A new linear printed vivaldi antenna array with low sidelobe level and high gain for the band 3.5 GHz

play adapters ANVIDIA GeForce GT 1030
 -30
 Processors Intel(R) Core(TM)i-8500CPU @3.00GHz (x8)
 RAM 8 GHz -40
 -50
 0
 Normalized Amplitude (dB)
 -60
 Proposed Vivaldi antenna array
 -5
 Uniform antena array
 -70
 -10
 -180 -140 -100 -60 -20 20 60 100 140 180
 Theta (degree)
 -15
 |(dB) Figure 11. Simulation result of radiation pattern with proposed and
 11 uniform weights.
 -20
 |S
 0.25
 -25
 -25
 0.45
 0.5
 -30
 0.55
 -26
 0.75
 -35
 3.2 3.3 3.4 3.5 3.6 3.7 3.8
 -27
 Frequency (GHz)
Figure 9. Reflection coefficient simulation with different distances of
the back reflector. SLL (dB) -28
 -5 18.0
 -29
 SLL
 Gain
 -10 16.4
 -30
 3.40 3.42 3.44 3.46 3.48 3.50 3.52 3.54 3.56 3.58 3.60
 Frequency (GHz)
 -15 14.8
 Figure 12. Simulation result of SLL over frequency when d f = 0.5λ.
 SLL (dB)
 -20 13.2
 Gain (dBi)
 -25 11.6 the reflector has also been investigated. Figures 9 and 10
 show the variation of the bandwidth, maximum gain
 -30 10.0 and SLL when d f is changed. The maximum bandwidth
 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 can be achieved at the frequency of 3500 MHz while the
 d / 
 f distance is about 0.5λ. As presented in Figure 10, the
 distance df can be determined equal to 0.5λ in terms
Figure 10. SLL and gain simulation with different distances of the of having both a low SLL (-29.2 dB) and the highest
back reflector.
 gain (16.5 dBi). The simulation result of the radiation
 pattern with d f = 0.5λ has been presented in Figures 11
4.4) with the overall dimensions of 503 × 192 × 1.6 mm3. and 12. As presented in Figure 11, the maximum SLL
The back reflector plays a role as a mirror reflecting of the array with the proposed amplitude excitation
the electromagnetic wave according to the image the- weights is 11.5 dB better than that one with uniform
ory [21]. With the presence of the reflector, the elec- excitation weights. Figure 12 shows that the SLL over
tromagnetic wave has been removed from the bottom the frequency range of 3400-3600 MHz always is better
side of this array and has been forwarded to above the than -26 dB, the maximum SLL suppression has been
top side. Thus the maximum gain can be improved. achieved by more than 29 dB in the frequency range of
 d
However, the gain and the radiation direction depend 3490-3550 MHz. Thus, the distance f has been finally
 chosen equal to 0.5λ in this design.
on the distance d f . In this work, all simulations have
been done by using CST Microwave Suite 2018 with
the computer configuration as presented in Table V. 3 Experimental Results
The Vivaldi antenna array has been simulated and op-
timized its elements and feeding-network parameters. A prototype of the proposed Vivaldi array antenna has
The influence of the distance from the antenna array to been fabricated and measured. Figure 13 shows the
L. X. Truong et al.: A New Linear Vivaldi Antenna Array with Low Sidelobe Level and High Gain 35
 0
 3450 MHz
 3500 MHz
 -10
 3520 MHz
 3550 MHz
 3590 MHz
 -20
 -30
 Figure 13. Fabricated Vivaldi antenna array.
 -40
 -4
 -50
 Simulation
 -6 Amplitude (dB) Normalized
 Measurement
 -60
 -8
 -180 -150 -120 -90 -60 -30 0 30 60 90 120 150 180
 Theta (Degree)
 -10
 | (dB)
 -12
 11 Figure 15. Measurement results of the radiation pattern in E-plane at
 |S different frequencies.
 -14
 Table VI
 -16
 The Maximum Measured SLL (dB)
 -18
 Frequency (MHz) 3450 3500 3520 3550 3590
 -20
 3.40 3.45 3.50 3.55 3.60 SLL (dB) -24.5 -27 -26.5 -25.5 -25
 Frequency (GHz)
 Table VII
 Comparison with Other Works
Figure 14. Simulation and measurement results of reflection coeffi-
cients.
