2021 International Conference on Microwave and Millimeter Wave Technology (ICMMT) | 978-1-6654-3437-9/21/$31.00 ©2021 IEEE | DOI: 10.1109/ICMMT52847.2021.9618009
A Broadband Linear to Circular Polarization
Converter for 5G Millimeter Wave Communication
Wei-Ning Yinga, Tao Xua, Yu Lua, Guo-Qiang HEb, and Xue-Xia Yangb, c
a
School of Communication and Information Engineering
Key Laboratory of Specialty Fiber Optics and Optical Access Networks,
Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication
c
Shanghai Institute for Advanced Communication and Data Science
Shanghai University
Shanghai 200444, People’s Republic of China
ghe@shu.edu.cn, yang.xx@shu.edu.cn
b
Abstract-This paper presents a design and simulation of a
subwavelenth polarization converter unit operating in 5G
millimeter wave frequency. The converter consists of two metal
metasurface patterns and a dielectric layer sandwiched by the two
metasurfaces. Simulation shows that the converter owns more
than 3 GHz bandwidth with axial ratio of circular polarization
lower than 3 dB, insertion loss less than 1.5 dB, and VSWR lower
than 2, which can adapt to the millimeter wave frequency band of
5G communication.
Index Terms-Linear polarization, Circular polarization,
Polarization converter, 5G
I.
INTRODUCTION
Due to its unique characteristics, circular polarization wave
is less affected by multipath effect and better propagation
characteristics in the transmission process, as a result, it has
been widely used in the fields of communication and
localization systems. With the increasing functionalities of
modern wireless systems, they commonly require the antennas
owning linear and also circular polarizations or conversion
between these two polarizations. For a long time in the past, the
research on the polarization converter has been focused on the
military applications. In recent years, with the rapid
development of mobile and satellite communications, remote
sensing, and other wireless technologies, the research interests
of polarizers have been greatly expanded.
There are many different routines to realize polarization
conversion. The most traditional and common way is to use
Faraday Effect. However, it requires a thick media layer, which
results in high profile and is expensive to use [3-4]. Other
designs include waveguide type, surface selection type based
FSS [1], hypersurface material type [5-8]. Jian Peng Luo et. al.
studied and designed a polarization converter using pure water
in [9].
In addition, another important research area is adjusting the
physical structure and parameters of the polarizer to make it
work in different frequency bands. Most of the current research
focuses on Ka band [10] and K-band [11] for satellite
communications. What’s more, terahertz band [12] is also a hot
research topic. But there is less research on 5G band, in addition,
many studies on the linear to circular polarization conversion
only shows narrow operating bandwidth.
With the development of 5G communication, the trend of
ground mobile communication and satellite communication
network is becoming more and more integrated, which makes
the existing dual polarization antenna difficult to meet the
requirements. Therefore, it is essential to implement a
polarization converter for the 5G communication antenna
systems.
Inspired by the model structure in [11], a subwavelength unit
owning the ability of polarization conversion between linear
and circular is designed and simulated in the frequency range
24.25 GHz – 27.5 GHz. A similar metal-patterned metasurface
unit operating in the reflection type is applied to independently
control reflection amplitude and phase for frequency controlled
beam steering [13].
II. STRUCTURE AND SIMULATION
As shown in the Fig.1 (a), the unit is composed of two metal
pattern layers separated by a dielectric substrate Rogers
RT5880 with a thickness of 1 mm. The structures of the two
metal layers have the same pattern, which consists of a split ring
and a narrow patch arm. The main parameters of the unit
labeled in the Fig. 1 (a) - (c) is given in the Table I. Different
from the unit in [11], the two ends of the narrow metal patch
are connected to the metal ring as shown in Fig. 1(b). CST
Microwave Studio is employed to simulate the converter unit.
An x-direction linearly polarized millimeter wave normally
imping on the unit, and two orthogonal linearly polarized
electromagnetic waves propagated through the unit. As shown
in Fig.2, amplitudes of the two orthogonal electromagnetic
components are the same, and their phase difference is about
positive 90 degrees between x and y directions, which forms a
right-handed circular polarization.
978-1-6654-3437-9/21/$31.00 ©2021 IEEE
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Fig.1. Schematic diagram of the converter. (a) View from the z-axis; (b)
metallic layer; (c) side view.
In order to quantify the performance of this polarization
conversion unit, the scattering parameters of linear polarized
wave are converted into circular polarization scattering
parameters by referring to the formula in [11]. The reflection
coefficient in the frequency band is less than -10 dB, and the
transmission coefficient is higher than -1.5 dB. The
transmission coefficient and phase near the working frequency
band are determined by Fig. 2.
