A pencil-beam planar dipole array antenna for IEEE 802.11ac outdoor access point routers
A Pencil-Beam Planar Dipole Array Antenna for
IEEE 802.11ac Outdoor Access Point Routers
Tang The Toan1, Nguyen Manh Hung1
Nguyen Minh Tran1, Truong Vu Bang Giang2,∗
1University of Hai Duong
2VNU University of Engineering and Technology, 144 Xuan Thuy, Cau Giay, Hanoi, Vietnam
Abstract
In this paper, a new design of pencil-beam planar dipole array antenna (PDAA) with reflector back has been
designed and fabricated for IEEE 802.11ac outdoor applications. The proposed antenna is a planar array combined
with a reflector. The planar array is comprised of 4
×
4
×
3 single elements which are placed on an FR4-epoxy
substrate with the size of 241 mm 194 mm 1.6 mm. This design has very good simulation results in terms of the
×
×
radiation pattern, gain and input impedance bandwidth. A very high gain of 18.2 dBi has been achieved at 5.5 GHz,
and the bandwidth is relatively wide with about 23% of the center frequency, which covers the whole bandwidth
allocated for the application. A prototype has been fabricated and measured. The measurement results have very
good agreements with the simulated data.
Received 22 March 2016, Revised 24 June 2016, Accepted 26 September 2016
Keywords: Pencil-Beam, High gain, IEEE 802.11ac, Microstrip antenna.
1. Introduction
band compared with the existing 802.11
standards working at both 2.4 GHz band
and 5 GHz band, and allows to support very
wide bandwidth up to 160 MHz. However,
the propagation loss in this band is about 8
dB higher than that at 2.4 GHz. Therefore,
for outdoor applications especially, antennas
Nowadays, Internet users are demanding
for more streaming videos, database searches,
file transfers, and cloud-based storage
applications on a daily basis. This places
increasing requirements on a future network
ability to provide consistent bandwidth, data
generation in Wi-Fi networking standards,
promises to bring extraordinary improvements
in data rate, wireless reliability, coverage
and quality, which can meet human demands.
This new standard operates only at 5 GHz
In the literature, several high gain antennas
have been proposed [4-7]. Reference [
presented a new design of PDAA including
of 4 8 elements for WLAN application. The
4]
×
antenna can operate at 5.2/5.8 GHz with really
wide bandwidth of 1.97 GHz and high gain
of 17.53 dBi at 5.8 GHz. M. Song and J. Li
∗ Corresponding author. Email.: giangtvb@vnu.edu.vn
26
27
maximum gain of the proposal is about 18.2
dBi at 5.5 GHz and the HBPW is 12
1o at
.
E-plane. A prototype has been fabricated
and measured. The comparison between
simulation results and measured data has also
been presented, and good agreements have
been obtained.
Europe and Japan channel allocations
US and Global channel allocations
Fig. 1. Bandwidth channel allocations for
IEEE 802.11ac.
2. Design and simulation of the array
2.1. Antenna design
In order to build an array, a single element
has been designed to operate at the 5.37 GHz.
The design of the patch follows the equations
of designing the rectangular shape patch in
[
×
] proposed a high gain array antenna with
8 4 elements applied for WLAN/WiMAX
applications. The antenna can cover the
frequency band of 5.07 - 5.94 GHz at -15
dB return loss (or VS WR <
highest gain of the proposed antenna is about
22.78dBi at 5.5GHz and the HBPW is 12
040
at E-plane. In addition, the antenna array
with six antenna elements for the application
The operation frequency range is 5 - 6 GHz,
and the simulated gain is about 11dBi. In
1.43). The
dipole, the antenna consists of two patches
arranged symmetrically on two side of the
FR4-epoxy substrate. The width of the patch
.
is approximately λe f f
impedance of this patch has been calculated
/4 (6 mm), and the input
fed at the center by the 50 Ohm transmission
line, and the width of this line can be deduced
impedance bandwidth, the rectangular patch
has been truncated at the top corner. The final
shape of the element is shown in Fig. 2.
millimeter wave identification (MMID) has
been studied. The antenna was placed on
Taclamplus substrate with thickness of 0.1 mm
and relative permittivity
ꢀ = 2.1 at 60 GHz.
This proposal can achieve the gain of 23 dBi,
but the operational bandwidth is only 3% of
the center frequency.
ꢀ
ꢁ
2
ꢀr2
L
Zin ≈ 90
(1)
ꢀr − 1 W
In this paper, a high gain planar array
ꢂ
ꢀ
ꢁꢃ−1
antenna with 8
for IEEE 802.11ac outdoor applications. The
antenna has been designed on a FR4-epoxy
×
6 elements has been proposed
η
√
W
h
W
h
Zc =
+ 1.393 + 0.677ln
+ 1.44
π ꢀre
(2)
substrate, which has the permittivity of
ꢀ
= 4
.
2
where W is the width of the line, ꢀre is the
effective permittivity of the substrate, and h is
the substrate thickness.
After designing the single patch, the
corporate feeding network has been
and the 3D size of 241 mm 194 mm
×
×
1.6
mm. The constructed array can provide a wide
impedance bandwidth (about 23%) with the
return loss less than -10dB which can well
meet the bandwidth allocated worldwide. The
introduced to construct the array.
In
28
Fig. 2. The configuration of single element.
Table 1. The parameters of the
single element (unit: mm)
Fig. 3. The proposed array antenna.
