VOL. 11, NO. 14, JULY 2016 ISSN 1819-6608 ARPN Journal of Engineering and Applied Sciences ©2006-2016 Asian Research Publishing Network (ARPN). All rights reserved. www.arpnjournals.com 8822 PROXIMITY COUPLED ANTENNA WITH STAR GEOMETRY PATTERN AMC GROUND PLANE M. Abu, M. Muhamad, H. Hassan, Z. Zakaria and S. A. M. Ali Centre for Telecommunication Research and Innovation, Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya, Durian Tunggal, Melaka, Malaysia Email: maiza_zatul84@yahoo.com ABSTRACT In this paper, a conventional proximity coupled microstrip antenna operating at 2.45 GHz is firstly designed as a reference antenna. Then, the proximity coupled microstrip antenna is incorporated with a star geometry pattern artificial magnetic conductor (AMC) as the ground plane. Performance comparison is analyzed between the conventional antenna and the antenna with the AMC ground plane. The proximity antenna with star geometry pattern AMC ground plane successfully enhances the efficiency and gain by 8 % and 3 % as compared to the conventional antenna. In addition, the size of the proximity antenna with star geometry pattern AMC ground plane is reduced by 13 % as compared to conventional antenna. It shows that AMC as a ground plane to the antenna are able to reduce the size, enhance the gain and efficiency of the antenna. Keywords: artificial magnetic conductor, star geometry pattern, proximity coupled microstrip antenna, efficiency, gain. INTRODUCTION Microstrip antenna In application of aircraft, spacecraft, satellite and missile application, they require a low profile antenna, lower cost and size, ease of installation and aerodynamic profile (Constatine A. Balanis, 2005). Recently, most of government and commercial applications, such as mobile radio and wireless communication meet these specifications (Constatine A. Balanis, 2005). Therefore, microstrip antennas are used. As shown in Figure-1, Microstrip antennas have a very thin ) ( 0   t , where ) ( 0  is the free space wavelength and a metallic strip (patch) where a small fraction of a wavelength ) ( 0   h usually ) 05 . 0 003 . 0 ( 0 0     h is located above a ground plane (Constatine A. Balance, 2005). (a) Top View (b) Side View Figure-1. Microstrip antenna (Constatine A. Balanis, 2005). Microstrip antennas have many advantages compared to conventional microwave antennas and covered the broad frequency range from ~100 MHz to 100 GHz ~ (R. Garg, P. Bhartia, I. Bahl, and A. Ittipiboon, 2001).These included lightweight and low volume, low profile planar configuration which can be easily made conformal to hose surface and low fabrication cost. The limitations of microstrip patch antenna are narrow bandwidth, low efficiency, low gain and low power handling capacity (R. Garg, P. Bhartia, I. Bahl, and A. Ittipiboon, 2001) However, these limitations can be minimized by using many methods. For example, bandwidth can be increased by using fed methods. One of the most popular fed methods is proximity coupling. The multilayer proximity-coupling or electromagnetically-coupling technique consists of two-layer substrate as shown in Figure-2. The upper substrate used for the radiator (patch) and the bottom substrate used for feedline. There is a contact which provided between the patch and the microstrip line in order to increase the bandwidth of the patch. Figure-2. Proximity-coupled fed (Constatine A. Balanis, 2005). The substrate parameters can be chosen separately. The upper substrate on which the antenna is