Low Profile Dual-Polarized Wideband Antenna
Abdul Sattar Kaddour1, Serge Bories1, Anthony Bellion2 and Christophe Delaveaud1 1CEA, LETI, MINATEC Campus, Univ. Grenoble-Alpes, 38054 Grenoble, France
2CNES 18 avenue Edouard Belin, 31401, Toulouse, France
Abstract - A low profile dual-polarized unidirectional
wideband antenna based on two crossed magneto-electric dipoles is proposed. The antenna consists in folding the radiating element, the height of the radiation element is reduced to 0.11λ0
where λ0 is the wavelength at the lowest operation frequency for a standing wave ratio (SWR) <2 corresponding to a reduction factor of 37%. The antenna has been prototyped using 3D
printing technology and evaluated in an anechoic chamber. The measurement results are in excellent agreement with simulations. The measured input impedance bandwidth is 54.2% from 1.8
GHz to 2.9 GHz with SWR<2.
Index Terms — wideband antenna, magneto-electric dipole, dual polarized, unidirectional radiation, 3D printing.
1. Introduction
Recently, many efforts has been made to design wideband
antennas satisfying telecommunication requirements such as
wide impedance matching, unidirectional and stable radiation
pattern with low profile and light weight needs. The state of
art shows that “Magneto Electric” dipole antennas proposed
by K. M. Luk [1]-[2] are promising solutions with excellent
radiation characteristics and wide impedance matching. These
antennas are based on the concept of complementary antenna
or Huygens source [3]. However, these antennas suffer from
large height size. In order to reduce the antennas height many
techniques were proposed as dielectric loading materials [4]
or folding structure [5].
In this paper, we propose a method for reducing the height
of the dual-polarized wideband magneto-electric dipole
antenna presented in [2] by folding the antenna structure.
Antenna miniaturization can be achieved by increasing the
current path length. The height of the proposed radiating
element is only 0.11λ0, which is reduced by 37% comparing
with the original design.
2. Antenna Design
A 3D view of the proposed antenna is presented Fig. 1(a),
the antenna consists of four horizontal plates operate together
as two crossed electric dipoles. Each horizontal plate is
shorted to the ground plane through two vertical folded plates
Fig. 1(b). Each adjacent vertically oriented plates and the
ground between them act like a magnetic dipole. These
elements form two crossed magneto-electric dipoles
generating a dual polarization at ± 45°.
The antenna is excited by two “Г” shaped probes (Fig. 1.(c))
built using three portions of PCB on RT5870 substrate having
a thickness of 0.8 mm and relative permittivity of 2.3. These
probes are orthogonally placed in the gaps between the
vertical folded plates. The port 1 is the lower probe and the
port 2 is the higher probe. Two 50 Ω SMA connectors are
placed under the ground plane and connected to the two
feeding probes. The shorter and the higher probes excite the
+45° and -45° polarization respectively.
(a)
(b) (c)
Fig. 1. 3D view of the proposed antenna.
To improve the radiation characteristics the magneto-
electric dipoles are mounted on a square cavity. The position
and the dimension (, ) of the folded part of the vertical
plates are optimized to obtain a maximum impedance
bandwidth while maintaining an electrically small size of the
radiation element. Detailed dimensions of the antenna
structure are summarized in Table 1.
(a) (b)
Fig. 2. a) Photo of 3D printed horizontal and vertical
folded plates, b) Photo of the prototyped antenna.
Proceedings of ISAP2016, Okinawa, Japan
Copyright ©2016 by IEICE
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Each horizontal plate and vertical plates where combined in
a single piece and fabricated by 3D printing technology (Laser
Sintering) in Plastic PC/ABS and electroplated with a 50 µm
copper thickness. These pieces have a granular finishing due
the 3D printing technique and a dark color caused by copper
oxidation see Fig. 2. The antenna total weight is 105 g.
TABLE I
Dimensions of the proposed antenna (mm)
Parameter G S L w ℎ ℎ
Value 112 47 6.5 27 14 2 16
Parameter t
Value 1 1 10 15.5 36 13 3
Parameter
Value 17.3 36 15 2.8 5 4.5 6.5
3. Results and discussion
The simulated and measured standing wave ratio (SWR)
and total realized gain from Port 1 and Port 2 are shown in the
Fig. 2. It can be seen that the antenna operates from 1.8 to
3.2 GHz with a bandwidth of 56% (SWR<2) and from 1.77 to
3.14 GHz with a bandwidth of 55.8% (SWR<2) for ports 1
and Port 2, respectively, the common bandwidth of the two
ports is 54.2% (SWR <2). Over the operating frequency the
measured broadside gain at ( = 0°) for port 1 and for port 2
are 7.2 dBi ± 1.5 dB. The difference of 1 dB between
simulation and measurement is probably due to the low
conductivity of copper used in fabrication process and the
difference between port 1 and Port 2 is due to the dissymmetry
between the two excitation probes. The coupling between Port
1 and Port 2 is below -25 dB in the operation band.
