Wideband Design of Dual-Polarized Planar Dipole for Base Station Antenna Application

A novel dual-polarized planar crossed-dipole antenna for frequency band 1.4-2.7 GHz is suggested for mobile communication base stations. The proposed antenna is based on modified planar crossed dipoles with the arm profile approximated with Bezier curves of third order. The extension of operational frequency band up to about an octave is achieved due to the fine adjustment of mutual electromagnetic coupling between the crossed dipoles arms by means of the multi-parametric optimization of the arm profile. The parameters of Bezier curve are the variables by the numerical optimization. Each crossed dipole is excited by microsrtip line stub which is fed by the standard 50-Ohm coaxial line. The linear S-element planar crossed dipoles antenna array for the base stations was designed. The antenna array characteristics correspond to the requirements for the base station antennas. The isolation between two orthogonal polarizations is better than 25 dB, the reflection coefficient is less than –14dB, the beamwidth in horizontal plane for the level –10 dB is stable and it is equal to 12$0^{\circ}+18^{\circ}/-7^{\circ}$, the cross polarization in all directions is –17.5 dB.