International Journal Of Computational Engineering Research (ijceronline.com) Vol. 3 Issue. 1 ||Issn 2250-3005(online)|| ||January || 2013 Page 105 Bandwidth Enhancement of A 2×2 Triangular Microstrip Patch Antenna Using Triangular Lattice Ebgs in the Ground Plane Jalaj Sharma 1 , Sunil Kumar Singh 2 1,2, Department of Electronics & Communication Jabalpur Engineering College, Jabalpur- 482011, India Abstract: Triangular lattice Electromagnetic Band-Gap (EBG) Structure in the ground plane is used in the design of a Triangular Microstrip Patch Antenna (TMPA) Array to improve its bandwidth. The patch elements are equilateral triangular in shape. The Equilateral Triangular Microstrip Patch Antenna (ETMPA) Array design has four patch elements in 2×2 form with ground plane having circular cutouts forming triangular lattice EBG. The ETMPA array with EBG provides better antenna gain and bandwidth. The ETMPA Array with EBG gives an impedance bandwidth of 16.76GHz and a percentage bandwidth of 110% while ETMPA Array gives an impedance bandwidth of 2.46GHz and a percentage bandwidth of 17.7%, thus an increment of approximately 500% in impedance bandwidth is observed. The achieved bandwidth of the ETMPA array with EBG extends from 2.7034GHz to 19.4649GHz. The array gain with EBG structure improved to 14.6dBi which is 9.7dBi for ETMPA array without EBG. Ke ywor ds : ETMPA, ETMPA Array, Electromagnetic Band-Gap (EBG), Impedance Bandwidth, Percentage Bandwidth, Triangular Lattice. 1. Introduction With the increasing utilization of high performance antennas in the wireless communication applications, the popularity of microstrip patch antenna has increased a lot, though it has limitations like narrow bandwidth, low gain, low efficiency, spurious feed radiations etc. Efforts have been made to improve the performance of the microstrip patch antenna using various techniques. Some of these techniques are to increase the substrate height or using aperture coupled feed etc. These techniques increases the bandwidth of the patch antenna to some extent but also increases the surface waves on the substrate causing distortion in the radiation pattern and reducing the gain and directivity of the patch antenna [6]. Arrays is also one of the solution for increasing the gain and directivity of the antenna, though they also have limitations narrow bandwidth, spurious signal feed radiations, low efficiency etc. To overcome above problems Electromagnetic Band- Gap (EBG) substrates and materials have attracted much attention of the researchers in microwave and antenna communities. EBG has many applications in the field of microwaves and millimeter waves device development, as well as antenna designing. EBG material, in general, are periodic structures that forbid the propagation of electromagnetic surface waves within a particular frequency band called the band-gap [8]. In this paper we have designed triangular lattice of circular holes in the ground plane to improve the gain and bandwidth of the ETMPA Array. We have used simulating software HFSS v13 for designing the array and simulating the results. HFSS software works on the Finite Element Method (FEM) in which triangular elements are used for surface meshes and tetrahedron elements for volumetric meshes. For achieving maximum band-gap we have used r/a= 0.45 and a/λ g = 0.5, where r is the radius of circular holes in the ground plane, a is the separation between the holes and λ g is the guided wavelength [7]. 2. Design Of An ETMPA Array Microstrip Patch Antenna in general have a conducting patch on a grounded microwave dielectric substrate and have attractive features like low profile, light weight, easy fabrication and conformability to mounting hosts [3]. But above all these attractive features microstrip patch antenna have one disadvantage that they provide narrow bandwidth and for practical utilization we need to enhance the bandwidth of the patch antenna. Thus to overcome the above problem we can form an assembly of radiating elements in a specific electrical and geometrical configuration, which is referred to as an array. An array may have a number of elements in different geometrical configuration; each element is provided with the same magnitude of electric current and is in same phase. To provide very directive patterns, it is essential that the fields from the elements of array should interfere constructively (add) in a desired direction and interfere destructively in the remaining space [1]. Triangular patch is one of a basic patch geometry used in several applications because of being physically smaller than other patch geometries like rectangular and circular patches. The resonance frequency of a triangular patch can be found using the cavity model, in which the triangle is surrounded by a magnetic wall along the periphery. Corresponding to several modes the resonance frequency of an equilateral triangular patch can be given as [2]: