shaped Slot Antenna for Wireless Body Area Network - IEEE Xplore

37 downloads 615 Views 2MB Size Report
... National School of Technical Education (ENSETI ENSIAS) Rabat, Morocco. 2 STRS Laboratory, National Institute of Post and Telecommunications (INPT).
Flexible Miniaturized UWB CPW II- shaped Slot

Antenna for Wireless Body Area Network (WBAN) Applications Amal AFYF I

,

,'

'* , Larbi BELLARBI ' , Fatima RIOUCH

2,

Anouar ACHOUR 4 Mohamed.Adel SENNOUNI

"

Abdelhamid ERRACHID

3,

Electrical Engineering Laboratory (LGE), Higher National School of Technical Education (ENSETI ENSIAS) Rabat, Morocco 2

STRS Laboratory, National Institute of Post and Telecommunications (INPT). Rabat Morocco 3

Institute of Analytic Sciences (ISA) Lyon University-France 4

LITEN Laboratory of FST-Settat-Morocco

( * ) [email protected]; [email protected] Abstract-A

flexible microstrip antenna printed on a Kapton

design, low cost, easy system implant etc. So the design should

Polymide substrate, excited by a CPW feed line, and operated in

be such that antennas performance is not deteriorated even if

S-band at 3.5GHz, is successfully validated. Unlike previous

they are bent. During last few years researchers have been

flexible antennas, this structure offers a very thin thickness (O.16mm) with overall dimensions of 36x25 mm2 that assure an

working on various aspects in wearable antenna designs.

easy integration into clothes and wireless body area network

(WBAN)

systems. Modeling and performance evaluation of the

proposed antenna in term of return loss, voltage standing wave ratio,

radiation

pattern,

and current distribution have been

carried out using CST -MW STUDIO Software. Keywords-Flexible

Microstrip

Antenna;

Some researchers have proposed flexible antennas which can be easily integrated into clothing [6-19]. This paper is organized as follows: Section II and III respectively introduce,

Design Procedures and Simulation

Results for the proposed antenna. Conclusion is shown in

Kapton

Polymide;



Section

IV.

As

antenna

in

subsequent

optimization

STUDIO.

simulations with CST Microwave Studio [8]. I.

of

described

Band; Wireless Body Area Network (WBAN) Systems; CST-MW

TABLET.

INTRODUCTION

structures

market

analysis,

the

revenue

of

Professional & Amateur Sport Training

flexible Wearable WBAN

300 billion USD in 2028 [1]. Their light weight, low-cost

Asthma

manufacturing, ease of fabrication, and the availability of

Sleep staging

flexible

substrates

(i.e.:

papers,

textiles,

and

Medical

Wearable Health Monitoring Implant WBAN

plastics) make flexible electronics an appealing candidate for

Diabetes Control Cardiovascular Detection

the next generation of consumer electronics [2]. Moreover, recent

developments

in

miniaturized

and

flexible

Cancer Detection

energy

Remote control of

storage and self-powered wireless components paved the road

Ambient Assisted Living (AAL)

Medical Devices

for the commercialization of such systems [3]. Consistently,

Patient Monitoring Tele-medicine Systems

the new wireless protocols for body area networks (WBANs)

Real Time Streaming

are highly attractive as future solutions for a wide ranging applications

including,

military,

health

care,

by

Battle Management

electronics is estimated to be 30 billion USD in 2017 and over

inexpensive

the

out

Soldier Fatigue Assessment and

Recent years have witnessed a great deal of interest from to

sections,

carried

WBAN ApPLICATIONS

both academia and industry in the field of flexible electronics. According

was

Entertainment Applications

sport

Emergency(non-medical)

Non-Medical

entertainment and many others have been categorized into two

Emotion Detection

main areas by the IEEE 802.15.6 standard. These two areas are

Secure Authentication

medical and non-medical (Conswner Electronics) [4-5]; shown

Personal information sharing

in Table I. While talking about wireless body area networks, suddenly it comes into mind that how the signals would be

II.

communicated? Well, an antenna, which is a fundamental part of the network, is the answer for this. Flexible antenna is one of the most fascinating and cutting edge research areas of modern era. It provides a wearable interface between human and the machine. Since we are talking about wearable antennas, it is necessary to mention here that antennas for such applications should possess certain properties like light weight, confonnal

52

A. To

ANTENNA DESIGN

Choice of antenna substrate comply

with

flexible

technologies,

integrated

components need to be highly flexible and mechanically robust; they also have to exhibit high tolerance levels in tenns of bending repeatability and thermal endurance. A lot of design approaches of flexible and confonnal antennas were reported

978-1-4673-8096-6/15/$31.00 ©201 5 IEEE

in

the

literature

including

Electro-textile [9],

paper-based A

[10], fluidic [11], and synthesized flexible substrates [12]. Kapton Polyimide film was chosen as the antenna substrate due to its good balance of physical, chemical, and electrical properties with a low loss factor over a wide frequency range ( tan ()

=

0.002 ). Furthermore, Kapton Polyimide offers a

very low profile (50.8 fJm) yet very strength

of

165

MPa

at

73°F,

a

robust

with

dielectric

a

tensile

strength

of

3500-7000 volts/mil, and a temperature rating of -65 to 150°C [13]. Other Polymer based and synthesized flexible substrates have been also used in several designs [14-15].

