DOI : 10.17577/IJERTV6IS050584
- Open Access
- Total Downloads : 242
- Authors : Shilpa Waghmare, O. P. Sharma
- Paper ID : IJERTV6IS050584
- Volume & Issue : Volume 06, Issue 05 (May 2017)
- DOI : http://dx.doi.org/10.17577/IJERTV6IS050584
- Published (First Online): 29-05-2017
- ISSN (Online) : 2278-0181
- Publisher Name : IJERT
- License:
This work is licensed under a Creative Commons Attribution 4.0 International License
An Improved Design of Slotted Microstrip Patch Antenna for X Band and Ku band Applications
Shilpa Waghmare Research Scholar Dept. of ECE
Poornima College of Engineering Jaipur, India
O.P.Sharma Professor Dept. of ECE
Poornima College of Engineering Jaipur, India
Abstract: A comparative design of a rectangular shaped microstrip patch antenna for X band and Ku band application is analyzed in this paper. The proposed antenna of
-
* 10.50 square mm is placed over dielectric substrate of 15
* 15 * 1.5 mm having dielectric constant of 4.4. The proposed antenna is designed, optimized and analyzed with HFSS simulator.
Keywords: Microstrip Patch Antenna, Return Loss, HFSS, X and Ku band.
-
INTRODUCTION
The microstrip antenna has attracted interest of researchers due to size compactness, light weight and low cost. The severe disadvantage of microstrip antenna is the narrow bandwidth. To overcome this problem without disturbing their principle advantage a number of methods and structures have been recently investigated. Most of the antenna is designed to improve upon bandwidth by Wideband patch antenna structures [1], multiband antenna [2], log periodic structures [3], Triple band (L shaped) patch antenna [4], resonator antenna, spiral antenna [5]. Further need of improvement in bandwidth is justified by various other designs of Dual Band X Shape Microstrip Patch Antenna for Satellite Applications [6], Microstrip Patch Antenna with an End Fire Radiation [7], Coaxial fed Micro strip Patch Antenna for 2.4GHz Bluetooth Applications [8], Inverted S-shaped compact antenna for
-
ANALYSIS MODEL FOR MICROSTRIP ANTENNA
There are several types of analysis model available for microstrip patch antenna in which transmission line model is simplest with good physical insight [12].
In the transmission line model, the microstrip patch antenna is represented by two slots of height h and width W and separated by a low impedance transmission line of length L as shown in figure 1.
L
Dielectric Substrate (h)
Ground plane
Figure1: Electric field lines between patch and ground plane.
The dimensions of the patch are finite with the length and width, so the fields at the edges of the patch undergo fringing. Due to this fringing effect an effective dielectric constant r eff is introduced to account for this effect. The
expression for r eff is
X-band applications [9] and X band printed microstrip
= 1+r 1r (1 + 12 h )12
(1)
compact antenna with slots in ground plane and patch [10]. The purpose of this paper is to introduce the narrow bandwidth characteristics of patch antenna. The patch is
feed by coaxial feed line.
The proposed antenna is simulated in X-band of frequency 8 to 12 GHz and Ku band of 12-18 GHz. These bands are popular radar frequency sub-bands used in civil, military, government institutions for weather monitoring, air traffic control, defence tracking and vehicle speed detection.
This paper consists of V Sections. Brief introduction is discussed in Section I. Section II describes the Analysis Model for microstrip antenna. Section III describes Antenna designs and its simulated results for Conventional Rectangular patch Antenna, Slotted Microstrip Patch Antenna-1 and 2. Comparative results for all structures are discussed in Section IV. Section V concludes the paper.
r eff 2 2 w
Where r eff = Effective dielectric constant, = Dielectric constant of substrate, h = Height of dielectric substrate, W = Width of the patch
The resonating length of the patch is not exactly equal to the physical length due to the fringing effect. The fringing effect makes the effective length of the patch longer than its physical length as shown in the figure 2 below. A very popular and practical approximate relation for the normalized extension of the length is calculated as follows[11].
= 0.412 r eff +0.30 ( 0.264+W/h)
r eff 0.258 0.813W/h
(2)
Now the effective length of the patch Leff
Leff = 2L+ L (3)
For a given resonance frequency fr , the effective length is the width W is represented in equation 4.
W =
c 1+r 1
(
2 fr 2
) 2 (4)
Expression makes the width W equal to about half a wavelength. It leads to good radiation efficiency and acceptable dimension [13].
Figure 4: Geometry of Structure1 (Conventional Rectangular Patch antenna)
Simulation results obtained by this conventional Rectangular Patch are given in figure 5. It is observed that rectangular patch antenna has -10dB return loss from 8.5 GHz to 9.3 GHz and resonates at 8.7 GHz frequency which is close to the desired frequency of 9 GHz. The gain is 2.15 dB as seen in radiation pattern of figure 6.
