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准八木天线具有较好的方向性,但其带宽还不能满足实际应用需要。为解决双频带准八木天线带宽较低的问题,提出了一种新型双频准八木天线,其具有相对带宽较大的两个工作频带,并可以应用于定向WLAN/Wimax通信系统。该天线采用喇叭形巴伦来增加带宽,采用多支节结构的两对辐射偶极子来激发两个不同的频率。低频辐射偶极子采用阶梯阻抗来减小物理尺寸,通过合理配置两对辐射偶极子和反射器可以获得良好的辐射特性。使用Ansoft HFSS对天线进行优化,并制作了实物。实验测量结果显示该天线S11<-10 d B的频段为2.36~2.8 GHz和3.3~3.8 GHz,前后比均在10 d B以上,带内增益分别在6 d B和8 d B以上。
The quasi-Yagi antenna has a good directivity, but its bandwidth can not meet the actual application needs. In order to solve the problem of low bandwidth of dual-band quasi-Yagi antenna, a new dual-band quasi-Yagi antenna is proposed, which has two working bands with relatively large bandwidth and can be used in directional WLAN / Wimax communication system. The antenna uses a trumpet-shaped balun to increase bandwidth and uses two pairs of radiation dipoles with multiple branches to excite two different frequencies. The low-frequency radiation dipole adopts the ladder impedance to reduce the physical size, and good radiation characteristics can be obtained by reasonably arranging two pairs of radiation dipoles and reflectors. Using Ansoft HFSS to optimize the antenna, and made in kind. The experimental results show that the frequency band of S11 <-10 d B is 2.36-2.8 GHz and 3.3-3.8 GHz, both anterior-posterior ratio is above 10 d B and the in-band gain is above 6 d B and 8 d B respectively.