Near-field antenna for wireless power transmission with four coplanar antenna elements that each follows a respective meandering pattern
A near-field antenna is provided, which includes: a reflector and four distinct antenna elements, offset from the reflector, each of the four distinct antenna elements following respective meandering patterns. Two antenna elements of the four antenna elements form a first dipole antenna along a first axis, and another two antenna elements of the four antenna elements form a second dipole antenna along a second axis perpendicular to the first axis. The near-field antenna further includes: (i) a power amplifier configured to feed electromagnetic signals to one of the dipole antennas, (ii) an impedance-adjusting component configured to adjust an impedance of one of the dipole antennas, and (iii) switch circuitry coupled to the power amplifier, the impedance-adjusting component, and the dipole antennas. The switch circuitry is configured to switchably couple the first dipole antenna to the power amplifier and the second dipole antenna to the impedance-adjusting component, and vice versa.
1. A near-field antenna comprising:
a reflector;
four distinct coplanar antenna elements, offset from the reflector, each of the four distinct antenna elements following respective meandering patterns, wherein:
two antenna elements of the four coplanar antenna elements form a first dipole antenna along a first axis; and
another two antenna elements of the four coplanar antenna elements form a second dipole antenna along a second axis perpendicular to the first axis;
a power amplifier configured to feed electromagnetic signals to at least one of the first and second dipole antennas;
an impedance-adjusting component configured to adjust an impedance of at least one of the first and second dipole antennas; and
switch circuitry coupled to the power amplifier, the impedance-adjusting component, and the first and second dipole antennas, the switch circuitry being configured to:
(i) switchably couple the first dipole antenna to the power amplifier and the second dipole antenna to the impedance-adjusting component, or
(ii) switchably couple the second dipole antenna to the power amplifier and the first dipole antenna to the impedance-adjusting component.
2. The near-field antenna of claim 1 , wherein:
in a first mode of operation for the near-field antenna, the switch circuitry couples (i) the first dipole antenna to the power amplifier and (ii) the second dipole antenna to the impedance-adjusting component; and
in a second mode of operation for the near-field antenna, the switch circuitry couples (i) the second dipole antenna to the power amplifier and (ii) the first dipole antenna to the impedance-adjusting component.
3. The near-field antenna of claim 2 , wherein:
in the first mode of operation for the near-field antenna, the first dipole antenna is to receive electromagnetic waves from the power amplifier and radiate the received electromagnetic waves having a first polarization; and
in the second mode of operation for the near-field antenna, the second dipole antenna is to receive electromagnetic waves from the power amplifier and radiate the received electromagnetic waves having a second polarization different from the first polarization.
4. The near-field antenna of claim 3 , wherein a wireless-power-receiving device, located within a threshold distance from the near-field antenna, is configured to harvest the radiated electromagnetic waves and use the harvested electromagnetic waves to power or charge an electronic device coupled with the wireless-power-receiving device.
5. The near-field antenna of claim 1 , further comprising a controller configured to control operation of the switch circuitry and the power amplifier.
6. The near-field antenna of claim 5 , wherein the controller is configured to control operation of the switch circuitry and the power amplifier based on one or more of: (i) a location of a wireless-power-receiving device, (ii) a polarization of a power-receiving-antenna of the wireless-power-receiving device, and (iii) a spatial orientation of the wireless-power-receiving device.
7. The near-field antenna of claim 1 , further comprising:
a first feed connected to a first of the two antenna elements of the first dipole antenna and the switch circuitry, wherein the first feed is configured to supply electromagnetic signals to the first antenna element of the first dipole antenna that originate from the power amplifier when the power amplifier is switchably coupled to the first dipole antenna by the switch circuitry; and
a second feed connected to a first of the other two antenna elements of the second dipole antenna and the switch circuitry, wherein the second feed is configured to supply electromagnetic signals to the first antenna element of the second dipole antenna that originate from the power amplifier when the power amplifier is switchably coupled to the second dipole antenna by the switch circuitry.
8. The near-field antenna of claim 1 , wherein:
a first antenna element of the four distinct coplanar antenna elements is a first pole of the first dipole antenna;
a second antenna element of the four distinct coplanar antenna elements is a second pole of the first dipole antenna;
a third antenna element of the four distinct coplanar antenna elements is a first pole of the second dipole antenna; and
a fourth antenna element of the four distinct coplanar antenna elements is a second pole of the second dipole antenna.
