非均匀覆盖层谐振腔天线设计

Non-uniform superstrate resonant cavity antenna design

提出了一种非均匀覆盖层谐振腔天线设计方法.通过构造反射系数幅值随天线口径面位置变化的函数来实现谐振腔天线覆盖层的非均匀化.使用金属化过孔作为周期结构覆盖层的谐振单元,分别设计出满足反射系数变化的变谐振单元长度和变过孔直径的两种非均匀覆盖层谐振腔天线.它们的阻抗特性、方向图和增益,同具有等反射系数变化规律的非均匀介质覆盖层谐振腔天线一致.结果表明,覆盖层的反射系数变化规律是非均匀覆盖层谐振腔天线的决定因数.设计出的两种非均匀覆盖层谐振腔天线实测|S_(11)|< -10dB阻抗带宽均大于8%,增益均大于18dBi,同时在阻抗带宽内增益相比峰值增益下降均小于1.5dB.

A novel non-uniform superstrate resonant cavity antenna （RCA） design method was proposed. The non-uniform superstrate was constructed by changing the reflection coefficient at different location of the aper- ture. The values of the reflection coefficients were determined by a given function. Metallic via was chosen as the unit of superstrate, whose reflection coefficient can be determined by changing via diameters or by changing unit length between vias. According these two ways, two kinds of non-uniform superstrate RCAs were de- signed, both followed the same reflection coefficient function. The performances of two kinds of antennas were very similar, and both satisfy the results forecasted by the reflection coefficient function. The results indicated that reflection coefficient characteristic was the important impact factor for non-uniform superstrate RCA. Two prototype antennas were fabricated and measured. The measured ｜S11｜〈-10 dB impedance bandwidth and gain of the two antennas were both greater than 8% and 18 dBi, respectively. The gain only dropped within 1.5 dB from the peak gain in the impedance bandwidth.