Dual-Wideband Dual-Polarized Magnetoelectric Dipole Antenna for 4G/5G Microcell Base Station

Congcong Zhu, Bin Wang, Wei Luo, Honggang Hao, Ping Wang
2020 Electronics Letters  
A novel dual-wideband dual-polarised magnetoelectric (ME) dipole antenna for the fourth generation (4G)/fifth generation (5G) microcell base station is proposed. Using a pair of orthogonal ME dipoles and Γ-shaped tapered cross feeding lines, the initial antenna achieves dualband and dual-polarised. Then, four U-shaped gaps, added in electric dipoles, effectively extend the lower impedance bandwidth. Finally, a circular parasitic patch with capacitive properties is innovatively loaded above the
more » ... E antenna, which obviously reduces the highresonant frequency from 5.5 to 4.9 GHz. Meanwhile, a box-shaped reflector is employed to achieve stable gain and radiation patterns. As a result, the measured results show the good dual-wideband performance of 52.4% (2.14-3.66 GHz) and 7.4% (4.68-5.04 GHz) with voltage standing wave ratio (VSWR) < 2, high isolation (>25 dB) and high gain (9.5 and 5.5 dBi, respectively). In addition, a stable radiation pattern with a half-power beam width of 63.5°+ 6.8°and good cross-polarisation discrimination (>20 dB) on the E-plane is realised over these two bands. Introduction: In 2017, the Chinese Ministry of Industry and Information Technology announced that frequencies 3.3-3.4 GHz (indoor only), 3.4-3.6 and 4.8-5.0 GHz were allocated for the fifth generation (5G) [1]. At the same time, as telecommunication vendors gradually abandon second generation (2G) and third generation (3G), base station antennas that can simultaneously support fourth generation (4G) and 5G bands will be an inevitable trend in the future. Meanwhile, dual-polarised antennas, providing polarisation diversity, can effectively reduce the effects of multipath fading and increase the capacity of mobile communication systems, which are the first choice of base stations [2] . In addition, for indoor base station antennas that are strictly limited by installation space, it is more valuable to use one antenna to achieve multiple bands. Therefore, it is of great significance to study dual-band dual-polarised antennas for 4G/5G microcell base stations with directional radiation, high isolation, and a stable radiation pattern. With a simple structure and excellent performance, the magnetoelectric (ME) dipole antenna, designed by Luk and Wong [3], has attracted extensive attention and further research. By adding a parasitic patch above the antenna, a U-shaped folded ME dipole antenna with a wide bandwidth of 72.7% (1.61-3.45 GHz) was proposed in [4] . To realise dual-band capability, ME dipole antennas with different structures have appeared, such as multilayer structure [5-7], parasitic patch [8, 9] , special E-dipole [10, 11] etc. In [5], a dual-layer ME dipole antenna fed by a U-shaped feeding line was devised, the lower layer of which was used to implement the lower band and the upper layer of the upper band. Then, four hook-shaped branches were added at the corner of the upper layer to expand the upper band. As a result, dualwide bands of 51.3% (1.68-2.84 GHz) and 11.4% (5.31-5.95 GHz) were obtained. In [9], a novel directional dipole with dual bands of 40.5% (0.68-1.03 GHz) and 50.6% (1.67-2.80 GHz) was presented, in which two crooked arms were designed to generate the lower band, and four Γ-shaped branches, fixed at the corner of the ground, were introduced to expand it. In addition, a double reflecting floor was adapted to effectively improve the radiation pattern in the upper band. By properly designing the feeding and antenna size, a dual-band ME dipole antenna was proposed in [11] . Then, a parasitic E-dipole and a director were designed to broaden the lower and upper band, respectively. Finally, the antenna obtained 46.7% (2.3-3.7 GHz) and 22.2% (5-6.25 GHz) impedance bandwidth. These above-mentioned ME dipole antennas all realise dual-band character and good performance; however, they are just single-polarised. In [12], a dual-polarised ME dipole antenna with dual-wideband (0.8-0.96 and 1.7-2.7 GHz) and high isolation (>25 dB) was presented. First, this antenna achieved a dualpolarised character and an upper band by using a pair of orthogonal ME dipoles fed by Γ-shaped cross-feeding lines. Then, a ring-shaped parasitic patch was loaded above the antenna to create a lower resonance frequency. In [13] , fed by two orthogonal Γ-shaped feeding lines, a dual-band, dual-polarised ME-dipole antenna with double structure was proposed, which had bandwidths of 22.6% (3.25-4.08 GHz) and 19.6% (4.29-5.22 GHz). However, these dual-band dual-
doi:10.1049/el.2019.3535 fatcat:i34vdo2zyrgnlh3nr3edlr65gq