Many passive and wireless devices, such as RFID tags or batteryless wireless sensors, are designed to control electromagnetic field backscattered by the devices, in order to maximize the interrogation range (or the device-to-reader separation distance) and/or to mitigate the electromagnetic clutter. In this letter, we show that a linearly polarized (LP) electromagnetic field can be converted into a circularly polarized field by using a passive and chipless device. The device, also called tag, consists of a one-port antenna loaded by a passive impedance, whose value is derived from a rigorous electromagnetic model including structural and antenna scattering modes. The experimental validation of predicted linear-to-circular polarization conversion is reported in the case of a patch antenna illuminated by a LP field. At the operating frequency of 2.6 GHz, the measured axial ratio of the electric field backscattered by the tag is lower than 1 dB.

中文翻译：

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通过无源阻抗进行天线负载以实现线圆极化转换


许多无源和无线设备，例如 RFID 标签或无电池无线传感器，旨在控制设备反向散射的电磁场，以最大化询问范围（或设备到读取器的间隔距离）和/或减轻电磁杂波。在这封信中，我们展示了可以通过使用无源无芯片器件将线偏振（LP）电磁场转换为圆偏振场。该设备也称为标签，由一个加载无源阻抗的单端口天线组成，其值源自包括结构和天线散射模式的严格电磁模型。在 LP 场照射贴片天线的情况下，报告了预测的线偏振到圆偏振转换的实验验证。在2.6GHz工作频率下，测得标签反向散射电场轴比低于1dB。