CROSS REFERENCE TO RELATED APPLICATION

The present application claims priority to Korean Patent Application No. 10-2019-0167530, filed Dec. 16, 2019, the entire content of which is incorporated herein for all purposes by this reference.

BACKGROUND

1. Field of the Disclosure

The present disclosure relates to an electromagnetic-wave-transmissive module of a vehicle radar, and more particularly, to an electromagnetic-wave-transmissive module of a vehicle radar, which minimizes a dielectric impact reflection effect, which occurs when an electromagnetic wave radiated from an antenna is transmitted through a radome and a transmissive cover.

2. Description of the Related Art

Recently, with the development of high-frequency wireless communication technology and increased interest in automobile safety technology, demand for vehicle radar technology has increased. A representative example of application of vehicle radar technology is a smart cruise system. The smart cruise system detects the movement of a preceding vehicle using a radar device mounted at the front of a vehicle and thus operates the engine and brakes thereof to accelerate or decelerate the vehicle to avoid preceding vehicles and change lanes, or to accelerate to an initially set speed and then maintain constant-speed driving when there is no preceding vehicle.

To realize such a smart cruise system, the vehicle is equipped with a radar device and collects information regarding the presence and movement of preceding vehicles through the transmission and reception of electromagnetic waves radiated from the radar device. In general, the radar device includes an antenna configured to transmit and receive electromagnetic waves, internal electronic parts such as a millimeter-wave radio-frequency integrated circuit (RFIC), and a radome for protecting the same. Further, a transmissive cover for protecting the radar device is disposed in front of the radome.

FIG. 1is a view showing a general electromagnetic-wave-transmissive module of a vehicle radar according to the prior art. The electromagnetic wave radiated from an antenna10of a radar device mounted within a vehicle is sequentially transmitted through a radome20and a transmissive cover30and is then radiated forwards. The electromagnetic wave radiated from the antenna10is changed in terms of wavelength and is attenuated due to the dielectric permittivity of the medium through which the electromagnetic wave is transmitted.

In further detail, as shown inFIG. 1, the electromagnetic wave radiated from the antenna10is mostly transmitted through the radome20to the transmissive cover30when coming into contact with the radome20, but a part thereof is reflected on the radome20. When the electromagnetic wave that is radiated from the antenna10and is then incident on the radome20is defined as a first incident wave L1and when the electromagnetic wave reflected on the radome20is defined as a first reflection wave R1, the transmittance of the radome20is a value obtained by subtracting the first reflection wave R1from the first incident wave L1. When the electromagnetic wave that is transmitted through the radome20and is then incident on the transmissive cover30is defined as a second incident wave L2and when the electromagnetic wave reflected on the transmissive cover30is defined as a second reflection wave R2, the transmittance of the transmissive cover30is a value obtained by subtracting the second reflection wave R2from the second incident wave L2.

The electromagnetic wave radiated from the antenna10is partially reflected while being transmitted through the radome20and the transmissive cover30. Accordingly, only a transmission wave L3obtained by subtracting the first reflection wave R1and the second reflection wave R2from the first incident wave L1is radiated forwards. Therefore, to improve the efficiency of transmission and reception of the electromagnetic wave radiated from the antenna10, it is important to improve the electromagnetic-wave transmittance of the radome20and the transmissive cover30.

The contents described as the background art are merely for understanding the background of the present disclosure, and should not be taken as corresponding to the related arts already known to those skilled in the art.

SUMMARY

The present disclosure provides an electromagnetic-wave-transmissive module of a vehicle radar, in which a coating layer is formed on a radome or a transmissive cover disposed on a path through which an electromagnetic wave radiated from an antenna is transmitted based on dielectric permittivity, thereby improving the transmittance of the radome or the transmissive cover through which the electromagnetic wave is transmitted.

An electromagnetic-wave-transmissive module of a vehicle radar according to an exemplary embodiment of the present disclosure is a transmissive module through which an electromagnetic wave radiated from an antenna of a radar mounted within a vehicle is transmitted. The electromagnetic-wave-transmissive module may include one or more of a radome covering the antenna and a transmissive cover, which is disposed to be spaced apart from a front side of the antenna and through which a radio wave radiated from the antenna and then transmitted through the radome may be subsequently transmitted. At least one coating layer, which includes Polytetrafluoroethylene (PTFE) and which has a dielectric permittivity higher than the dielectric permittivity of air and lower than the dielectric permittivity of the radome and the transmissive cover, may be formed on the surface of at least one of the radome and the transmissive cover.

The coating layer may be a dome coating layer formed on at least one surface of the radome, among surfaces thereof. The dome coating layer may include a first dome coating layer formed on the surface of the radome facing an antenna. The dome coating layer may further include a second dome coating layer formed on the surface of the first dome coating layer facing the antenna, and the dielectric permittivity of the second dome coating layer is lower than the dielectric permittivity of the first dome coating layer. The dome coating layer may also include a third dome coating layer formed on an opposite surface of the surface of the radome facing the antenna.

The coating layer may be a cover coating layer formed on at least one surface of the transmissive cover, among surfaces thereof. The cover coating layer may include a first cover coating layer formed on the surface of the transmissive cover facing the radome. The cover coating layer may further include a second cover coating layer formed on the surface of the first cover coating layer that faces the radome, and the dielectric permittivity of the second cover coating layer is lower than the dielectric permittivity of the first cover coating layer. The cover coating layer may also include a third dome coating layer formed on an opposite surface of the surface of the transmissive cover facing the radome.

The coating layer may have a dielectric permittivity of about 1.7 to 3.0 and a surface roughness of about 2.0 or less based on Ra. Additionally, the coating layer may have a thickness of about 1 to 100 μm. An impregnating material contained in the coating layer may have a particle size of about 50 nm to 1 μm.

According to an exemplary embodiment of the present disclosure, it may be possible to form a coating layer having a dielectric permittivity lower than that of a radome and a transmissive cover on the radome or the transmissive cover through which an electromagnetic wave radiated from an antenna is transmitted to prevent the transmittance of the electromagnetic wave from being reduced, thereby improving the electromagnetic-wave output efficiency of a radar.

