Dielectric Material Characterization for Reflectarray Antennas Designed at Sub-6GHz and Millimeter Wave Bands of 5G

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Dielectric Material Characterization for Reflectarray
Antennas Designed at Sub-6GHz and Millimeter
Wave Bands of 5G
Sher Dali Khan
Faculty of Electrical and Electronic
Engineering Technology,
Universiti Teknikal Malaysia Melaka
(UTeM)
sherdalikhan2292@gmail.com
Izhar Ahmed Sohu
Faculty of Electronic and Computer
Engineering,
Universiti Teknikal Malaysia Melaka
(UTeM)
Izharahmedsohu@gmail.com
Muhammad Inam Abbasi
Faculty of Electrical and Electronic
Engineering Technology,
Universiti Teknikal Malaysia Melaka
(UTeM)
inamabbasi@utem.edu.my
Sanaullah Khan
Faculty of Electronic and Computer
Engineering,
Universiti Teknikal Malaysia Melaka
(UTeM)
sanaullah.af45@gmail.com
Imran Mohd Ibrahim
Faculty of Electronic and Computer
Engineering,
Universiti Teknikal Malaysia Melaka
(UTeM)
imranibrahim@utem.edu.my
Abstract—The future compliance of reflectarray antenna
necessitates a methodical examination of its primary
traditional configurations to anticipate improvements. The
current design, which utilizes microwave and millimeter wave
frequencies, serves as a fundamental foundation for further
investigation. This study offers a comparison and
characterization of various dielectric substrates employed in
Sub-6 GHz and millimeter wave reflectarray antenna, based on
unit cells designed at 3.5 GHz and 28 GHz. The analysis utilizes
a range of commercially accessible dielectric materials
characterized by dielectric permittivity (ɛr) values spanning 2
to 3.6 and loss tangent (tan) values ranging from 0.0009
to 0.001.The performance of different dielectric materials in
the design of infinite reflectarray is assessed in terms of
bandwidth and reflection loss, providing a comprehensive
comparison. It is observed that the bandwidth of patch element
unit cells at different levels exhibits significant variations
depending on the material properties, with a 10% bandwidth
range. Furthermore, it is illustrated that the reflectarray
antenna's reflection loss can be deconstructed into dielectric
and conductor losses, both contingent upon the material
properties utilized in the design. This article presents a
comparison of eleven distinct substrate materials that have the
potential to result in disruptive designs for both the
architecture and components, thereby impacting the
performance of the reflectarray antenna.
Keywords— Reflectarray, Bandwidth, Dielectric loss, Conductor
loss, Dielectric Materials
I. INTRODUCTION
The surge in innovation has led to the emergence of fifth-
generation (5G) communication systems, showcasing data
rates potentially a thousand fold greater than existing
systems. This advancement has posed numerous challenges
for antenna designers who must now create antennas that
meet the specific requirements of wide bandwidth, high
gain, high efficiency, polarization diversity, and adaptive
beam steering [1]. Consequently, significant changes to the
structural design of existing communication systems are
necessary to accommodate the adoption of 5G technology
[2],[3].
Recognizing the significance of millimeter waves, the
allocation of 5G frequency bands was determined during the
World Radio communication Conference (WRC-15) with
the aim of facilitating future developments [4]. A range of
frequency bands, starting from 24.25 GHz up to 86 GHz,
were suggested for 5G, covering a variety of applications
[5].
One potential solution to compensate for the losses incurred
is the utilization of high gain antennas. The parabolic dish
antenna, which possesses high gain and efficiency, has
proven successful in many wireless communication systems
as a directional antenna. However, it does have limitations,
as it requires mechanical movement to scan the main beam
and is not flat [6], making it challenging to mount [7] on
different structures. Furthermore, its large size results in
occupying more space than a flat antenna [8]. In order to
address these issues, a dual layer configuration can be
employed, with each layer dedicated to a specific frequency
band. Alternatively, a single layer design can be utilized,
incorporating two distinct resonant structures tailored to
different frequency bands. A proposal for a single layer,
dual band circular polarized reflectarray antenna has been
put forth [9]. Various reflectarray antenna designs have been
suggested for mm-wave and 5G communication systems
[10], including band loaded dielectric resonator antenna
[11]. Additionally, electronic beam skimming has been
shown to reduce the required hardware typically used in
traditional high gain beam scanning antennas and improve
antenna efficiency [12]. Several antenna structures, such as
single layer and those employing Micro Electro Mechanical
Systems on the resonant elements [12], [13], as well as
utilizing the variable capacitance [16], [17], of varactor
diodes [14], [15], have been explored for their suitability in
mm-wave and 5G communication systems [18].
