Modified Circular Common Element 4 Port MIMO Antenna Using Diagonal Parasitic Element

A 4-port multiple input multiple-output (MIMO) antenna with common radiating element is proposed for 2.4 GHz Wi-Fi applications. It comprises a modified circular radiator fed by four identical modified feedlines, partial ground planes and a diagonal parasitic element (DPE). The parasitic element is used to enhance the inter-port isolation. The antenna has a 2:1 VSWR impedance band 2.34-2.56 GHz and nearly omnidirectional radiation patterns. The radiation efficiency is more than 79 % and gain is 2 dBi at resonant 2.43 GHz. The isolation in the given frequency band is 10 dB. At the 2.43 GHz, the isolation between adjacent ports (1, 2 and 1, 4) is 14 dB and between opposite ports (1, 3) is 12 dB. The mean effective gain (MEG) ≤-2.7 dB and envelope correlation coefficient (ECC) is < 0.01. The diversity gain is about 10 dB between adjacent ports and the -10 dB total active reflection coefficient (TARC) bandwidth is 202 MHz. To check the effectiveness of Wi-Fi antenna near the human body or head the specific absorption rate (SAR) is observed < 1.6 W/Kg by CST simulation tool.

一种针对2.4 GHz Wi-Fi应用的四端口多输入多输出（MIMO）共辐射单元天线被提出。该天线由四个相同的改进馈线、部分接地平面以及一个对角寄生单元（DPE）供能的改进圆形辐射器组成。该寄生单元被用于增强端口间的隔离。该天线具有2:1的VSWR阻抗带宽，频率范围为2.34-2.56 GHz，并呈现近似全向的辐射模式。辐射效率超过79%，在谐振频率2.43 GHz处增益为2 dBi。在指定频率范围内，隔离度为10 dB。在2.43 GHz频率下，相邻端口（1, 2和1, 4）之间的隔离度为14 dB，相对端口（1, 3）之间的隔离度为12 dB。平均有效增益（MEG）≤-2.7 dB，包络相关系数（ECC）小于0.01。相邻端口之间的多样性增益约为10 dB，-10 dB总有效反射系数（TARC）带宽为202 MHz。为了验证人体或头部附近Wi-Fi天线的有效性，通过CST仿真工具观察到特定吸收率（SAR）< 1.6 W/Kg。