CPW-Fed Dual Dipole Antenna for WLAN Communication - IEEE Xplore

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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 ...
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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