INTERNATIONAL JOURNAL OF TECHNOLOGY ENHANCEMENTS AND EMERGING ENGINEERING RESEARCH, VOL 2, ISSUE 2 21 ISSN 2347-4289 Copyright © 2014 IJTEEE. Microstrip V Slot Patch Antenna Using An H –Slot Defected Ground Structure (DGS) Rammohan Mudgal, Laxmi Shrivastava Department of Electronics, Madhav Institute of Technology & Science, Gwalior E-mail : rammohan977@gmail.com, lselex@yahoo.com ABSTRACT: This paper presents the Microstrip patch antenna for WLAN applications with planar geometry and it consists of a defected ground (DGS), a feed, a substrate, and a patch. The design with DGS has been analyzed taking different dimensions of H Slot and achieve optimized dimensions with the help of CST, Microwave Studio commercial software for WLAN band at 5.20 GHz frequency with corresponding bandwidth of 310 MHz to optimize antenna’s properties. Results show that the final designed antenna has favorable characteristics at this frequency. General Terms: Microstrip Antenna. DGS, WLAN, CST. 1. INTRODUCTION The microstrip patch antenna is one of the most useful antennas for low cost and compact design for RF applications and wireless systems. In wireless mobile communication and satellite applications, microstrip antenna has attracted much interest because of their small size, low cost on mass production, light weight, low profile and easy integration with the other components [1-2]. The major drawback of microstrip patch antenna is the narrow bandwidth. There are many approaches that can be implemented in order to enhance the Bandwidth of the microstrip patch antenna. An individual microstrip patch antenna has a typical gain of about 6 dB. Several approaches have been used to enhance the bandwidth by perturbing the higher order mode by interpolating surface modification into patch geometry. Gain enhancement by cutting rectangular hole on another inserted layer. A symmetrical hole on the inserted layer is used which is the major frequency in modern wireless communication era [3]. But the most unique technique to reduce the size of patch is to defect the ground. While comparing the antenna with the defected ground structure and the antenna without the defected ground, the antenna having defected ground structure reduces the size of antenna [4]. The percentage of reduction of size depends upon the ground area that is defected. Defected Ground Structure disturbs the shielded current distribution that depends on the dimension and shape of the defect. The current flow and the input impedance of antenna are then influenced by the disturbance at shielded current distribution due to the DGS structure. The DGS structure can also use to control the excitation and the electromagnetic waves propagating through the substrate layer [5]. In this paper, microstrip antenna for WLAN applications at frequency 5.20 GHz is designed and simulated using the CST Microwave Studio. 2. GEOMETRY OF MICROSTRIP PATCH ANTENNA In this antenna, the substrate has the thickness of h=1.524 mm and a relative permittivity r = 4.4. The Length and Width of patch are 11.84 mm and 19.06 mm respectively and length and width of substrate are 22.64 mm and 26.96 mm respectively. The structure used for ground is defected ground structure. The main concept behind the proposed antenna is to implement DGS structure to enhance the bandwidth of the designed antenna. Microstrip patch antenna can be fed by different types of methods such as microstrip line feed, aperture coupling, electromagnetic coupling, coaxial probe feed and coplanar waveguide (CPW). The DGS consists of the two rectangular areas and one connecting slot in the ground plane [6] as shown in figure 1. In this work, microstrip line (50 ohm) feed has been used. In this design defected ground structureis used which gives the very good resonance. Antenna is designed for the resonating frequency of 5.20 GHz and is analyzed by using the CST Microwave Studio software. For the designing of rectangular microstrip patch antenna, the following relationships are used to calculate the dimensions of the rectangular microstrip patch antenna [7-8].   =   +1 2 +   −1 21+  ݓ The effective length is given by   =  2     The length extension (ΔL) is given by ∆L = 0.41h   +0.3   −0.258 ×  ݓ  +0.264  ݓ  +0.8 The actual length (L) of patch is obtained by: