Design of broadband dual-polarized antenna with integrated Marchand balun

A design of broadband dual-polarized antenna with low cross polarization and high isolation was presented. The antenna is composed of a cross dipole, a folded ground, two feeding networks, and a reflector. The impedance bandwidth was enhanced by utilizing the mutual coupling between the two dipoles. A kind of meandering folded Marchand balun was skillfully integrated on the support column of the antenna to excite the dipole differentially, which can deliver both balanced（within 0.5 d B） power splitting and consistent（±5°） phase shifting from 1.71 GHz to 2.17 GHz. The standing wave ratios（SWRs） of each port are less than 1.5. By using this feeding network, the antenna has good performance in isolation（> 45 d B） and cross polarization（> 30 d B） over the entire operating frequency band. Moreover, the gain（;.6 d B） of the proposed antenna is stable with frequency and the antenna structure is very firm due to the support column. The proposed antenna can be easily formed an array for digital cellular system（DCS）, personal communications service（PCS） and 3rd generation（3G） applications.