A Compact Omnidirectional Antenna for WLAN/WiMAX/5G Mobile Communication Applications

This paper introduces a compact, multi-band omnidirectional antenna suitable for using in WLAN, WiMAX, and
$\boldsymbol{5}\mathbf{G}$
mobile communication systems. The dielectric substrate of the antenna is made of FR-4, and it is composed of a microstrip feed line, a radiating patch, and a ground plane. The miniaturization and multi-band characteristics of the antenna are achieved through the implementation of various techniques, including using etched electrical resonator (EER), incorporating the J-shaped branch, and utilizing the split ring resonator (SRR) structure. The matching of antenna impedance is achieved by implementing rectangular slots on the floor. The test result indicates that the antenna proposed in this paper exhibits a reflection coefficient
$\vert \mathbf{S}\boldsymbol{11}\vert \leq -\boldsymbol{10}\mathbf{dB}$
within the frequency range of
$\boldsymbol{1.68} \sim \boldsymbol{1.96} \mathbf{GHz}, \boldsymbol{2.32}\sim \boldsymbol{2.76}\ \mathbf{GHz}, \boldsymbol{3.37}\sim \boldsymbol{4.30}\ \mathbf{GHz}, \boldsymbol{47.73}\sim \boldsymbol{4.98}\ \mathbf{GHz}$
and
$\boldsymbol{5.67}\sim \boldsymbol{5.90}\ \mathbf{GHz}$
, which means this antenna can be utilized in various scenarios, such as WLAN, WiMAX, and wireless mobile communication terminals.