Train communication systems with shielded antennas
Wireless communication systems for a vehicle, such as a train, are disclosed. In an embodiment, the wireless communication system includes a communication unit, an antenna, a power cable, a data transferring path, and a protective shield. The communication unit is arranged inside the vehicle. The antenna is provided on or above an exterior metal surface, such as the roof, of the vehicle. The power cable and the data transferring path connect the antenna and the communication unit. The protective shield is made of a conductive material, and is electrically and mechanically bonded to the exterior metal surface of the vehicle. The protective shield includes a cavity for accommodating the antenna, and at least one waveguide aperture extends through the protective shield and into the cavity.
1. A wireless communication system for a vehicle, comprising:
a communication unit arranged inside the vehicle;
an antenna provided on or above an exterior metal surface of the vehicle;
a power cable connecting the antenna to the communication unit;
a data transferring path connecting the antenna to the communication unit; and
a protective shield made of a conductive material;
wherein:
the protective shield is electrically and mechanically bonded to the exterior metal surface of the vehicle;
the protective shield comprises a cavity for accommodating the antenna;
an exterior wall of the protective shield has a thickness of larger than 1 cm;
a waveguide aperture extends through the protective shield and into the cavity;
the waveguide aperture has a thickness of larger than 1 cm; and
the waveguide aperture enables radio frequency waves to pass through the protective shield into and out from the antenna.
2. The wireless communication system of claim 1 , wherein the antenna operates at a frequency larger than 1 GHz.
3. The wireless communication system of claim 1 , wherein the antenna is an active antenna.
4. The wireless communication system of claim 3 , wherein the antenna comprises an array of antenna elements; and each antenna element is connected to a separate transceiver.
5. The wireless communication system of claim 4 , wherein:
the protective shield comprises a plurality of waveguide apertures; and
each antenna element is provided with a respective waveguide aperture.
6. The wireless communication system of claim 1 , wherein the protective shield is made of a solid metal material.
7. The wireless communication system of claim 1 , wherein:
the protective shield includes a base area, a top area, and side walls;
the base area is in contact with the exterior metal surface of the vehicle;
the top area is opposite to the base area;
the base area is larger than the top area;
the side walls extend between the base area and the top area; and
at least one of the side walls is arranged in a slanted disposition.
8. A wireless communication system for a vehicle, comprising:
a communication unit arranged inside the vehicle;
an antenna provided on or above an exterior metal surface of the vehicle;
a power cable connecting the antenna to the communication unit;
a data transferring path connecting the antenna to the communication unit; and
a protective shield made of a conductive material; wherein:
the protective shield is electrically and mechanically bonded to the exterior metal surface of the vehicle;
the protective shield comprises a cavity for accommodating the antenna;
a waveguide aperture extends through the protective shield and into the cavity;
the waveguide aperture enables radio frequency waves to pass through the protective shield into and out from the antenna;
the waveguide aperture has a rectangular or circular cross-section; and
the waveguide aperture has a cross-sectional dimension of less than 10 mm.
9. A wireless communication system for a vehicle, comprising:
a communication unit arranged inside the vehicle;
an antenna provided on or above an exterior metal surface of the vehicle;
a power cable connecting the antenna to the communication unit;
a data transferring path connecting the antenna to the communication unit; and
a protective shield made of a conductive material; wherein:
the protective shield is electrically and mechanically bonded to the exterior metal surface of the vehicle;
the protective shield comprises a cavity for accommodating the antenna;
the protective shield comprises a plurality of waveguide apertures;
the plurality of waveguide apertures extend in parallel with each other;
the plurality of waveguide apertures are provided in a plane in parallel with the exterior metal surface; and
the plurality of waveguide apertures form a row of waveguide apertures.
10. A wireless communication system for a vehicle, comprising:
a communication unit arranged inside the vehicle;
an antenna provided on or above an exterior metal surface of the vehicle;
a power cable connecting the antenna to the communication unit;
a data transferring path connecting the antenna to the communication unit; and
a protective shield made of a conductive material; wherein:
the protective shield is electrically and mechanically bonded to the exterior metal surface of the vehicle;
the protective shield comprises a cavity for accommodating the antenna;
the protective shield comprises a plurality of waveguide apertures;
the plurality of waveguide apertures extend in parallel with each other;
the plurality of waveguide apertures are provided in two or more planes in parallel with the exterior metal surface; and
the plurality of waveguide apertures form rows and columns of waveguide apertures.
11. The wireless communication system of claim 1 , wherein:
the communication unit comprises at least one router in the vehicle;
the router is configured to receive and transmit wireless data packets from and to a stationary communication server outside the vehicle through at least one exterior mobile network via the antenna; and
the router is configured to receive and transmit wireless data packets from and to at least one client onboard the vehicle via at least one access point connected to the router.
12. The wireless communication system of claim 11 , wherein the wireless communication operates in compliance with Wireless Local Area Network (WLAN) standards.
13. The wireless communication system of claim 11 , wherein the wireless communication operates in compliance with cellular network standards.