Choice offeed technique

B.

It is worth mentioning that there are several techniques used to characterize the electromagnetic properties of thin and flexible films/substrates such as: the near field microscopy, Co­ planar Waveguide CPW approach, differential open resonator method, and goniometric time domain spectroscopy method [16-17]. However, in this work, Co-Planar Waveguide (CPW) Fig.l. The proposed flexible CPW antenna

is preferred over other feeding techniques since no via holes or shorting

pins are

involved,

in addition to several useful

characteristics such as: low radiation losses, larger bandwidth, improved impedance matching, and more importantly, both radiating element and ground plane are printed on the same side of the substrate, which promotes low fabrication cost and

The table below presents the various parameters of the antenna shown in the Fig.l. TABLE I!.

PHYSICAL DIMENSIONS OF THE ANTENNA

complexity. C.

Antenna parameters

In this paper a flexible CPW rectangular antenna 3 (25X36XO.16 mm ) with a II- shaped slot in the medium of the radiator and two tuning stubs is developed. The extremely thin Kapton-substrate Hs used in the design makes the antenna suitable for being implemented or pasted on clothes. Fig.l shows the geometry shape of the proposed antenna. The ungrounded antenna is etched on Kapton Polyimide substrate with a thickness of Hs and dielectric constant of 3.4. in order to maintain the flexibility of the antenna the excitation is made through a 50n CPW feed line. Then by using optimization solver in CST-MW Studio several optimization processes was applied until we got the desired performances of the antenna. Table

below

presents

the

optimized

parameters

of

the

developed antenna.

D.

RESULTS AND DISCUSSION

To show the effect of the structure geometry, we have started from a simple rectangular patch (Antenna a), and by adding respectively a II- shaped slot (Antenna b), and tuning stubs we arrived to model the proposed design (Antenna c), Fig.2

53

VSWR (a)

(b)

(c)

Fig. 2. The geometric shape of the CPW rectangular antenna: (a) simple rectangular antenna,(b) CPW rectangular antenna with IT-shaped slot in the radiator,and (c) CPW rectangular antenna with two antiparallel tuning stubs in the ground and IT-shaped slots in the radiator. Fig. 4. The simulated VSWR of the three antenna structures

This section mainly presents the major simulation results of the designed antenna. From Fig.3 it is seen that the antenna (c) has a good impedance matching with a return loss of about -32dB at the operating frequency of 3.SGHz. Moreover the antenna shows a broadband propriety with an impedance bandwidth of about S70MHz which is from 3.23GHz to 3.7SGHz as shown in Fig.3. Further Fig.4 shows the obtained simulated Voltage Standing Wave Ratio (VSWR). From the graph it's clear that at 3.SGHz the antenna provides a

In Fig.S, the simulated variation of the antenna input impedance versus frequency of the developed antenna can be seen. the

It is observed that the antenna is quit well matched to SO n

impedance. Then at the operating frequency of

3.SGHz, the average value of the resistance (real part) is SO Ohms, also the average value of the reactance (imaginary part) is O-Ohms which provides the adequate input impedance matching at the desired resonant frequency.

minimum VSWR of about 1.0S (less than 2), which is within the recommended range. The obtained result indicates that the transmitter and antenna are well matched and a maximum possible amount of energy is absorbed at the input terminal

Return Loss (dB)

with a minimum reflected power.

Fig. 5. Simulated antenna impedance (Ohm) vs. frequency of the proposed CPW antenna

Current distribution determines how the current flows on the patch antenna. Fig. 6 demonstrates these results. We observe

a

high

strength

of

current

radiates

along

the

transmission line, the edges of tuning stubs, and the IT-shaped Fig. 3. Simulated return loss of the different antenna structures

54

slot.

Gain (dB) Fig. 6. Current density at 3. 51 GHz

The radiation pattern taken for the far-field at 3.51GHz is indicated by the 3D view in Fig.7. The directivity of the Fig. 9. Simulated antenna gain vs Frequency

proposed antenna is about 3dBi. Further, Fig.8 indicates that the antenna provides a directional behavior in both E-plan (a)

III.

and H-plan (b).

CONCLUSION

A newly miniaturized CPW antenna structure has been successfully designed and simulated via CST Microwave Studio. The performance criteria extracted from the software includes Return Loss, YSWR, Radiation Pattern, and Surface Currents, provide clear indication that the proposed design is suitable for WBAN applications; due to its good matching input impedance at the operating frequency of 3.5GHz and its broadband propriety. Further, the miniaturized size of the developed antenna with the enhanced gain of 4dB that exhibits at 3.5GHz, are good features for such applications. Future work will focused to explore the accuracy issues observed here for the inclusion of the body phantom in the simulation model before the realization stage and measurement tests. REFERENCES

Fig. 7. 3D radiation pattern at 3. 51GHz

[I]

J. Hu, "Overview of flexible electronics from ITRls viewpoint. VLSI

[2]

A. Nathan and B.

Test Syposium (VTS)",2010 28th,19-22 April ,84. R. Chalamala, "Special

Electronics Technology,

Part

I:

Systems

Issue

on

and

Flexible

Applications".

