A compact triple band monopole antenna with a simple modified C-shape structure for vehicle-to-everything (V2X) application is presented. The proposed multiband vehicle antenna with three C-shaped round stubs structure satisfies the worldwide interoperability for microwave access (WiMAX), wireless local area network (WLAN), and wireless access in vehicular environment (WAVE) bands. The three resonant frequencies are implemented with three C-shaped round stubs, and they are simply controlled by adjusting the round stub length without influence each other. The presented antenna demonstrated good impedance bandwidth and nearly omnidirectional radiation patterns over the whole operating bands. The field communication tests by connecting the vehicular communication module were also performed and verified in the view of automotive vehicle antenna application.
INTRODUCTIONRecently, with the development of communication technologies such as 5G wireless communication, dedicated short range communication (DSRC), and Wi-Fi, research on high-reliability and low-latency autonomous vehicles that automatically recognize the driving environment and drive without a driver is being actively conducted. Vehicle-to-everything (V2X) is an essential technology for autonomous driving and has been standardized by DSRC in the US and cooperative intelligent transportation System (C-ITS) in Europe. Recently, mobile telecommunication operators have introduced and utilized cellular V2X (C-V2X), which is characterized by high reliability, short latency, and high data processing capacity. Also, researches on WAVE communication systems based on IEEE 802.11p MAC class using 5.85-5.925 GHz frequency bandwidth that provides vehicle to vehicle (V2V), pedestrian to vehicle (P2V), vehicle to infrastructure (V2I) in vehicle networking (IVN), and infrastructure to infrastructure (I2I) communication network functions are actively taking place in [1][2][3][4][5][6][7].Modern automotive antennas are usually placed in a small space on car case. These automotive antenna modules like shark-fins contain antennas for GPS/GNSS navigation, DMB, digital audio broadcasting (DAB), emergency call (eCall), long-term evolution (LTE), Wi-Fi, WLAN, WiMAX, multiple-input multiple-output (MIMO) antennas for cellular systems, diversity antennas for V2X and satellite digital audio radio (SDARS). However, the antenna design suffers from limited space, the coupling between antennas, and shadowing of other radiation patterns due to a multitude of near-field effects. Also optimum positions are difficult to identify [8][9][10][11][12][13][14][15].Several microstrip-feed and CPW-feed printed monopole antennas that can support WLAN and WiMAX applications, while potentially applicable as V2X vehicle antenna, have been reported and well designed to meet a dual or triple band operation [16][17][18][19][20][21][22][23][24][25][26]. In [27], two open ended inverted L-shaped slots on the radiation patch have been designed, but the slot position and dimension were ambiguous, and the E-pla...