A Novel Dipole Configuration With Improved Out-of-Band Rejection and its Applications in Low-Profile Dual-Band Dual-Polarized Stacked Antenna Arrays

In this communication, a novel dipole configuration with reactive loadings is proposed for the design of low-profile dual-band dual-polarized stacked antenna arrays. For lower band (LB1, 3.3-3.6 GHz) dipole, its inductive loadings are implemented at the end of each dipole arm to suppress the basic resonant mode for band rejection at higher frequencies. For higher band (HB2, 4.8-5.0 GHz) dipole, its LC loadings are implemented at the beginning of each dipole arm, where the inductor and the capacitor, respectively, increase the Q-factor for improving the out-of-band rejection and balance the impedance matching. Hence, LB1 and HB2 dipoles can be closely stacked with high isolation. Moreover, a dual-band artificial magnetic conductor (AMC) reflector is adopted for reducing the distance between the antenna and the ground plane. Consequently, the overall height of the proposed one is only 0.16 λ
_L
( λ
_L
being the free-space wavelength at the center frequency of LB1), which is smaller than the previous dual-band stacked designs. The measurement results demonstrate that the array achieves good impedance matching, high isolation, and stable radiation patterns simultaneously, indicating it as a promising candidate for sub-6 GHz base-station services.