| 摘要 |
<p>This invention relates to dynamically controlled, electronic article surveillance (EAS) systems whereby an array of antenna elements is digitally phased and actively driven for concurrent transmission, and digitally phased and combined in the receiver unit to improve detection. In particular, the individual frequency and phase of the plurality of the transmit/receive signals are rapidly varied to allow for automated manipulation (steering) of the transmit field pattern and receive field sensitivity. The invention achieves the following features via means of digital phasing and dynamic computer control: sufficient far-field cancellation, null-free detection and uncompromised detection performance regardless of tag's orientation while using single transmission drivers to drive entire antenna structures, whether loop antenna or ferrite core antenna, using a phase coupler, thereby allowing more efficient system operation or additional features such as deactivator antenna operation.</p> |
