Abstract—This paper proposes the development and design of double layer metamaterials based on electromagnetic band gap (EBG) rods as a superstrate of a resonator antenna to enhance required antenna characteristics for the mobile base station. The metallic rod type metamaterial can partially reflect wave of a primary radiator. The antenna was designed and analyzed by a simulation result from CST Microwave Studio and designed technique could be confirmed by a measurement results from prototype antenna that agree with simulation results. The results indicate that the antenna can also generate a dual polarization by using a 45˚ oriented curved strip dipole located at the center of the reflector plane with double layer superstrate. It can be used to simplify the feed system of an antenna. The proposed antenna has a bandwidth covering the frequency range of 1920 – 2200 MHz, the gain of the antenna increases up to 14.06 dBi. In addition, an interesting sectoral 60˚ pattern is presented in horizontal plane. Keywords—Metamaterial, electromagnetic band gap, dual polarization, resonator antenna. I. INTRODUCTION UAL polarization antennas with sector-shaped radiation pattern are often required for the mobile communication systems. To radiate the dual polarized wave, two dipole antennas need to be used with dual feeding. They are placed on a reflector plane at ±45˚ angle and arrayed to improve the gain [1]-[4]; however, it is hard to fabricate the feed system. Even though the dipole antenna is still interesting in wireless communication systems, it has elementary structure, simple concept, and broadband characteristics [5]-[7]. One solution to enhance the gain of an antenna is using metallic reflector plane as shown in Fig. 1 (a). The metallic reflector is located at the back of a dipole antenna with gap as a quarter wavelength. Usually, the main disadvantage of an antenna on metallic plane is making the overall size of the antenna too big and bulky for the low frequency range of operations. Moreover, the reflector plane cannot suppress the surface wave, so an antenna gain and efficiency will then be greatly decreased [8]-[10]. Figs. 2 (a) and 3 (a) show radiation patterns of a curved strip dipole on reflector plane. Due to a 45˚ oriented primary radiator located over the reflector plane, its polarized waves values are equal in both x (horizontal) and y (vertical) axis with the maximum gain of 7.6 dBi at 2100 MHz. In this case, when a 45˚ oriented curved strip dipole on reflector plane has a positive effect on the pattern, it is leaving N. Fhafhiem, P. Krachodnok, and R. Wongsan are with the School of Telecommunication Engineering, Suranaree University of Technology, Nakhonratchasima 30000, Thailand (e-mail: m5140732@g.sut.ac.th, priam@sut.ac.th, rangsan@sut.ac.th, respectively). the beam at its centre. In recent years, metamaterials based on electromagnetic band gap (EBG) structures have been widely investigated in the antennas domain to enhance gain and radiation efficiency. The metamaterials classified by a permittivity and permeability are primarily dependent on the geometrical properties of an inclusion shape and mutual distance between the lattices constant. EBG is not only used to a reflector plane [11]-[13], but also adapted for a superstrate of the primary radiator with reflector plane [14]-[17]. The main advantage of the EBG resonator is enhancing gain and efficiency. To confirm the advantage of the EBG resonator, we presented the radiating curved strip dipole antenna with cavity wall which is composed of single layer EBG as a superstrate and metallic reflector [18]. Unfortunately, few papers were proposing the EBG structures for polarization adjustment [19], [20]. In this paper, the metallic rods are used to a partially reflective surface (PRS) of a 45˚ oriented curved strip dipole located at the center of the reflector plane. The horizontal polarized partially reflective surface (PRS polar H) is placed above a primary radiator as shown in Fig. 1 (b). Not only it can improve the gain in horizontal polarization (as seen in Fig 2 (b)), but also the gain in vertical polarization is improved by using the vertical polarized partially reflective surface (PRS polar V) as shown in Figs. 1 (c) and 2 (c). A part from this, both of superstrate layers contribute to symmetrical radiation pattern of the antennas demonstrated in Figs. 2 (b), 2 (c), 3 (b) and 3 (c). Two layers of metallic rod type metamaterials, horizontal and vertical polarizations, are combined for dual polarization with high gain. However, the square antenna is not suitable and does not meet the requirements of the sector antenna element, in this paper; the antenna is reduced in size and added the vertical walls in yz plane for wide beamwith in horizontal plane. II. PARTIALLY REFLECTIVE SURFACE STRUCTURE In this paper, we firstly simulate the unit cell of metamaterial, a unit cell defined by parameters a 0 , g 0 , and t 0 , shown in Fig. 4 (a). Aluminium rod is surrounded by four periodic boundaries. This model can be used to estimate the transmission and the reflection of the aluminium rods structure. The resonant frequency is determined by the parameter of the aluminium rod structure, especially by the width and thickness of rod structure. An aluminium rod structure is divided into polarized groups which are PRS horizontal polarization (PRS polar H) and PRS vertical polarization (PRS polar V). The PRS polar H and V structures resonating at 2100 MHz are designed and denoted in Figs. 4 (b) and 4 (c). The parameters N. Fhafhiem, P. Krachodnok, R. Wongsan Design of a Dual Polarized Resonator Antenna for Mobile Communication System D World Academy of Science, Engineering and Technology International Journal of Electronics and Communication Engineering Vol:8, No:7, 2014 1032 International Scholarly and Scientific Research & Innovation 8(7) 2014 scholar.waset.org/1307-6892/9998638 International Science Index, Electronics and Communication Engineering Vol:8, No:7, 2014 waset.org/Publication/9998638