A 2.4-GHz Printed Meander-Line Antenna for USB

546IEEE MICROW A VE AND WIRELESS COMPONENTS LETTERS,VOL.15,NO.9,SEPTEMBER 2005

A 2.4-GHz Printed Meander-Line Antenna for USB

WLAN With Notebook-PC Housing

C.-C.Lin ,Student Member,IEEE ,S.-W.Kuo ,Student Member,IEEE ,and H.-R.Chuang ,Member,IEEE

Abstract—A 2.4-GHz meander-line antenna printed on a USB-WLAN card is presented for WLAN applications.The HFSS 3-D EM simulator is employed for design simulation.The printed meander-line antenna is realized on a FR-4PCB substrate.The measured VSWR is less than 2from 2.4to 2.5GHz.Besides different orientations,the meander-line antenna printed on a simulated USB-WLAN card was attached to the side wall of a notebook-PC to investigate the PC housing effects on the antenna radiation patterns.

Index Terms—Antenna,meander-line,notebook-PC housing,printed,WLAN.

I.I NTRODUCTION

I

N THE WLAN card design,the typical type is the PCMCIA WLAN card.Many printed antennas have been reported for the PCMCIA applications [1],[2].Recently,the miniaturized WLAN card which uses the USB connector can be used on the external of the notebook PC.The USB connector can be bended and hence the antenna on the WLAN card can be adjusted with different orientation when attached on the side wall of a note-book PC (see Fig.1top and Fig.3bottom).Hence,the using posture of a USB-WLAN card can be adjusted for better recep-tion and communication performance.

This letter presents a 2.4-GHz meander-line printed antenna for WLAN applications [3].The HFSS 3-D EM simulator is used for design simulation.The antenna is fabricated on a double-sided FR-4printed circuit board for experimental measurements.The antenna patterns and polarizations are presented and compared for different -orientation usages.Also,the meander-line antenna printed on a USB-WLAN card was placed at different positions on a notebook-PC to investigate the effects of the notebook -PC housing on the antenna radiation patterns.

II.A NTENNA D ESIGN

A useful way to make the conventional linear wire antennas shorter is to bend a wire according to some geometrical con?g-urations,such as the structure of the mender line [4],[5].Fig.1shows the illustration of a printed meander-line antenna for the USB-WLAN card.The ground plane to emulate the RF board is about

5020mm and the space for the printed meander-line antenna is about

1020mm .It is noted that the selection of

Manuscript received December 1,2004.The review of this letter was arranged by Guest Editors H.Nikookar and R.Prasad.

The authors are with the Institute of Computer and Communication Engi-neering,Department of Electrical Engineering,National Cheng-Kung Univer-sity,Tainan,Taiwan,R.O.C.(e-mail:chuang_hr@https://www.360docs.net/doc/d110600546.html,.tw).Digital Object Identi?er

10.1109/LMWC.2005.855387

Fig.1.Illustration of a printed meander-line antenna for the USB-WLAN card attached to a notebook-PC and the simulated antenna current distribution on the top and ground

plane.

Fig.2.Photograph of a realized antenna on a FR-4substrate and measured antenna input VSWR.

the space for the antenna and ground printed in the backside is the same with ones of a practical case.The substrate is the FR-4PCB.The meander shape,with the width and gap of the meander-line antenna are 1and 2mm,respectively,has been tuned to resonate at 2.4-GHz band.Fig.1also shows the simu-lated antenna current distribution.Fig.2shows the photograph of a realized antenna on a FR-4substrate and measured antenna

1531-1309/$20.00?2005IEEE

LIN et al.:2.4-GHz PRINTED MEANDER-LINE ANTENNA

547

Fig.3.Measured H-plane antenna patterns of different antenna orientations.

input VSWR.The measured VSWR is less than 2from 2.4to 2.5GHz.

As mentioned,the meander-line antenna printed on the USB-WLAN card can be placed with arbitrary orientations due to the adjustable USB connector.As shown in Fig.3(bottom),three practical orientations are considered here.?Case 1:the vertical orientation.

?Case 2:the horizontally-upward orientation.?Case 3:the horizontally-lateral orientation.

Fig.3(top)shows the measured H-plane antenna patterns.As shown in the ?gure,if the antenna is vertically oriented (case 1),the dominant polarization

is -?eld and the pattern is quite omni-directional.When the meander-line antenna is placed horizontally with two different orientations (case 2and 3),the measured patterns show that

the -

and -polarization ?elds of the two cases are close with an average-gain difference of about 4dB.Also,the average antenna gain of the case 2and 3is about 8to 10dB less than that of the case 1for

the -

and -polarization ?elds.

