International Journal of Scientific & Engineering Research, Volume 5, Issue 12, December-2014 594

ISSN 2229-5518

Design of CPW-Fed Monopole Antenna with L- shape and T-shape for WLAN/Wi-MAX Applications

K. Lakshmi Prasanna1 B. Rama Rao2 Dr.P.V.Sridevi3

1. M.Tech Scholar, Dept of ECE, AITAM Tekkali, A.P., INDIA. kanithi.prasanna@gmail.com

2. Assoc. Prof., Dept of ECE, AITAM Tekkali, A.P., INDIA. e-mail: ramu_sri07@rediffmail.com

3. Assoc. Prof., Dept of ECE, A.U. College of Engg. Vizag. A.P.e-mail:pvs6_52yahoo.co.in

Abstract: A novel dual-band design of a finite ground coplanar waveguide (CPW )-fed monopole antenna is presented for simultaneously satisfying wireless local area network (W LAN) and worldwide interoperability for Microwave Access (W iMAX) applications. The proposed antenna, comprising a rectangular planar patch element embedded with L shape and T-shape slots in the middle of the patch element. The simulated -10 dB bandwidth for return loss is from 2.0 to 2.2 GHz and 2.8GHz to 3.1 GHz, covering some of the W iMAX and W LAN bands. Prototypes of the obtained optimized antenna have been designed and constructed. The Antenna has 22.5 % (-10 dB return loss) band width ranging from 2 to 2.2 GHz, and -21 dB return loss is from 2.85 to 2.95 GHz. The parametric study is performed to understand the characteristics of the proposed antenna. Also, good antenna performances such as radiation patterns and antenna gains over the operating bands have been observed and VSW R is 1.6 at 2.4 GHz.

Key Terms : Ground plane, Coplanar Wave guide ,Narrow band, Monopole antennas, W iMAX and W LAN.

——————————  ——————————

I. INTRODUCTION

The wireless communication industry is integrating a number of services like Bluetooth, WLAN etc to the hand held communication devices. Therefore, in the present scenario, the bandwidth requirement of the antenna while maintaining the compactness becomes more critical. Transmission lines are energy guiding devices that can be used to transfer electromagnetic signal from one part of the system to another. The coplanar waveguide has made much attention in the high frequency researchers because of its attractive features. This paper presents the results of the investigations carried out to find the radiations characteristics or resonance phenomena in a finite ground coplanar waveguide fed strip monopole. The first part of this paper includes results of investigations carried out to study the behavior of a finite ground coplanar wave guide fed strip monopole while the second part of the paper provides the development of a T shape and L shaped monopole antenna from the strip monopole. A parametric study which depicts the effect of various antenna parameters is carried out and conclusions are made from the results. The analysis includes simulation studies using Ansoft HFSS and measured results with Vector Network Analyzer.
Monopole antennas have found widespread applications in wireless mobile communication systems. The increasing use of mobile communication systems has stimulated the interest in the dual-frequency monopole antennas for dual band operation. Numerous designs of dual-frequency compact monopole antennas have been reported, including the use of a
center-fed monopole surrounded by multiple parasitic monopoles D. Liu [3], R. Schlub et al [4].
It is noted that the above mentioned monopole antennas are commonly mounted above a large ground plane and excited by a probe feed. Recently, the microstrip-line-fed technique has also been applied for designing dual frequency printed monopole compact antenna and reported in H. M. Chen [5] and F. S. Chang, S. H. Yeh, and K. L. Wong [6]. A monopole antenna fed by a coplanar waveguide (CPW) have been reported in Homg-Dean Chen et al [7]. CPW-fed antennas have many attractive features, such as no soldering points, easy fabrication and integration with monolithic microwave integrated circuits, and a simplified configuration with a single metallic layer. Thus, the designs of the CPW-fed antennas have recently received much attention.
Fuhl.J et al. [8] analysed the performance of a radiation coupled Dual L antenna, placed on the back side of the metallic housing of the handset, resulting in a improved radiation pattern pointing away from the user's head. The antenna was designed for operation in the GSM 900 frequency band. K.Hettak et al. [9] presented the design and experimental results of a coplanar waveguide (CPW) aperture coupled patch antenna for EHF band around 37 GHz. The antenna structure combined the advantages of CPW with those of aperture coupled Microstrip Antennas and also reduced the number of metal1ization levels. N.Chiba et al. [10] proposed a compact dual band internal antenna fed by a single feed, designed for the 90011800 MHz band. The antenna comprised of an outer λ/4 annular ring antenna with a short circuited plane and an inner λ/4 rectangular patch antenna, designed for

