Dual-Polarized Multi-Resonance Antennas With Broad Bandwidths and Compact Sizes For Base Station Applications
Dual-Polarized Multi-Resonance Antennas With Broad Bandwidths and Compact Sizes For Base Station Applications
Dual-Polarized Multi-Resonance Antennas With Broad Bandwidths and Compact Sizes For Base Station Applications
ABSTRACT In this paper, a novel design method for dual-polarized multi-resonance antennas is presented
for base station applications. The radiator of the antenna is configured as cross-dipoles with four thin
metal strips connected to the adjacent dipole arms. The attached strips create multiple current paths
and introduce additional resonant points. As a result, the bandwidth of the antennas is broadened while
maintaining a very compact size. Based on this working mechanism, two multi-resonance antennas are
designed, fabricated, and tested. The antennas achieve bandwidths of 46.7% and 66.7% respectively, with
excellent matching capabilities. The antennas also exhibit high port isolation levels and stable radiation
performances. The promising wideband performances with compact physical sizes make the antennas
highly suitable for the base station applications.
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SUN et al.: DUAL-POLARIZED MULTI-RESONANCE ANTENNAS WITH BROAD BANDWIDTHS AND COMPACT SIZES
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dipole. At 2.3 GHz, the currents are accumulated along the
four connecting strips, with some extending to the side of
dipole arms. The current distribution on each strip resem-
bles the short dipole case, and the −45◦ -polarized radiation
is achieved by the co-radiation of four current paths. The
current distributions in Fig. 3 show that there are different
dominant current paths at different frequencies on the same
radiator’s aperture, which helps to achieve multiple resonant
points across a wideband with a compact configuration.
For the presented radiator, two parameters are directly
related with the length of current paths, which are the
length of dipole LD, and the length of the connecting strip
LS. Therefore, these two parameters will have dominating
impacts on the resonant points and the input impedances
of the radiator. The input reactance and resistance with dif-
ferent LD and LS values are shown in Figs. 4(a) and 4(b).
Obviously, there are two resonant points (reactance = 0) at
all reactance curves, suggesting the radiator exhibits intrinsic
dual-resonant property. As shown in Fig. 4(a), LD mainly
influences the first resonant frequency at a lower band.
Increasing LD moves the first resonant point to a lower
frequency. As shown in Fig. 4(b), LS dominates the second
resonant frequency at a higher band. Increasing LS decreases
the second resonant frequency. These findings agree with
the current distribution in Fig. 3 that LD and LS determine
the length of current paths in the lower and higher bands,
respectively.
It is also noted from Figs. 4(a) and 4(b) that the radi-
ator has a relatively large resistance level, and that larger
LD or smaller LS increase the resistance across the band.
Therefore, appropriate values should be selected to make the
radiator have desired resonance frequencies and reasonable
resistance level for impedance matching. Other parameters
of the radiator shown in Fig. 2 also have certain effects on
the input impedance, and they are optimized in the design
process as well. The optimized dimensions of the radia-
tor are LD = 27.5 mm, WD = 12 mm, LS = 29.7 mm,
WS = 0.8 mm and G = 11 mm. The input impedance is
shown in Fig. 4(c). Across the targeted band from 1.7 GHz
to 2.7 GHz, the radiator has two resonant frequencies at FIGURE 4. The influence of (a) dipole length LD, and (b) strip length LS on the input
1.85 GHz and 2.22 GHz with impedance varies from 125 reactance and resistance of the multi-resonance radiator. (c) The input impedance of
the radiator with optimized dimensions.
to 260 . Later on, baluns are designed to match the radiator,
which will be explained in the next section.
B. IMPEDANCE MATCHING OF THE MULTI-RESONANCE to avoid overlapping with each other. The optimized dimen-
ANTENNA sions are marked in the figures. As the working mechanism
To provide balanced feeds to the multi-resonance dipole radi- and implementation of baluns have been thoroughly carried
ators and transform the input impedance for matching, two out in [14]–[16], we here only briefly describe the matching
baluns are designed following the guidelines in [14]–[16]. process of this multi-resonance antenna.
