Transactions Template


 

 

JOURNAL OF ENGINEERING RESEARCH AND TECHNOLOGY, VOLUME 1, ISSUE 3, 2014 

 

  

91  

Bandwidth enhancement of patch antenna with anisotropic 

substrate using inset L-shaped feed and L slots on ground plane 

Amel Boufrioua1 

1Electronics Department, Technological Sciences Faculty, University Constantine 1,  

Ain El Bey Road, 25000, Constantine, Algeria, e-mail boufrioua_amel@yahoo.fr 

 

Abstract—in this paper, an inset L-shaped feed rectangular patch antenna with dual L slots etched on the ground 
plane is proposed and analysed for increasing band width of microstrip patch antenna. The results in terms of 
return loss and radiation pattern are given. The results show that dual wide bands are achieved and a better 
impedance matching for the upper and lower resonances are obtained.Simulation results for the effect of uniaxial 
substrate on the return loss and bandwidth of the rectangular patch antenna using inset L-shaped feed with dual 
rectangular slots on the ground plane are also presented. Our results of return loss using Ansoft HFSS are 
compared with those available in the literature which shows a good agreement. 

Index Terms—Wide band antenna, rectangular patch, anisotropic substrate, modified ground plane.  

 

I INTRODUCTION

 
The development of modern wireless communication 

leads to the need for broadband antennas found a wide 

spread application in the wireless communication industry 

because of their attractive features such as easy fabrication, 

cost, linear and circularly polarized radiation characteristics. 

Because of these attractive features of the broadband anten-

nas are used in many wireless applications such as Wi-Fi, 

Bluetooth, GSM and GPRS. 

 

The rectangular and circular patches are extensively used 

radiators which have very limited bandwidth [1]. These 

limits the applications in several practical cases, and the 

narrow bandwidth of the microstrip antenna can be widened. 

Recently, most of the research on microstrip antennas fo-

cused on methods to increase their bandwidth [2-10]. Sever-

al patch designs with single feed, dual frequency operation 

have been proposed recently [3-10]. When a microstrip 

patch antenna is loaded with reactive elements such as slots, 

stubs or shorting pin, it gives tunable or dual frequency 

antenna characteristics [8]. Since the slots are cut at an ap-

propriate position inside the patch, they neither increase the 

patch size nor largely affect the radiation pattern of the patch 

[9]. These slots can take different shapes like, rectangular or 

square slot, step slot, tooth-brush shaped slot, V-slot, U-slot, 

etc [9]. The slot adds another resonant mode near the fun-

damental mode of the patch and realizes dual frequency 

response [9]. 

 

The study of anisotropic substrate is interesting since it has 

been found that the use of such materials may have a beneficial 

effect on circuit or antenna [2]. However, the designers should 

carefully check for the anisotropic effects in the substrate materi-

als with which they will work. 

 

In this paper, a novel wide band rectangular patch anten-

na printed on isotropic or uniaxial anisotropic substrate is 

designed by using inset L-shaped feed with dual L slots on 

the ground plane. The proposed antenna provides a signifi-

cant size reduction and can completely increase the band 

width. In this paper the performance analyses of the pro-

posed antenna are presented using Ansoft HFSS software, 

which is based on Finite Element Method, different paramet-

ric studies will be allowed and the effect of the various an-

tenna parameters on the return loss and the radiation of the 

proposed antenna will be presented, also we will present the 

effect of the uniaxial substrate on the band width and the 

return loss with lower and upper resonant frequencies. 

 

II ANTENNA DESIGN 

A  Simple rectangular patch antenna 
The proposed structure of inset L-shaped feed with dual L 

slots on the ground plane given in this study to increase the 

band width, based on the simple rectangular microstrip patch 

which is designed first in order to compare it with the pro-

posed structure. 

 

The geometry for the simple rectangular microstrip patch 

of dimension W × L (see Figure 1) printed on the grounded 

substrate, which has a uniform thickness of h and having a 

relative permittivity εr and the dielectric material is assumed 

to be nonmagnetic with permeability 0. 

 



 Amel Boufrioua/ Bandwidth enhancement of patch antenna with anisotropic substrate using inset L -shaped feed and L slots on ground 

plane (2014) 

 

  

92  

 

 

 

 

 

 

 

 

 

 

 

 
Figure 1 Geometry of a simple rectangular patch antenna 

 

Table 1 shows the different parameters of the simple rec-

tangular patch antenna. 

 

TABLE 1 
Design parameters of a simple rectangular patch antenna 

 

Parameters Value 

W 15.8 mm 

L 8 mm 

h 1.6 mm 

Relative permittivity 𝜀𝑟=4.5 

Ground plane  34*20 mm2 

 
 

Figure 2 Simulation of return loss S11 of a simple rectangular patch 

antenna 

 

Figure 2 shows the frequency response of the simple rec-

tangular patch antenna. 