Figure 2: Top view
0.00
XY Plot 32
HFSSDesign1 ANSOFT
Curve Info
pin_T1))
_T1,coax_
(coax_pin eep
dB(St etup1 : Sw
S
-2.50
dB(St(coax_pin_T1,coax_pin_T1))
-5.00
-7.50
-10.00
-12.50
-15.00
-17.50
-20.00
5.00 7.50 10.00 12.50 15.00
Freq [GHz]
Figure 3: Side view
As shown in figure 3, the normal components of
Figure 5: Return loss versus Frequency Plot for Conventional Rectangular Patch antenna (Structure 1)
electric field has equal amplitude but opposite phase at the edges, so cancel out each other in perpendicular direction [14].
-
ANTENNA DESIGNS AND SIMULATED RESULTS
-90
-60
Name
Theta
Ang
Mag
m1
-2.0000
-2.0000
2.1597
-30
Radiation Pattern 23
0
m1
30
1.60
0.20
60
-1.20
-2.60
90
HFSSDesign1 ANSOFT
Curve Info
dB(GainTotal) Setup1 : Sw eep Freq='10GHz' Phi='0deg'
dB(GainTotal) Setup1 : Sw eep Freq='10GHz' Phi='90deg'
-
Conventional Rectangular Patch Antenna
The conventional rectangular patch of 7.5 * 10.5 square mm is placed over dielectric substrate (FR4) of 15 * 15 * 1.5 cubic mm and has dielectric constant of 4.4. The
-120
-150
-180
150
120
proposed geometry is as shown in figure 4. The coaxial feeding technique is used.
Figure 6: Radiation pattern of Structure 1 for Conventional Rectangular
Patch antenna
Return loss is logarithmic ratio which is measured in dB that compares the power reflected by the antenna to power that is fed into antenna. The optimal feed location is found out to be at (x ,y) of (-3.5, 0) with a S11 of -18.5 dB. The % Bandwidth obtained is 8.62%.
S
2726
-32.
TABLE I. EFFECT OF FEED LOCATION WITH CENTER FREQUENCY, S11 AND PERCENT BANDWIDTH
Name m01.00
m2
m3
-5.00
m4
m5
949
-9.3
958
-9.6
dB(St(coax_pin_T1,coax_pin_T1))
-10.00
-15.00
-20.00
-25.00
-30.00
X
9.2000
Y
-10.2425
6500
1000
10.
1000
9.
6500
13.
13.
XY Plot 39
m2
m1
m5
194
-9.7
t etup1 : Sw eep
m4
HFSSDesign1 ANSOFT
pin_T1))
<>Info_T1,coax
Curve
(coax_pin
dB(S
_
m3
S No.
Feed location (X,Y) mm
Center Frequency (GHz)
S11 (dB)
%BW
1.
(0 , -5)
7
-11
5.71
2.
(0, -2)
7
-11
5.71
3.
(0, -2.5)
6.5
-20
9.2
4.
(0 ,-3)
6.3
-17
9.5
5.
(-1 ,0)
13.5
-14
3.7
6.
(0.2, 0)
13.4
-12
2.98
7.
(0.75, 0)
13.4
-13
3.73
8.
(-3, 0)
8.6
-14
5.81
9.
(-3.2, 0)
8.4
-17
8.33
10.
(-3.5, 0)
8.7
-18.5
8.62
-35.00
5.00 7.50 10.00 12.50 15.00
Freq [GHz]
Figure 8 : Return loss versus frequency plot of Structure 2 for
radius=1.5 mm
Table I shows the result obtained from observing the different feed point locations. After identification feed point remains same for all the geometries.
-
Slotted Microstrip Patch Antenna-1
For increasing the bandwidth, four semicircular cuts of
1.5 mm radius are cut in the conventional patch at the four corners. Figure 7 ( a ) shows the geometry of resultant patch antenna. The similar semicircular cut of radius of 2
-60
-90
-120
-30
-150
Radiation Pattern 19
0
1.00
-3.00
-7.00
-11.00
-180
30
150
60
90
120
HFSSDesign1 ANSOFT
dB(GainTotal) Setup1 : Sw eep Freq='10GHz' Phi='0deg'
dB(GainTotal) Setup1 : Sw eep Freq='10GHz' Phi='90deg'
Curve Info
mm, 2.5 mm and 2.8 mm obtained at the four corners of patch are shown in figure 7 (b), (c) and (d) respectively.
radius= 1.5mm
radius
=2.5mm
7(a)
7 (c)
Figure 9: Radiation pattern of Structure 2 for radius=1.5 mm
The simulated results of the each the antenna geometries obtained by semicircular cut of radius of 1.5mm, 2 mm, 2.5 mm and 2.8 mm at the four corners of patch are listed in the table II. A comparison chart is shown in figure 10, 11 and 12 for resonant frequency, gain and percentage bandwidth.