Fig. 3. Simulated and measured SWRs and gains of the
low profile dual polarized antenna.
The proposed radiation element of the antenna has a
dimension of 0.36 × 0.36 × 0.11 compared to the
antenna in [2] where the radiation element has a dimension of
0.33 ×0.33 ×0.18where is the wavelength at the
lowest operation frequency for SWR<2 (without taking into
account the ground plane dimension).
The simulated and measured normalized realized gain
radiation pattern at 1.8 GHz and 3 GHz for port 1 and port 2
at = +45° and = −45° respectively are depicted in
Fig. 4. The radiation patterns are identical for both ports. At
1.8 GHz the -3dB beam for both ports is 72° and 75°
respectively. At 3 GHz, the antenna electrical size becomes
too large which explains the poor beam width of 45° and 43°
for port 1 and port 2 respectively. The cross-polarization level
is always less than -19 dB.
Fig. 4. Simulated and measured radiation patterns.
4. Conclusion
A low profile dual-polarized antenna based on magneto-
electric dipole antenna has been designed and prototyped.
Measured and simulated results are in good agreement, the
antenna has an impedance bandwidth of 54.2% with SWR<2
and a broadside gain varying from 6 to 9 dBi. These
performances prove the feasibility and reliability of the 3D
printing technology in wireless communication for low cost
fabrication. The radiation element height was reduced to
0.11λ0 corresponding to a reduction factor of 37% compared
to [2]. In the next prototypes, 3D printed pieces will be
electroplated with a better quality copper to improve the
conductivity of the radiation elements.
Acknowledgment
The authors wish to thank the CNES, French space agency
for partially funding this work.
References
[1] Luk, K. M., & Wong, H. (2006). A new wideband unidirectional
antenna element. Int. J. Microw. Opt. Technol, 1(1), 35-44.
[2] Mingjian Li and Kwai-Man Luk, "Wideband Magnetoelectric Dipole Antennas With Dual Polarization and Circular Polarization," in IEEE
Antennas and Propagation Magazine, vol. 57, no. 1, pp. 110-119, Feb.
2015. [3] A. Clavin, "A new antenna feed having equal E- and H-plane patterns,
"iRE Trans. Antennas Propag., vol. 2, no.3, pp. 113-119, Jul. 1954.
[4] Siu, L.,Wong, H., & Luk, K. M. (2009). A dual-polarized magneto-electric dipole with dielectric loading. Antennas and Propagation, IEEE
Transactions on, 57(3), 616-623.
[5] Mingjian Li; Luk, Kwai-Man, "A low-profile magneto-electric dipole antenna," in Electromagnetics; Applications and Student Innovation
(iWEM), 2012 IEEE International Workshop on , vol., no., pp.1-2, 6-9
Aug. 2012.
Sim. Co Polar Sim. Cx Polar Meas. Co Polar Meas. Cx Polar
Port 1 at 1.8 GHz
-20 -10 0 +90°
+60°
+30°
0°
-30°
-60°
-90°
-120°
-150°
+180°
+150°
+120°
dBi
-20 -10 0 +90°
+60°
+30°
0°
-30°
-60°
-90°
-120°
-150°
+180°
+150°
+120°
dBi
-20 -10 0 +90°
+60°
+30°
0°
-30°
-60°
-90°
-120°
-150°
+180°
+150°
+120°
dBi
-20 -10 0 +90°
+60°
+30°
0°
-30°
-60°
-90°
-120°
-150°
+180°
+150°
+120°
dBi
Port 2 at 1.8 GHz
Port 1 at 3 GHz Port 2 at 3 GHz
1.5 1.7 1.9 2.1 2.3 2.5 2.7 2.9 3.1 3.3 3.50
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
5.5
6
Frequency (GHz)
SW
R
1.5 1.7 1.9 2.1 2.3 2.5 2.7 2.9 3.1 3.3 3.50
1
2
3
4
5
6
7
8
9
10
11
12
Realiz
ed g
ain
at θ
=0°(
dB
i)
Sim. (Port 1) Sim. (Port 2) Meas. (Port 1) Meas. (Port 2)
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