Nowadays wireless technologies increasingly pervade our society. Technologies such as cellular phones, Bluetooth devices, and wireless local area network (WLAN) have brought mobility and flexibility to our everyday lives and open new opportunities to industry. Some of the place wireless coverage is low. When a device of wireless far away from the transmit device, the signal will be low. Undesired interference effect the wireless system performs. Signal noise will cause the interference of signals, and then will affect signals performs. This book proposes the design and deployment of frequency selective surface (FSS) structure to enhance WLAN application signal. The FSS structure acts as a band pass square-loop filter to increase the signal strength of WLAN signal 2.4GHz.