| 摘要 |
A multi-field antenna able to receive a signal over one field selected from a plurality of different fields of the antenna includes an interface to connect the antenna to a signal processing device, such as an RFID reader, to receive and process the signal. The antenna includes a first magnetic loop configured to be tuned by a first tuner to provide a first volume field for reading data; a second magnetic loop configured to be tuned by a second tuner to provide a second volume field for reading data, the second volume field being smaller than the first volume field; and a switch to configure the first tuner and the second tuner to select the one field from the plurality of fields. The multi-field antenna can have a wide volume field selected to detect items within a large area and then the multi-field antenna can be switched to select a smaller volume field to detect items within a substantially smaller area. In a preferred embodiment, the multi-field antenna further includes ; a first metallic element configured to cover at least a portion of the second magnetic loop, the first metallic element comprising a slot extending from one end of the first metallic element to a point proximal an opposite end of the first metallic element. Also preferably, the multi-field antenna can also create a point volume field, smaller than the second volume field, to localize detected objects within a still smaller area.
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