International Journal of Future Generation Communication and Networking Vol. 4, No. 3, September, 2011 47 Current Distribution Dynamics in Microstrip Patch Antenna Arrays Ali W. Azim, Shahid A. Khan, Zeeshan Qamar, K. S. Alimgeer, S. M. Ali COMSATS Institute of Information Technology, Islamabad, Pakistan aliwaqarazim@gmail.com Abstract This paper presents a novel way for achieving endfire radiation pattern using microstrip patch antenna array. The extensively used microstrip patch antennas i.e. rectangular and circular microstrip patch antennas, either single patch or in an array configuration do not have an endfire radiation pattern. The antenna array presented in this paper is designed by changing the geometry of the antenna and current distribution. Array consists of U-shaped radiating elements which alter the radiation pattern of individual radiating element and a partial ground plane is used to change the current distribution. In start, the paper presents the parametric study of novel single U-shaped antenna and afterwards a complete analysis of current distribution for two element, four element and eight element U-shaped microstrip antenna arrays is given. Keywords: Antenna array, broadside, endfire, U-shaped patch, current distribution, partial ground plane. 1. Introduction The extensive, rapid and explosive growth in wireless communication technology and communication systems is prompting the extensive use of low profile, low cost and easy to manufacture antennas. All these requirements are efficiently realized by microstrip antennas. Microstrip antennas grant RF engineers with innumerable advantages as compared to conventional antennas; such as small size, low profile, low cost, light weight, mechanically robust, easy integration in electronic and communication systems [1,2] and bulk production. In terms of performance, single element microstrip antennas have limited performance and mostly do not fulfill the requirements of systems in which they are integrated because of certain demerits such as low gain, narrow bandwidth, high side lobe levels etc., but in real time applications, efficient performance is required [3,4]; which leads towards designing of microstrip antenna arrays [4]. The significant advantages of microstrip antenna arrays are that they are highly directive and have higher performance in terms of bandwidth and gain. The most significant advantage of antenna arrays is that the direction of maximum radiation can be changed and thus they can be used in beam scanning capabilities [1,3]. The significant change in radiation pattern of arrays can be achieved by changing current distribution array [1,3], incorporating phase delay between from element to element [2,4], change in the radiation characteristics of individual radiating structure in an array [1,5], change in the geometry of the array and by changing the inter-element spacing [2,5]. The two main classifications of array on the basis of direction of maximum radiation are broadside and endfire antenna arrays. Broadside arrays are those arrays in which the direction of maximum radiation is perpendicular to the axis of the array i.e. if an array is placed in x-y plane along x-axis, then the direction of maximum radiation is along y-z plane; and on the other hand endfire arrays have direction of maximum radiation parallel to the axis of the array