| 摘要 |
A transmit and receive loop antenna (10) includes a first loop element (12) coupled to an electrical circuit element for generating near fields and far fields and a shunt loop element (16) surrounding the first loop element (12) such that voltages are induced in the shunt loop element (16) by the fields generated by the first loop element (12). The shunt loop element (16) is constructed from a continuous loop of conductor to maximize current from the voltages induced in the shunt loop element. The current in the shunt loop element generates fields which largely cancel the fields generated by the first loop element in the far field. Thus, the first loop element (12) and the shunt loop element (16) establish a surveillance zone in an area proximate the loop elements.
|
