Efficient radiating omnidirectional loops for collocated polarization diversity MIMO dipoles

Design and implementation of efficient radiating omnidirectional loops have been studied. A modified shielded loop with four feeding sections has been proposed. Measured results show that good impedance matching, omnidirectional radiation pattern, and good radiation efficiency have been achieved. A combination of the proposed loop and a half-wavelength E-dipole in a collocated position has also been examined. Extremely low correlation achieved indicates that this antenna can be used as a reference for evaluating the MIMO performance of future collocated polarization diversity based antennas, and a measurement antenna for measuring the polarization at the mobile as well.