Patent ID: 7075440

Claim:
An electronic article surveillance system, comprising: a) a marker that exhibits magnetomechanical resonance at a resonant frequency in response to the incidence thereon of an alternating electromagnetic interrogating field and radiates a marker dipole field in response to incidence of said interrogating field, said marker comprising: i) at least one magnetomechanical element comprising a plurality of elongated strips composed of magnetostrictive amorphous metal alloy and providing said mechanical resonance, said strips having centers that are substantially coincident; ii) a bias means for magnetically biasing and thereby arming said magnetomechanical element to resonate; and iii) a housing enclosing said magnetomechanical element and said bias means, wherein said magnetomechanical element is free to mechanically vibrate in said housing at said resonant frequency, said resonant frequency being substantially equal to said preselected interrogating frequency and ranging from about 70 to 300 kHz, whereby said marker is provided with a signal-identifying characteristic of a ring-down of said dipole field; b) an interrogating means for generating said electromagnetic interrogating field having a preselected interrogating frequency; c) a detecting means for detecting said signal-identifying characteristic; and d) an indication means activated by said detecting means in response to the detection of said signal-identifying characteristic.