 

B  Rectangular patch antenna using inset L-
shaped feed and L slots in the ground plane 

The geometry for the proposed antenna based on the 

previous simple rectangular patch is shown in figure 2, in 

this case two L-shaped slots with the same dimensions are 

etched on the ground plane and the feeding is accomplished 

with inset L-shaped feed. 

TABLE 2 

Design parameters of the rectangular patch antenna usingin-

set L-shaped feed with dual L slots on the ground plane 

 

Parameters Value 

W 15.8 mm 

L 8 mm 

h 1.6 mm 

Microstrip feed line 2.8 mm 

Hs=HFI  6 mm 

WFI =HFL 0.5mm 

WL=WFL 2mm 

Ws=HL 12 mm 

Relative permittivity 4.5 

Ground plane  34*20 mm2 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 
Figure 3 Geometry of inset L-shaped feed with L-slots in the ground 

plane 
 

 
 

Figure 4 Comparison of return loss and bandwidth between the 

Frequency (Ghz) 

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(d
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Our results 

[3] 

W 

 

L 

 

WFI WFL 

HFI 

 

Sh 

 
WL 

 

HL 

W 

 

L 

Ws 

Hs 

Hh 

HFL 

Frequency (Ghz) 

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(d
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Simple antenna 

Proposed antenna 



Amel Boufrioua/ Bandwidth enhancement of patch antenna with anisotropic substrate using inset L -shaped feed and L slots on ground plane 
(2014) 

  

93  

proposed structure and the simple rectangular patch antenna 

 

 

It is clear that dual frequencies with a very significant 

improvement in the bandwidth of the proposed rectangular 

patch using inset L-shaped feed with dual L slots on the 

ground plane are obtained compared to the simple rectangu-

lar patch antenna. 

 

C  Different parametric study 
The parameters given in Table 2 are fixed; we varied WL 

to 2mm, 4mm and 6mm. Variation of return loss as a func-

tion of frequency for different value of slot width of the L 

slot etched on the ground plane WL is shown in figure 5, also 

it is worth noting that a comparison study on the return loss 

S11 between the structure with the dual L slots on the 

ground plane and the structure with dual rectangular slots on 

the ground plane which is obtained by taking the parameter 

Hh of the L slot on the ground plane equal zero is given. 

 

 
 

Figure 5 Comparison of return loss of the structure with (Hh=0) and 
the structure with Hh=6mm, with three values of WL (mm) 

 

It is clear that a significant improvement in the band-

width of the proposed antenna using inset L-shaped feed 

with dual L slots on the ground plane are obtained compared 

to the rectangular patch using inset L-shaped feed with rec-

tangularslots on the ground plane in the case with Hh =0, 

Also we can see clearly that for the parameter (WL = 2 mm) 

we have a wider band width with an optimum matching. 
 

The radiation patterns for upper resonant frequency for 

different value of slot width of the L slot etched on the 

ground plane WL of our proposed structure using inset L-

shaped feed with dual L slots on the ground plane compared 

with the radiation pattern of a simple rectangular patch an-

tenna are illustrated by the figures below (Fig 6 and 7). 

 

The rectangular patch using an insef L feed with a dual 

rectangular slots on the ground plane is obtained when the 

parameter Hh of the proposed structure given by Figure 3 is 

taken equal zero (Hh=0), because this structure is simpler 

than the previous one we will give some results pertaining to 

this case in the next figures (8 and 9).  

 

 
Figure 6 Radiation pattern of a simple rectangular patch 

 
 
 

Figure 7 Radiation pattern of the rectangular patch antenna using 
inset L-shaped feed with dual L slots on the ground plane 

 

The parameters given in Table 2 are fixed, variation of 

return loss as a function of frequency for different value of 

the length notch of the inset L-shaped feed WFL is shown in 

figure 8. 

 

In the case of Figure 9, the rectangular patch using an inset 

L feed with dual rectangular slots on the ground plane is also 

studied; the patch is embedded in a substrate containing aniso-

tropic materials with the optical axis normal to the patch and has 

a uniform thickness h. The relative permittivity in this casecan be 

presented by a tensor with the relative permittivity in the direction 

perpendidicular to the optical axis denoted εx (with εx= εy) and 

the relative permittivity in the direction of the optical axis denot-

ed εz as given by [2, 11]. 

 

Frequency (Ghz) 

R
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rn
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o
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, 
S

1
1

 (
d
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) 

(d
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) 

Hh=0 

WL=2mm 

WL=4mm 

WL=6mm 



 Amel Boufrioua/ Bandwidth enhancement of patch antenna with anisotropic substrate using inset L -shaped feed and L slots on ground 

plane (2014) 

 

  

94  

It is worth noting that the results of figures 5and 8 agree 

very well with those obtained by S.Satthamsakul et al. [3]. 