This paper provides a detailed analysis and comparison of
different materials used for unit cell reflectarray elements
operating at different frequencies, specifically 3.5 GHz and
28 GHz.
2023 IEEE 16th Malaysia International Conference on Communication (MICC), Kuala Lumpur, Malaysia, 10-12 December 20232023 IEEE 16th Malaysia International Conference on Communication (MICC), Kuala Lumpur, Malaysia, 10-12 December 20232023 IEEE 16th Malaysia International Conference on Communication (MICC), Kuala Lumpur, Malaysia, 10-12 December 2023
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2023 IEEE 16th Malaysia International Conference on Communication (MICC) | 979-8-3503-0434-3/23/$31.00 ©2023 IEEE | DOI: 10.1109/MICC59384.2023.10419832
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II. DESIGN OF UNIT CELLS
Figure 1 showcases the proposed unit cell, with Figure 1(a)
measuring 42.83 mm x 42.83mm and Figure 1(b) measuring
5.35 mm x 5.35 mm. This unit cell demonstrates resonance
across discrete frequency bands, specifically at 3.5 GHz and
28 GHz, featuring infinite boundaries. The substrate
dimensions are 0.6λ at 3.5 GHz and 0.6λ at 28 GHz in
relation to wavelength. Furthermore, the lower resonant
frequency is affected by the scaling factor S11, leading to
diverse values.
III. DISTINCTION OF REFLECTION PERFORMANCE IN
REFLECTARRAYS
The majority of the reflection loss in reflectarray antennas is
attributed to the conductor loss and dielectric absorption in
the dielectric layer. Factors such as the substrate thickness,
conducting material used for the patch element, and the
ground plane also play a role in the reflection loss of the
reflectarray antenna. The high electric fields in the substrate
region, along with the copper loss, contribute to the
dielectric loss. The most significant loss occurs at the
resonant frequency due to the high electric field distribution
and surface currents. To investigate the loss process in
reflectarray antennas, an infinite reflectarray with a
0.035 mm patch element thickness (copper) and 01 mm
substrate thickness was created using a commercially
available CST MW computer model. The aim was to
minimize conductor loss by employing a Perfect Electric
Conductor (PEC) for the patch element and ground plane,
while monitoring the dielectric loss using different dielectric
materials. The patch elements and ground plane were
designed using copper with a conductivity of 59.6 Ms/m at
20 °C.
Table 2 presents the computed losses for various dielectric
materials. The table reveals that materials with high loss
tangent values, such as Taconic TLC-27 and Taconic
TLC 30 shown in Fig. 2, exhibit a high reflection loss
primarily due to dielectric loss at 3.5 GHz, as depicted in
Fig. 4 at 28 GHz. This is attributed to the significant
dielectric absorption displayed by these materials in the
reflectarray antennas' dielectric layer. On the other hand,
materials with low reflection loss include Rogers RT5880
and Rogers 6002, which have low loss tangent values. This
is because these dielectric materials possess low loss
characteristics, with copper and conductor losses accounting
for the majority of losses in this type of reflectarray antenna
design.
Table 2 delineates the reflection loss across various
materials. Illustrated in Fig. 2, Rogers RT5880,
characterized by an exceptionally low loss tangent
value (tan δ=0.0009), demonstrates elevated dielectric loss
in contrast to copper loss. Conversely, Rogers, featuring a
high loss tangent value (tan δ=0.0012), presents lower
dielectric loss. The phase loss of different dielectrics, shown
in Fig. 3, indicates that Rogers TC350 has a value of
0.49 (degree/MHz) and Rogers 5880 has a value of
0.93 (degree/MHz) at 3.5GHz, as shown in Fig. 5 at 28GHz.
(a)
(b)
Fig. 1. (a) Reflectarray unit cell 3.5GHz and 28GHz, (b) infinite boundary
of the unit cell at 3.5GHz.
