  Citation: Faouri, Y.S.; Ahmad, S.; Parchin, N.O.; See, C.H.; Abd-Alhameed, R. A Novel Meander Bowtie-Shaped Antenna with Multi-Resonant and Rejection Bands for Modern 5G Communications. Electronics 2022, 11, 821. https:// doi.org/10.3390/electronics11050821 Academic Editors: Faisel Tubbal, Ladislau Matekovits and Raad Raad Received: 7 February 2022 Accepted: 4 March 2022 Published: 6 March 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). electronics Article A Novel Meander Bowtie-Shaped Antenna with Multi-Resonant and Rejection Bands for Modern 5G Communications Yanal S. Faouri 1 , Sarosh Ahmad 2,3, * , Naser Ojaroudi Parchin 4 , Chan Hwang See 4 and Raed Abd-Alhameed 5 1 Department of Electrical Engineering, The University of Jordan, Amman 11942, Jordan; y.faouri@ju.edu.jo 2 Department of Signal Theory and Communication, Universidad Carlos III de Madrid, Leganes, 28911 Madrid, Spain 3 Department of Electrical Engineering and Technology, Government College University Faisalabad, Faisalabad 38000, Pakistan 4 School of Engineering and the Built Environment, Edinburgh Napier University, Edinburgh EH10 5DT, UK; n.ojaroudiparchin@napier.ac.uk (N.O.P.); c.see@napier.ac.uk (C.H.S.) 5 Faculty of Engineering and Informatics, University of Bradford, Bradford BD7 1DP, UK; r.a.a.abd@bradford.ac.uk * Correspondence: saroshahmad@ieee.org Abstract: To support various fifth generation (5G) wireless applications, a small, printed bowtie- shaped microstrip antenna with meandered arms is reported in this article. Because it spans the broad legal range, the developed antenna can serve or reject a variety of applications such as wireless fidelity (Wi-Fi), sub-6 GHz, and ultra-wideband (UWB) 5G communications due to its multiband characteriza- tion and optimized rejection bands. The antenna is built on an FR-4 substrate and powered via a 50-Ω microstrip feed line linked to the right bowtie’s side. The bowtie’s left side is coupled via a shorting pin to a partial ground at the antenna’s back side. A gradually increasing meandering microstrip line is connected to both sides of the bowtie to enhance the rejection and operating bands. The designed antenna has seven operating frequency bands of (2.43–3.03) GHz, (3.71–4.23) GHz, (4.76–5.38) GHz, (5.83–6.54) GHz, (6.85–7.44) GHz, (7.56–8.01) GHz, and (9.27–13.88) GHz. The simulated scattering parameter S 11 reveals six rejection bands with percentage bandwidths of 33.87%, 15.73%, 11.71, 7.63%, 6.99%, and 12.22%, respectively. The maximum gain of the proposed antenna is 4.46 dB. The suggested antenna has been built, and the simulation and measurement results are very similar. The reported antenna is expanded to a four-element design to investigate its MIMO characteristics. Keywords: multi-band; UWB; 5G communications; sub-6 GHz; notches; bowtie-shaped; multiband; MIMO; time-domain analysis 1. Introduction Modern wireless communication devices, which have evolved fast over the last four decades, are required to support a variety of applications, including real-time voice com- munication, text messaging, Wi-Fi, Bluetooth, Global Positioning System (GPS), video apps, and among others. All these applications operate in distinct frequency bands, necessitating the use of frequency reconfigurable antennas or multiband antennas to handle several applications with a single antenna. Frequency diversity can be configured electronically by utilizing varactors [1–3], micro-electromechanical systems (MEMS) [4], PIN diodes [5,6], or liquid metal [7]. On the other hand, designing an antenna in which its reflection coefficient spans the UWB range has grown in popularity, for its lowliness, inexpensive production costs, small power consumption, simplicity of production, and large bandwidth; so, the federal communication commissions (FCC) allowed UWB to use the unlicensed operating band from 3.1 to 10.6 GHz in 2002 [8]. Several UWB antennas utilize this band completely, Electronics 2022, 11, 821. https://doi.org/10.3390/electronics11050821 https://www.mdpi.com/journal/electronics