457
CPW-Fed Dual Dipole Antenna for WLAN Communication Hyeonjin Lee
Jinwoo Jang, Yeongseog Lim
Dept. of Electrical and Electronics Engineering
Dept. of Electronics Engineering
Dongkang College University
Chonnam National University
Gwang ju Metropolitan City, South Korea
Gwang ju Metropolitan City, South Korea
[email protected]
Abstract- A compact printed dual dipole structure with CPW-fed for WLAN operations is proposed in this paper. The proposed antenna, which consists of dual dipole strips, has modified monopole and modified strips by the ground plane. The proposed antenna has been
obtained
good
radiation
characteristics.
This
antenna
is
effectively covered 5 GHz (5.15-5.825 GHz) bands. The measured peak gain is 2.8 dBi at 5.32 GHz. Effects of varying the monopole dimensions and the ground-plane size on the antenna performance have been studied. Keywords- Dual dipole; CPW-fed; WLAN;
Compact antenna;
a zero input reactance thus eliminating the need for tuning to achieve a conjugate impedance match. We obtain a resonant condition for a half-wave dipole the physical length must be somewhat shorter than a free space half-wavelength, and as the antenna wire thickness is increased, the length must be reduced more to achieve resonance. As usual, the current distribution is placed along the z-axis and for the half-sine wave current on the half-wave dipole, the current distribution is written as (1)
I. Recently,
INTRODUCTION (HEADING 1)
there
communications,
are
and
rapid
developments
in order to
in
wireless
satisfy WLAN
(IEEE
(1)
802.l1a) standards in the 5,150-5,350 MHz and 5,470-5,725, 5,725-5,825MHz bands, wideband operations of the printed 12 dipole antennas are required [ , 1. The printed dipole antennas
Where f3
=
27i / A .This current goes to zero at the ends (for
are very suitable to be integrated on the circuit board of a
Z
communication device, leading to the attractive features of
center( Z
occupying very small volume of the system and decreasing the
radiation pattern. Since it is a z-directed line source, we can
fabrication cost of the final product [3,41. The proposed dipole
=
±A / 4 ) and its maximum value =
0).
(1m)
occurs at the
From this current, we can calculate the
find the electric field as (2)
antenna has two separated dipoles of strip arm that the modified dual monopole and the modified strip line by ground
iii
plane are printed on single sides of a dielectric substrate. In this paper, we demonstrate a novel and simple design of the modified wideband dipole antenna. Details of the antenna design are described, and prototypes of the proposed antenna for WLAN operations in the 5.2 GHz bands have been constructed and tested. The proposed antenna obtained good impedance bandwidth at 5.15-5.35 and 5.725-5.825 GHz for IEEE 802.11a.
=
(2)
Fig. 1 shows the geometry and dimensions of the proposed antenna
for wideband WLAN applications.
The
antenna
consists of two parts which are a modified dual monopole and a modified strip line by ground plane. The two ground planes are placed symmetrically on both sides of the CPW line. A modified strip line by ground plane is matched taper matching method. The dual dipole antenna is excited by the CPW line of
II.
DESIGN OF ANTENNA
A very widely used antenna is the half-wave dipole antenna.
50 [Q] and is printed on the FR4 substrate with a thickness of 1.52 mm and relative permittivity of 3.5. The proposed antenna is fed into coplanar waveguide (CPW)-fed method and is
It is a linear current whose amplitude varies as one-half of be a
matched impedance by adjusting the width of the microstrip
filament of current. Also, it could be imagined to flow on an
line or the gap of planar wave guard. The length and width of
infinitely thin, perfectly conducting, half-wave dipole that has
both strips are optimized by using a commercial tool, Ansoft's
a diameter much smaller than its length. The advantage of a
HFSS, in order to obtain the design goals at both frequency
half-wave dipole is that it can be made to resonate and present
978-1-4244-9799-71111$26.00 ©2011 IEEE
458
IV.
bands of interest. The vertical spacing between the strips and ground plane is adjusted to obtain good impedance matching.
CONCULSION
Wideband operations of a novel printed dual dipole structure antenna have been demonstrated. Constructed prototype is
III.
