A Low-Cost and Wideband Dual-Polarized Filtering Stacked Patch Antenna Without Extra Circuit

In this paper, a low-cost wideband dual-polarized filtering stacked antenna for 5G applications is proposed. Without additional filters, the filtering characteristic is achieved by improving the feedlines. Based on the stacked patch antenna, two new radiation nulls are generated respectively in the upper and lower sidebands by introducing a quarter-wavelength short-circuited stub at the end of the microstrip feedline and a half-wavelength open-circuited U-shaped stub located directly under the H-shaped aperture. The measured results show that the proposed antenna has an excellent performance. The impedance bandwidth ($\left|\mathrm{S}_{11}\right|\lt -15 \mathrm{~dB}$ and $\left|\mathrm{S}_{22}\right|\lt -15 \mathrm{~dB}$) is up to 21.4% (3-3.72 $\mathbf{G H z}$) and the measured port isolation is lower than $\mathbf{- 3 0} \mathbf{~ d B}$ over the operating band. A maximum gain of 8.8 dBi is achieved with a fluctuation of only 1.2 dB within the band and the suppression level is greater than 19 dB within the range from 1 GHz to 6 GHz.