Research Article A Compact Triple Band EBG Using Interdigital Coplanar Waveguide Structure for Antenna Gain Enhancement Prapoch Jirasakulporn , 1 Pongsathorn Chomtong , 2 Kamorn Bandudej, 3 and Prayoot Akkaraekthalin 1 1 Department of Electrical and Computer Engineering, King Mongkut’s University of Technology North Bangkok, Pracharat 1 Road, Angsue, Bangkok 1518, ailand 2 Department of Teacher Training in Electrical Engineering, Faculty of Technical Education, King Mongkut’s University of Technology North Bangkok, Pracharat 1 Road, Angsue, Bangkok 1518, ailand 3 NationalAstronomicalResearchInstituteofailand(NARIT),PrincessSirindhornAstroPark,260Moo4,Donkaew,Maerim, Chiangmai, ailand CorrespondenceshouldbeaddressedtoPongsathornChomtong;tonkmutnb@hotmail.com Received 6 August 2020; Revised 6 October 2020; Accepted 21 November 2020; Published 11 December 2020 AcademicEditor:Seong-YoupSuh Copyright©2020PrapochJirasakulpornetal.isisanopenaccessarticledistributedundertheCreativeCommonsAttribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. AnewtriplebandEBGunitcellwithcompactsizehasbeendesigned,fabricated,andtested.eproposedEBGunitcellisbasedona squaremushroom-likeEBG(M-EBG)structurewithaninterdigitalcoplanarwaveguide(ICPW).Withthistechnique,thesizeofthe proposed ICPW-EBG structure has been reduced from λ/2 to λ/4 compared with the conventional M-EBG unit cell dimension, whichis18 × 18mm 2 .eproposedunitcellwasdesignedinordertorespondforthreefrequencybandsat1.8GHz,2.45GHz,and 3.7GHz.Anarrayof10 × 10 unit cell was also designed as a reflector with an overall dimension of 181.8 × 181.8mm 2 . e dipole antennaswereimplementedoverthedesignedreflectorwithashortdistanceof λ/8toradiateelectromagneticwave.esimulation results showed that the ICPW-EBG reflector can improve directivity of the dipole antenna to be 9.12dB at 1.8GHz, 9.02dB at 2.45GHz,and8.40dBat3.7GHz.emeasurementdirectivitiesagreedwellwithsimulationresultsincluding8.72dBat1.8GHz, 8.56dBat2.4GHz,and8.1dBat3.7GHz.isisthefirstdesignoftriplebandEBGunitcellwith50%sizereductioncomparedwith theconventionalstructureatthesamefrequency.edesignedICPW-EBGreflectorwithdipoleantennaresultsinthetripleband operation, low-profile and high gain suitable for modern wireless communication systems. 1. Introduction Development and design of telecommunication equipment inthismoderneramustrespondtotheneedofusers.Most mobile equipment must be designed for use of multifre- quency bands including LTE, WLAN, WiMax, and Blue- tooth. Likewise, an antenna, one of the major communication equipment, needs not only to operate for multiple frequencies but also to have low profile, compact size,andhighgain.However,designofanantennahavingall thesefeaturesisverycomplex.erearemanytechniquesto designanantennatooperatewithmultifrequencyband,low profile, small size, and high gain. One of the popular techniques is to design the antenna with artificial material, which is not found in nature, called metamaterial having negative refractive index property, or left-hand material (LHM),theoreticallydiscussedbyV.G.Veselagoin1968[1]. LHM has negative refractive index corresponding to neg- ative relative dielectric permittivity and negative relative magnetic permeability values. e permittivity and per- meability characteristics are the macroscopic responses of homogeneous medium when applying electromagnetic fields[2].LHMscanbeappliedwithelectromagneticdevices in microwave and terahertz frequency bands such as an- tenna,balun,transmissionline,andcouplercomponent[3]. Especially, with the negative refractive index of LHMs, the antenna can improve their characteristics of antenna gain, wideband, and multiband [4]. e LHMs are divided into Hindawi International Journal of Antennas and Propagation Volume 2020, Article ID 2856807, 18 pages https://doi.org/10.1155/2020/2856807