Antenna structure and wireless communication device using the same
An antenna structure suitable for 5G use in controlling direction of radio beams and in increasing antenna gain includes a substrate, an array of antennas, a main body, a lens array, a grounding plate, and a high-impedance surface (HIS) layer embedded into the substrate. The array of antenna units is positioned on the substrate surface under the protection of the main body. The lens array includes a lens units for each antenna unit, the lens units concentrate the beams generated by the antenna units. The grounding plate is underneath and grounds the antenna units. The HIS layer suppresses surface waves generated by the lens arrays and the substrate and increases a gain of the antenna structure in certain directions.
1. An antenna structure comprising:
a substrate comprising a first surface and a second surface opposite to the first surface;
an array antenna positioned on the first surface, the array antenna comprising a plurality of antenna units;
a main body covering the substrate and receiving the array antenna therein;
a lens array comprising a plurality of lens units corresponding to the plurality of antenna units, the lens units being configured to concentrate beams generated by the antenna units;
a grounding plate positioned at the second surface and configured to ground the array antenna; and
a high-impedance surface (HIS) layer embedded into the substrate, the HIS layer being configured to suppress surface waves generated by the lens arrays and the substrate to increase a gain of the antenna structure;
wherein the HIS layer comprises a plurality of circular holes, each circular hole having same radius, and each antenna unit having same radius, the radius of each circular hole being greater than the radius of each antenna unit.
2. The antenna structure of claim 1 , wherein the main body is made of materials which have a dielectric constant of 3 to 4.
3. The antenna structure of claim 1 , wherein each of the plurality of antenna units comprises a first feeding portion and a second feeding portion configured to feed current to each a corresponding one of the antenna units thereby activating each of the antenna units to generate electromagnetic waves of a horizontal polarization and a vertical polarization.
4. The antenna structure of claim 1 , wherein each of the antenna units has a substantially circular shape and a same size, and each of the lens units has a substantially circular shape and a same size, each of the lens units is concentric with the corresponding one of the antenna units and covers the corresponding antenna unit.
5. The antenna structure of claim 1 , wherein each of the lens units is a cavity formed on a curved surface of the main body thereby forming a lens function.
6. The antenna structure of claim 1 , wherein the HIS layer is a periodic square structure, the HIS layer comprises a plurality of spaced square cells, a length of each side of each of the square cells is approximately 0.25×λ 1 to 0.5×λ 1 wherein λ 1 is a wavelength of electromagnetic waves to be transmitted or have been received by the antenna structure transmitted in the substrate.
7. The antenna structure of claim 1 , wherein the plurality of circular holes correspond to the plurality of antenna units, each of the plurality of circular holes is concentric with the corresponding antenna unit.
8. The antenna structure of claim 7 , wherein a distance between center points of adjacent antenna units is approximately 0.45×λ to 0.6×λ, a diameter of each of the lens units is approximately 0.45×λ to 0.6×λ, wherein λ is a wavelength of electromagnetic waves which can be transmitted or received by the antenna structure.
9. The antenna structure of claim 1 , further comprising a metal mesh, wherein the metal mesh comprises a plurality of metal strips, each of the metal strips is positioned between adjacent rows of the antenna units or adjacent columns of the antenna units and is coplanar with the antenna units, the metal strips are configured to reduce interference between the antenna units.
10. A wireless communication device comprising:
an antenna structure comprising:
a substrate comprising a first surface and a second surface opposite to the first surface;
an array antenna positioned on the first surface, the array antenna comprising a plurality of antenna units;
a main body covering the substrate and receiving the array antenna therein;
a lens array comprising a plurality of lens units corresponding to the plurality of antenna units, the lens units being configured to concentrate beams generated by the antenna units;
a grounding plate positioned at the second surface and configured to ground the array antenna; and
a high-impedance surface (HIS) layer embedded into the substrate, the HIS layer being configured to suppress surface waves generated by the lens arrays and the substrate to increase a gain of the antenna structure;
wherein the HIS layer comprises a plurality of circular holes, each circular hole has a same radius, each antenna unit has a same radius, the radius of each circular hole being greater than the radius of each antenna unit; and
wherein each of the antenna units has a substantially circular shape and a same size.
11. The wireless communication device of claim 10 , wherein the main body is made of materials which have a dielectric constant of 3 to 4.
12. The wireless communication device of claim 10 , wherein each of the plurality of antenna units comprises a first feeding portion and a second feeding portion configured to feed current to each a corresponding one of the antenna units thereby activating each of the antenna units to generate electromagnetic waves of a horizontal polarization and a vertical polarization.
13. The wireless communication device of claim 10 , wherein each of the lens units has a substantially circular shape and a same size, each of the lens units is concentric with the corresponding one of the antenna units and covers the corresponding antenna unit.
14. The wireless communication device of claim 10 , wherein each of the lens units is a cavity formed on a curved surface of the main body thereby forming a lens function.
15. The wireless communication device of claim 10 , wherein the HIS layer is a periodic square structure, the HIS layer comprises a plurality of spaced square cells, a length of each side of each of the square cells is approximately 0.25×λ 1 to 0.5×λ 1 , wherein λ 1 is a wavelength of electromagnetic waves to be transmitted or have been received by the antenna structure transmitted in the substrate.
16. The wireless communication device of claim 10 , wherein the plurality of circular holes correspond to the plurality of antenna units, each of the plurality of circular holes is concentric with the corresponding antenna unit.
17. The wireless communication device of claim 16 , wherein a distance between center points of adjacent antenna units is approximately 0.45×λ to 0.6×λ, a diameter of each of the lens units is approximately 0.45×λ to 0.6×λ, wherein λ is a wavelength of electromagnetic waves which can be transmitted or received by the antenna structure.
18. The wireless communication device of claim 10 , wherein the antenna structure further comprises a metal mesh, the metal mesh comprises a plurality of metal strips, each of the metal strips is positioned between adjacent rows of the antenna units or adjacent columns of the antenna units and is coplanar with the antenna units, the metal strips are configured to reduce interference between the antenna units.