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A Low-Profile Ultra-Wideband Directional
Radiation Conformal Antenna Filled with Medium
Shu LIN, Jian-lin JIAO, Shou-lan LIU, Yu-wei ZHANG, Cai-tian YANG School of Electronics and Information Engineering, Harbin Institute of Technology
Harbin, China
Abstract - A low-profile ultra-wideband directional
radiation conformal antenna filled with medium is proposed. The antenna is a TEM horn structure consisting of a conformal triangular metal sheet, a metal floor with a radius of curvature
of 127 mm, and a loading medium. The antenna was modeled and simulated in the CST Microwave Studio® software. The simulation results show that the VSWR of the antenna is less
than 2.5 in the frequency range of 4.8-21.1 GHz and has an impedance bandwidth of 4.4:1. The gain reaches 7.2-9.6 dBi in the frequency range, the lobe width is 23°-76.4° and the
maximum height is 12 mm. The antenna can be used in the field of conformal antennas on cylindrical aircraft surface.
Index Terms — Low profile, ultra-wideband, directional,
conformal.
1. Introduction
Ultra-wideband directional radiating antennas have the
characteristics of wide frequency band and good directivity.
They are widely used in the field of electronic
reconnaissance, DOA and passive radar [1-3]. These
antennas are generally installed on aircraft and sometimes
need to conform to the surface of aircraft which has a greater
impact on antenna performance [4-6]. Considering the
application field, it is required that the working state of the
antenna is the receiving antenna. Therefore, the impedance
matching requirements of the antenna can be appropriately
reduced, so the VSWR of the antenna is generally required
to be less than 2.5 [7]. While the requirement for
directionality is high, so it is necessary to ensure a stable
directional radiation pattern within a wide band. [8].
In this paper, a low-profile ultra-wideband directional
radiation conformal antenna is designed, characterized by its
low profile, which is in conformity with the cylindrical
surface, and has an ultra-wideband stable pattern bandwidth
and impedance bandwidth. The antenna is modeled and
simulated in CST Microwave Studio® software. The design
results and simulation analysis results are given in this paper.
The paper is divided into the following sections: 1.
Introduction, 2. Antenna Structure, 3. Simulation Results
and Analysis, 4. Characteristics of the Proposed Antenna, 5.
Conclusion.
2. Antenna Structure
Fig. 1 shows the structure of the proposed antenna. The
antenna consists of two metal plates filled with relative
permittivity εr=3.3 and loss tangent tanδ=0.003 medium
material and is fed with coaxial lines. Due to the introduction
of the filling medium material, the antenna does not
introduce special supporting parts.
(a) (b)
(c) (d)
Fig. 1. The structure of the proposed antenna. (a) Aerial
view. (b) Front view. (c) Left view. (d) Top view.
3. Simulation Results and Analysis
(1) Simulation Results
Fig. 2 shows the simulation results of the reflection
coefficient, normalized pattern and gain of the antenna. It
can be seen that the VSWR of the antenna in the frequency
range of 4.8-21.1 GHz is less than 2.5. The radiation pattern
in this band is directional radiation, with a half-power lobe
width of 23°-76.4° and in-band gain of 6.05-9.51 dBi.
Simulation results show that the antenna exhibits an ultra-
wideband directional radiation effect.
(a) (b)
85.2
18.6
unit:mm
100
8.3
unit:mm
79.1
18.6
unit:mm
5 10 15 20
0
5
10
15
20
25
VS
WR
Frequency/GHz
-30
-20
-10
0
0
30
60
90
120
150
180
210
240
270
300
330
-30
-20
-10
0
f=5GHz
f=12GHz
f=17GHz
2018 International Symposium on Antennas and Propagation (ISAP 2018)October 23~26, 2018 / Paradise Hotel Busan, Busan, Korea
[ThP-21]
707
(c)
Fig. 2. (a) The VSWR of the antenna. (b) The pattern of the
antenna. (c) The gain of the antenna.
(2) Analysis of Simulation Results
It is analyzed from the perspective of impedance. The
designed feeding height of the antenna at the coaxial feed
end is h=0.57 mm, and the structure presents a gradient form
of the microstrip transmission line. According to the
impedance calculation formula (1) of the microstrip
transmission line, it can be calculated that the impedance of
the feed port Z01 is equal to 50.33 Ω.
