A Pencil-Beam Planar Dipole Array Antenna for IEEE 802.11ac Outdoor Access Point Routers. 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..
VNU Journal of Science: Comp. Science & Com. Eng., Vol. 32, No. 3 (2016) 26–31
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
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
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 rate [1, 2]. The IEEE 802.11ac, the ﬁfth generation in Wi-Fi networking standards, promisestobringextraordinaryimprovements in data rate, wireless reliability, coverage and quality, which can meet human demands. This new standard operates only at 5 GHz
Correspondingauthor. Email.: firstname.lastname@example.org
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 required to gain more than 10 dBi .
In the literature, several high gain antennas have been proposed [4-7]. Reference  presented a new design of PDAA including of 48 elements for WLAN application. The 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
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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
Europe and Japan channel allocations
US and Global channel allocations
Fig. 1. Bandwidth channel allocations for IEEE 802.11ac.
 proposed a high gain array antenna with 84 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 VSWR < 1:43). The 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 of IEEE 802.11a has been developed in . The operation frequency range is 5 - 6 GHz, and the simulated gain is about 11dBi. In , a high gain antenna array for 60 GHz millimeter wave identiﬁcation (MMID) has been studied. The antenna was placed on Taclamplussubstratewiththicknessof0.1mm and relative permittivity = 2:1 at 60 GHz.
simulation results and measured data has also been presented, and good agreements have been obtained.
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 . As the structure of double-sided printed dipole, the antenna consists of two patches arranged symmetrically on two side of the FR4-epoxy substrate. The width of the patch is approximately ef f=4 (6 mm), and the input impedance of this patch has been calculated by the equation (1) . This single element is fed at the center by the 50 Ohm transmission line, and the width of this line can be deduced from the equation (2). In order to improve the impedance bandwidth, the rectangular patch has been truncated at the top corner. The ﬁnal shape of the element is shown in Fig. 2.
This proposal can achieve the gain of 23 dBi, but the operational bandwidth is only 3% of the center frequency.
Zin 90r 1 W (1)
In this paper, a high gain planar array antenna with 86 elements has been proposed for IEEE 802.11ac outdoor applications. The antenna has been designed on a FR4-epoxy substrate,whichhasthepermittivityof = 4:2 and the 3D size of 241 mm194 mm1.6 mm. Theconstructedarraycanprovideawide
1 Zc = p +1:393+0:677ln +1:44
re (2) where W is the width of the line, re is the eective permittivity of the substrate, and h is the substrate thickness.
impedance bandwidth (about 23%) with the After designing the single patch, the return loss less than -10dB which can well corporate feeding network has been meet the bandwidth allocated worldwide. The introduced to construct the array. In
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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 w1 3 w2 4.3 w3 6 L8 7.5
Parameters Value L5 6.7 L6 7 L7 9.75
Table 2. The parameters of the planar array (unit: mm)
Parameters Value Parameters Value L 241 L2 59
W 194 L3 36 L1 59 L4 46.5
particular, the T-junction dividers are utilized to guarantee the equivalent power at each element of the array. The proposed array 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 (L1, L2) to ensure that all sub-arrays will be in phase. The ﬁnal
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.
geometrical arrangement of 4 4 3 elements with dimensions of 241 mm 194 mm has been constructed and presented in Fig. 3. The reﬂector, which is an FR4 board 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 been indicated in Fig. 4. The simulated result
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.
T.T. Toan et al. / VNU Journal of Science: Comp. Science & Com. Eng., Vol. 32, No. 3 (2016) 26–31 29
The gain of the antenna model is also Table 3. The summary of the simulation results
presented in Fig. 5 and Fig. 6. It is easily 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 fabricated (as shown in Fig. 7) in order 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.
Fig. 6. The gain over the frequency band.
3.2. Measurement data
The measurement data of the prototype was compared with the simulation results as given
in Fig. 8. It is clearly that good agreement
The obtained results have been summarized in the following table:
between measurement and simulation has been obtained.
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20 Sim ulation
M easurem ent
-90 -60 -30 0 30 60 90
Fig. 8. Comparison between the simulation and measurement results.
(a) E- plane
Additionally, the measured radiation
patterns in E and H planes have also 20 been demonstrated and compared with the
simulation in Fig. 9. 10
Table 4. Comparison between simulation and 0 measurement data
M easurem ent
Parameters Bandwidth at RL=-10 dB Peak gain at 5.5 GHz Side lobe level
Simulation 1400 MHz (4.5 - 5.9 GHz)
Measurement 1300 MHz (4.6 - 5.9 GHz)
- 16.32 dB
-90 -60 -30 0 30 60 90
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 the proposed array is 12:5o, while at the H-plane it is 17:8o. The measured peak gain 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
(b) H - plane
Fig. 9. Comparison of the radiation pattern of the array.
has high gain with pencil beam which meets the requirements of IEEE 802.11ac.
This paper has proposed a new design of planardipolearrayantenna. Thearrayantenna
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comprising of 4 4 3 elements has been 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.
This work has been partly supported by Vietnam National University, Hanoi (VNU), under Project No. QG. 16.27.
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