Low-Profile and Wideband Microstrip Antenna With Stable Gain for 5G Wireless Applications

A low-profile microstrip antenna with stable radiation pattern in a relatively wide band is presented for 5G operation. Four resonant modes with different frequencies are integrated in a single structure to enhance the bandwidth with stable gain, and well matched by introducing the folded walls. An impedance bandwidth of 58.3% has been achieved from 2.84 to 5.17 GHz with a compact structure of ${\text{0.84}}\lambda _{0}\,\times \,{\text{0.68}}\lambda _{0}\,\times \,{\text{0.06}}\lambda _{0}$ , where $\lambda _{0}$ is the free-space wavelength at the center frequency of 4 GHz. The measurement results show that the proposed antenna is with the merits of average gain of 5 dBi, stable radiation patterns, low cross polarization, and low backlobes, exhibiting potentially use for the applications of 5G wireless communication systems.