Parameters Value Parameters Value
Table 2. The parameters of the planar array (unit: mm)
w1
w2
w3
L8
3
4.3
6
L5
L6
L7
6.7
7
9.75
Parameters Value Parameters Value
L
W
L1
241
194
59
L2
L3
L4
59
36
46.5
7.5
particular, the T-junction dividers are utilized
to guarantee the equivalent power at each
element of the array. The proposed array
loss is less than -10 dB. Therefore, it is proved
that the antenna can work well at the channel
bandwidth allocated for IEEE 802.11ac.
consists of 12 sub-arrays, with 2
×
2 elements
in each one. In addition, the sub-arrays
have been spaced at regular distances of
approximately
all sub-arrays will be in phase. The final
geometrical arrangement of 4
elements with dimensions of 241 mm
λ (L1, L2) to ensure that
×
4
×
3
194
×
mm has been constructed and presented in
with the same size of the radiating array, is
placed 6 mm away from the main planar array.
2.2. Simulation Results
The simulated return loss of the array has
shows that the operating range of the antenna
covers from 4.5 to 5.9 GHz when the return
Fig. 4. The simulated return loss of the array.
29
Table 3. The summary of the simulation results
The gain of the antenna model is also
seen that the max gain is 18.2 dBi (at 5.5
GHz) and the average gain of the array at the
whole 5 GHz band is really stable at about
17.5 dBi, which meets the gain requirement
for outdoor applications.
Parameters
Frequency range
Peak gain
Simulation Results
4.5 - 5.9 GHz
18.2 dB (at 5.5 GHz)
3. Fabrication and measurement
3.1. Fabrication of the Array
After optimizing, a prototype has been
to validate the simulation results. It is
then measured by using the Vector Network
Analyzer (VNA) and Near Field System.
Fig. 5. The 3D gain total at 5.5 GHz.
Fig. 7. The fabricated antenna sample.
3.2. Measurement data
The measurement data of the prototype was
compared with the simulation results as given
between measurement and simulation has
been obtained.
Fig. 6. The gain over the frequency band.
The obtained results have been summarized
in the following table:
30
20
Simulation
Measurement
10
0
-10
-20
-30
-90
-60
-30
0
30
60
90
Theta [Degree]
Fig. 8. Comparison between the simulation and
measurement results.
(a) E- plane
Additionally, the measured radiation
patterns in E and H planes have also
been demonstrated and compared with the
simulation in Fig. 9.
20
10
Simulation
Measurement
0
Table 4. Comparison between simulation and
measurement data
-10
-20
-30
Parameters
Bandwidth at
RL=-10 dB
Peak gain
at 5.5 GHz
Side lobe
level
Simulation
1400 MHz
(4.5 - 5.9 GHz) (4.6 - 5.9 GHz)
Measurement
1300 MHz
18.2 dBi
-14.4 dB
18.64 dBi
- 16.32 dB
-90
-60
-30
0
30
60
90
Theta [Degree]
(b) H - plane
It is noticed that the measurement results
in terms of the return loss and the radiation
pattern meet very well with the simulation
data. The measured HPBW of E-plane of
Fig. 9. Comparison of the radiation pattern
of the array.
the proposed array is 12
.
5o, while at the H-
plane it is 17
.
8o. The measured peak gain
has high gain with pencil beam which meets
the requirements of IEEE 802.11ac.
at 5.5 GHz is 18.64 dBi compared to 18.2
dBi in the simulation. In addition, the side
lobe level (SLL) in measurement result is
about -16.32 dB which is much better than
the simulation one, with -14.4 dB of SLL.
Therefore, it is evident that the array antenna
4. Conclusions
This paper has proposed a new design of
planar dipole array antenna. The array antenna
31
comprising of 4
×
4
×
3 elements has been
[4] J. J. J. Y. Y. Lu, H. C. Huang, Design of high gain
planar dipole array antenna for wlan application,
Progress in Ninth International Conference on
Intelligent Information Hiding and Multimedia
Signal Processing (2013) 1–4.
constructed from the FR4-epoxy substrate.
Good agreements between measurement and
simulation have been obtained. It can be a
good product for Wi-Fi ac outdoor access
point (AP) routers.
[5] J. S. L. M. J. Song, A high gain array antenna
for wlan - wimax applications, Progress in
Microwave, Antenna, Propagation, and EMC
Technologies for Wireless Communications
(MAPE), 2011 IEEE 4th International
Symposium 61 (2011) 5–7.
[6] C. H. Lin, D. C. Chang, M. F. Liu, C. K. Chang,
S. T. Peng, High gain antenna array for ieee
802.11a access point, Progress in Microwave
Conference, APMC 2008, Asia Pacific (2008) 1–
4.
Acknowledgements
This work has been partly supported by
Vietnam National University, Hanoi (VNU),
under Project No. QG. 16.27.
References
[7] J. F. J. Saily, A. Lamminen, Low cost high
gain antenna arrays for 60 ghz millimetre wave
identification (mmid), Sixth ESA Workshop on
Millimetre-Wave Technology and Applications
- Fourth Global Symposium Millimetre Waves,
[1] M. R. R. Watson, D. Huang, Understanding the
ieee 802.11ac wi-fi standard, Preparing for the
next gen of WLAN.
[2] S. S. P. Engineer, An introduction to 802.11ac,
Quantenna Communications, INC.
[3] T. V. B. G. N. M. Tran, A sprout - shaped
fan beam linear array antenna for ieee 802.11ac
outdoor wireless access point, The 2016 Vietnam-
Japan International Symposium on Antennas and
Propagation (2016) 102–106.
Espoo, Finland.
[8] R. Garg, P. Bhartia, I. Bahl, A. Ittipiboon,
Chapter 6 - Dipole and Triangular Patch Antennas,
Microstrip Antenna Design Handbook (2001).
[9] K. B. Y. Huang, Chapter 5, Section 5.2,
Subsection 5.2.5: Microstrip Antennas, Antennas
From Theory to Practice (2008).
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