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, 33-3.6 GHz) dipole. its inductive loadings are implemented at the end of each dipole arm to suppress the bask 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 lambda(L) (lambda(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.