International Journal of Scientific & Engineering Research, Volume 5, Issue 12, December-2014 595

ISSN 2229-5518

the lower and higher resonant frequency respectively. The
radiation patterns of the antenna were shown to be almost similar to that of a conventional λ/4 Microstrip antenna with a short-circuited plane.

II. DESIGN EQUATIONS PRINTED STRIP MONOPOLE

From the exhaustive experimental, FDTD computations and
simulation studies the following design equation are derived for an optimized printed strip monopole. The resonant frequency(fr) of the monopole with dielectric constant (εr ) and thickness of (h)
The Effective dielectric constant can be obtained by

∈eff

= ∈r +1 (1 + 0.3 * h)

The Length of strip can be calculated by the equation

Ls =

0.42 * c

(1)

f r *

∈eff

The Width of Ground plane is obtained by the equation

Wg =

1.38 * c

(2)

f r *

∈eff

The Length of Ground plane is calculated by the equation (3),

Lg =

0.36 * c

(3)

f r *

∈eff

Fig1:Geometry of proposed antenna
Resonant frequency (GHz),

= + 2

 21 +

65 + 18 − 

B. L shape monopole: The analysis of finite ground coplanar

f r 3

∈ref

 Ls Wg

3

Lg 

waveguide fed monopole antenna is presented in this session. The antenna consists of a coplanar wave guide designed for
The width of the monopole is set as width of 50Ω micro strip feed line. Since the field components are not confined to the substrate alone effective dielectric constant 'εeff ' has to be used in calculation. Here 'c' is the velocity of electromagnetic wave in free space. The constants in the above equations are derived from exhaustive parametric analysis.

II. ANTENNA DESIGN

A. Monopole with feed length 21mm: The analysis of finite ground coplanar waveguide fed monopole antenna is presented in this session. The antenna consists of a coplanar wave guide designed for 50Ω input impedance, fed with an SMA connector. The center conductor of the FGCPW is extended to form a strip monopole of dimension ‘Lm’. The initial design parameters for the FGCPW fed strip monopole antenna are, Lg = 19mm, Wg = 19mm, g = 0.35mm, Wc =

3mm and Lm = 21mm. The geometry of the strip monopole
antenna is depicted in fig 1
50Ω input impedance, fed with an SMA connector. The center conductor of the FGCPW is extended to form a strip monopole of dimension ‘Lm’. The initial design parameters for the FGCPW fed strip monopole antenna are, L = 13mm, W
= 3mm, gap between the ground plane and monopole =

0.35mm, W1 = 3mm, Lg=20mmand Wg = 20mm. The Fig.4 shows the Geometry of the Finite Ground Coplanar Waveguide Fed Strip Monopole Antenna. (L = 13mm, L1=16mm,W = 3mm, gap between the ground plane and monopole = 0.35mm, W1 = 3mm, Lg=20mmand Wg = 20mm, h=1.6mm and εr =4.4). The optimum parameters are obtained with the aid of Ansoft HFSSv12 software is shown in Fig.2.

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ISSN 2229-5518

Fig 2. Geometry of proposed L-Shaped antenna by Ansoft
HFSS

Fig 3 :Geometry of proposed L-Shaped antenna
3mm, gap between the ground plane and monopole = 0.35mm, W1 = 3mm ,LG=20mm and WG = 20mm, h=1.6mm and εr=4.4) is shown in Fig.4. The optimum parameters are obtained with the aid of Ansoft HFSS.

III. RESULTS

The microstrip monopole, L-Shape and T-Shape antennas are designed by Ansoft HFSS simulation software and fabricated on FR-4 substrate, the prototypes are tested on Vector Network Analyzer (VNA)-E5071C. The parameters like return losses and VSWR are presented for the optimized set of antenna parameters in Fig.5 to Fig 10.

