轮胎嵌入式小型化UHF RFID 电子标签弯折天线设计

为提高轮胎嵌入式UHF RFID 电子标签读取可靠性,需要解决一对矛盾,即一方面,为保证电子标签与轮胎有良好的粘合性和绑定性,要求标签天线尺寸足够小;另一方面,轮胎无线电环境差,轮胎材料对电磁波的固有介质损耗和干扰要求电子标签天线尺寸应足够大,以提高电磁辐射能力。针对以往设计方法复杂、不利于标签与轮胎绑定的问题,根据Bode-Fano 阻抗匹配的约束,利用弯折天线的周期性和紧凑性,提出了一种简单、具有良好阻抗特性和绑定特性的轮胎嵌入式小型化UHF RFID 弯折天线方法,设计了一种物理空间受限的轮胎嵌入式小型化UHF RFID 弯折天线。HFSS 仿真验证表明,设计的天线在833 ~971MHz 频带范围内回波损耗小于-10dB,覆盖了美国RFID 标准带宽902 ~928MHz,最大辐射增益为2. 4dBi。最后,通过设计的轮胎嵌入式RFID 电子标签测试,结果表明:当读取距离小于90cm 时,标签识别率大都大于80%;当读取距离小于50cm 时,标签识别率大于90%,标签与轮胎具有良好的绑定效果,满足设计要求。

Design of a Miniaturized UHF RFID Tag Meander Line Embedded in Tire

To improve the reliability of RFID system embedded in tire, it needs to solve a couple of contradictions. In one hand, in order to ensure the tags and tires is good adhesion and binding, the size of antenna of tags should be small enough. In the other hand, the radio environment of tiers is not ideal. Because tire has intrinsic dielectric loss and disturbs electromagnetic wave, the size of antenna of tags should be large enough so as to improve the ability of electromagnetic radiation. The methods before of design for tag antenna are complex and are not suited to bind the tags and tires. According to the Bode-Fano impedance match limitations, using periodicity and compactedness of meander line, a design method with the miniaturized UHF RFID tag meander line embedded in tire is presented. The method is simple, has good impedance match properties and bind properties. Also, a miniaturized UHF RFID tag meander line antenna embedded in tire is designed,where the size of the tag antenna is limited. The result of HFSS simulation shows that the tag antenna's return loss is less than -10dB in 833 ~971MHz, which covers USA bandwidth 902 ~928MHz . The biggest gain is 2. 4dBi. Eventually, the result of experiment shows, the identification probability is almost larger than 80% when the read distance is less than 90cm,and it is larger than 90% when the read distance is less than 50cm. Besides, it has good bind properties between tags and tires. So it meets the requirements of design.