| 主权项 |
1. A near field antenna utilized for an object detecting device, for sensing a plurality of units under test of at least an object under test, the object under test having a plurality of surfaces, each surface of the object under test disposed with at least one unit under test, the near field antenna comprising:
a periodic guided-wave structure, disposed below the object under test, having a plurality of conductive units periodically arranged on a first plane; a metallic reflection portion, disposed under the periodic guided-wave structure, the metallic reflection portion and the periodic guided-wave structure forming an enclosed space; and two near field magnetic coupling antennas, disposed on a second plane parallel to the periodic guided-wave structure, located in the enclosed space formed by the metallic reflection portion and the periodic guided-wave structure, the two near field magnetic coupling antennas respectively located in two sides of a symmetrical center on the second plane, the distances from each of the near field magnetic coupling antennas to the symmetrical center being the same, each near field magnetic coupling antenna comprising:
a plurality of annularly arranged radiators, with a first gap formed between any two adjacent radiators; andan annular conductive portion, having a plurality of annular conductive segments, each annular conductive segment partially overlapping two adjacent radiators, with a second gap formed between the two adjacent annular conductive segments and the annular conductive portion surrounding the radiators;wherein the two adjacent radiators are associated with a feed point and a ground point, and the feed point and the ground point are defined in the neighborhood of the first gap between the two adjacent radiators; wherein the feed point and the ground point of one of the two near field magnetic coupling antennas are fed by a first coaxial cable with a first feeding direction, the feed point and the ground point of another one of the two near field magnetic coupling antennas are fed by a second coaxial cable with a second feeding direction, the first feeding direction and the second feeding direction are parallel to the periodically arranged conductive units, and the first feeding direction and the second feeding direction are opposite directions; wherein an angle formed by a line segment connecting the two near field magnetic coupling antennas and the periodically arranged conductive units is between 30 degrees and 50 degrees. |