RESULT AND DISCUSSION
studied WLAN operations in the IEEE 802-11a bands and
Fig. 2 is shown measured and simulated return loss. In this
good antenna performances of the operating frequencies. The
study, Arm_I, Arm_w is attempted optimization for the
proposed antenna has a low profile and is easily able to feed
obtained results of Fig. 2. It is clearly seen that WLAN (IEEE
by
802-11a) band covered. Reasonable agreement between the
characteristics of dual main beam and 12.4 dBi pick gain. The
microstrip
line.
The
proposed
antenna
has
the
measured and the simulated results is obtained. This resonant
proposed antenna is a simple and effective feeding structure in
frequency had a 10 dB impedance bandwidth of 850 MHz
design, has adequate operational bandwidth, and has suitable
(5.15--6.0 GHz). The design parameters of the proposed
radiation patterns such that it is commercially suitable for use
antenna are presented in Table 1.
in WLAN applications.
Table 1. Optimized parameter of proposed antenna parameter Arm 1
Arm w Feed-w Fig.
3
value
parameter
25
GND X
21
9
GND Y
20
appeared
REFERENCES
Value [I]
Zhanwei Zhou, Shiwen Yang, and Zaiping Nie, "A Novel Broadband Printed Dipole Antenna With Low Cross-Polarization" IEEE Trans. on Antennas and propagation, Vol. 55, No. II, November 2007 page 30913093
[2]
Y.L.Kuo and K.L.Wong, "Printed double-T monopole antenna for 2.415.2 GHz dual-band WLAN operations" IEEE Trans. Antennas Propag, vol 51, no 9, pp 2187-2192. Sep 2003. 5.
[3]
Tzyh-Ghuang Ma and Shyh-Kang Jeng "A Printed Dipole Antenna With Tapered Slot Feed for Ultrawide-Band Applications", IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 53, NO. II, NOVEMBER 2005.
Gap current
path
and
it
show
same
characteristics of conventional dipole antenna. Fig. 4 was shown the simulated 3D radiation pattern at 5.3GHz, and was obtained about 12.4 dBi pick gain. Also, the proposed antenna had the characteristics of dual main beam. A manufactured photograph of the proposed antenna is shown in Fig. 7.
[4 ]
J. S. Wong, "Microstrip tapped-line filter design," IEEE Transactions on
Microwave Theory and Techniques, voI.MTT-27, no. I, pp. 44-50, Jan.
1979.
�
: o �;;;: ,..�......... ==-
-�
. .
_Arm_l_
.------, ..-
I I I·. I I .. \ ----t- ------ t
�-20
"0 c:
('J ... � '---_ L..._ .--. -----' �Gnd_x_ � feed_w
l
t ... �------------ ------------� � h T
Figure 1. Geometry of proposed antenna.
. .•
•
,...
• •
I
.3
i'I
•
----1--
-10
� -30
-- Simulated Measured
Q)
P:::
I � I " I -r
.
• •
.. . . .
....
.
•
..
•
I I I '1-----
I I I I ____L _____I _____ ..J_____ _ I I I • • • •
-40 3
4
5
Frequency
6
[GHz]
Figure 2. Return loss of measurement and simulation.
7
459
90
�.. . . .. ..... ................ -......................... .. . --- ..........
_ ......
.
':
,
:� j: ' \'"
::i
"
... .
... ... ...
. .. ... . ..
,
, ..
.
r ..... - ..... -.,.
:: ;
.
180
Figure
3.
Current displacement on conductor plan of proposed antenna.
rETotal[mV]
270
1.Z't67e+00't 1. 1705e+OO't
5.4GHz
1.09't3e+oo,+ 1.0181e+00't
Figure 5. Radiation pattern of proposed antenna.
9. '+18ge+003 8.6S6ge+003 7.89'tge+OO3 7.132ge+003 6.370ge+003 S.60Sge+003 If.8'+68e+003 't.0S'tSe+003 3.3228e+003 2.5608e+003 L 7988e+003 1.0368e+OO3 2.7't76e+OO2
Figure . 3D plot of radiation pattern. 90
Figure 6. Photograph of manufactured antenna.
180
o
270
5.15GHz