A C-band retrodirective array is presented.A single antenna is designed for both receiving and retransmitting where the isolation is provided by the hybrid coupler.The heterodyne technique is used for the phase-conj ugation process which is achieved by a passive field effect transistor(FET) mixer with a shared input/output port.The proposed array has the characteristics of low cost,compact size,high isolation and long working distance. A four-element prototype is demonstrated with an interrogating frequency of 5.81 GHz and a local oscillator frequency of 11.6 GHz.Measured results verify that the system has good retrodirectivity over an incident range of ±33°which is suitable for radio frequency identification (RFID) application.%通过射频混频技术实现单元相位共轭的方式，设计了一个C波段方向回溯阵列，采用收发共用天线单元减小阵列体积.混频模块基于输入/输出共用端口的场效应晶体管混频器完成相位共轭，引入定向耦合器用于提高收发端口的隔离度并抑制射频泄露信号，该阵列具有成本低、体积小、隔离度高、作用距离远等优点.制作了四元方向回溯阵列，在发射信号频率为5.81 GHz、本振信号频率为11.6 GHz时，进行了测试，结果表明，该阵列在±33°入射角度范围内具有良好的方向回溯功能，可应用于射频识别系统中.
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