A Wideband Colinearly Polarized Composite Antenna With High Isolation

In this paper, a high-isolation two-port co-linearly polarized (co-LP) composite antenna is proposed. Dipole and W8JK array modes with co-LP omnidirectional patterns can be simultaneously supported by a plate with two etched back-to-back tapered slots. A microstrip differential and a T-divider coupling feeding networks are developed to selectively excite the dipole and W8JK modes, which results in high isolation and low correlation between two co-LP ports without using any decoupling structures. Reflecting ground is applied to realize the directional radiation. Measurement results show that the overlapped operating band of the antenna can cover 3.4–4.1 GHz with low measured envelope correlation coefficients (< 2.5 × 10
⁻³
) and high isolation (> 20 dB). A dual-polarized four-port element with good performances can be easily obtained based on the proposed co-LP antenna. The simulated results of the four-port prototype indicate that the proposed antenna is a promising candidate for the future compact massive MIMO array antenna.