# Design of Triple-Band (DSRC, 5G, 6G) Antenna for Autonomous Vehicle Telematics
## 1 Introduction  
In 2022, the National Highway Traffic Safety Association announced that about 43,000 people died in traffic accidents in 2021. The traffic death rate in 2021 is 10.5% higher than the death rate in 2020 and has the highest number of fatalities since 2005 [1]. A group of technology company executives agree that more advanced devices and tests in cellular vehicle-to-everything (C-V2X) are needed to prevent such casualties [2]. V2X includes the communication between vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I). It delivers advanced safety features, such as blind-spot warnings, forward collision warnings, an emergency vehicle-approaching sign, and traffic and travel condition data to find the shortest and safest path to the destination [3]. Current V2X communication is built upon dedicated short-range communications (DSRC), operating between 5.85 and 5.925 GHz [4]. The DSRC-employed applications include, but are not limited to, electronic parking and toll payments, emergency warning systems, and cooperative adaptive cruise control. However, the DSRC suffers from limited coverage, a low data rate, and unstable communication in dense and high-mobility environments. In 2019, 5G-based V2X communication was introduced to enable higher safety and infotainment services, such as vehicle platooning, advanced driver assistance, and remote driving [5]. Despite the DSRC and 5G-employed V2X communication, which can perform the currently demanding applications, it is anticipated that such communication cannot provide the required and future applications, such as 3D navigation, immersive entertainment, and other V2X communications. This is due to an increase in autonomous vehicles and the explosive growth of communication devices. To address such issues, 6G technology that operates from 100 GHz to 3 THz has received much attention because data rates of up to terabits per second and end-to-end latency of less than 0.1 ms can be achieved, which is over one order of magnitude better than 5G communication, [6]. High bandwidth and datarates and low latency increase the safety, reliability, and general capabilities of autonomous vehicles and make more robust V2X communications possible at 6G frequencies. Although the upcoming 6G wireless communication network can operate both current and future applications, employing a 6G network on V2X communication will not occur soon, i.e., at least ten years from now. Further, existing DSRC and 5G networks can still provide the services to specific applications, even if the 6G network is fully installed and utilized. Therefore, a system that simultaneously operates at DSRC, 5G, and 6G frequency bands is indispensable. Recently, many multi-band antennas have been reported [7; 8; 9; 10; 11; 12] for V2X and 5G communication. We reported a dual-frequency antenna covering DSRC and 5G networks [7; 8], but this does not include the 6G network. [PERSON] et al. fabricated a miniaturized broadband-multiband planar monopole antenna covering 2 to 2.74 GHz and 4 to 8 GHz [9]. [PERSON] et al. reported a triple-band antenna loaded with the reflector surface that operates in 2.4/5.8 GHz WLAN and sub-6 GHz 5G communication spectrum [10]. [PERSON] et al. developed a linear tapered slot Vivaldi antenna operating in the frequency range of a mid-band 5G network (3.3-6 GHz) [11]. [PERSON] et al. investigated a modified planar inverted-F antenna (PIFA) and a \"Y\"-shaped monopole sharing a common aperture [12]. The designed PIFA operates at 1.8, 2.4, and 3.5, while the monopole operates at 5.85 GHz. Even though these reported antennas cover many bands, they suffer from a low antenna gain, large size, and limited operating frequency bands. Accordingly, no antenna covers the existing DSRC network, current 5G network, and upcoming 6G network simultaneously with a high gain and a directional radiation pattern. Thus, this paper presents a stacked patch triple-band antenna with a simple structure, which operates at 5.9 GHz (DSRC), 28 GHz (5G), and 136.3 GHz, 142.5 GHz, and 154.5 GHz (6G).