1
01
1
2
120 21 ln 1
2
11 1 1 1 10
2
e
e r
W WZ
h h
h
W
(1)
where W=1 mm, h=0.57 mm, εr=3.3. The structure can be
regarded as a radiation gap at the radiation end, and its
impedance can be calculated by the formula (2).
2
02
30
r
DZ
l
(2)
Where D is the directivity of the antenna, l is the width of
the antenna at the radiation end which is equal to 18.6 mm.
The impedance Z0 of the radiation end is equal to 207.5 Ω
because of the existence of the medium. It can be seen from
Fig.3 that the impedance Z0 can be well matched with the
impedance Z02 of the antenna at the radiation end in a wide
frequency range.
Fig. 3. The impedance of the radiation end and the
impedance of the antenna.
4. Characteristics of the Proposed Antenna
Comparing the antenna of this article with those in other
literatures, it can be seen that under the same antenna profile,
the proposed antenna has wider impedance bandwidth and
better directional radiation characteristics which is due to the
fact that the antenna is filled with medium and the
wavelength of the waveguide is reduced. The structural
feature of the antenna is that it is a conformal antenna with a
cylinder with a small radius of curvature, so it has a very
broad application field.
5. Conclusion
A low-profile ultra-wideband directional radiation
conformal antenna loaded with medium is proposed. The
antenna can be conformal to a cylindrical aircraft and can be
widely used in the field of electronic reconnaissance, DOA
and passive radar.
Acknowledgment
The authors would like to thank CST Ltd. Germany, for
providing the CST Training Center (Northeast China Region)
at our university with a free package of CST MWS software.
References
[1] Nitika et al., “Novel UWB slotted I-shaped flexible microstrip patch
antenna design for satellite reconnaissance, amateur radio, future soil moisture and sea surface salinity missions,” 2016 Progress in
Electromagnetic Research Symposium (PIERS), Shanghai, 2016, pp.
5056-5061. [2] R. Zhou and H. Xin, “A novel direction of arrival estimation
technique using a single UWB antenna,” 2010 IEEE Antennas and
Propagation Society International Symposium, Toronto, ON, 2010, pp. 1-4.D.
[3] M. Pachiyaannan and G. K. D. P. Venkatesan, “Dual-Band UWB
Antenna for Radar Applications: Design and Analysis,” 2016 8th International Conference on Computational Intelligence and
Communication Networks (CICN), Tehri, 2016, pp. 196-199.
[4] V. Sachdeva, P. K. Mishra, D. Sharma and S. D. Gupta, “Design of Antenna Conformal to Cylindrical Surface for Aircrafts,” 2015 Fifth
International Conference on Communication Systems and Network
Technologies, Gwalior, 2015, pp. 33-36. [5] D. L. Zeppettella and M. Ali, “Analysis of structural effects on
conformal antenna performance,” 2017 IEEE International
Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting, San Diego, CA, 2017, pp. 2545-2546.
[6] R. Sahoo, D. Vakula and N. V. S. N. Sarma, “A wideband conformal
slot antenna for GPS application,” 2017 Progress in Electromagnetics Research Symposium - Fall (PIERS - FALL),
Singapore, 2017, pp. 589-592.
[7] PENG Xu-fei，LI Li-gong. “Research and Design of Onboard
Double Antenna Orientation BD2 Receiver,” Journal of Ordnance
Equipment Engineering, 2017(5):110-113. (in Chinese) [8] D. Patron, D. Piazza and K. R. Dandekar, “Wideband planar antenna
with reconfigurable omnidirectional and directional radiation
patterns,” in Electronics Letters, vol. 49, no. 8, pp. 516-518, April 11 2013.
5 10 15 20
0
2
4
6
8
10
Gai
n/d
Bi
Frequency/GHz
6 8 10 12 14 160
50
100
150
200
250
300
Imp
edan
ce/
Frequency/GHz
Z0
Z02
2018 International Symposium on Antennas and Propagation (ISAP 2018)October 23~26, 2018 / Paradise Hotel Busan, Busan, Korea
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