TABLE I
PARAMETERS OF THE CONVERTER
parameter
length(mm)
parameter
length(mm)
ri
1.235
d
0.95
rs
1.805
h
0.66
a
4.75
s
1.235
The axial ratio of the converted circular polarization wave is
computed through the formula [11]
AR  g  g 2  4 sin 2  / g  g 2  4 sin 2 
Fig. 2. Transmission coefficients in dB and phases of X and Y linearly
polarized wave components of the converted RHCP wave.
Last but not least, it is found that when the outer diameter of
the metal layer increases or the opening decreases (that is, the
length of the outer arc increases), the operating frequency will
move to the lower frequency. When the outer diameter rs of the
metal layer increases, the frequency with equal amplitude and
phase difference of 90°in X and Y directions will change from
a broad band, and then to a crossed point. And increasing the
width of the patch follows the same rule. The operating
frequency of the converter can be designed to fit specific
applications by physically tuning its structural parameters.
(1)
where g and φ are determined by
x
x
g  TFP
TFPy  TFPy TFP
  TFPx  TFPy .
(2)
(3)
It is calculated that the internal axial ratio of the operating
frequency band 24.25 GHz-27 GHz is less than 2 dB, and the 3
dB axial ratio bandwidth covers the frequency range 24.25-27.5
GHz, which meets the application requirements, as shown in
Fig. 3. What is more, as shown in Fig. 4, the voltage standing
wave ratio (VSWR) is between 1.05 and 1.25, less than 2,
which also meets the requirements.
Fig. 3. Axial ratio of the converted RHCP wave enabled by the proposed
converter.
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Fig. 4. VSWR of the proposed linear to circular polarization converter.
III. CONCLUSION
In this paper, a polarization conversion unit working in the
5G millimeter wave band is proposed, which can realize the
conversion from linear polarization to circular polarization in
the 24.25 GHz-27.5 GHz band. Simulation implemented by
using CST shows that the unit has low reflection loss, high
transmission coefficient, low axial ratio and standing wave ratio
in a broad bandwidth. At the same time, the unit structure only
owns one dielectric layer and simple metal pattern, which is
easy to fabrication and low cost. The working frequency can be
adapted to the desirable band by designing the arc length of the
metal layer.
Microwave Workshop Series on Advanced Materials and Proc-esses for RF
and THz Applications, 2016.
[7] Xing Yang Yu, Xi Gao, Xu Han, Si Min Li, Wei Ping Cao, Xin Hua Yu,
and Yan Nan Jiang, “High performance terahertz polarizati-on converter
based on double V-shaped metasurface,” IEEE Internat-ional Conference
on Communication Problem-Solving, 2015.
[8] Jing Zhao, Yannan Jiang, and Congcong Shi, “Linear-to-circular polarization converter utilizing double-arc-based metasurface at terahertz frequency,” International Symposium on Antennas,Propagationand
EM Theory, 2018.
[9] Jianpeng Luo, Zibin Chi, Zhuowei Wang, Zhuozhu Chen, Zhenxin Hu, Xin
Tian, and Duo-Long Wu, “A pure water linear-to-circular polarization
converter,” International Workshop on Electromagnetics:Applications and
Student Innovation Competition, 2019.
[10] Parinaz Naseri, Sérgui A.Matos, Jorge R. Costa, Carlos A. Fernandes, and
Nelson J. G.Fonseca, “Dual-band dual-linear-to-circular polarization
converter in transmission mode application to K/Ka-band satellite
communications,” IEEE Transactions on Antennas and Propagation, vol.
66, no. 12, pp. 7128-7137, Dec. 2018.
[11] Parinaz Naseri, Rashid Mirzavand, and Pedram Mousavi, “Dual-band
circularly polarized transmit-array unit-cell at X and K bands,” 10th
European Conference on Antennas and Propagation, 2016.
[12] Parinaz Naseri, and Pedram Mousavi, “K-band circularly-polarized
reconfigurable
transmit-array
unit-cell,”
IEEE
International
Symposiumon Antennas and Propagation & USNC/URSI National Radio
Science Meeting, 2015.
[13] Shengli Jia, Xiang Wan, Pei Su, Yongjiu Zhao, and Tiejun Cui,
“Broadband metasurface for independent control of reflected amplitude
and phase,” AIP Advances, vol. 6, no. 3, pp. 045024, 2016.
ACKNOWLEDGMENT
This work is supported by the National Natural Science
Foundation of China (NSFC) under Grant No. 62001280,
Shanghai Pujiang Program (20PJ1404300), 111 Project
(D20031), and Guangxi Key Laboratory of Wireless Wideband
Communication and Signal Processing.
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