宽带圆极化整流天线的研究与设计

针对空间微弱射频能量收集，提出了一种宽带圆极化整流天线，其主要由射频能量接收天线和多频整流电路构成.为了获得宽频带特性，接收天线的辐射贴片采用对数周期交叉偶极子.同时，两对交叉偶极子均由环形的90°相位延迟线连接，且相互正交，从而实现天线的圆极化特性.多频整流电路由两个单阶电压倍压整流电路并联而成，为了提高整流电路的性能和效率，引入了具有两个枝节的新型阻抗匹配电路.仿真结果表明:接收天线的阻抗带宽和3 dB轴比带宽分别为1 100 MHz和350 MHz；多频整流电路的功率灵敏度达到-35 dBm，最大RF-DC整体转换效率可达76.5%.在辐射强度为6.02 μT，负载电阻为700 Ω时，测得整流天线负载端的输出电压约为139 mV，因此该整流天线适用于低功率射频能量收集应用.

Research and design of broadband circularly polarized rectenna

A broadband circularly polarized rectifying antenna (rectenna) for the micro-radio energy harvesting in space,which consists of a radio frequency (RF) energy receiving antenna and a multi-band rectifying circuit is proposed in this paper.The log periodic cross dipole is used to obtain wideband characteristics on the radiation patch of the receiving antenna.At the same time,two pairs of orthogonal crossed dipoles are connected by a curved 90 degree phase delay line,which is aim to achieve the circular polarization characteristics of the antenna.The multi-band rectifying circuit is composed of two single-stage voltage doubler rectifying circuit.A new impedance matching circuit with two branches is introduced to improve the performance and efficiency of the rectifying circuit in parallel.The simulation results show that the impedance bandwidth and the 3 dB axial ratio bandwidth of the receiving antenna are 1100 MHz and 350 MHz respectively.The power sensitivity of multi-band rectifying circuit reaches-35 dBm,and the maximum RF-DC conversion efficiency is up to 76.5％.The measured output voltage of the rectenna is about 139 mV when the radiation intensity is 6.02 μT and the value of load resistor is 700 Ω,so it is suitable for low power RF energy harvesting applications.