Gain enhancement for multiband fractal antenna using hilbert slot frequency selective surface reflector

In this paper, the gain enhancement for a multiband antenna with Hilbert fractal slot in a modified rectangular patch is presented. The composite structure including a wide slot, a Hilbert fractal slot with 1^st iteration, and modified rectangular patch used as additional resonators producing multi-resonant frequencies are developed. The antenna gain can be enhanced by using frequency selective surface (FSS) reflector. The proposed FSS is optimized to control the phase and the magnitude of S-parameters of reflection and transmission characteristics over a bandwidth suitable for multiband antenna. FSS layer has been designed and employed with a unit cell of Hilbert fractal slot. Experimental results show good multiband operation at the frequency ranges of 870 - 960 MHz, 1710 - 1880 MHz, 1.85 - 1.99 GHz, 1.92 - 2.17 GHz, 2.3 - 2.36 GHZ and 2.4 - 2.485 GHz, respectively. Finally, the designed antenna can operate and cover the applications of GSM, DCS, PCS, UMTS, WiMAX and WLAN IEEE802.11 b/g. Moreover, the antenna gains at the operating frequencies of 0.9, 1.8, 1.92, 2.045 and 2.45 GHz are 7.607, 10.41, 9.54, 8.67 and 7.98 dBi, respectively.