applied
sciences
Article
Miniaturized PIFA for 5G Communication Networks
Eugene Rhee
Department of Electronic Engineering, Sangmyung University, Seoul 03016, Korea; eugenerhee@smu.ac.kr;
Tel.: +82-41-550-5413
Received: 6 January 2020; Accepted: 13 February 2020; Published: 15 February 2020
Abstract: This paper designed a miniaturized Planar Inverted-F Antenna for 5G communication
networks, including Long-Term Evolution Advanced mobile communication services. By showing
the radiation pattern, voltage standing wave ratio, and antenna gain of the designed Planar Inverted-F
Antenna, this paper evaluates its performance. To show the key characteristics of the Planar
Inverted-F Antenna, this paper modeled and simulated it with various variances. Moreover, the real
Planar Inverted-F Antenna was fabricated and measurements were done to validate the simulated
characteristics of the internal antenna.
Keywords: antenna; PIFA; LTE; 5G; communication
1. Introduction
Today, the miniaturization of the antenna is becoming increasingly needed due to the small size
of the wireless communication system. As the size of the antenna is mainly determined by the wave
length, it is difficult to miniaturize the antenna for current mobile communication services. To overcome
this difficulty, the method of using dielectric materials with high permittivity to miniaturize the antenna
has been studied by many researchers [1–11]. However, this method causes a decline of the antenna
gain due to the decline of the radiation effectiveness and dielectric loss. For this reason, the need
to study the miniaturization of the antenna by modifying the structure of the antenna, not by using
dielectric materials has increased. Therefore, this paper suggests a new method for designing a compact
multi-band internal antenna with a patch and a ground plane for common mobile communication
services. A patch antenna is a low-profile radio antenna which can be installed on a flat surface.
It consists of a flat metal patch that is mounted over a ground plane. Patch antennas have a structure
that is easy to fabricate, modify and customize. The original type of the patch antenna is the microstrip
antenna. Two metal plates form a resonance in microstrip transmission lines which have a length of
approximately one-half wavelength of the radio waves, and at these microstrip transmission lines,
radiation occurs due to discontinuities. The radiation at the microstrip transmission lines gives the
antenna a larger electric field area than its physical dimensions, which means that the antenna can
be resonant. Usually, the length of the microstrip transmission line is slightly shorter than one-half
a wavelength at the interested frequency, and a patch antenna is built on a dielectric plate. The
designed multi-band internal antenna can cover the frequency bands for Global System for Mobile
communications (GSM), Digital Cellular System (DCS), Personal Communications Service (PCS),
Wideband Code Division Multiple Access (WCDMA), Long Term Evolution (LTE) communication
services, and 5G communication networks. As mentioned above, there are many methods for the
miniaturization of the antenna. In consideration of the antenna gain and the effectiveness, modifying
the structure of the antenna is a better method to miniaturize the size of the antenna than using
dielectric materials with high permittivity. Therefore, this paper suggests a new structure of a compact
multi-band internal antenna for mobile handsets for WCDMA800, WCDMA850, GSM900, DCS, PCS,
WCDMA2100, LTE2100 communication services and 5G communication networks.
Appl. Sci. 2020, 10, 1326; doi:10.3390/app10041326
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This paper is organized as follows. In Section 2, we design a multi-band internal antenna for various
mobile communication services. In Section 3, we introduce a coordinate system for analyzing various
antenna characteristics. Afterwards, we simulate and measure antenna characteristics, including
antenna gain, voltage standing wave ratio (VSWR), and radiation pattern, in Sections 4 and 5. Finally,
we conclude the paper and lay out our future research plan on related topics in Section 6.
2. Long-Term Evolution Advanced Mobile Service
A Planar Inverted-F Antenna (PIFA) is about half the size of general dipole antenna and has a
conductor layer in it as the ground layer. The relationship between broad band width characteristics
and the thickness of the material can be determined by the following Equation.
Ah
BW =
√ =
λ0 εr
for A = 180:
W
L
h
√ ≤ 0.045
λ0 ε r
for A = 200:
0.045 ≤
(1)
(2)
h
√ ≤ 0.075
λ0 εr
(3)
h
√
λ0 εr
(4)
for A = 220:
0.075 ≤
And
r
1.6
D 0.2W + 6.6 + 10 log( √ )dB.
