2016, 33rd NATIONAL RADIO SCIENCE CONFERENCE (NRSC 2016), Feb 22-25, 2016, Aswan, Egypt Arab Academy for Science, Technology & Maritime Transport B6 57 Dual-band Microstrip Antenna for WiMAX Applications Using Complementary Split Ring Resonators Mohamed A. Bassiuny 1 , Ehab K. I. Hamad 2 , Wael A. Aly 3 , and Mohamed Z. M. Hamdallah 1 1 Electronics & Communication Department, Arab Academy for Science, Technology and Maritime Transport, South Valley Branch, Aswan, Egypt 2 Electrical Engineering Department, Aswan Faculty of Engineering, Aswan University, Aswan 81542, Egypt, 3 Electronics & Communication Department, Arab Academy for Science, Technology and Maritime Transport, Alexandria Branch, Alexandria, Egypt ABSTRACT A new design of dual-band microstrip antenna is presented in this paper using metamaterial concept. By etching a metamaterial unit cells that have a resonance frequency of 5.3 GHz within the ground plane of a conventional patch resonates at 3.6 GHz, a dual resonance response is created to satisfy the requirement of covering the middle and upper bands of Wi-MAX.A detailed study of the placement of the unit cell is introduced and the most suitable one is chosen to be the place of our unit cell. Multi-unit cell concept is used for performance enhancement of the fabricated design to achieve a good matching with the simulated one. Keywords: Metamaterial; Metasurface; Multi band antennas; Circular unit cell; Split ring resonator. I. INTRODUCTION All the designers of patch antennas for wireless communications are looking for several methods to enhance the performance of their designs even by enhancing the gain , bandwidth, and other antenna parameters or by reducing the size whilst others doing their best to add another resonances to their designs without the need of increasing the overall antenna size [1], [2], [3]. All these improvements can be done by incorporating medium with simultaneously negative permeability and permittivity that was hypothesized by Veselago in the late 1960s [4]. The first medium was proposed in 2000 by Pendry and it was consists of a bulky combination of metal wires and split-ring resonators (SRRs) [5]. For the planner designs, the use of that medium which called metamaterial was no longer useful so the need of a new material which exhibits a performance near that of the metamaterial was raised. SRRs was the solution of that problem. The SRR electromagnetic properties have been already analyzed in [6], [7]. Thus when a time varying magnetic field applied parallel to the SRRS, an electromotive force around the resonator is generated then a current loop is generated in the rings. The gapes that created in the rings made a capacitance that are responsible of closing the loop of the created current. All the above ensures that the SRR acts as an LC tank circuit with a selective resonance frequency which can be changed by varying the ring, and the gap dimensions. The use of the SRRs, when loaded to a transmission lines, to create a bass band is due to negative  -behavior that can be produced [8]. Due to the duality theorem, the complementary of the split ring resonator (CSRR) has a stop band behavior and this is of course due to its negative  -property [9]. The enhancement techniques using metamaterial may use the simple basic SRR unit cells [10] or a complicated metamaterial as [11]. Two designs of dual band metamaterial-based microstrip antenna are presented in this paper. The first one is a compact size patch antenna with etched ground structure. The second relatively large design have two approaches one contains a unit cell etched in the ground plane, acts as the second resonator, forming a defected ground structure (DGS) and the other design is an antenna with unit cell etched in the patch. The patch resonance frequency is 3.6 GHz, middle Wi-MAX band, and the unit cell has a resonance of 5.3 GHz, upper Wi-MAX band. Finite Element Method (FEM)-based, High Frequency Structure Simulator (HFSS) is used to simulate and optimize the geometrical parameters of the proposed designs. Full discussion on these designs are presented in the following sections. II. CSRR'S EFFECTIVE PARAMETERS DETERMINATION The CSRR unit cell is designed, by designing a SSR, with approximately the same dimensions of CSRR, and replacing the metal of the structure with apertures, and the apertures with metal plates as Babinet’s principle states 978-1-4673-9652-3/16/$31.00 ©2016 IEEE