World Applied Sciences Journal 12 (8): 1321-1326, 2011 ISSN 1818-4952 © IDOSI Publications, 2011 Corresponding Author: Ahmed Al Shaheen, On a one-year sabbatical leave from the College of Medicine, Misan University, Maysan, Iraq, E-mail: ahabood@ualr.edu. . 1321 An Ultra Wide Band Antenna Design for Indoor Geolocation Applications Ahmed Al Shaheen and Hussain Al-Rizzo 1 2 On a one-year sabbatical leave from the College of Medicine, Misan University, Maysan, Iraq 1 Department of Systems Engineering, Donaghey College of Engineering and Information Technology, 2 University of Arkansas at Little Rock, 2801 S University Avenue., Little Rock, AR 72204, USA Abstract: In this paper, we present a miniaturized, Ultra Wide Band (UWB) elliptical slot antenna with a circular stub as a tuning element printed on a FR4 substrate with a dielectric constant of 4.4 operating in the frequency range from 2 GHz up to 14 GHz over which the return loss below -10 dB. The antenna is intended to operate in a system designed to assist the visually impaired in indoor navigation utilizing UWB technology. The concentric circular tuning stub is introduced in order to tune and hence improves coupling of the higher-order modes when the electrical path of the slots and tuning stub becomes an integer number of the guide wavelengths surface current distributions are provided at these higher-order modes to demonstrate the working principle, the frequency response of S as well as the radiation patterns in two principal planes at 3.1 GHz, 6.4 11 GHz, 10.6 GHz and 11 GHz. A graded feed design has been developed to improve the matching of the input impedance of the source over the operating bandwidth of interest. The performance of the proposed feed in terms of bandwidth achieved is shown to outperform the conventional rectangular and tapered feed designs reported in the literature. A parametric study has been conducted to identify the critical parameters that affect the performance of the antenna design in terms of tuning, gain and bandwidth. It has been found that for a properly designed graded feed, the most significant geometrical parameter which affects the bandwidth is the slot dimension especially in the higher frequency regime. On the other hand, we have found that the gap between the tuning stub and the slot has no significant effect on the input impedance. Key words: Printed antenna Ultrawideband technology Slotted ground plane Wireless communication INRODUCTION special needs, the elderly and children who are away from Ultra-wide-band (UWB) technology is receiving demand portable equipment in hospitals and to find considerable research interest in numerous wireless specific items in warehouses with accuracy better than communication applications because it allows for one meter [2]. It is well known that the key to solving this extremely high data throughput with low power problem is the combination of different positioning consumption for short range of about 10 m [1]. UWB techniques [3]. systems are most suitable for digital domestic applications A wide variety of UWB antenna designs have been due to the low power consumption and hence prolonged reported in the literature. The majority of the previous battery life, high speed data transfer for multimedia designs attempts focused on how to achieve a wider content and short range connectivity for data transfer to impedance matching bandwidth to prevent and distortion other devices. An emerging research demand pertains to in both radiation pattern and pulse shape. Results the design of UWB wearable antennas of low complexity reported in [4] revealed that the planar UWB monopoles and cost as alternative to replace wired connectivity are favorable due to their matching impedance bandwidth option [1]. which may be greater than 10:1. Accurate indoor geolocation is an important and An UWB antenna design has been introduced in [5] novel emerging technology for commercial and which enhanced the impedance bandwidth to a ratio of public safety. In commercial applications for 10:1 and increased the gain from 5 dBi to 8 dBi over the residential and nursing homes, there is an increasing operating bandwidth. Two different planar inverted cone need for indoor geolocation systems to track people with antennas were proposed in [5]. visual supervision, to navigate the blind, to locate in-