Patent ID: 8933790
Filing Date: 2015-01-13
Classification: G08B,H01Q

Abstract:
1. An electronic article surveillance system comprising: a plurality of antenna structures, each antenna structure including three or more loops and wherein each antenna structure is connected to a single transmission driver, for generating respective electromagnetic fields from each antenna structure, and wherein said single transmission driver is arranged to drive said loops of said antenna structure in such a way that the vector sum of said electromagnetic fields of said antenna structures is null in a far field and wherein no vector is separated by another vector by 180° of phase; a plurality of electronics boards and wherein each electronics board has two independent transmission drivers thereon, and wherein one of said transmission drivers drives a first antenna structure and wherein the other one of said transmission drivers drives a second antenna structure; and wherein each of said antenna structures is coupled to said single transmission driver via a phase coupler, said phase coupler converting a transmission driver signal into two distinct phase driver signals for driving a first set of loops and a second set of loops for an antenna structure.