9. The near-field antenna of claim 1 , wherein:
the two antenna elements that form the first dipole antenna each include two segments that are perpendicular to the first axis; and
the other two antenna elements that form the second dipole antenna each include two segments that are parallel to the first axis.
10. The near-field antenna of claim 1 , wherein:
a first end portion of the respective meandering pattern followed by each of the four distinct antenna elements borders a same central portion of the near-field antenna;
a second end portion of the respective meandering pattern followed by each of the four distinct antenna elements borders a distinct edge of the near-field antenna; and
a longest dimension of the respective meandering pattern followed by each of the four distinct antenna elements is closer to the distinct edge of the near-field antenna than to the same central portion of the near-field antenna.
11. The near-field antenna of claim 10 , wherein a shortest dimension of the respective meandering pattern followed by each of the four distinct antenna elements is closer to the same central portion of the near-field antenna than the distinct edge of the near-field antenna.
12. The near-field antenna of claim 1 , wherein the reflector is a solid metal sheet of copper or a copper alloy.
13. The near-field antenna of claim 1 , wherein the reflector is configured to reflect at least a portion of the electromagnetic signals radiated by the first or second dipole antennas.
14. The near-field antenna of claim 1 , wherein the four distinct coplanar antenna elements are formed on or within a substrate.
15. The near-field antenna of claim 14 , wherein the substrate comprises a metamaterial of a predetermined magnetic permeability or electrical permittivity.
16. The near-field antenna of claim 1 , wherein the respective meandering patterns are all the same.
17. The near-field antenna of claim 16 , wherein the two antenna elements that form the first dipole antenna are aligned along the first axis such that the respective meandering patterns followed by each of the two antenna elements are mirror images of one another.
18. The near-field antenna of claim 17 , wherein the other two antenna elements that form the second dipole antenna are aligned along the second axis such that the respective meandering patterns followed by each of the other two antenna elements are mirror images of one another.
19. A method of wirelessly charging a receiver device, the method comprising:
providing a near-field antenna that comprises:
a reflector;
four distinct coplanar antenna elements, offset from the reflector, each of the four distinct antenna elements following respective meandering patterns, wherein: (i) two antenna elements of the four coplanar antenna elements form a first dipole antenna aligned with a first axis; and (ii) another two antenna elements of the four coplanar antenna elements form a second dipole antenna aligned with a second axis perpendicular to the first axis;
switch circuitry coupled to at least two of the four coplanar antenna elements;
a power amplifier coupled to the switch circuitry; and
an impedance-adjusting component coupled to the switch circuitry;
instructing the switch circuitry to couple: (i) the first dipole antenna to the power amplifier, and (ii) the second dipole antenna to the impedance-adjusting component;
instructing the power amplifier to feed electromagnetic signals to the first dipole antenna via the switch circuitry, wherein:
the electromagnetic signals, when fed to the first dipole antenna, cause the first dipole antenna to radiate electromagnetic signals to be received by a wireless-power-receiving device located within a threshold distance from the near-field antenna, and
an impedance of the second dipole antenna is adjusted by the impedance-adjusting component so that the impedance of the second dipole antenna differs from an impedance of the first dipole antenna.
20. A non-transitory computer-readable storage medium storing executable instructions that, when executed by one or more processors of a near-field antenna with a reflector, four distinct coplanar antenna elements, switch circuitry coupled to at least two of the four coplanar antenna elements, a power amplifier coupled to the switch circuitry, and an impedance-adjusting component coupled to the switch circuitry, cause the near-field antenna to:
instruct the switch circuitry to couple: (i) the first dipole antenna to the power amplifier, and (ii) the second dipole antenna to the impedance-adjusting component;
instruct the power amplifier to feed electromagnetic signals to the first dipole antenna via the switch circuitry, wherein:
the electromagnetic signals, when fed to the first dipole antenna, cause the first dipole antenna to radiate electromagnetic signals to be received by a wireless-power-receiving device located within a threshold distance from the near-field antenna, and
an impedance of the second dipole antenna is adjusted by the impedance-adjusting component so that the impedance of the second dipole antenna differs from an impedance of the first dipole antenna.