Here,the average gain in the

H-plane,

,is the average of gain values of the

associated points in the H-plane which can be formulated

as

(1)

where

is the value of the antenna gain at each speci ?ed posi-tion.In this letter,we have measured 180points of the antenna gain value in the H-plane (2per point).The average gain is the average of gain values of the associated 180points.

III.E FFECTS OF N OTEBOOK -PC H OUSING

To study the effects of the notebook-PC housing on the antenna performance,the fabricated meander-line antenna (printed on a simulated USB-WLAN card)was attached to

the side wall of a notebook-PC and placed in a chamber room to measure the antenna patterns.Fig.4shows the measured H-plane patterns of three different antenna orientation alone (in free space)and those when attached to a notebook-PC for comparison.

a)Vertical-orientation:It is observed that the average gain levels of

both -

and -pattern are close to those in free space,except that

the -pattern has a null in the 210di-rection when the antenna is attached to the notebook-PC.It might be due to the blocking effect of the open screen of the laptop.

b)Horizontally-upward orientation:Since the main body of the notebook PC lying on the same plane

(-plane)of the printed antenna,signi ?cant housing effects are expected and the measured results show that

both -

and -pat-tern have about 10to 15dB average attenuation.

c)Horizontally-lateral orientation:The same results as in (b)are observed and also

both -

and -pattern have about 10to 15dB average attenuation due to the housing effect.The above comparison shows that it seems for the 2.4-GHz meander-line printed antenna the vertical orientation posture has less in ?uence by the notebook-PC housing on the antenna pattern performance.

IV .C ONCLUSION

This letter presents a 2.4-GHz meander-line antenna printed on a simulated USB-WLAN card for external WLAN applica-tion.The HFSS 3-D EM simulator is employed for design sim-ulation.The printed meander-line antenna is realized on a FR-4PCB substrate.The measured VSWR is less than 2from 2.4to 2.5GHz.Since the USB connector can be bended and hence the antenna on the WLAN card can be adjusted with different ori-entation for better reception and communication performance.Measured results show that,if the antenna is vertically oriented,

548IEEE MICROW A VE AND WIRELESS COMPONENTS LETTERS,VOL.15,NO.9,SEPTEMBER

2005

Fig.4.Measured H-plane patterns of the fabricated 2.4-GHz printed meander-line antenna with three different orientations attached to the side wall of a notebook-PC.

the dominant polarization

is -?eld and the pattern is quite omni-directional.While for the antenna placed horizontally,the measured patterns show that the average antenna gain is about 8to 10dB less than that of the vertical orientation for both of

the -

and -polarization ?elds.The fabricated meander-line antenna (printed on a simulated USB-WLAN card)was attached to the side wall of a notebook-PC to study the ef-fects of the notebook-PC housing on the antenna performance.For vertical-orientation posture,the average gain levels of

both

-and -pattern are close to those in free space,except that

the -pattern has a null in the 210direction when the antenna is attached to the notebook-PC.For the horizontally-orientation

posture,

both -

and

-pattern have about 10to 15dB av-erage attenuation due to the housing effect.It may be due to that the main body of the notebook PC lying on the same plane of the printed antenna.Hence,it suggested that for the 2.4-GHz meander-line printed antenna the vertical orientation posture

may have the least in ?uence by the notebook-PC housing on the antenna pattern performance.

R EFERENCES

[1]H.-R.Chuang and L.-C.Kuo,“3-D FDTD design analysis of a 2.4GHz

polarization-diversity printed dipole-antenna with integrated balun and polarization-switching circuit for WLAN and wireless communication applications,”IEEE Trans.Microwave Theory Tech.,vol.51,no.2,pp.374–381,Feb.2003.

[2] C.Soras et al.,“Analysis and design of an inverted-F antenna printed on

a PCMCIA card for the 2.4GHz ISM band,”IEEE Antennas Propagat Mag.,vol.44,no.2,pp.37–44,Feb.2002.

[3] C.-C.Lin,S.-W.Kuo,and H.-R.Chuang,“A 2.4-GHz printed meander-line antenna for WLAN applications,”in IEEE AP-S Int.Dig.,vol.3,Jun.2004,pp.2767–2770.

[4]G.Marrocco,“Gain-optimized self-resonant meander line antennas for

RFID applications,”IEEE Antennas Wireless Propagat.Lett.,vol.2,pp.302–305,2003.

[5]T.J.Warnagiris and T.J.Minardo,“Performance of a meandered line

as electrically small transmitting antenna,”IEEE Trans.Antennas Prop-agat.,vol.46,no.12,pp.1797–1876,Dec.1998.