C.T shape monopole:

Name X Y m10.00 5.4875 -15.3220 m2 5.4270 -10.0308 m3 5.6265 -10.0000

-2.00

-4.00

XY Plot 3

HFSSDesign1 ANSOFT

Curve Inf o dB(St(Rectangle3_T1,Rectangle3_T1))

Setup1 : Sw eep

HFSS model of T shape monopole: The analysis of finite ground coplanar waveguide fed monopole antenna is presented in this session. The antenna consists of a coplanar wave guide designed for 50Ω input impedance, fed with an SMA connector. The center conductor of the FGCPW is extended to form a strip monopole of dimension ‘Lm’. The initial design parameters for the FGCPW fed strip monopole antenna are, L = 23mm, W = 3mm, L1=19mm gap between the ground plane and monopole = 0.35mm, W1 = 3mm

,LG=20mmand WG = 20mm. The geometry of the strip
monopole antenna is depicted in fig.1

-6.00

-8.00

-10.00

-12.00

-14.00

-16.00

m2 m3

2.00 3.00 4.00 5.00 6.00 7.00 8.00

Freq [GHz]

(a)

(b)

Fig.5: a)Simulated Return loss characteristics(in Ansoft HFSSv12) b) Return loss characteristics by network analyzer for Monopole L=21mm

Name X Y

3m01.00 5.5352 1.0518

25.00

20.00

15.00

10.00

5.00

XY Plot 6

HFSSDesign1 ANSOFT

Curve Inf o

VSWRt(Rectangle3_T1) Setup1 : Sw eep

Fig4:Geometry of proposed T-Shape antenna
Geometry of the Finite Ground Coplanar Waveguide Fed Strip
T-shape Monopole Antenna.( L = 23mm, L1=19mm,W =

0.00

3.50 4.00 4.50 5.00 5.50 6.00 6.50 7.00 7.50 8.00

Freq [GHz]

(a)

International Journal of Scientific & Engineering Research, Volume 5, Issue 12, December-2014 597

ISSN 2229-5518

(b)

Fig6:a) Simulated VSWR characteristics b) VSWR characteristics by network analyzer for Monopole L=21mm

B. L shape monopole: The proposed antenna is simulated in Ansoft HFSS v12 software and fabricated and its practical results are obtained using Vector Network Analyzer(VNA)- E5071C

(b)
Fig 8: a) Simulated VSWR characteristics b) VSWR
characteristics by network analyzer

C) T shape monopole:

The proposed antenna is simulated in Ansoft HFSS v12 software and the results obtained are shown below,

Name X Y m10.00 6.2915 -13.9932 m2 6.1910 -10.0626 m3 6.6332 -10.0058

-2.00

XY Plot 8

HFSSDesign1 ANSOFT

Curve Inf o dB(St(Rectangle3_T1,Rectangle3_T1))

Setup1 : Sw eep

Name X Y

m10.00 6.0201 -19.6515

XY Plot 3

HFSSDesign1 ANSOFT

Curve Info dB(St(Rectangle3_T1,Rectangle3_T1))

Setup1 : Sw eep

-2.50

-4.00

-6.00

-5.00

-8.00

-7.50

-10.00

m2 m3

-10.00

-12.00

-12.50

-14.00

4.00 4.50 5.00 5.50 6.00 6.50 7.00 7.50 8.00

Freq [GHz]

-15.00

(a)

(b)

-17.50

-20.00

4.00 5.00 6.00 7.00 8.00 9.00 10.00

Freq [GHz]

Fig.7 :
Fig.10 :Simulated Return loss characteristics(in Ansoft
HFSSv12)
a)Simulated Return loss characteristics(in Ansoft HFSSv12)
b) Return loss characteristics by network analyzer for L-Shape

Name X Y

1m51.00 6.0352 1.2198

12.50

10.00

7.50

XY Plot 6

HFSSDesign1 ANSOFT

Curve Info

VSWRt(Rectangle3_T1) Setup1 : Sw eep

Name X Y

1m11.25 6.2915 1.4990

XY Plot 9

HFSSDesign1 ANSOFT

Curve Inf o

VSWRt(Rectangle3_T1) Setup1 : Sw eep

5.00

9.25

2.50

7.25

5.25

0.00

4.00 5.00 6.00 7.00 8.00 9.00 10.00

Freq [GHz]

