Broadband collocated antennas with three orthogonal polarizations

In this work, new designs of three collocated antennas, with orthogonal polarizations, are presented. These types of antennas can find applications in Multiple Inputs Multiple Outputs (MIMO) systems or in base stations antenna arrays. A cross-dipoles and a folded monopole are designed and optimized. Two configurations are analyzed at 2.45GHz and 5.5GHz with broadband and high isolation performance characteristics. The monopole is tested with two or four arms, and the dipole height is either a quarter-wavelength or half-wavelength for broadside or conical radiations. Numerical and experimental results are presented to validate the proposed concept.