  Citation: Shrestha, S.; Zahra, H.; Kiyani, A.; Asadnia, M.; Abbas, S.M.; Mahmoud, A. Miniaturized Wideband Antenna Prototype Operating over the Ku-Band. Micromachines 2022, 13, 471. https:// doi.org/10.3390/mi13030471 Academic Editors: Zebing Mao, Jin Xie and Hong Ding Received: 26 February 2022 Accepted: 16 March 2022 Published: 19 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/). micromachines Article Miniaturized Wideband Antenna Prototype Operating over the Ku-Band Sujan Shrestha 1, * , Hijab Zahra 1 , Arslan Kiyani 1 , Mohsen Asadnia 1 , Syed Muzahir Abbas 1,2 and Abdelhady Mahmoud 3 1 School of Engineering, Faculty of Science and Engineering, Macquarie University, Sydney, NSW 2109, Australia; hijab.zahra@hdr.mq.edu.au (H.Z.); arslan.kiyani@mq.edu.au (A.K.); mohsen.asadnia@mq.edu.au (M.A.); syed.abbas@mq.edu.au (S.M.A.) 2 BENELEC Technologies, Botany, NSW 2019, Australia 3 Faculty of Engineering, Benha University, Benha 13512, Egypt; abdoeng78@gmail.com * Correspondence: sujan.shrestha1@students.mq.edu.au Abstract: A wideband antenna is proposed based on three-dimensional printing technology. The antenna was designed using the PREPERM 10 material, with permittivity ǫ r = 10, where the overall height of the proposed prototype was maintained as 12.83 mm (0.51λ), having a lateral dimension of 60 mm × 60 mm, at an operating frequency of 12 GHz (λ = 25 mm). The proposed antenna achieved a wide frequency bandwidth with a voltage standing-wave ratio (VSWR) of less than two, from 10 GHz to 15 GHz in the Ku-band, where the maximum directivity was 20 dBi over a reflection coefficient bandwidth of 50%. It showed a miniaturized non-uniform metasurface of 2.4λ × 2.4λ × 0.51λ that was placed at 16.5 mm (0.66λ) above the ground plane, which was 2.4λ × 2.4λ × 0.04λ in dimension. Thus, the overall height of the proposed antenna system from the feed source was 29.33 mm (1.17λ). The total weight of the system including the designed structures made of PREPERM 10 and ABS with copper-painted prototypes was 96 g and 79 g, respectively. The measured results were consistent with the simulated results, demonstrating the feasibility and effectiveness of the proposed method. Keywords: wideband operation; microwave communication; 3D printing 1. Introduction The need for high-data-rate, compact-size, and low-power-consumption antennas is a growing area of study, in particular for wideband communication systems, which depend on the efficient design of such antennas [1]. In order to maintain efficient voice and video transmission, there is a requirement for a large bandwidth with a higher gain. Dielectric lens [2] antennas show those characteristics with simple feeding methods. However, those lenses are higher in profile and a have bulky size. Similarly, reflect array antennas [3–5] and transmit array antennas [6,7] generate wideband characteristics that depend in particular on the ratio of the focal distance to the diameter of the antenna’s aperture, as well as on the designed patches on the substrate layers. This will ultimately increase the overall antenna height, and those structures show greater aperture dimensions. In order to address such issues for wide bandwidth operation, several designed superstrates have been studied. The use of substrate layers was shown in [8–10] in the design of a single-layer substrate with diverse materials [11], and partially reflecting surfaces (PRSs) designed with a single dielec- tric material [12] were studied. Those prototypes utilize expensive dielectric slabs using a standard ceramic cutting process, which are bulky in nature. Most recently, metasurfaces were studied that were electrically thin and showed a periodic structure, which were im- plemented in a printed circuit board (PCB). A compact low-cost PRS having a non-uniform double-sided printed single-layer dielectric slab was proposed in [13]. Similarly, different shapes of unit cell patch designs were studied in [14–19], where the use of electrically thin substrates with the respective designed patches was shown. This further shows the design Micromachines 2022, 13, 471. https://doi.org/10.3390/mi13030471 https://www.mdpi.com/journal/micromachines