A compact dual‐polarized cavity‐backed annular slot antenna for indoor mimo systems

A unidirectional, dual-polarized multi-input multi-output (MIMO) antenna is designed for indoor 2.4-GHz WLAN application. The proposed antenna consists of a cavity-backed annular slot and two inverted microstrip fed lines which are mutually orthogonal. To further suppress the cross polarization levels and enhance the ports isolation, two grounded strips, being opposite to the microstrip lines of the same size, are introduced above the annular slot. Meanwhile, a conductor pillar is loaded into the back cavity. The experimental results show that this antenna has the ports isolation of more than 28 dB and the cross-polarized levels of less 30 dB than the copolarization over the working band. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:384–388, 2015