The circuit model of the balun are shown in Fig. 5(a). It As shown in Fig. 5(a), the input impedance of the radiator
consists of two line-transformers TL1 and TL2 and a series is firstly connected with the series resonator, then trans-
resonator formed by open circuit line (OCL) and short circuit formed by two line-transformers and fed by a 50 port.
line (SCL). The optimized values of the circuit compo- The transformed input reactance and resistance at different
nents are listed in Table 1. The balun is implemented with matching stages are plotted in Figs. 6(a) and 6(b) respec-
microstrip structures, as shown in Fig. 5(b). The feed lines tively. According to Fig. 6(a), the radiator has two resonant
for the two baluns are arranged at slightly different heights frequencies at 1.85 GHz and 2.22 GHz. The series resonator
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SUN et al.: DUAL-POLARIZED MULTI-RESONANCE ANTENNAS WITH BROAD BANDWIDTHS AND COMPACT SIZES
FIGURE 6. (a) Input reactance and (b) input resistance of the antenna at different
FIGURE 5. (a) Circuit model, and (b) microstrip realization of the baluns. stages.
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FIGURE 11. Simulated and measured HPBW and realized gain of the dual-polarized
FIGURE 9. Simulated and measured S-parameters of the dual-polarized multi-resonance antenna.
multi-resonance antenna.
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SUN et al.: DUAL-POLARIZED MULTI-RESONANCE ANTENNAS WITH BROAD BANDWIDTHS AND COMPACT SIZES
FIGURE 12. (a) Perspective view of the RCMR antenna. (b) Detailed view of the
TCMR radiator. (c) Detailed views of the two baluns.
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SUN et al.: DUAL-POLARIZED MULTI-RESONANCE ANTENNAS WITH BROAD BANDWIDTHS AND COMPACT SIZES
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18 VOLUME 1, 2020
HAI-HAN SUN received the bachelor’s Y. JAY GUO (F’14) received the bachelor’s
degree in electronic information engineer- and master’s degrees from Xidian University,
ing from the Beijing University of Posts and China, in 1982 and 1984, respectively, and
Telecommunications, Beijing, China, in 2015, the Ph.D. degree from Xian Jiaotong University,
and the Ph.D. degree in engineering from the China, in 1987.
University of Technology Sydney, Australia, in He held various senior technology leader-
2019. She is currently a Research Fellow with the ship positions with Fujitsu, Siemens, and NEC,
School of Electrical and Electronic Engineering, U.K. In 2014, he served as the Director of
Nanyang Technological University, Singapore. CSIRO over nine years. He is a Distinguished
Her research interests include the base station Professor and the Founding Director of the Global
antennas and the ground penetrating radar. Big Data Technologies Centre, University of
Technology Sydney, Australia. He has published over 460 research papers
including 250 journal papers, and holds 26 patents in antennas and wire-
less systems. His research interest includes antennas, mm-wave and THz
communications, and sensing systems as well as big data technologies.
CAN DING received the bachelor’s degree in micro- Dr. Guo has won a number of most prestigious Australian Engineering
electronics from Xidian University, Xi’an, China, Excellence Awards in 2007 and 2012, and the CSIRO Chairman’s Medal
in 2009, and the Ph.D. degree from Macquarie in 2007 and 2012, and was named one of the most influential engineers
University, Sydney, Australia, in 2015. in Australia in 2014 and 2015. He has chaired numerous international
From 2012 to 2015, he was under the cotutelle conferences and served as guest editor for a number of IEEE pub-
agreement between Macquarie University and lications. He is the Chair Elect of International Steering Committee
Xidian University. During this same period, he and International Symposium on Antennas and Propagation. He was the
was also with Commonwealth Scientific and International Advisory Committee Chair of IEEE VTC2017, the General
Industrial Research Organisation DPaS Flagship, Chair of ISAP2015, iWAT2014, and WPMC2014, and the TPC Chair
Marsfield, Australia. From 2015 to 2017, he was of IEEE WCNC in 2010, and IEEE ISCIT in 2012 and 2007. He
an industrial-sponsored Post-Doctoral Research served as the Guest Editor of special issues on “Antennas for Satellite
Fellow with the Global Big Data Technologies Centre, University of Communications” and “Antennas and Propagation Aspects of 60-90
Technology Sydney, where he is currently a Lecturer. His research interest is GHz Wireless Communications,” both in the IEEE TRANSACTIONS ON
in the area of base station antennas, reconfigurable antennas, phase shifters, ANTENNAS AND PROPAGATION, the Special Issue on “Communications
and fibres for wireless communication and sensing. Challenges and Dynamics for Unmanned Autonomous Vehicles,” in the
Dr. Ding is a recipient of the Australia Research Council Distinguish IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, and the
Early Career Researcher Award Fellow in 2020. Special Issue on “5G for Mission Critical Machine Communications,” in
the IEEE Network Magazine. He is a fellow of the Australian Academy of
Engineering and Technology and IET, and he was a member of the College
of Experts of Australian Research Council from 2016 to 2018.
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