RESEARCH ARTICLE Spur line integrated single-/dual-/triple-notched ultra-wideband monopole antenna Chittajit Sarkar 1 | Chinmoy Saha 2,3 | Latheef A. Shaik 2 | Jawad Y. Siddiqui 4 | Yahia M. M. Antar 3 1 Department of Electronics and Communication Engineering, Swami Vivekananda Institute of Science and Technology, Kolkata, West Bengal, India 2 Department of Avionics, Indian Institute of Space science and Technology, Thiruvananthapuram, Kerala, India 3 ECE Department, Royal Military College of Canada, Kingston, Ontario, Canada 4 Institute of Radio Physics and Electronics, University of Calcutta, Kolkata, West Bengal, India Correspondence Chittajit Sarkar, Department of Electronics and Communication Engineering, Swami Vivekananda Institute of Science and Technology, 256 N.S Road, Mayfair Eternity,A-404, Kolkata, West Bengal 700145, India. Email: chittajit_sarkar@yahoo.co.in. Abstract Design and realization of spur line loaded frequency-notched planar ultra-wideband (UWB) antenna is proposed in this article. Accommodating the spur line (lines) of quarter wavelength long on the feeding microstrip line of UWB antenna, contrib- utes to the notch-filtering action in the feeding section itself which in turn can pro- vides single/double/triple notch (notches) within the UWB spectrum of the antenna. The proposed technique is very simple and radiator independent as the fil- tering is performed in the feed region and hence the UWB radiator can be indepen- dently designed. The spur line based filtering sections are first separately designed and verified by S-parameter measurements of the fabricated prototypes. Single, double, and triple spur line loaded microstrip sections are separately used as the feed section of a circular monopole antenna (MPA) to invoke single-, dual-, and triple-notched UWB response of the MPA. All the designed prototypes are fabri- cated and characterized in terms of impedance and radiation parameter measure- ments, yielding very close correspondence with that of results obtained from full wave simulation. KEYWORDS notched antenna, spur line filter, UWB antennas 1 | INTRODUCTION History of ultra-wideband (UWB) technology dates back to 1886 with the generation of short pulse by Heinrich Hertz. 1 However, early obstacle and various practical limitations of UWB technology, like high-dispersion of UWB signals, power restriction, and short-range, and so on, research on UWB technology remained dormant for several decades. Mitigation of these early challenges faced by UWB technol- ogy, coupled with the ever increasing demand of high speed and high data rate communication, created a new milestone in wireless industry in 2002 when an exclusive spectrum of 3.1 to 10.6 GHz was allocated for UWB communication by federal communications commission (FCC) with constrained power level. 2 However, the spectrum overlapping of this licensed UWB spectrum with various narrow band services, such as Wi-MAX (3.3-3.7 GHz), WLAN (5.170- 5.815 GHz), and 7.25 to 7.75 GHz X-band satellite down- link, and so on, imposed additional constrains of inhibiting propagation around the frequency/frequencies of the narrow band services. Numerous UWB researches/groups have addressed this narrow band interference rejection issues over the last decades. These interference mitigation techniques in UWB antenna, commonly known as “frequency-notching”, resulting into frequency-notched UWB antenna, can be broadly classified into three categories: (a) introducing shaped slots on the radiator/or in the feed region,(b) using parasitic resonator around/beneath the radiator, 3-8 and Received: 31 March 2019 Revised: 26 June 2019 Accepted: 19 September 2019 DOI: 10.1002/mmce.21995 Int J RF Microw Comput Aided Eng. 2019;e21995. wileyonlinelibrary.com/journal/mmce © 2019 Wiley Periodicals, Inc. 1 of 10 https://doi.org/10.1002/mmce.21995