Broadband antenna system for a vehicle
A broadband antenna system for a vehicle, comprising a ground plane circumscribed by a rectangle having major and minor sides, a dielectric substrate comprising a first portion area, a radiating element for operating at a frequency band and having at least three angles and three sides, a first side being substantially aligned with one side of the rectangle, and a first angle having an apex being the closest point of the radiating element to the ground plane, and a conductive element having at least a first portion extending between the radiating element and one side of the first portion area, wherein each major side has an electric length of at least 0.13λ, being λ the lowest frequency of the antenna system, and the first angle having an aperture lower than 156°.
1. A broadband antenna system ( 1 ) for a vehicle, comprising:
a ground plane ( 2 ) circumscribed by a rectangle having major ( 2 a ) and minor ( 2 b ) sides,
a dielectric substrate ( 3 ) comprising a first portion area ( 3 a ),
a radiating element ( 4 ) for operating at at least one frequency band of operation, the radiating element ( 4 ) disposed on top of a first portion area ( 3 a ) of the substrate ( 3 ), and having at least three angles and three sides, a first side ( 7 ) being substantially aligned with one side ( 2 a , 2 b ) of the circumscribed rectangle and a first angle ( 6 ) having an apex, the apex being the closest point of the radiating element ( 4 ) to the ground plane ( 2 ),
a grounding point ( 9 ) disposed at one extreme of the first portion area ( 3 a ) of the substrate ( 3 ) and coupled to the ground plane ( 2 ),
a feeding element ( 8 ) electromagnetically coupled with the radiating element ( 4 ) through the apex of the first angle ( 6 ), and
a conductive element ( 5 ), electrically isolated from the radiating element ( 4 ), disposed on the first portion area ( 3 a ) of the substrate ( 3 ) and coupled to the grounding point ( 9 ), the conductive element ( 5 ) having at least a first portion ( 5 ′) extending between the radiating element ( 4 ) and one of the sides of the first portion area ( 3 a ) of the substrate ( 3 ),
wherein each major side ( 2 a ) of the ground plane ( 2 ) has an electric length (Lgp) of at least 0.13λ, with λ being the lowest frequency of the antenna system ( 1 ), and wherein the first angle ( 6 ) of the radiating element ( 4 ) has an aperture lower than 156°, and wherein the conductive element ( 5 ) has an electric length (Lce), and wherein the sum of the electric length (Lgp) of the major side ( 2 a ) of the circumscribed rectangle of the ground plane ( 2 ) and the electric length (Lce) of the conductive element ( 5 ) ranges from 0.18λ, to 0.22λ.
2. A broadband antenna system ( 1 ) for a vehicle, according to claim 1 , wherein the radiating element ( 4 ) has a length (Lre) measured from the first side ( 7 ) to the first angle ( 6 ) lower than 1/10λ, and a width (Wre) measured as the length of the first side ( 7 ) of the radiating element ( 4 ) lower than ⅛λ, being k the lowest frequency of the antenna system ( 1 ).
3. A broadband antenna system ( 1 ) for a vehicle, according to claim 1 , wherein the conductive element ( 5 ) is spaced from the radiating element ( 4 ) at least 50 μm.
4. A broadband antenna system ( 1 ) for a vehicle, according to claim 1 , wherein the first portion ( 5 ′) of the conductive element ( 5 ) is bigger than ⅛λ, being k the lowest frequency of the antenna system ( 1 ).
5. A broadband antenna system ( 1 ) for a vehicle, according to claim 1 , wherein the substrate ( 3 ) comprises a second portion area ( 3 b ), and wherein the ground plane ( 2 ) is disposed on said second portion area ( 3 b ).
6. A broadband antenna system ( 1 ) for a vehicle, according to claim 1 , wherein the radiating element ( 4 ) has a substantially triangular configuration.
7. A broadband antenna system ( 1 ) for a vehicle, according to claim 1 , wherein the radiating element ( 4 ) has curved sides ( 11 ).
8. A broadband antenna system ( 1 ) for a vehicle, according to claim 1 , wherein the radiating element ( 4 ) has concave-shaped sides.
9. A broadband antenna system ( 1 ) for a vehicle, according to claim 1 , further comprising a matching network coupling the radiating element ( 4 ) with the feeding element ( 8 ).
10. A broadband antenna system ( 1 ) for a vehicle, according to claim 1 , wherein the conductive element ( 5 ) has an open extreme shape as a space-filling curve.
11. A broadband antenna system ( 1 ) for a vehicle, according to claim 1 , further comprising at least one additional antenna selected from the group of: a satellite digital audio radio services (SDARS) antenna, a global navigation satellite system (GNSS) antenna, a digital audio broadcasting (DAB) antenna, and an AM/FM antenna.
12. A broadband antenna system ( 1 ) for a vehicle, according to claim 1 , wherein the frequency band of operation is the LTE frequency band of operation, and λ corresponds to the lowest frequency of the LTE band, which is 700 MHz.
13. A broadband antenna system ( 1 ) for a vehicle, according to claim 12 , wherein the LTE frequency band of operation comprises a first band ranging from 700 MHz to 960 MHz, a second band ranging from 1400 MHz to 1500 MHz, a third band ranging from 1700 MHz to 2200 MHz, and a fourth band ranging from 2500 MHz to 2700 MHz.
14. A shark fin antenna ( 15 ) comprising a broadband antenna system ( 1 ) for a vehicle according to claim 1 , further comprising a cover for enclosing at least the first portion area ( 3 a ) of the substrate ( 3 ), and where the antenna system ( 1 ) is adapted to be attached to the vehicle.