In this paper, Characteristics mode analysis (CMA) is introduced to study the dual-polarization behavior of simple monopole antenna. The antenna consists of monopole feed with symmetric arms (SA), resonating at 2.45 GHz and right-handed stub (RHS) is connected to resonate at 5.8 GHz. The SA has linear polarization and RHS has circular polarization. CMA is introduced to explore dual-polarized properties and validated on modal metrics. The intuition of antenna design is further extended to 4-port MIMO antenna configuration. Due to rotationally symmetrical connected ground topology, another induced resonance at 1.54 GHz is observed. A L-shaped stub is further connected to one-end of the monopole arm of each antenna element, that function as 2.5 GHz resonator and an effective isolator. The overall antenna dimension is 0.3$\lambda$ $\times$ 0.3$\lambda$ $\times$ 0.018$\lambda$ (where $\lambda$ is the lowest operating wavelength) and the elements are spatially separated with edge-to-edge spacing of 0.018$\lambda$ with port isolations $>$15 dB. The MIMO antenna operates at 1.54 GHz, 2.5 GHz with linear polarization and at 5.63 GHz as circular polarization. The antenna gains with radiation efficiencies are 0.62 dBi ($>$60%), 4 dBi ($>$70%) and 4.25–6 dBc ($>$80%). The computed ECC_far−fields is $<$ 0.3, showing its potential for pattern and polarization diversity MIMO environments. A prototype antenna is fabricated and measured with good agreements and found compatible for L-band, lower WLAN and upper WLAN applications.

本文介绍了特征模态分析（CMA），以研究简单单极天线的双极化行为。天线由带有对称臂（SA）的单极馈电组成，在2.45 GHz处谐振，右手短截线（RHS）连接到5.8 GHz处谐振。SA具有线性极化，RHS具有圆极化。引入CMA是为了探索双极化特性，并已通过模态指标进行了验证。天线设计的直觉进一步扩展到4端口MIMO天线配置。由于旋转对称连接的地面拓扑，在1.54 GHz处观察到另一个感应共振。一个L形短截线还连接到每个天线元件的单极臂的一端，用作2.5 GHz谐振器和有效的隔离器。天线总尺寸为0.3$\lambda$ $\times$ 0.3$\lambda$ $\times$ 0.018$\lambda$ （在哪里 $\lambda$ 是最低的工作波长），并且元素在空间上隔开，边到边的间距为0.018$\lambda$ 具有端口隔离 $>$15分贝。MIMO天线在1.54 GHz，2.5 GHz线性极化和5.63 GHz圆极化下工作。具有辐射效率的天线增益为0.62 dBi（$>$60％），4 dBi（$>$70％）和4.25–6 dBc（$>$80％）。计算的ECC_远场为$<$0.3，显示其在模式和极化分集MIMO环境中的潜力。原型天线的制造和测量符合良好协议，并且与L波段，较低WLAN和较高WLAN应用兼容。