RESEARCH ARTICLE Dual-band (5G millimeter-wave and dedicated short-range communication) stacked patch antenna for advanced telematics applications Woncheol Lee 1 | Yang-Ki Hong 1 | Hoyun Won 1 | Minyeong Choi 1 | Nathan Seongheon Jeong 1 | Jaejin Lee 2 1 Department of Electrical and Computer Engineering, The University of Alabama, Tuscaloosa, Alabama 2 Client Research and Development, Intel Corporation, Hillsboro, Oregon Correspondence Yang-Ki Hong, Department of Electrical and Computer Engineering, 3043 H.M. Comer, The University of Alabama, Tuscaloosa, AL 35487. Email: ykhong@eng.ua.edu Funding information The University of Alabama Abstract The designed and fabricated patch antenna covers both dedicated short-range communication (DSRC) and Fifth Generation (5G) millimeter-wave (mmW) bands for advanced telematics. The fabricated antenna has a small volume of 2.7λ H × 2.6λ H × 0.15λ H , where λ H is the air wavelength of the highest operating frequency. The antenna performances, such as S-parameters, the realized gain at boresight (RG 00 ), antenna radiation efficiency, and radiation patterns, are reported. The simulated results are in good agreement with the measured ones. Despite the fabricated antenna’s compactness, port isolation higher than 31 dB was achieved. Not only high RG 00 s of 6.8 and 12 dBi were obtained at DSRC and 5G mmW bands, respectively, but also an efficiency greater than 90% was observed at both frequency bands. Lastly, the fabricated antenna shows better performance than the previously reported dual-band antennas. KEYWORDS 5G, DSRC, dual-band, stacked patch antenna, telematics 1 | INTRODUCTION According to the World Health Organization (WHO), roughly 1.25 million people died in 2015 due to traffic acci- dents. The accidents cost approximately 3% of their gross domestic product in most countries. 1 To decrease traffic acci- dents, the U.S. Department of Transportation has demanded future automobiles and roads to incorporate dedicated short- range communication (DSRC: 5.85-5.925 GHz) devices, which accommodate vehicle-to-vehicle (V2V) and vehicle- to-infrastructure (V2I) communications, which offers blind spot warning, forward collision warning, rollover warning, electronic parking, toll payments, etc. 2 To realize the DSRC communication, two types of equip- ment are required: the onboard unit (OBU) placed inside the vehicle and the roadside unit (RSU) located on the part of infrastructure. For the OBU, an omnidirectional pattern is needed to send or receive information in all directions, whereas for the RSU, a directional radiation pattern is necessary. 2,3 Recently, automotive industries have been investigating fifth generation (5G) wireless communication to accommodate mobile entertainment and/or fully autonomous systems, which cannot be realized by DSRC. To facilitate this need, the U.S. Federal Communication Commission (FCC) announced the frequency spectrum above 24 GHz bands, including 27.5-28.5 GHz, 37-39 GHz, and 64-71 GHz, on July 14, 2016. 4 To enable DSRC and 5G networks simultaneously, the antenna needs to be operational at dual-frequency bands. Recently, dual-band antennas, which have a frequency ratio (f H /f L , where f H and f L are the upper and lower operating fre- quency, respectively) greater than 3, have been extensively studied. 5–8 These reported dual-band antennas do not pro- vide the multi-operating modes of a single antenna, such as a multiband antenna, 9,10 because of the harmonics of the antenna at upper-frequency bands. 7,8 Therefore, two anten- nas were closely placed or integrated to operate at dual-band with a high frequency ratio. In References 5,6, a dual-feed dual-band stacked patch antenna operates at both 2.5 and 8.2 GHz bands, and folded-parallel-plate antenna covers both 2.4 and 24 GHz. However, these antennas show a high profile of 1.8λ H (64 mm) and 1.73λ H (21.57 mm), respec- tively, where λ H is the air wavelength of the highest fre- quency. Alternatively, a dielectric resonator antenna (DRA) was integrated into a patch-loaded slot antenna to operate at 5.2 and 24 GHz with compactness. 7 Even with the small volume of 3.2λ H ×2λ H × 0.12λ H , good isolation between Received: 22 September 2018 DOI: 10.1002/mop.31737 Microw Opt Technol Lett. 2019;1–7. wileyonlinelibrary.com/journal/mop © 2019 Wiley Periodicals, Inc. 1