εr
(5)
where BW is a broad band width, A is the area of the dielectric material, h is the thickness of the dielectric
material, λ0 is the wavelength, εr is the dielectric permittivity, D is the directivity of the antenna, W
and L are the width and length of the radiating element in a PIFA respectively [12]. As Equation (1)
shows, the frequency band for a broad band width is proportional to the thickness of the material
and is inversely proportional to the dielectric permittivity. Moreover, Equation (2) shows that the
directivity of the antenna decreases as the dielectric permittivity increases. In designing the multi-band
internal antenna, as the thickness of the dielectric material increases, the broad band characteristic of
the antenna is improved. However, this also makes the width of the microstrip line increase, which
means that the unwanted radiation occurs from the feed. To solve this problem, this paper suggests
the structure of the multi-band internal antenna, as shown in Figure 1, and the designed multi-band
internal antenna is shown in Figure 2.
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Figure
Inverted-FAntenna
Antenna(PIFA).
(PIFA).
Figure1.1.Structure
Structure of
of the
the Planar Inverted-F
Figure 2.
2. Fabricated
Fabricated PIFA.
Figure
PIFA.
3. Planar
Inverted-F
3. Planar
Inverted-FAntenna
Antenna
paper,
multi-band
internal
antenna
WCDMA800,
WCDMA850,
GSM900,
DCS,
In In
thisthis
paper,
thethe
multi-band
internal
antenna
forfor
WCDMA800,
WCDMA850,
GSM900,
DCS,
PCS,
PCS, WCDMA2100,
mobile communication
services,
5G communication
networks
is
WCDMA2100,
LTE2100LTE2100
mobile communication
services,
and 5Gand
communication
networks
is modeled,
modeled,
and
the
antenna
characteristics
are
simulated
with
the
coordinate
system.
This
antenna
is
a
and the antenna characteristics are simulated with the coordinate system. This antenna is a flat antenna
flat
antenna
with
a
smaller
area
of
rectangular
patch
plate
on
top
of
the
ground
surface
of
the
plate,
with a smaller area of rectangular patch plate on top of the ground surface of the plate, consisting
of a ground
surface,
patch,
feeder, short-circuit
pin (or short-circuit
strip).
PIFA
as a
of consisting
a ground surface,
patch,
feeder,
short-circuit
pin (or short-circuit
strip). PIFA
acts
as aacts
radiation
radiation
element
the patch is
resonated
with surface
the ground
surfaceelectric
by current
electric
charge.the
element
as the
patchas
is resonated
with
the ground
by current
charge.
Moreover,
Moreover,
the
height,
width,
length
and
position
of
the
short-circuit
wires
determine
bandwidth,
height, width, length and position of the short-circuit wires determine bandwidth, gain and resonant
gain and resonant frequency. PIFA can be built into a mobile phone because it does not have any
frequency. PIFA can be built into a mobile phone because it does not have any protrusions, and two
protrusions, and two antennas can be attached to either side of the mobile phone or overlaid for
antennas can be attached to either side of the mobile phone or overlaid for dual mode of two frequency
dual mode of two frequency bands to improve its orientation. To improve the narrowband problem
bands to improve its orientation. To improve the narrowband problem of existing PIFA, this paper
of existing PIFA, this paper suggests a modified PIFA form that positions the short-circuit between
suggests a modified PIFA form that positions the short-circuit between the radiant element and the
the radiant element and the ground surface. It also has the radiation patch to have wider
ground
surface. It also has the radiation patch to have wider bandwidth. The desired bandwidth (5.2%)
bandwidth. The desired bandwidth (5.2%) was obtained with the minimum height of the antenna (h
was
obtained
minimum
height
of the
(h = 0.015λ)
forTouse
as built-in
to theslim,
handset
= 0.015λ) forwith
use the
as built-in
to the
handset
inantenna
the proposed
manner.
make
the antenna
this in
the proposed manner. To make the antenna slim, this paper investigated how the location (Zs ), width
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(W
(d), short
strip
height
(h), and
(ε ) affected the antenna. With these factors,
s ), length
paper
investigated
how
the
location
(Zs),dielectric
width (Wchange
s), lengthr (d), short strip height (h), and dielectric
this
paper
also
compared
the
bands
with
the
existing
PIFA
antenna
represented
the proposed
change (εr) affected the antenna. With these factors, this paper
also and
compared
the bands
with the
pattern
H and
E plane.
existingas
PIFA
antenna
and represented the proposed pattern as H and E plane.
