A multi-port interconnected magneto-electric dipole antenna array for 5G
applications
Zihao Chen1, Wenxu Zhang1, Kai-xu
Wang1
1 College of Electronics and Information Engineering,
Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China
Email: wangkaixu@hit.edu.cn.
This letter reports a 28-GHz multi-port magneto-electric (ME) dipole
array for 5G applications. The proposed antenna array enlarges the
system polarization diversity with the capability of being utilized as a
balanced antenna, a dual-polarized antenna and a circularly polarized
antenna. Co-planar waveguide (CPW) lines are used to connect ME dipole
radiators to achieve a high gain with simple feeding structure. The
proposed antenna array exhibits a -10dB impedance bandwidth of 12.8%
and a maximal peak realized gain of 13.52 dBi as a balanced antenna, and
exhibits a -10dB impedance bandwidth of 28.57%, a 3-dB axial ratio
bandwidth of 16% and a maximal peak realized gain of 12.15 dBi as a
circularly polarized antenna.
Introduction: The 5G communication has attracted more and more
research passion from both academic and industry due to its advantages
of high data rates, high reliability and low delay. Millimeter wave
bands have abundant working spectrum for 5G communication compared with
low-frequency bands, which helps to achieve high data rate [1]. The
high propagation attenuation and multipath propagation in
millimeter-wave band degrade the communication system performance.
Dual polarized and circularly
polarized antenna arrays with high gain and wide bandwidth are highly
demanded to resolve this problem.
A lot of dual polarized and circularly polarized antennas are reported
for 5G communication applications. Patch and slot are widely used in
early researches [2]-[5]. A dual-band miniaturized e-shaped
antenna with circular polarization at 28 and 38 GHz in [2]. An -10
dB impedance bandwidth of 18.42%, a maximal gain of 12.69 dBi and a 3dB
axial ratio (AR) bandwidth of 1.65% are achieved with a 2×2 array.
Dual-polarized cavity-backed bow-tie slot arrays are designed and
integrated on the frame of the mobile handset in [3]. The 1×4 array
can achieve a maximal gain of 12. 8 dBi and -10 dB impedance bandwidth
of 4.28%. The bandwidth of these antennas is narrow and techniques are
need to broaden their bandwidth.
Magneto-electric (ME) Dipole is a good antenna candidate for 5G
communication applications due to its wide impedance bandwidth and
stable unidirectional gain patterns. The magneto-electric dipole model
with a significant impact was firstly proposed by Kwai-Man LUK in 2006
[6]. The dual polarized and circularly polarized ME dipole antenna
are realized with the SIW feeding method in [7-8]. The two-layer SIW
feeding network makes the design and fabrication complicated. A
millimeter-wave dual-polarized ME-dipole antenna is reported in [9].
Two pairs of orthogonally oriented feed probes are used to feed the
antenna. The antenna exhibits 50% impedance bandwidth, 17.8 dB port
isolation, and up to 9.4 dBi gain. A circularly polarized differentially
fed ME-dipole array is reported in [10]. It manages to achieve -10
dB impedance bandwidth of 32.2% with a broadside left-handed CP gain
from 10.2 to 11.8 dBic. However, they lack of design flexibility to
support different polarizations.
In this letter, we present a novel design of ME dipole antenna array for
5G applications and demonstrate its flexibility to configure the antenna
to multiple antennas. We show that the antenna can be used as a balanced
antenna, dual-polarized antenna, as well as a circularly polarized
antenna through changing the amplitude and phase of the feeding ports.
An interconnected ME dipole radiator is specially designed to achieve
high gain without complex feeding network.
Antenna design and operating principle: The multi-port
interconnected ME dipole antenna array is designed on a PCB substrate of
Rogers 5880 with thickness of 1.57 mm, εr = 2.2
and tanδ=0.0009. The antenna radiator consists of four ME dipole
elements. For each ME dipole element, four identical metallic patches
are printed on the top of the substrate, which realize the electrical
dipole. The inner edges of the metallic patches are shorted to ground
through three metallic vias, which form the magnetic dipole together
with the ground plane. Cross strips, which are fed by the vias at one
end, are used to excite the antenna with the electric fields in the
x-direction and in the y-direction. CPW lines are utilized to transmit
energy between elements. The length of the CPW lines is specially
designed to keep the current distributions of the ME dipole elements are
in phase. The radiators are designed symmetrically in the x-direction
and the y-direction to achieve symmetrical radiation performance when
the antenna array radiates linearly polarized waves in the x-direction
and the y-direction. The detailed dimensions of the proposed antenna
array are listed in Table I. Four feeding ports on the cross strips are
arranged on the cross strips to enlarge the design flexibility of the ME
dipole antenna array. Port 1 and 4 can be configured as one balanced
antenna which radiates polarized waves in the y-direction and ports 2
and 3 as another balanced antenna which radiates polarized waves in the
x-direction. The current are orthogonal on the cross strips which
results in low coupling level between two polarizations, which enables
the propose multiport interconnected ME dipole antenna array to support
the simultaneous reception in two polarizations or transmission in
either polarization. Circular polarization can be realized as well by
exciting the feeding ports with equal amplitude and a phase difference
of 90o.