1 Abstract— A new microstrip-fed monopole antenna with simple planar structure of size 24×28×1.6 mm 3 is presented for ultra-wideband (UWB) applications. The antenna structure consists of V-shaped patch, microstrip-fed line and partial ground plane structure. With the inclusion of U-shaped slot on to the patch, a frequency notched characteristics is achieved which can reject the frequency band of 5.15- 5.825 GHz. The effects of dimensional parameters on antenna performance such as length and width of U shaped slot, size of the ground plane have been investigated through a parametric study and design results from parametric simulations are presented. The electric current distributions on the patch are also exhibited in this paper. Simulation results confirm that the presented antenna has a large bandwidth below (S11≤ -10 dB) covering the ultra- wideband frequency range of (3.15-13.2 GHz) with band notch characteristics at WLAN band. The proposed antenna creates a monopole like pattern in the E-plane and omnidirectional radiation pattern in the H-plane. Index Terms— UWB, monopole antenna, printed antenna, notch band. I. INTRODUCTION Ultra-wideband (UWB) technology has developed rapidly over the past several years due to its high date rate in short range communication. As the antenna is the essential part for UWB technology, both at the receiver and at the transmitter, subject to performance requirements while at the same time supporting demand constraints to incorporate it in terminals, a lot of effort has been expended to date on to the development of UWB antenna. The advantages of microstrip antennas such as lightweight, compact and cost effective create them a good contestant for UWB antenna design. However, the main disadvantage of microstrip patch antennas is their narrow bandwidth. Therefore, various designs and techniques have been reported in the literature to improve their bandwidth, including the use of thicker substrates, different shape patches and probes, addition of parasitic patches [1]–[4] and cutting of slot [5]. Recently, different types of microstrip antennas for UWB technology have been examined and implemented with different feed lines, such as microstrip line [6–15], coplanar waveguide (CPW) [16–22], and double-sided microstrip antennas with a modified ground plane. For example in [9] to enhance the impedance bandwidth, antenna parameters are optimized and the ground plane is modified by cutting slots on the top edge to form a symmetrical saw-tooth shape. Furthermore, miniaturization of antennas is also a highly desired attribute, and it represents another challenge in the M A Matin is with the department of Electrical and Electronic Engineering, Institut Teknologi Brunei, email: matin.mnt@gmail.com. . design of such antennas. There have been many papers about the UWB antenna [23], but these antennas contain many parameters for the complicated structures leading to increased fabrication costs and antenna size. Hence, the aim of this paper is to present a new UWB microstrip antenna with a compact size that operates across the entire ultra-wide spectrum defined by FCC. The characteristics of the presented antenna are investigated through a parametric study. The simulated results show ultra-wide bandwidth performance and stable omni-directional radiation patterns. In addition, the physical size of the proposed antenna is substantially smaller than recently developed UWB antennas in [24] by 42.4%, and in [25] by 37.2%. Moreover, the presented design offers a chance to implement notch characteristic on the antenna itself to create a band rejection in the WLAN range so as to allow the UWB system to operate smoothly without any sort of interference. II. ANTENNA STRUCTURE AND DESIGN (a) (b) a b c e f g h i Lground k Fig.1 Geometry of proposed antenna (a) top view (b) bottom view The geometry of the antenna is shown in Fig. 1 which comprises of V-shaped patch, microstrip feed and partial ground plane structure. The surface area of proposed design is 24×28 mm 2 . The antenna feed structure consists of a microstrip line of width 2 mm connected to the radiating patch. The patch and feed line are printed on the top side of the FR4 substrate with dielectric constant of 4.4, loss tangent of 0.02 and thickness of 1.6 mm. The ground plane is printed on the bottom side of the substrate. The antenna is symmetrical and the length of the arms is equal. The height of the feed gap between the radiator and the ground plane is “k”. The optimized parameter values are given in Table 1. The antenna is located in the x-y plane and the normal direction is z-axis. A New Design and Analysis of Microstrip-fed Ultra-wideband Printed Monopole Antenna M A Matin INTERNATIONAL JOURNAL OF COMMUNICATIONS Volume 9, 2015 ISSN: 1998-4480 15