发明授权
US06236315B1 Method and apparatus for improving the interrogation range of an RF tag 有权
用于改善RF标签的询问范围的方法和装置

Method and apparatus for improving the interrogation range of an RF tag
摘要:
A method for increasing the interrogation range of an RF Tag in a radio communication system using RF Tags with two reflecting antenna elements. The second reflecting antenna element is predeterminately positioned, and preferably aligned, with respect to the first reflecting antenna element in the direction of expected incident RF radiation and is spaced from the first reflecting antenna element at a predetermined fixed distance. The first and second reflecting antenna elements are alternately pulsed on and off such that while the first reflecting antenna element is in a signal reflecting operating state, the second reflecting antenna element is in a substantially non-reflecting state and vice versa. The alternate pulsing and predetermined fixed spacing between the first and second elements generates a known phase difference between the reflected signals of the first and second reflecting antenna elements. The phase difference is preferably 180 degrees which may be achieved by spacing the second reflecting antenna element from the first reflecting antenna element at a distance equivalent to ¼ of the wavelength of the interrogating signals.
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