Journal of Production and Industrial Engineering Volume 5, Issue 1, June 2024, pp 38 - 45 https://doi.org/10.26706/jpie.5.1.20244042 38 Journal of Production and Industrial Engineering https://www.rame.org.in/jpie/ New Design of a Triple-Band Antenna for Controlling Radiation Patterns in Half-Width Microstrip Leaky Wave Antennas Mowafak K. Mohsen College of Computer Science and Information Technology, University of Kerbala, Iraq. *Corresponding Author: mowafak.k@uokerbala.edu.iq Abstract: A uniform half-width microstrip leaky wave antenna (HW-MLWA) featuring a single slot near the port is presented. This antenna operates across three frequency bands and can control the radiation pattern of the main beam in boresight directions by adjusting the operating frequency. The scanning angles for the main beam range from 13° to 38°, 41° to 48°, and 51° to 55° as the operating frequency sweeps through 4.15 to 4.75 GHz, 4.85 to 5.15 GHz, and 5.4 to 5.65 GHz, respectively. The maximum gains during the main beam scanning for the first, second, and third bands are 9.92 dBi, 9.2 dBi, and 8.6 dBi, with a maximum gain variation of 2.1 dB across all bands. Keywords: LWA; HW-MLWA; Control Radiation Pattern; Triple Band; Gain Variation. 1. Introduction The concept of using leaky-wave antennas as low-profile antennas has been recognized since the late 1970s [1]. Recently, microstrip leaky wave antennas have gained popularity due to their low-profile design, ease of manufacturing, and inherent capabilities for controlling the main beam direction. The fundamental principle involves a patch line that does not radiate, with the electric field confined between the microstrip line and the ground plane. The half-width microstrip leaky wave antenna (HW-MLWA) is a notable design that promotes a microstrip radiation line operating in the first higher-order mode, EH1. In an HW-MLWA, an array of vias shorts one edge of the radiation line to the ground plane, which suppresses the dominant mode and activates the line in its EH1 mode. The radiation pattern of the main lobe direction of a leaky wave antenna is frequency- dependent, determined by the relationship involving the phase constant and the free space wave number. Low-profile microstrip leaky wave antennas (MLWAs) radiate or leak waves that propagate along the axial direction of the ground plane. They are designed to support only the EH1 mode, with leakage occurring within a specific frequency range, defined by lower frequency fl and upper frequency [2][3][4][5][6][7][8][9] where the attenuation constant equals the phase constant and the latter equals the free space wave number[10]. (f) o k β(f) 1 sin θ   (1) In the leaky wave phenomenon, the angle of the main lobe beam direction, denoted as ɵ, follows the relation sin(ɵ o )= β/ ko θo. The phase constant is a nonlinear function of frequency due to the dissipative nature of the EH1 mode, resulting in a frequency- dependent ɵ. Consequently, the main lobe angle shifts with changes in operating frequency. Various methods have been proposed to control the radiation pattern, addressing the frequency dependency of the main lobe direction. These capabilities enable effective integration with microwave and millimeter-wave antennas and circuit devices [11][12][13][14]. Article – Peer Reviewed Received: 15 March 2024 Accepted: 25 May 2024 Published: 30 June 2024 Copyright: © 2024 RAME Publishers This is an open access article under the CC BY 4.0 International License. https://creativecommons.org/licenses /by/4.0/ Cite this article: Mowafak K. Mohsen, “New Design of a Triple- Band Antenna for Controlling Radiation Patterns in Half-Width Microstrip Leaky Wave Antennas”, Journal of Production and Industrial Engineering, RAME Publishers, vol. 5, issue 1, pp. 38-45, 2024. https://doi.org/10.26706/ijceae.5.1.2 0244042