Proceedings of the IEEE, 93(7),1235-1238,2005. [3]

Y. Huang, C. Jiankui, Y. Zhouping and X. Youlun. "Roll-to-Roll Processing Interfacial

of

Flexible

Residual

Heterogeneous Stress.

Electronics

With

Low

Components, Packaging

and

Manufacturing Technology", IEEE Transactions on Sept., 1(9), 13681377,2004. [4]

R. J.

Langley, K.

L.

Ford, and H.

J.

Lee, "Switchable on/off­

body communication at 2. 45 GHz using textile microstrip patch antenna

on stripline"

Antennas

and

Propagation

(EUCAP), 6th

European Conference,2012,pp. 728-731.

(a)

(b)

[5]

Fig. 8. 2D polar radiation pattern at 3. 51GHz for the antenna array; (a) E­ Plan,and (b) H-Plan.

Fig.

9 shows

the

gain

variation

[6]

over

the

operating

frequency band. The graph result shows that the proposed antenna provides a peak gain at 3.51GHz of about 4dB.

S.

Movassaghi, M.

Abolhasan, J.Lipman, "Wireless

Body

Area

Networks: A Survey", IEEE Communications Surveys & Tutorials. Hoagland, H. ; Morrow, B. ; "Using rainwear as switching jackets: a reasonable solution for electric arc exposure" , Industry Applications, IEEE Transactions on,Volume 36, Issue 5,Page(s):1241 - 1246, Sept. ­ Oct. 2000.

55

[7]

M. Swaminathan, Bavisi, A, Yun, W. , Sundaram, V. , Govind, V. and Monajemi, P. , "Design and fabrication of integrated RF modules in LCP Substrates", Industrial Electronics Society (lECON), November 2005.

[8] [9]

CST Microwave Studio Suite 2011. P. Salonen, KJaehoon and patch wearable textile

S. Y. Rahmat, "Dual-band

antenna".

E-shaped

IEEE Antennas and Propagation

Society Symposium, 1,466-469,2005. [10]

D. E. Anagnostou, A. A. Gheethan, A. K. Amert and K. W. Whites, "A Direct-Write

Printed

Antenna

on

Paper-Based

Organic

Substrate

for flexible Displays and WLAN Applications". Display Technology, Journal of,6(11), 558-564,2010. [11]

K.

Masahiro, L.

Xiaofeng, K.

Choongik, M.

W.

Hashimoto, J.

Benjamin,H. Donhee and M. George,"White sides Stretchable Microfl uidic Radio frequency Antennas", Wiley Inter science,Adv. Mater. ,22, 2749-2752,2010. [12]

AC. Durgun, M. S. Reese, C. A Balanis, C. R. Birtcher, D. R. Allee and

S.

Yenugopal, "Flexible

propagation

Society

bow-tie

International

antennas.

Symposium

Antennas

and

(APSURST)", 2010

IEEE, 1. [13]

Du Pont Dupont Kapton Polyimide specification sheet.

[14]

AGheethan, and D. Anagnostou, "Dual Band-Reject UWB Antenna with Sharp Rejection

of

Narrow

and

Closely-Spaced

Bands",

Antennas and Propagation, IEEE Transactions on 0. (99),1,2013. [15]

G. De Jean, R. Bairavasubramanian,D. Thompson, G. E. Ponchak,M. M. Tentzeris, and J. Papapolymerou, "Liquid Crystal polymer (LCP)", IEEE, 4,22-26,2006.

[16]

AKarbassi, D. Ruf, A. D. Bettermann,C. A Paulson,V. D. Weide, W. Daniel,H. Tanbakuchi and R. Stancliff, "Quantitative scanning near­ field

microwave

measurement".

microscopy

Review

of

for

thin

film

dielectric

constant

Scientific Instruments, 79(9), 094706-

094706-5,2007. [17]

L. Ming, J. Fortin, J. Y. Kim, G. Fox, F. Chu, T. Davenport, Lu. Toh­ Ming and Z. XiCheng, "Dielectric constant measurement of thin films using goniometric terahertz time-domain spectroscopy. Selected Topics in Quantum Electronics",2011.

[18]

P. Salonen, J. Rantanen, , "A Dual Band and Wide-Band Antenna on Flexible Substrate for Smart Clothing", 27th Annual Conference of the IEEE,Yol.1,2001.

[19]

B. Sanz-Izquierdo, M. I. Sobhy, J. C. Batchelor "UWB Wearable Bulton Antenna", European

Conference

on

Antennas

EuCAP06, Nice,France,p. 131,2006 November.

56

and

Propagation