UWB Circular Monopole Antenna with Fractal Slots for Triple Band-Notch Characteristics Kiran Nadeem 1 , Zeeshan Ahmed 1,2 , Iram Nadeem 3 , Ferdows B. Zarrabi 4 , Khurram Saleem Alimgeer 1 1 Department of Electrical Engineering, COMSATS University Islamabad, Islamabad, Pakistan 2 Deparment of Electrical Engineering, Military College of Signals, National University of Science & Technology, Islamabad, Pakistan 3 Department of Information and Communication Engineering, Chosun University, South Korea 4 Department of Electrical Engineering, Isfahan (Khorasgan) Branch, Islamic Azad University, Isfahan, Iran {kiran.nadeem, khurram_saleem} @comsats.edu.pk, zeeshanahmed.msee19@students.mcs.edu.pk, iram@chosun.kr, ferdows.zarrabi@yahoo.com Abstract— In this paper, a Co-Planar Waveguide (CPW)-fed circular monopole antenna for Ultra Wide Band (UWB) applications is presented. The proposed antenna is etched on FR- 4, which is cost effective substrate having relative permittivity of 4.4 and 1.6mm thickness. The size of the antenna is 60mm×60mm×1.6mm. Fractal slots are placed in circular patch for making frequency notch bands. The final antenna covers 1.75GHz to 11.0GHz with three rejection bands at 2.18GHz, 3.165GHz and 4.58GHz. Current distribution for four different frequencies at 2.2GHz, 3.2GHz, 4.55GHz and 7GHz is described. In addition, the antenna efficiency for the entire resonating frequency band is presented. The results depict that the antenna’s maximum gain is between -9dBi and 6.2dBi. The comparison of experimental and simulation results are also discussed. Keywords—UWB, fractal, notch, monopole antenna I. INTRODUCTION In the last decade, wireless communication systems have improved rapidly and can be found in different devices such as tablets and cellular devices because they are cost effective and have fast access. The broadband systems are designed and developed for rapid communication and support transfers at high data rate [1-3]. UWB systems are being used in different wireless communication, such as medical procedures to detect breast cancer and in military system applications. It is useful because of its economic benefits and capability [4-5]. IEEE 802.11a standard is 5.15 GHz - 5.35 GHz and 5.725 GHz - 5.825 GHz is used for sending and receiving bands, 5.25 GHz - 5.85 GHz for WiMAX. IEEE 802.11bg is widely applied for 2.4GHz (2.40 GHz–2.484 GHz) for WLAN systems [6-8]. Frequencies of Digital Cellular Systems DCS (1.71 GHz-1.88 GHz), UMTS (1.92GHz-2.17GHz), PCS (1.75GHz-1.87GHz) and WLAN (2.4GHz) are the standards operated for wireless communications which are lower than the UWB frequency range. In 2002, Federal Communication Commission (FCC) legalized 3.1GHz - 10.6GHz for low power UWB applications. It is used for indoor communication devices [8]. For several portable applications, there is a need to design a compact sized, cost-effective antenna, which could be used for multi-band applications. For UWB applications, Co-Planar Waveguide (CPW)-fed antenna is widely implemented model of radiator with benefits like wider bandwidth, less dispersion and lesser radiation leakage when compared with the microstrip lines. Monopole antennas are considered for UWB applications because of attractive features such as good radiation properties, wide frequency, ease of fabrication and simple structure. Therefore, the combination of a monopole antenna with CPW feed is noticed, to design UWB antenna for WLAN communication systems [9]. For WLAN systems and mobile communications, microstrip compact multi-band antennas can be used. In order to design multi-band antennas, several methods have been used such as slot technique to design notch band [10], SRR and NRI-TL metamaterial [11- 12], and fractal method [13]. Recently, many researches have applied fractal methods to design multiband and reconfigurable compact UWB antenna [14]. Most famous and widely used fractal geometries are Sierpinski, Koch, Hilbert model [15-18]. In the presented research, a CPW-fed circular monopole antenna is described for UWB frequency range, which is modified for frequencies of 2GHz-12GHz. Arc fractal slots are used for inserting notch frequencies. The effect of the slots rotation at return loss is studied. The antenna has three rejection bands. It covers frequencies of 1.75GHz-2GHz for PCS (1.75GHz-1.87GHz), 1480MHz-1590MHz for GPS applications and 2.215GHz- 2.835GHz for WLAN and Bluetooth. It can also cover WiMAX (3.2GHz - 4.125GHz) and fourth generation (4G) mobile communication systems or IMT advanced systems and 4.9GHz-10.6GHz for UWB wireless access including WLAN. II. ANTENNA GEOMETERY Fig. 1 depicts the configuration of microstrip antenna. The proposed antenna is etched on cost effective substrate FR- 4 , that has relative permittivity of 4.4 and thickness of 1.6mm. The dimensions of antenna are 60mm×60mm×1.6mm. The circular CPW-fed monopole microstrip antenna with radius of 271 2018 International Conference on Frontiers of Information Technology (FIT) 978-1-5386-9355-1/18/$31.00 ©2018 IEEE DOI 10.1109/FIT.2018.00054