V2X Introduction and Antenna Solutions

What is V2X/C-V2X

Vehicle to Everything (V2X) is a new generation of information and communication technology that connects vehicles to everything. V stands for vehicle and X stands for any object that interacts with the vehicle. Currently, X mainly includes vehicles, people, roadside infrastructure and networks.

C-V2X stands for cellular vehicle-to-everything. C-V2X is a cellular network-based V2X technology defined by 3GPP based on LTE-R14 technology, so it is also called LTE-V. There are two main types: centralized (LTE-V-Cell) and distributed (LTE-V-Direct). The centralized type requires the support of base stations and defines the communication mode between the vehicle and the road test communication unit and the base station; the distributed type does not require base stations as support and defines the communication mode between vehicles.

Functions of V2X

X is a variable, which can be replaced by V, I, P, N, etc., so it can realize multiple functions, as shown below:

V2N is the connection between vehicles and the Internet (Vehicle to Network), which is the Internet of Vehicles.

V2V is the connection between vehicles and vehicles (Vehicle to Vehicle).

V2I is the connection between vehicles and infrastructure (Vehicle to Infrastructure), where I includes traffic facilities and equipment such as traffic lights, bus stops, telephone poles, buildings, overpasses, tunnels, roadblocks, etc.

V2P is the connection between vehicles and pedestrians (Vehicle to Pedestrian), etc.

Design ideas for V2X

Linear average gain: ≥3.2 dBi @ Zone A (θ=84°--96°) (directional antenna)

≥0.3 dBi @ Zone A (θ=84°--96°) (omnidirectional antenna)

≥-6.2 dBi @ Zone B (θ=84°--96°)

To meet the above requirements, the antenna's radiation surface should be as horizontal as possible, then a display antenna is required.

Antenna group vibration

The radiation pattern of an antenna array depends on the type, orientation, position in space, and amplitude and phase of the current that excites the individual elements used. To simplify the discussion of antennas, we assume that each element in the antenna array is a point source with the same direction and isotropy. The resulting pattern is called a group element.

The array factor of isotropic point sources of equal amplitude and phase separated by half a wavelength

Dipole array pattern a

Dipole array pattern b

V2X antenna box appearance

According to the traditional display antenna, to meet the C-V2X requirements, the antenna box size is very large. Currently, the height that car companies can provide does not exceed 30mm. In order to meet the requirements, the size is small while retaining the display form.

V2X antenna test data

Line-side V2X

V2X antenna test data

Board-side V2X

Line end 2D direction map

PHI-0

PHI-90

THETA-90

2D Direction Diagram of Board End

PHI-0

PHI-90

THETA-90

Why are there two V2X antennas?

The car is surrounded by metal, which has a shielding effect. A moving car needs to be able to control the surrounding objects at all times, so multiple V2X antennas are needed. However, the antenna area is limited, and the isolation degree also needs to be considered.

The antenna is designed diagonally to take 360° into consideration