A novel broadband high-isolation cross dipole utilizing strong mutual coupling

A novel broadband cross dipole with high isolation and low cross polarization is presented in this paper. By skillfully utilizing the strong mutual coupling between the two dipoles, very good impedance match, sufficiently high isolation and low cross polarization can be achieved simultaneously. To get a directional radiation pattern, a metal reflector is placed under the antenna. The simulated measured results show that a more than 56% impedance bandwidth for SWR<1.5 from 1.66GHz to 2.96GHz is achieved, within which the port isolation is larger than 30dB. As an important advantage, the input impedance of the antenna can be changed within certain limits by properly adjusting the configuration, thus the antenna can be fed directly by 50-ohm coaxial cables without using impedance transformers. Particularly, the mechanisms for wide impedance bandwidth and high port isolation are discussed in this paper.