An Improved Omni-Directional Microstrip Patch Antenna Array for WLAN Application

An improved omni-directional microstrip patch antenna array is prsented for 2.4-GHz wireless local area network (WLAN). The considerable radiation performance is guaranteed by two microstrip patch elements fed in series. Compared with conventional designs, a transition section is introduced at the bottom of the patch elements to achieve better impedance matching. Therefore, our proposed antenna array achieves good omni-directional radiation while enhancing the impedance matching. The proposed antenna array achieves a bandwidth of 17.7% (2.21-2.64 GHz) for $\mathbf{VSWR}\leq 2$. The radiation patterns in the azimuthal plane with a gain variation less than 1.0 dB and a gain more than 3.8 dBi are obtained within the WLAN band (2.4-2.483 GHz).