4. Simulation
4. Simulation
For the simulations, High Frequency Structure Simulator (HFSS) program ver. 11, which is based
For the simulations, High Frequency Structure Simulator (HFSS) program ver. 11, which is
on the Finite Integration Method (FINM), is used to analyze the designed multi-band internal antenna
based on the Finite Integration Method (FINM), is used to analyze the designed multi-band internal
for mobile communication. The radiation pattern of the multi-band internal antenna is simulated
antenna for mobile communication. The radiation pattern of the multi-band internal antenna is
at H-plane, E1-plane, and E2-plane respectively, and the simulated radiation patterns are as shown
simulated at H-plane, E1-plane, and E2-plane respectively, and the simulated radiation patterns are
in Figures 3–5.
as shown in Figures 3–5.
Figure 3.
3. Radiation
(H-Plane).
Figure
Radiation Pattern
Pattern (H-Plane).
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55 of
Figure 4.
4. Radiation
Radiation Pattern
Pattern (E1-Plane).
(E1-Plane).
Figure
Radiation
Pattern
(E1-Plane).
Figure 5.
5. Radiation Pattern
Pattern (E2-Plane).
Figure
Figure
5. Radiation
Radiation Pattern (E2-Plane).
(E2-Plane).
As mentioned
mentioned above,
above, this
this paper
paper suggests
suggests the multi-band
multi-band internal antenna
antenna for WCDMA800,
WCDMA800,
As
As
mentioned above,
this paper
suggests the
the multi-band internal
internal antennafor
for WCDMA800,
WCDMA850, GSM900,
GSM900, DCS,
DCS, PCS,
PCS, WCDMA2100,
WCDMA2100, LTE2100
LTE2100 mobile
mobile communication services,
services, and 5G
5G
WCDMA850,
WCDMA850,
GSM900, DCS,
PCS, WCDMA2100,
LTE2100 mobilecommunication
communication services,and
and 5G
communication
networks.
Figures
4–6
show
the
radiation
pattern
of
the
internal
antenna
at
824
MHz
communicationnetworks.
networks. Figures
Figures 4–6
4–6 show
communication
show the
the radiation
radiation pattern
patternof
ofthe
theinternal
internalantenna
antennaatat824
824MHz
MHz
−2.17 GHz
GHz frequency
frequency band.
band. To
To prove
prove the
the antenna
antenna characteristics
characteristics of
of the
the designed
designed multi-band
multi-band internal
internal
−2.17
antenna in
in numerical
numerical value,
value, Tables
Tables 11 and
and 22 show
show the
the voltage
voltage standing
standing wave
wave ratio
ratio (VSWR)
(VSWR) and
and the
the
antenna
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−2.17 GHz frequency band. To prove the antenna characteristics of the designed multi-band internal
Appl. Sci. 2019, 9, x FOR PEER REVIEW
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antenna in numerical value, Tables 1 and 2 show the voltage standing wave ratio (VSWR) and the
peak
peak gain
gain of
of the
the antenna
antenna at
at each
each frequency
frequency band,
band, and
and the
the radiation
radiation pattern
pattern of
of the
the antenna
antenna is
is almost
almost
omni-directional,
as
shown
in
Figures
3–5.
In
the
simulation
of
the
radiation
pattern,
the
impedance
omni-directional, as shown in Figures 3–5. In the simulation of the radiation pattern, the impedance
bandwidth
at 960
960 MHz.
MHz.
bandwidth is
is set
set from
from 824
824 MHz
MHz to
to 2.17
2.17 GHz,
GHz, and
and the
the insertion
insertion loss
loss is
is the
the minimum
minimum at
Although
Although the
the simulated
simulated radiation
radiation patterns
patterns at
at H-plane
H-plane and
and E-plane
E-plane are
are not
not symmetric
symmetric patterns,
patterns, they
they
show
forward
and
backward
patterns.
Moreover,
the
radiation
patterns
are
the
maximum
show forward and backward patterns. Moreover, the radiation patterns are the maximum at
at the
the
perpendicular
direction
to
the
antenna
side.
perpendicular direction to the antenna side.
Figure 6.
6. Measurement
Measurement Setup.
Setup.
Figure
Table
Table1.1. Simulation
Simulation Result
Result (VSWR).
(VSWR).