 References [16] [10] [8] This work
 Element No. 10 10 8 10
fabricated antenna. Frequency (MHz) 9000 5500 7300 3500
 SLL (dB) -25.3 -26.0 -23.0 -27.0
 The reflection coefficient (S11) has been measured by
using the device Anritsu BTS Master 8222A. Radiation Cross-polarization (dB) -25 -20 -30 -20
patterns have been measured in the far-field region by Maximum gain (dBi) 14.5 17.5 15.7 16.5
using a test antenna chamber, which has the size of 26 Substrate RO4350 RT/5870 RT/5880 RO4003C
× 10 × 10 m3. The measurement has been set with the
frequency step size of 10 MHz and the resolution of
 ◦
the radiation pattern of 1 . The measurement data has The maximum measured SLL is approximately -27.0
been collected and compared to that of the simulated dB, while the simulation result with co-polarization is
one. It is noted that in all figures, the coordinate axes -29.2 dB. On the other hand, neither SLL measurement
(Oz) have been aligned with the maximum direction of nor simulation results is above -20 dB with cross-
the main lobe for the comparison of the simulation and polarization.
measurement results. As indicated in Figure 16, the measurement results
 The measurement and simulation of the reflection still have a slight difference from the simulated ones.
coefficient are presented in Figure 14. The antenna has It may be caused by some reasons. Firstly, SLLs is
the bandwidth of 140 MHz (from 3450 to 3590 MHz) normally very low; thus, it can be changed by inter-
at -10 dB of S11. ference, such as refecting signals from other directions
 The measured radiation patterns at the frequencies of in the measurement process. Secondly, array fabrica-
3450 MHz, 3500 MHz, 3520 MHz, 3550 MHz and 3590 tion may have errors, which is also a factor leading
MHz have been presented in Table VI and Figure 15. to inaccuracy measurement of the radiation pattern.
According to the measurement data, SLLs at those However, the error of -2.2 dB may be an acceptable
frequencies have been suppressed by more than 25 level. For comparison, the measurement data in this
dB. The best SLL suppression has been achieved by work has been compared with that of [8], [10] and [16]
approximately 27.0 dB at the frequency of 3500 MHz. as shown in Table VII. The proposed Vivaldi antenna
 The simulated and measured radiation patterns at array has a SLL of -27.0 dB that is better than SLLs
the frequency of 3500 MHz have been compared in in [8], [10] and [16]. The antenna gain in this work is
detail, as shown in Figure 16. Both co-polarization and about 16.5 dBi that is 1 dB lower than the gain in [10].
cross-polarization data are considered in the E-plane The proposed antenna in this work has better gain and
and H-plane. Obviously, measurement results agree SLL suppression than those in [8] and [16]. The cross-
well with simulation data. The proposed antenna array polarization in this work is equivalent that in [10] and
has the direction of maximum radiation in E-plane. worse than those in [8] and [16].
36 REV Journal on Electronics and Communications, Vol. 10, No. 1–2, January–June, 2020
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L. X. Truong et al.: A New Linear Vivaldi Antenna Array with Low Sidelobe Level and High Gain 37
[21] C. A. Balanis, “Chapter 15: Reflector antennas,” in An- Truong Vu Bang Giang received the BS and
 tenna Theory Analysis and Design, 3rd ed. New York: MS degree from the VNU-University of Sci-
 John Wiley & Sons, Inc, 2011. ences, in 1994 and 1997, respectively, and the
 Dr.-Ing. (Ph.D.) degree in Electrical Engineer-
 ing from the Hamburg-Harburg University of
 Technology, Hamburg, Germany, in collabo-
 ration with the Institute of Communications
 Luong Xuan Truong received the BS and MS and Navigation, German Aerospace Center,
 degree from the VNU-University of Engineer- in 2006. He is now the Executive Deputy Di-
 ing and Technology in 2009 and 2011, respec- rector of Science and Technology Department
 tively. He is now a Ph.D. student at VNU of Vietnam National University, Hanoi, and
 University of Engineering and Technology. He as the Secretary of the National Research Program for Sustainable
 now works at The Authority of frequency Development of North-West Region of Vietnam. He is currently the
 management of Vietnam as a researcher in Deputy Editor in Chief of Journal of Science, Vietnam National
 the field of frequency spectrum policy and University, Hanoi, Member of IEEE MTTs, and APS. He has served
 planning, primarily, the spectrum for IMT sys- as the Steering Committee (Co-Chair), Organizing Committee (Chair
 tems. and Co-Chairs) or Technical Committee of ATC, REV-ECIT, VJMW,
 His current research interests include RF VJISAP conferences in Vietnam; Scientific and Technical Committee,
techniques for spectrum sharing between IMT and other wireless International Transaction Journal of Engineering, Management, Ap-
systems, microstrip antennas for Mobile and active antenna systems. plied Sciences and Technologies (ITJEMAST).
 His current research interests include Microstrip Antennas for
 Mobile and Handheld Devices; Analysis and Design of conformal
 Antennas; Digital Beamforming and Beamsteering for Smart Anten-
 nas.
 Tran Minh Tuan received the BE degree and
 ME degree in Satellite Communications from
 Moscow Institute of Technology in Russia
 in 1994 and 1995, respectively. In 2004, he
 received a Ph.D. degree in electronics and
 telecommunications at Hanoi University of
 Technology, Vietnam. From 2012, he is the
 Associate Professor in the VNU University of
 Engineering and Technology, Hanoi National
 University. Now he is Vice President of Na-
 tional Institute of Information and Communi-
 cations Strategy, MIC of Vietnam.
 His current research interests include master plans, strategies,
 policies in the fields of telecommunications, ICT, Cyber Security, In-
 ternet media and digital economy development, and radio/television
 broadcasting/propagation.