energies Article Investigation of Broadband Printed Biconical Antenna with Tapered Balun for EMC Measurements Abdulghafor A. Abdulhameed 1,2,* and ZdenˇekKubík 1 1 Department of Electronics and Information Technology, Faculty of Electrical Engineering, University of West Bohemia, 301 00 Pilsen, Czech Republic; [email protected] 2 Department of Electrical Techniques, Qurna Technique Institute, Southern Technical University, Basra 61001, Iraq * Correspondence: [email protected] Abstract: This article investigates the design, modeling, and fabrication of small-size (150 × 90 × 1.6 mm) broadband printed biconical antenna. The proposed antenna is intended for use a reference antenna for electromagnetic interference measurement inside the EMC chamber. The reflection coefficient (S11-parameter) is verified by modeling the equivalent circuit of the structure in terms of lumped elements. This structure offers a −10 dB impedance bandwidth (from 0.65 GHz to 2.3 GHz) with the tapered balun feeding method. Therefore, it has a high probability of estimating the electromagnetic waves emitted from several applications such as GSM, LTE, UMTS, 3G, Wi-fi, Bluetooth, ZigBee and more. The simulated standard antenna parameters are compatible with the measured parameters results. Furthermore, azimuth omnidirectional radiation pattern and well-realized gain (3.8 dBi) are achieved, reflecting good values of antenna factor compared to the commercial design. Keywords: antenna factor; balun feeding technique; biconical antenna; EMC measurement; wideband Citation: Abdulhameed, A.A.; Kubík, Z. Investigation of Broadband Printed Biconical Antenna with Tapered Balun for EMC 1. Introduction Measurements. Energies 2021, 14, Recently, electronic devices have become more popular and are becoming smaller 4013. https://doi.org/10.3390/ in size. According to their applications, the radiation of these devices is occupying the en14134013 electromagnetic spectrum from DC frequency to GHz. Furthermore, electromagnetic inter- ference (EMI) will occur between these devices as long as they share the same range [1]. Academic Editor: Andrea Mariscotti The devices’ ability to work together without any effect against each other is called elec- tromagnetic compatibility (EMC) [2]. Emission and immunity are essential criteria for Received: 7 June 2021 EMI measurements. Three mandatory aspects should exist to generate EMI phenomena, Accepted: 25 June 2021 Published: 3 July 2021 the source of the electromagnetic waves, the victim affected by the source, and the path between the source and the victim. This path can be either radiated or conducted [3,4]. Publisher’s Note: MDPI stays neutral There are three radiation regions for each radiated element, near field region, reactive with regard to jurisdictional claims in near-far field region (Fresnel), and far-field region (Fraunhofer) [5]. These regions have published maps and institutional affil- their radius (R) related to their wavelength and the higher dimension D, as shown in iations. Figure1 . Two methods were proposed for EMI measurement based on radiated element regions and the power of the interference source. The far-field method uses an antenna to estimate the propagated electrical field inside the chamber [6]. In contrast, the near-field method utilizes probes to collect the induced magnetic and electrical field above the printed circuit board (PCB) [7]. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. The antennas used for the EMC test should have specific characteristics such as wide This article is an open access article bandwidth, high gain, omnidirectional radiation pattern, and good antenna factor. These distributed under the terms and designed antennas are intended to work in the very high frequency (VHF) and ultra-high conditions of the Creative Commons frequency (UHF) bands (30–1000 MHz and 1000–3000 MHz, respectively) [8], to detect Attribution (CC BY) license (https:// the interference emitted from the most critical applications in these bands such as GSM creativecommons.org/licenses/by/ (850–900 MHz), LTE (1800 MHz), UMTS or 3G (2100 MHz), Wi-fi, Bluetooth, Zigbee 4.0/). and more (2400 MHz) [9,10]. VHF and UHF bands are classified based on the European Energies 2021, 14, 4013. https://doi.org/10.3390/en14134013 https://www.mdpi.com/journal/energies Energies 2021, 14, x FOR PEER REVIEW 2 of 14 interference emitted from the most critical applications in these bands such as GSM (850– Energies 2021, 14, 4013 900 MHz), LTE (1800 MHz), UMTS or 3G (2100 MHz), Wi-fi, Bluetooth,2 of 15 Zigbee and more (2400 MHz) [9,10]. VHF and UHF bands are classified based on the European Telecom- munications Standards Institute (ETSI). The VHF band is covered by a biconical or log Telecommunications Standards