Design of decoupling network for monopole four square array antenna for multi-beam applications

Multi-beam antennas can be used for sectorization of 360° azimuthal coverage or diversity and MIMO concepts. One of the suitable realizations, where four monopoles antennas are placed at the corner of a square, is known as monopole four square array antenna to scan the beam in azimuth. In this paper a decoupling and matching network is presented to compensate for mutual coupling between array elements. The decoupling network design is based on the eigenmodes of the array admittance matrix and it is realized using microstrip lines.