Surface (FSS) as a superstrate has been ploacated in front of the feeding antenna, to enhanced bandwidth and gain of this antenna. A rectangular aperture mounted to a conducting ground plane feeds the antenna. The proposed simple 3×3 patch type FSS has considerably enhanced the antenna performance, including gain and bandwidth concurrently. The proposed structure has been simulated to validate the follobtawinedg results. The maximum gain of 16.03 dB, and 3-dB gain bandwidth of 19.7 % (14.25 – 17.35 GHz) has been achieved. Moreover, full metal structure is investigated, and approximately the same results have been obtained.