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...http://www.google.com.tw/patents/US6236315?utm_source=gb-gplus-share專利 US6236315 - Method and apparatus for improving the interrogation range of an RF tag