FrequencyRange
Range
Frequency
W800,
GSM900
W800,W850,
W850,
GSM900
DCS,
PCS,
WCDMA2100,
LTE2100
DCS,
PCS,
WCDMA2100,
LTE2100
824
824MHz
MHz
960
MHz
960
MHz
1710
MHz
1710
MHz
1920
MHz
1920
MHz
21702170
MHz
MHz
6.36.3
7.27.2
5.85.8
2.7 2.7
2.9 2.9
VSWR
VSWR[dBi]
[dBi]
Table2.2. Simulation
Simulation Result
Result (Peak
(Peak Gain).
Gain).
Table
W800,
W850,
GSM900
W800,
W850,
GSM900
824 MHz
960 MHz
824 MHz
960 MHz
H-plane
0.4
−4.3
Peak Gain
H-plane
0.4
−4.3
E1-plane
0.8
−5.6
Peak Gain
[dBi]
E1-plane
−5.6
1.4 0.8
−4.4
[dBi] E2-plane
Frequency
Range
Frequency
Range
E2-plane
1.4
−4.4
DCS,PCS,
PCS,
WCDMA2100,
LTE2100
DCS,
WCDMA2100,
LTE2100
1710 MHz
1920 MHz
2170 MHz
1920 MHz
2170 MHz
−3.1
0.0
−1.0
−3.1
0.0
−1.0
−2.2
1.4
2.6
−2.2
1.4
2.6
−2.7
1.5
3.0
1710 MHz
−2.7
1.5
3.0
5. Measurement
5. Measurement
The simulated multi-band internal antenna is fabricated, and the VSWR and gain of the internal
The simulated
multi-band
internal
antenna6.isFor
fabricated,
and the VSWR
andagain
of theanalyzer
internal
antenna
were measured
as shown
in Figure
the measurement
system,
network
antenna
were
measured
as
shown
in
Figure
6.
For
the
measurement
system,
a
network
analyzer
(Agilent
(Agilent 5071B), a calibration kit (Agilent 85033E), an adaptor (SMA Female ↔ SMA Male), and a
5071B),
a calibration
(Agilent 85033E),
an adaptor
(SMAand
Female
↔ SMAofMale),
and a measurement
measurement
cable kit
(SMS-SF141)
are used.
The method
procedure
the measurement
are as
cable
(SMS-SF141)
are used.
The
and procedure
of the measurement
follows. The
follows.
The shielded
box is
setmethod
to the port
of the network
analyzer, andare
theascalibration
forshielded
them is
box
is set
to the
port the
of the
network antenna
analyzer,toand
for them
done.
After
the
done.
After
setting
fabricated
thethe
setcalibration
JIG and unit
JIG, is
the
set JIG
is setting
connected
fabricated
antenna
to the
set JIG
unit JIG,
is connected
vertically
to the portto
inside
the
vertically to
the port
inside
the and
shielded
box the
andset
theJIG
unit
JIG is connected
horizontally
the port
shielded
box
and thebox,
unitrespectively.
JIG is connected
horizontally
to theofport
theanalyzer,
shielded box,
respectively.
inside the
shielded
With
the calibration
the inside
network
the coaxial
cable
fromthe
thecalibration
set JIG and
unit
JIG are
connected
to thecable
portfrom
inside
shielded
box.
In the
whole
With
of the
network
analyzer,
the coaxial
the the
set JIG
and unit
JIG are
connected
measurement
procedure,
the box.
measurement
should
be performed
on thethenon-conductive
table. As
to
the port inside
the shielded
In the whole
measurement
procedure,
measurement should
be
shown in Figures
7 and 8, the measured
VSWR in
satisfies
common
use specification
for the
performed
on the non-conductive
table. As shown
Figuresthe
7 and
8, the measured
VSWR satisfies
WCDMA800,
WCDMA850,
DCS, PCS, WCDMA850,
WCDMA2100,GSM900,
LTE2100DCS,
mobile
the
common use
specificationGSM900,
for the WCDMA800,
PCS,communication
WCDMA2100,
services, and 5G communication networks [13–15]. Figure 9 and Table 3 show the measured
radiation pattern and gain of the antenna respectively.
Appl. Sci. 2020, 10, 1326
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LTE2100 mobile communication services, and 5G communication networks [13–15]. Figure 9 and
Table 3 show the measured radiation pattern and gain of the antenna respectively.
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Figure 7.