TABLE 1. DIMENSIONS OF UNIT CELLS AT 3.5 GHZ AND 28 GHZ
Unit Cell for 3.5 GHz (mm)
Unit Cell for 28 GHz (mm)
W1
L1
Wp1
Lp1
W2
L2
Wp2
Lp2
42.83
42.83
26.85
27.5
5.35
5.35
3.5
1.94
Fig. 2. Reflection Loss for different substrates at 3.5GHz
Fig. 3. Reflection Phase for different substrates at 3.5GHz
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Fig. 4. Reflection Loss for different substrates at 28GHz
Fig. 5. Reflection Phase for different substrates at 28GHz
IV. BANDWIDTH EVALUATION OF REFLECTARRAYS
EMPLOYING VARIOUS MATERIALS
The materials specified in Table 2 are employed for the
creation of reflectarrays antennas with infinite resonance at
3.5 GHz and 28 GHz. The evaluation of bandwidth, which
is 10% and 50%, is conducted by considering the
permittivity of each dielectric material with a uniform
thickness of 01 mm. The calculated bandwidth for various
materials is presented in Table 2. The graphical depiction in
Fig. 6 illustrates that the bandwidth decreases as the
dielectric permittivity of the reflectarray's material
increases. Notably, Rogers RT5880LZ, with the lowest
dielectric permittivity, exhibits the largest 10% and 50%
bandwidths. Conversely, Rogers TC-350, possessing the
highest dielectric permittivity (єr=3.6), displays the lowest
10% and 50% bandwidths, as shown in Figure 6.
V. CONCLUSION
A novel and highly promising configuration for a DRA-
based reflectarray has been put forth in the Sub-6GHz and
28 GHz bands. As part of the future 5G reflectarray
communication systems, there is a plan to employ a single
band and single layer unit element antenna. This proposed
antenna exhibits resonance at the two designated
frequencies for 5G, namely 3.5 and 28 GHz. The findings
reveal that this antenna holds potential for deployment in the
design of comprehensive reflectarray systems, supporting
both single and dual resonance operations for future
communication systems. Moreover, the suggested design
features a straightforward single-layer structure, facilitating
an uncomplicated fabrication process. Based on the results
and the information provided in Table 2, it can be concluded
that Taconic TLY 3FF serves as the optimal dielectric
material for the forthcoming 5G reflectarray communication
systems.
Fig. 6. Bandwidth performance of reflectarray unit cells designed at
3.5GHz with different substrat
TABLE 2. REFLECTION LOSSES, BANDWIDTH, AND PHASE SLOPE OF DIFFERENT DIELECTRIC MATERIALS AT 3.5GHZ.
Material
Reflection loss
(dB)
10%
Bandwidth
50%
Bandwidth
Phase Slope
(⁰/MHz)
Name
єr
tan(δ)
Rogers RT5880LZ
2
0.0021
-0.82
1.37
4.13
0.70
Teflon
2.02
0.0004
-0.74
1.04
3.14
0.74
Rogers Rt 5880
2.2
0.0009
-0.27
1.7
5.1
0.93
Taconic TLF-3FF
2.33
0.0012
-0.61
1.05
3.15
0.53
Taconic TLC-27
2.75
0.003
-2.45
0.93
2.81
0.51
Rogers RT 6002
2.94
0.0012
-0.74
1.41
5.99
0.73
Rogers RO3003
3
0.0012
-0.52
1.05
3.17
0.55
Taconic NF 30
3
0.0013
-0.69
1.02
3.08
0.54
Taconic TLC-30
3
0.0028
-1.40
1.03
3.11
0.52
Taconic TLC-32
3.2
0.003
-1.67
0.98
2.96
0.52
Rogers TC350
3.6
0.001
-1.19
0.93
2.78
0.49
2023 IEEE 16th Malaysia International Conference on Communication (MICC), Kuala Lumpur, Malaysia, 10-12 December 20232023 IEEE 16th Malaysia International Conference on Communication (MICC), Kuala Lumpur, Malaysia, 10-12 December 20232023 IEEE 16th Malaysia International Conference on Communication (MICC), Kuala Lumpur, Malaysia, 10-12 December 2023
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ACKNOWLEDGMENT
This work is funded by Universiti Teknikal Malaysia
Melaka (UTeM) through Short Term Research Grant (PJP)
No. PJP/2022/FTKEE/S01882.
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