Issue link: https://te.mouser.com/i/1349110
TE Connectivity White Paper /// V2X - An important building block in Cooperative Intelligent Transport Systems (C-ITS) Page 9 V2X – An important building block in Cooperative Intelligent Transport Systems (C-ITS) Figure 14 shows a TE V2X antenna concept for minimizing the roof con- struction's influence on antenna per- formance. In this concept the antenna is lifted off the ground plane to the maxi- mum height of the antenna housing by means of a microstrip line and a balun. This minimizes the impact of roof curvatures or a glass roof. 4.2. Antennas for trucks All factors mentioned with regard to the directional characteristic re- quirements of V2X antennas ap- ply not only to passenger cars but also to trucks. However, due to their length, all-round visibility is much harder to achieve in trucks. Therefore, winglet antennas as shown in figure 15 are mounted to the left and right of the front end of the driver cabin. Figure 15 shows a new heavy-duty vehicle concept devel- oped by TE Automotive Wireless for different cabin constructions and trailer versions. Externalizing the ac- tual antenna into a so-called winglet with a flexible base generates good emittance from the vehicle, while a spring element integrated in the base point prevents antenna shear. Figure 16 illustrates directivity of a "winglet antenna" into the left half- space with resulting antenna gain from 2.1 dBi to 3.5 dBi. Figure 17 shows signal propagation as influenced by the form of a truck. The reflections of the electromag- netic waves on the vehicle cause an interference pattern. The winglet design of the antennas asures good coverage for also for the rear part of the trailer. 4.3. Antennas for two-wheelers Quite a different antenna challenge must be solved in motorcycles. While a car will remain more or less level on the road, a motorcycle will strongly shift around its longitudinal axis in any curve. This poses problems, as the V2X communication specifica- tions define vertical antenna polar- ization. Every time the motorcycle navigates a curve, the position of the antenna shifts, turning a vertical an- tenna into a mixture of vertical and horizontal antenna. To minimize this effect, TE Wireless, in cooperation with the Connected Motorcycle Con- sortium (CMC), has developed spe- cial antennas (figure 18). Related tests and studies have shown that motorcycle accessories, too, will impact antenna characteristics. Therefore, the use of double antenna systems is also recommended in V2X motorcycle technology applications. 4.4. Compensator Depending on the mounting scenari- os in the vehicle, coaxial cables often must cover long distances between antenna and V2X control unit. A con- ventional coaxial cable typically fea- tures approx. 0.12 dB attenuation per 10 cm at 5.9 GHz and approx. 0.4 dB attenuation per connector. In a 2 m cable this can result in up to 3 dB at- tenuation. Temperature effects and ageing may cause additional signal attenuation. Use of a compensator can balance these effects. Antenna recognition and additional important informa- tion, i.e. temperature and trans- mission power, is transferred to the V2X control unit via diagnostic interface. Fig. 14: V2X antenna concept with fully integrated antenna system for the shark fin. Fig. 15: V2X antenna concept with wing- let design for heavy-duty vehicles Fig. 16: Winglet antenna: (a) Antenna, (b) 3D antenna diagram, (c) 2D antenna diagram (c) (b) (a)