Antenna with improved illumination efficiency
First Claim
1. An antenna comprising:
- a first loop having at least one first conductor, the first loop having a first enclosed area defined by the area inside the perimeter of the first loop and having a first phase center point defined by the geometric center point of the first enclosed area;
a second loop having at least one second conductor, the at least one second conductor connected to the at least one first conductor, the second loop disposed a distance from and substantially parallel to the first loop, the second loop having a second enclosed area substantially equal in size to the first enclosed area and having a second phase center point, wherein a line normal to the plane of the first loop passes through the first and second phase center points, and a current supplied to the first and second loops is of equal magnitude and opposite polarity in the respective first and second loops;
a feed element coupled to one of the first and second loops to supply the current; and
a series element coupled between the first and second loops to reverse polarity of the current between the first and second loops.
1 Assignment
0 Petitions
Accused Products
Abstract
An antenna is provided including a first loop having at least one first conductor and a second loop having at least one second conductor, the second conductor connected to the first conductor. The first loop has a first enclosed area defined by the area inside the perimeter of the first loop and a first phase center point defined by the geometric center point of the first enclosed area. The second loop is coupled to the first loop and is disposed a distance from and substantially parallel to the first loop. The second loop has a second enclosed area substantially equal to the first enclosed area and a second phase center point. A line normal to the plane of the first loop passes through the first and second phase center points. The first and second loops are disposed to substantially reduce the far-field illumination, while substantially maintaining the near-field illumination at effective radio frequency identification system operational levels. The antenna may be used to energize devices through inductive coupling.
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Citations
15 Claims
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1. An antenna comprising:
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a first loop having at least one first conductor, the first loop having a first enclosed area defined by the area inside the perimeter of the first loop and having a first phase center point defined by the geometric center point of the first enclosed area; a second loop having at least one second conductor, the at least one second conductor connected to the at least one first conductor, the second loop disposed a distance from and substantially parallel to the first loop, the second loop having a second enclosed area substantially equal in size to the first enclosed area and having a second phase center point, wherein a line normal to the plane of the first loop passes through the first and second phase center points, and a current supplied to the first and second loops is of equal magnitude and opposite polarity in the respective first and second loops; a feed element coupled to one of the first and second loops to supply the current; and a series element coupled between the first and second loops to reverse polarity of the current between the first and second loops. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An antenna comprising:
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a first loop having at least one first conductor, the first loop having a first enclosed area defined by the area inside the perimeter of the first loop and having a first phase center point defined by the geometric center point of the first enclosed area; a second loop having at least one second conductor, coupled to the first loop and disposed a distance from and substantially parallel to the first loop, the second loop having a second enclosed area substantially equal in size to the first enclosed area and having a second phase center point; an outer loop coupled to the first and second loops, the first and second loops having a total enclosed area equal to the sum of the first and second enclosed areas, and the outer loop substantially parallel to the first loop and having an outer enclosed area equal to the total enclosed area and an outer phase center point, wherein a line normal to the plane of the first loop passes through the first, second, and outer center points, and a current supplied to the antenna flows in a first polarity and has a first magnitude in the outer loop and flows in a second polarity and has a second magnitude in the first and second loops, the first and second polarities opposite to each other, and the first and second magnitudes equal to each other; and a coupler element to couple the outer loop to one of the first and second loops, wherein a feed supplies a current in a first polarity to the outer loop and the coupler element is configured to supply the current in a second polarity to the one of the first or second loop, the second polarity opposite to the first polarity. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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Specification