초록 ▼

An antenna system for an electronic article surveillance system, comprising: a first, tunable transmitting loop; a second, tunable transmitting loop, the first and second transmitting loops being arranged for first and second modes of operation, the transmitting loops being field-coupled to one anot

An antenna system for an electronic article surveillance system, comprising: a first, tunable transmitting loop; a second, tunable transmitting loop, the first and second transmitting loops being arranged for first and second modes of operation, the transmitting loops being field-coupled to one another such that tuning the antenna system for one of the modes of operation detunes the antenna system for the other mode of operation; a tunable compensation coil field-coupled to each of the first and second transmitting loops, the tunable compensation coil enabling the antenna system to be tuned for operation in one of the modes at a first resonant frequency, and despite the detuning, enabling the antenna system to be tuned for operation in the other of the modes at a second resonant frequency independently of the tuning for the first mode of operation. The first and second resonant frequencies can be the same as or different from one another. One of the first and second modes of operation is as an in-phase rectangular loop and the other of the first and second modes of operation is as a "figure-8". The compensation loop encircles the first and second transmitting loops.

대표청구항 ▼

[ What is claimed is:] [1.] An antenna system for an electronic article surveillance system, comprising:a first, tunable transmitting loop;a second, tunable transmitting loop, said first and second transmitting loops being arranged for first and second modes of operation, said transmitting loops bei

[ What is claimed is:] [1.] An antenna system for an electronic article surveillance system, comprising:a first, tunable transmitting loop;a second, tunable transmitting loop, said first and second transmitting loops being arranged for first and second modes of operation, said transmitting loops being field-coupled to one another such that tuning said antenna system for one of said modes of operation detunes said antenna system for the other mode of operation; and,a tunable compensation coil field-coupled to each of said first and second transmitting loops, said tunable compensation coil enabling said antenna system to be tuned for operation in one of said modes at a first resonant frequency, and despite said detuning, enabling said antenna system to be tuned for operation in the other of said modes at a second resonant frequency independently of said tuning for said first mode of operation.