3.25

Fig11: Simulated VSWR characteristics

1.25

Freq [GHz]

The proposed antenna results obtained are shown below

(a)

4.00 4.50 5.00 5.50 6.00 6.50 7.00 7.50 8.00

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ISSN 2229-5518

Fig11: a)Proposed antenna testing by using Vector Network
Analyzer(E5071C) b) ResonantbFrequency
IV.

CONCLUSIONS

A Finite Ground plane monopole antenna covering WiMAX and WLAN bands is proposed. The various parameters of the proposed antenna are optimized through simulation. Prototype of the proposed antenna has been designed, simulated in Ansoft HFSSv12 software and the fabricated Antenna is tested using Vector Network Analyzer (VNA).The practical return loss bandwidths observed in Vector Network Analyzer are observed monopole is resonating at 5.84GHZ GHz with the improvement of return loss. The proposed antenna provides In the United States, seven frequency bands have been allocated by the Federal Communications Commission for uses that include cordless phones 5.8 GHz (allocated in 2003 due to crowding on the 2.4 GHz band). These are: nearly omni- directional radiation characteristics with moderate gain and efficiency which is suitable for the next generation wireless communication gadgets.

REFERENCES

[1.] Mandelbrot B. B., “The Fractal Geometry of Nature”, New York, W.H. Freeman and company, 1983.
[2.] Jaggar D.L.“On Fractal Electrodynamics” in Recent Advances in electro-magnetics theory, New York, Springer-Verlag, 1990, pp. 183-224.
[3.] D. Liu, "A dual-band antenna for cellular
applications," in Proc. IEEE Antennas Propagat. Soc.

1nt. Symp. , vol. 2, June 21-26, 1998, pp. 786-789.

[4.] R. Schlub, D. V. Thiel, lW. Lu, and S. G. O'Keefe, "Dual-band six-element switched parasitic array for smart antenna cellular communications systems," Electron. Lett., vol. 36, pp. 1342-1343,2000.
[5.] H. M. Chen, "Micro strip-fed dual-frequency printed triangular monopole," Electron. Lett., vol. 38, pp.
619-620, 2002.
[6.] F. S. Chang, S. H. Yeh, and K. L. Wong, "Planar monopole in wrapped structure for low-profile GSM/DCS mobile phone antenna," Electron. Lett., voL 38, pp. 499-500, 2002.

[7.] A CPW-Fed Dual-Frequency Monopole Antenna Homg-Dean Chen, Member, IEEE, and Hong-Twu Chen. Member. IEEE

[8.] Fuhl, P.Nowak and E.Bonek, "Improved internal antenna for hand-held terminals," Electron. Lett., vol.30, no.22, pp.1816-1818, 27 October 1994.
[9.] J K.Hettak, G.Delisle and M.Boulmalf, "A novel integrated antenna for millimeter-wave personal communications systems," IEEE Trans. Antennas Propagat., vo1.46, no.ll, pp.1757-1759, November
1998.
[10.] N.Chiba, T.Amano and H. Iwasaki, "Dual-
frequency planar antenna for handsets," Electron. Lett., vo1.34, no.25, pp.2362-2363, 10 December
1998.

Author Description:

K.Lakshmi Prasanna completed her

B.Tech in the year 2012. Now she is pursuing M.Tech

,AITAM Tekkali.

B. Rama Rao completed his Master of Technology in the stream of Radar and microwave engineering in the year of 2004

Now, he is working as Assoc. Professor in AITAM, Tekkali, India. Now, he is pursuing my Ph. D in the area of Fractal Antenna

Dr. P. V. Sridevi completed her Master of Engineering in the stream of applied electronics from PSG college of Engg. in the year of 1988 and Ph.D; in the area of Antennas and Microwave communications from Andhra University, Visakhapatnam Now, she is working as

Assoc. Professor in A U College of Engg.(A) Andhra
University Vizag, India