 

 
 

Figure  8 Variation of return loss as a function of frequency for dif-
ferent value of the length notch of the inset L-shaped feed WFL for 

(Hh=0) 

 

 

 
 

Figure 9 Effect of the uniaxial anisotropic substrate on the band 
width and the return loss of the rectangular patch using an insef L 

feed with dual rectangular slots on the ground plane 
 

From figure 9, the obtained results show that a signifi-

cant improvement in the bandwidth is achived for the aniso-

tropic ratio AR>1, it is worth noting that (AR=εx/εz). 

III CONCLUSION 

In this paper, analysis of inset L-shaped feed rectangular 

patch antenna with dual L slots etched on the ground plane 

has been studied. From the analysis it is found that a large 

band width can be achieved by this novel structure and con-

sequently this antenna is very suitable for many applications 

especially for applications in the access points of wireless 

communications. 

REFERENCES 

[1] J. J. Bahl and P. Bhartia, “Microstrip antennas,” Edited 
by M. A Dedham, Artech House, 1980. 

[2] A. Boufrioua, “Resistive rectangular patch antenna with 
uniaxial substrate”, In: Antennas: Parameters, Models 
and Applications, ch. 6, pp. 163-190, Edited by Albert I. 
Ferrero, Nova Publishers, New York. 2009. 

[3] S.Satthamsakul, N.Anantrasirichai, C. Benjangkaprasert 
and T. Wakabayashi, “Rectangular patch antenna with 
inset feed and modified ground-plane for wideband 
antenna,” SICE Annual Conference 2008, August 20-
22, 2008, Japan. 

[4] H. F. Pues and A. R. Van De Capelle, “An impedance 
matching technique for increasing the bandwidth of 
microstrip antennas,” IEEE Trans Antennas Propagat, 
vol. 37, pp. 1345-1354, 1989. 

[5] A. Boufrioua, “Bilayer microstrip patch antenna  loaded 
with U and half U-shaped slots,” ICMCS'14,4th IEEE 
International Conference on Multimedia Computing and 
Systems, April 14-16, 2014, Morocco. 

[6] M. K. Meshram, B. R. Vishvakarma, “Gap-coupled 
microstrip array antenna for wide-band operation,” 
International Journal of Electronics, vol. 88, pp. 1161-
1175, 2001. 

[7] J. A. Ansari, A. Mishra, “Half U-slot loaded 
semicircular disk patch antenna for GSM mobile phone 
and optical communications,” Progress In 
Electromagnetics Research C, vol. 18, pp. 31-45, 2011. 

[8] D. K. Srivastava, J. P. Saini, D. S. Chauhan, 
“Broadband stacked H-shaped patch antenna,” 
International Journal of Recent Trends in Engineering, 
vol. 2, pp. 385-389 , 2009. 

[9] A. A. Deshmukh, K. P. Ray, “Resonant length 
formulations for dual band slot cut equilateral triangular 
microstrip antennas,”Wireless Engineering and 
Technology, vol. 1, pp. 55-63, 2010. 

[10] J. A. Ansari, S. K. Dubey, P. Singh, R. U. Khan, B. 
R.Vishvakarma, “Analysis of U-slot loaded patch for 
dualband operation,” International Journal of 
Microwave and Optical Technology, vol. 3, pp. 80-84, 
2008. 

[11] A. Boufrioua, A. Benghalia, “Effects of the resistive 
patch and the uniaxial anisotropic substrate on the 
resonant frequency and the scattering radar cross section 
of a rectangular microstrip antenna,” Elsevier, AST, 
Aerospace Science and Technology, vol. 10, pp. 217-
221, 2006. 

 

 

Amel Boufrioua Was born in Constantine, Algeria; she received 

the B.S. degree in Electronic Engineering in 1996, the M.S. and 

Ph.D. degrees in Microwave from Electronics Department, Con-

stantine University, Algeria, in 2000 and 2006 respectively. From 

February 2002 to December 2003, she was a Research Assistant 

with Space Instrumentation Laboratory at the National Centre of 

Space Techniques “CNTS” (Oran, Algeria), and then in November 

2003, she was an Assistant Professor at the Electronic Engineering 

Department (Constantine University). Since 2008, she is a Lecturer 

with the electronic department, University Constantine 1; her area 

of interest is microwave and microstrip antennas. Dr. Amel Bou-

frioua is the corresponding author and can be contacted at: bou-

frioua_amel@yahoo.fr. 

Frequency (Ghz) 

R
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rn
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, 
S

1
1

 (
d
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) 

(d
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) 

εx= εy=3.6, εz=5 

εx= εy=5, εz=3.6 

εx= εy=5, εz=6.4 

εx= εy=6.4, εz=5 

εx= εy=εz=5 

Frequency (Ghz) 

R
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rn
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o
ss

, 
S

1
1

 (
d
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) 

(d
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) 

WFL=6mm 

WFL=4mm 

WFL=2mm 

WFL=0