Dual-Polarized Duplex Base-Station Antenna With a Duplexer-Integrated Balun

This letter investigates a highly integrated dual-polarized duplex antenna for modern base-station systems. The antenna comprises a pair of orthogonally placed dipole radiators, duplexer-integrated baluns (DIBs), and a reflector. The duplex function is achieved by integrating the dipole radiators with the highly isolated DIBs, using λ/4 parallel-coupled resonators and a U-shaped resonator. For each polarization, the antenna has two isolated ports for the low band and high band operations, enabling duplex operation. The antenna has a compact size of 0.35 λ
_L0
× 0.35 λ
_L0
× 0.17 λ
_L0
, where λ
_L0
denotes the free-space wavelength at the center frequency of the low band. Both simulation and measurement results demonstrate that each polarization of the antenna can simultaneously support two operation bands, respectively from 3.42 to 3.60 GHz and from 4.80 to 5.10 GHz. The interband isolation and polarization isolation are higher than 20 and 30 dB, respectively. The proposed antenna represents an appealing candidate for 5G sub-6 GHz base-station applications.