7. Measurement
Result (VSWR).
(VSWR).
Figure
Measurement Result
Figure 8.
8. Measurement
result (Smith
(Smith Chart).
Chart).
Figure
Measurement result
Appl. Sci. 2020, 10, 1326
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Figure9.
9.Measurement
Measurementresult
result(Radiation
(RadiationPattern).
Pattern).
Figure
Table 3. Measurement Result (Peak Gain).
Table 3. Measurement Result (Peak Gain).
W800, W850, GSM900
DCS, PCS, WCDMA2100, LTE2100
W800, W850, GSM900
824 MHz
960 MHz
824 MHz
960 MHz
H-plane 0.3 0.3
−4.2
H-plane
−4.2
Peak Gain
Peak Gain
E1-plane 0.7 0.7
−5.3
E1-plane
−5.3
[dBi] [dBi]
E2-plane
−4.2
E2-plane 1.4 1.4
−4.2
Frequency Range
Frequency Range
DCS, PCS, WCDMA2100, LTE2100
1710 MHz
1920 MHz
2170 MHz
1710 MHz
1920 MHz
2170 MHz
−2.9
0.1
−1.2
−2.9
0.1
−1.2
−2.0
1.2 1.2
2.4 2.4
−2.0
−2.5
−2.5
1.7 1.7
2.7 2.7
6.
6. Conclusions
Conclusions
A
A compact
compact multi-band
multi-band internal
internal antenna
antenna for
for mobile
mobile handsets
handsets which
which can
can cover
cover WCDMA800,
WCDMA800,
WCDMA850,
GSM900,
DCS,
PCS, WCDMA2100,
LTE2100 communication
services, 5G
WCDMA850, GSM900,
DCS,
PCS, WCDMA2100,
LTE2100 communication
services, 5G communication
communication
networks
is modeled,
simulated,
and
measured
in this paper.
This
multi-band
networks is modeled,
simulated,
and measured
in this
paper.
This multi-band
internal
antenna
shows
internal
antenna
shows
a
satisfactory
performance
for
a
common
application.
The
demonstration
a satisfactory performance for a common application. The demonstration compared with the actual
compared
with
the produced
actual results
of the
the possibility
antenna of
produced
confirmed
the in
possibility
of
results of the
antenna
confirmed
commercializing
the PIFA
the proposed
◦
commercializing
the
PIFA
in
the
proposed
way.
The
beam
width
at
E-plane
radiation
pattern
is
way. The beam width at E-plane radiation pattern is about 120 , and the gain is 5.6 dBi at 960 MHz.
about
120°,
and
the
gain
is
5.6
dBi
at
960
MHz.
The
radiation
patterns
at
E-plane
from
824
MHz
to
The radiation patterns at E-plane from 824 MHz to 2.17 GHz have similar patterns, and a side lobe
2.17
GHz have
similaraspatterns,
and a increases.
side lobe isHowever,
formed at
H-plane
as the
frequency not
increases.
is formed
at H-plane
the frequency
this
side lobe
is considered
to be a
However,
this
side
lobe
is
considered
not
to
be
a
big
problem
because
it
is
comparatively
very
small
big problem because it is comparatively very small to the main beam which is vertical to the antenna
to
the Therefore,
main beamthe
which
is vertical
to the antenna
Therefore,
designed
multi-band
internal
side.
designed
multi-band
internalside.
antenna
in thisthe
paper
can satisfy
the broadband
antenna
in
this
paper
can
satisfy
the
broadband
characteristics
in
the
view
of
an
impedance,
characteristics in the view of an impedance, radiation pattern, and gain.
radiation pattern, and gain.
Funding: This research was funded by Sangmyung University, grant number 2017-A000-0024.
Funding: This research was funded by Sangmyung University, grant number 2017-A000-0024.
Conflicts of Interest: The author declares no conflict of interest.
Conflicts of Interest: The author declares no conflict of interest.
Abbreviations
Abbreviations
The following abbreviations are used in this manuscript:
The following abbreviations are used in this manuscript:
WCDMA Wideband Code Division Multiple Access
Appl. Sci. 2020, 10, 1326
WCDMA
GSM
DCS
PCS
SMA
FINM
9 of 9
Wideband Code Division Multiple Access
Global System for Mobile Communications
Digital Cross-connect System
Personal Communication Services
Sub Miniature version A
Finite Integration Method
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