Non-Intrusive Control of Surface Impedance Using Parasitic Inclusions for Base Station Antennas

The paper presents a method to locally control the surface impedance around a typical antenna, and therefore, improve the antenna cross-polarization isolation. While manipulating the antenna input parameters, this approach tends to impose minimal intrusion to the antenna far-field pattern, favorably decoupling the challenges of controlling near and far fields parameters. The enabling elements to achieve such a control are miniaturized parasitic inclusions, which are deployed around the main antenna elements. The inclusions function as effective polarization isolators in one frequency band, while being invisible at relatively higher frequencies. Even though the method is fundamental in nature, the presentation will highlight its application to Base Station Antenna Arrays.