7/28/2019 Printed Dual Band Antena

1/2

Printed compact dual band antenna for2.4 and 5 GHz ISM band applications

S.H. Hwang, J.I. Moon, W.I. Kwak and S.O. Park

A printed compact dipole antenna for dual ISM band (2.44 and

5 GHz) is presented. The proposed antenna fed by using a 50 O

coaxial line occupies a volume of 15 40 1 mm3 (FR-4, permitti-

vity 4.6). The impedance bandwidth for 10 dB return loss is about

400 MHz (from 2170 to 2570 MHz) at 2.4 GHz band and over

2300 MHz (from 4690 to beyond 7000 MHz) at 5 GHz band. The

measured radiation gains range from 1.20 to 1.41 dBi at 2.4 GHz bandand from 2.25 to 3. 44 dBi at 5 GHz band, respectively.

Introduction: Recently, wireless communication devices have required

smaller and more highly efficient components. In particular, the rapid

development of wireless applications has promoted the antenna designed

as a small ground plane for dual ISM band, 2.4 GHz (2400-

2483 MHz) and 5 GHz (5150-5350=5725-5875 MHz), respectively.

This Letter proposes the asymmetric printed dipole-type antenna with

a small ground plane while retaining similar antenna performances to

the conventional PIFA. Unbalanced cur rent distribution of asymmetric

dipole arms is usually excited on the ground plane, and its antenna

performances are greatly influenced by the size of the ground plane

[1, 2]. The dipole arms of asymmetric length are designed to generate

two resonant modes for operating at the 2.4 and 5 GHz bands. Since

the asymmetric dipole arms, including a ground part, act as a primary

source of radiation, the small ground plate strongly influences the

antenna performance including return loss, bandwidth, and radiation

gain of operating frequencies [3]. The proposed printed dipole

antenna is very suitable for integration with wireless local area net-

work (WLAN) applications.

Antenna design: Fig. 1 shows the geometry of the proposed antenna

with printed dipole with different arm lengths. The geometrical

parameters of the length and width of striplines are optimised in an

attempt to achieve design goals at both the 2.4 and 5 GHz bands. The

ground plane and dipole antenna are printed on the same plane. The

conductor plane of the opposite side of the PCB is removed. An inner

feed conductor of the coaxial cable is connected to part A of folded

arm. The outer shielding ground of the coaxial cable is connecteddirectly to part E of the ground plate. To achieve 2.4 GHz band

resonant mode, the folded arm starting from the feeding point (part A)

to the end point (part D) passing through part C is chosen to be

31 mm, which corresponds approximately to a quarter wavelength at

the operating frequency of 2.4 GHz. Also, the folded configuration of

part D is inherently to achieve broader bandwidth and a compact

structure. A refinement is obtained by forming a ground plane from

part E to part F, the length of which is about 13 mm. It behaves

electrically as approximately a quarter wavelength at the 5 GHz band.

The small ground parts of E and F act also an important role to radiate

in the 2.4 GHz band as well as the 5 GHz band. This means that the

antenna would have good performance for real wireless communica-

tion devices which have only a small amount of space available at the

ground part.

feeding cable

40

9

13

14

2

12

4

6

5

15

235

units:mm

y

xz

CD

B A E

F

Fig. 1 Geometry of proposed antenna

Result: Computed and measured return loss data against frequency

are compared in Fig. 2. The simulation result was obtained from an

Ansoft HFSS. The return loss in Fig. 2 shows that the proposedantenna can operate to cover enough bandwidth at both 2.4 and 5 GHz

resonant frequency bands. The dominant current distribution occurred

at part A to D, which has an electrically-active quarter wavelength

length at 2.4 GHz band, and the induced current occurred also at part E to

F. In 5 GHz band, a folded arm from part A to part D behaves as a half

wavelength monopole antenna, and forming a folded monopole arm does

not change significantly the current distribution on the half wavelength of

antenna. However, these effects cause the overall induced current in part

C and D to be in phase with the current at point B. The simulated and

measured radiation patterns for the designed antenna at resonant

frequencies of 2440 and 5800 MHz are plotted in Figs. 3 and 4,

respectively. As shown in Figs. 3 and 4, the radiation patterns are

omni-directional and very similar to those of the x-directed dipole

antenna. The simulated and measured results agree well with each

other at both the 2.4 and 5 GHz band. The maximum simulated and

measured radiation gains are 1.95 and 1.41 dBi at 2.44 GHz and 3.24 and

3.44 dBi at 5.8 GHz, respectively.

-40

return

loss,dB

frequency, GHz

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0

measured resultsimulated result

0

-10

-20

-30

2.4 GHz ISM band 5 GHz ISM band

Fig. 2 Measured and simulated return losses of proposed antenna

Fig. 3 Measured and simulated radiation patterns at 2440 MHz

measured result simulated resulta x-y plane (Ef)b y-z plane (Ef)c x-z plane (Ey)

ELECTRONICS LETTERS 9th December 2004 Vol. 40 No. 25

http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-

7/28/2019 Printed Dual Band Antena

2/2

Fig. 4 Measured and simulated radiation patterns at 5800 MHz

measured result simulated resulta x-y plane (Ef)b y-z plane (Ef)c x-z plane (Ey)

Conclusion: A printed and compact dual band antenna has been

proposed and implemented. The proposed antenna indicates not only

a broad impedance bandwidth but also a good radiation performance in

spite of the small volume of 15 40 1 mm3 (FR-4). These character-

istics are very attractive for 2.4 and 5 GHz dual ISM band applications.

Acknowledgment: This work was supported by the National Research

Lab. (NRL) of the Ministry of Science and Technology, Korea, under

contract no. M1-0203-0015.

# IEE 2004 27 August 2004Electronics Letters online no: 20046579

doi: 10.1049/el:20046579

S.H. Hwang, J.I. Moon, W.I. Kwak and S.O. Park (School of

Engineering, Informat ion and Communications Universi ty, Daejeon,

Korea)

E-mail: hwangsh@icu.ac.kr

References

1 Lin, C.-C., Lee, G.-Y., and Wong, K.-L.: Surface-mount dual-loopantenna for 2.4=5 GHz WLAN operation, Electron. Lett., 2003, 39,(18), pp. 13021304

2 Moon, J.-I., Sim, D.-U., and Park, S.-O.: Compact PIFA for 2.4=5 GHzdual ISM-band application, Electron. Lett., 2004, 40, (14), pp. 844845

3 Huynh, M.-C., and Stutzman, W.: Ground plane effects on planarinverted-F antenna (PIFA) performance, IEE Proc., Microw. AntennasPropag., 2003, 150, (4), pp. 209213

ELECTRONICS LETTERS 9th December 2004 Vol. 40 No. 25