Institute (ETSI). The VHF band is covered by a biconical or logperiodic periodic antenna,antenna, while while the horn the antennahorn antenna covers the covers UHF band the above UHF 1 GHz band [11 ].above 1 GHz [11]. FigureFigure 1. Three 1. Three field regions field regions for any radiated for any element. radiated element. Several structures of the antennas were proposed to utilize in EMC measurement. In [12],Several the authors structures propose using of the characteristics antennas of were the sleeve proposed dipole antenna to utilize for EMCin EMC measurement. In measurement,[12], the authors which offerspropose 86% sizeusing reduction characteristics compared to of the the conventional sleeve dipole biconical antenna for EMC meas- antenna. The log-periodic dipole antenna’s frequency performances were improved in [13] usingurement, a saw-tooth which shape offers feedline. 86% The successivesize reduction dipoles will compared be arranged into the the horizontal conventional biconical an- planetenna. and The eliminate log-periodic the unwanted dipole vertical antenna’s electric field frequency component. performances A complementary were improved in [13] log-periodicusing a saw-tooth dipole array shape with cross-polarization feedline. The successive was proposed dipoles in [14]. will This structurebe arranged in the horizontal has an array of dipole antennas orthogonal to dipoles of conventional log-periodic dipole antennas,plane and offering eliminate a circular the polarization unwanted without vertical any hybrid electric junction. field The widthcomponent. of the A complementary ridgelog-periodic of the double dipole ridge guide array horn with (DRGH) cross-polarization antenna was tapered was linearly proposed in [15]. in This [14]. This structure has processan array maximized of dipole the effective antennas radiation orthogonal aperture and to reduced dipoles the of beamwidth conventional compared log-periodic dipole an- to conventional 1–18 GHz DRGH. tennas,Classical offering antennas a circular are large inpolarization size and heavy without in weight. any Therefore, hybrid using junction. printed The width of the ridge circuitof the technology double ridge (PCB) forguide antenna horn design (DRGH) is the antenna best choice was for thistapered purpose. linearly The in [15]. This process microstripmaximized antenna the has effective many advantages radiation such aperture as its low and cost, reduced low profile, the and beamwidth ease to compared to con- fabricateventional [16]. On1–18 the GHz other hand,DRGH. it suffers from the narrow bandwidth and low efficiency. The limited bandwidth is considered a big issue in EMC applications, which makes using the monopoleClassical and dipoleantennas printed are antennas large the in best size way and to overcome heavy thisin issue.weight. Therefore, using printed circuitThere technology will be a trade-off (PCB) between for theantenna impedance design bandwidth is the and best the size,choice especially for this purpose. The mi- forcrostrip this band antenna from 0.5 tohas 3 GHz many since advantages low frequency such needs as a largeits low size. cost, Different low kinds profile, and ease to fabri- of printed antennas were proposed to serve EMC applications. In [17], a wideband (0.8–2.5cate [16]. GHz) Onlog-periodic the other printed hand, antenna it suffers with 12from dipoles the was narrow presented. bandwidth The authors and low efficiency. The oflimited [18] show bandwidth the design and is considered development of a abig broadband issue in bi-conical EMC applications, printed dipole an- which makes using the tenna,monopole where a wideand impedancedipole printed bandwidth antennas was obtained the withbest theway help to of overcome balun feed and this issue. matching network. Ultra-wideband biconical (700 MHz–20 GHz) bilateral tapered slot an- tenna withThere dual-polarization will be a trade-off was investigated between for EMC the measurements. impedance Two bandwidth studies [19,20 and] the size, especially presentedfor this aband new UWB from Skeletal 0.5 to antenna 3 GHz for since EMC low measurements; frequency the needs VSWR a was large better size. Different kinds of thanprinted the classical antennas antenna were that was proposed used for the to sameserve purpose. EMC In applications. [21], the bulb shape In [17], was a wideband (0.8–2.5 proposed with ultra-wideband (0.79–1 GHz and 1.37–15 GHz), where the wide impedance matchingGHz) log-periodic was achieved with printed the help antenna of using the with stepped 12 partdipoles and feeding was presented. line. In [22], The authors of [18] show the design and development of a broadband bi-conical printed dipole antenna, where a wide impedance bandwidth was obtained with the help of