A Miniaturized Dual-Polarized Tri-band Antenna Based on Multimode and Stacked Scheme for Multiband Aperture-shared Base-Station Applications

A miniaturized dual-polarized tri-band antenna based on multimode and stacked scheme is proposed for multiband aperture-shared base station application. The proposed antenna covers the operation frequencies of 1427-1518 MHz (1 ^st band), 1920-2180 MHz (2 ^nd band) and 3300-3800 MHz (3 ^rd band), corresponding to the n1 band, n50-n51 bands and n78 band for 5G NR. Dual-mode operation is achieved by loading four split rings which are coupled to the folded dipole, thus providing the 1 ^st and 2 ^nd frequency bands. As to the 3 ^rd frequency band, a high-band element is stacked above the dual-band element. The 1 ^st and 2 ^nd frequency bands share one feeding structure, while the 3 ^rd frequency band is fed independently. Due to above strategies, radiation interference is avoided, stable broadside gains around 7dBi with a minor fluctuation of 1.65dB is realized within the three bands. Meanwhile, good isolation higher than 20dB between different frequency bands is achieved within a small area of 0.14 ² λ _L ² , where λ _L is the wavelength at the lowest frequency of 1427MHz. Besides, the middle-band to low-band (MB-LB) and high-band to middle-band (HB-MB) frequency ratio can be adjusted within the range of 1.27-1.61 and 1.64-2.5, respectively. These results indicate the proposed tri-band antenna a favorable candidate for multiband aperture-shared base station applications.