A dual band dual polarized microstrip antenna for WLAN applications. Sarin V.P,Nisha Nassar, Gijo Augustine, P. Mohanan , C.K Anandan and K. Vasudevan Centre for Research in ElecroMagnetics and Antennas (CREMA) Dept. of Electronics, Cochin University of Science And Technology, Kerala- 682 220, India. Ph:+91 484 2576418, Fax:+91 484 2575800 Email: vasudevan@cusat.ac.in Introduction A new design of a dual band dual polarized electromagnetically coupled slot loaded square patch antenna, covering the WLAN 5.2 / 5.8 GHz bands, is presented here .The proposed antenna covers 5.09 GHz -5.47 GHz and 5.7 GHz- 5.88 GHz bands .The slight bandwidth enhancement is achieved by using tapered slot structure. Details of the antenna design along with experimental and simulated results are presented here. Due to compactness, microstrip radiators are popular in communication electromagnetics. Many techniques are used for obtaining dual band operation in microstrip antennas .A variety of dual band microstrip antennas are available in literature .Two typical designs of dual band dual polarized microstrip antennas are presented in [1-2].An antenna which covers all the three WLAN bands is presented in [3].It uses the principle of tapering in the monopole antenna geometry for achieving bandwidth enhancement. In this paper, we are presenting a dual band tapered slot square patch antenna. Since the 2.4 GHz WLAN band has a higher interference from microwave ovens and cordless phones, the current trend is to use the 5.2/5.8 GHz bands. It covers both the above bands. Antenna Design The Proposed design consists of a square microstrip patch of side L=36mm, fabricated on an FR4 epoxy substrate of dielectric constant, r = 4.4 and height, h = 1.6mm (Figure 1). A major central square slot tilted by 45 degrees along its axis having dimension L 1 =23mm is fabricated initially for achieving tapered slot structure.. For obtaining proper return loss characteristics, a rectangular slot tilted by 45 degree is etched parallel to the lower left edge of the major slot. Ansoft High Frequency Structure Simulator (HFSS) is used to optimize the dimensions and positions of the slots .The dimensions of the minor slot are selected to be 14 mm by 3 mm .The antenna is electromagnetically coupled using a 50 transmission line fabricated on the same substrate and the feed point is optimized through simulation. The top view and the side view and of the fabricated antenna are shown in Figure 1(a) and 1(b) respectively. 978-1-4244-2042-1/08/$25.00 ©2008 IEEE