新型双频水平全向近场谐振寄生天线设计

Design of a new dual frequency horizontal omnidirectional near-field resonant parasitic antenna

针对电小天线的工程应用,设计了一种双频、水平全向辐射、水平极化和高辐射效率的近场谐振寄生(near-field resonant parasitic,NFRP)天线。该天线设计基于惠更斯源(Huygens source)原理,由3只NFRP单元组成,每只单元由一对埃及斧偶极振子(包括1只折合偶极振子和1只弯折偶极振子)和一对耦合馈电金属片构成。3只NFRP单元环绕天线轴心组成环形三元阵,其远场辐射场叠加组合为水平全向辐射方向图。通过恰当设计,位于天线外/内环的折合/弯折偶极振子有不同的电流分布模式,分别谐振于2.45 GHz和5.8 GHz,由此该天线实现了双频特性。设计和加工制作了天线样品并进行了测试。测试表明,作为电小尺寸的平面天线,天线直径仅为0.249λ(λ为工作波长),厚度0.009λ;其|S11|<-10 dB的工作频带为2.40 GHz^2.49 GHz和5.77 GHz^6.10 GHz;在两个工作频段的中心频点,天线增益分别为2.20 dBi和2.12 dBi、辐射效率达到82.4%和85.9%、水平全向方向图不圆度分别为±1.0 dB和±1.5 dB。

Aiming at the engineering application of electric small antennas,a near-field resonant parasitic(NFRP)antenna with dual-frequency,horizontal omnidirectional radiation,horizontal polarization and high radiation efficiency is designed.The antenna is based on Huygens source principle and consists of three NFRP elements,each consisting of a pair of Egyptian axe dipole(including a folded dipole and a bending dipole)and a pair of coupled feed metal plates.Three NFRP elements surround the axis of the antenna to form an annular three-element array,whose far-field radiation field is superimposed and combined into a horizontal omnidirectional radiation pattern.By the proper design,the folded/bending dipoles located outside/inside the antenna have different current distribution modes,which resonate at 2.45 GHz and 5.8 GHz,respectively,and thereby,a dual-frequency characteristic is realized.An antenna prototype is designed,fabricated and tested.The test results show,the antenna is with a diameter of only 0.249λ,whereλis the working wavelength of the antenna,a thickness of 0.009λ,and dual working frequency bands for|S11|<-10 dB of 2.40 GHz^2.49 GHz and 5.77 GHz^6.10 GHz.At the two central frequencies in its dual working bands,the antenna has the gain of 2.20 dBi and 2.12 dBi,and the radiation efficiency of 82.4%and 85.9%respectively.The antenna has good horizontal omnidirectional radiation characteristics,and the non-roundness of its horizontal omnidirectional pattern is±1.0 dB and±1.5 dB respectively in its dual working bands.