ircle
Radius (mm)
Resonant
frequency f1, f2 (GHz)
Gain (dB)
% BW BW1,BW2
S11 (dB)
1.5
9.65, 13.3
3.2
9.3, 4.1
-32,-13
2
10, 13.3
2.6
9.5, 5.2
-30,-20
2.5
10.3, 13.3
3.0
9.1, 5.9
-22,-24
2.8
10.6, 13.3
2.8
8.9, 5.6
-19,-15
TABLE II. COMPARISON RESULTS FOR DIFFERENT SEMICIRCULAR SLOTS
radius= 2 mm
Radius=2.8 mm
15 13.3
9.65
13.3
10
13.3 13.3
10.3 10.6
10
5
0
7 (b) 7 (d)
Figure 7 (a): Geometry of Structure 2 Slotted Microstrip Patch Antenna-1 with four semicircular slots of radius 1.5 mm (b) 2 mm (c) 2.5
mm (d) 2.8 mm
For the structure of figure 7 (a) the S11 parameter obtained is -32 dB. It is observed that the dual frequency operation can be achieved by cuts of semicircular shape of radius 1.5 mm at the four corners of patch of the antenna. Two resonating frequencies at 9.65 GHz and 13.3 GHz with % BW of 9.3 % and 4.1% respectively are obtained as shown in figure 8. The gain of 3.2 dB was observed from figure 9.
1.5mm 2mm cut 2.5mm 2.8mm
cut cut cut
Resonant frequency f1 (GHz) Resonant frequency f2 (GHz)
Figure 10: Resonant frequency Comparison chart for Structure 2
3.2
3
2.8
2.6
3.5
3
2.5
2
1.5
1
0.5
0
2mm
4mm 4mm
0.5mm
13( a) 13 (c)
1.5mm 2mm cut 2.5mm 2.8mm
cut cut cut
Gain (dB)
Figure11: Gain Comparison chart for Structure 2
1mm
4mm 7mm
0.5mm
8.9
5.6
9.1
5.9
9.5
5.2
9.3
4.1
15
10
5
0
-5
-10
-15
-20
-25
-30
-35
13( b)
13 (d)
2.8mm cut
2.5mm cut
2mm cut
1.5mm cut
Figure 13: Geometry of Structure 3 of Slotted Microstrip Patch Antenna-2 with rectangular Slot at right side (a) 4mm * 2mm (b) 4mm *
1mm (c)4mm * 0.5mm (d) 7mm * 0.5mm
Y
X
Name
m2
-13
m01.00 10.1500 -10.0293
-15
-19
11.2000 -9.5422
m-45.00
m3 13.1000 -9.8892
-20
13.9000 -9.7751
-22
dB(St(coax_pin_T1,coax_pin_T1))
m5 13.5000 -28.0483
XY Plot 50
HFSSDesign1 ANSOFT
Curve Info dB(St(coax_pin_T1,coax_pin_T1))
Setup1 : Sw eep
-24
m6
-10.00
-32
-30
-15.00
% BW 1 % BW 2 S11 (dB) of f1 S11 (dB) of f2
-20.00
10.6500 -18.9905
m1 m2 m3 m4
m6
Figure12: % Bandwidth and resonant frequency Comparison chart for Structure 2
It is observed that the gain is above 2 dB for all geometries. A dual band is observed in each structure in the X and Ku band. The return loss of structure of radius = 1.5 mm cut at corners is less at -32 dB at resonant frequency of
9.3 GHz.
-25.00
-30.00
m5
5.00 7.50 10.00 12.50 15.00
Freq [GHz]
Figure 14: Return loss versus frequency plot for Structure 3 of (4
*2)square mm slot
-
Slotted Microstrip Patch Antenna-2
For enhancing the bandwidth one rectangular slot of dimension (4mm * 2mm) is cut in the conventional patch at right side as shown in figure 13 (a). Four semicircular cuts of 2.5 mm radius at the four corners of the patch remain same for all the geometries of figure 13. Different slots of Rectangle of area (4 * 1) mm, (4 * 0.5) mm, (7 * 0.5) mm are shown in figure 13 (b), (c) and (d).
-90
-60
Name
Theta
Ang
Mag
m1
0.0000
0.0000
3.0483
-30
Radiation Pattern 13
0
m1
30
0.00
-5.00
60
-10.00
-15.00
90
HFSSDesign1 ANSOFT
Curve Info
dB(GainTotal) Setup1 : Sw eep Freq='9GHz' Phi='0deg'
dB(GainTotal) Setup1 : Sw eep Freq='9GHz' Phi='90deg'
-120 120
-150
-180
150
Figure 15: Radiation pattern of Structure 3 of (4 *2) square mm slot
3.07
3.08
3.08
3.08
Dual Band is observed in this structure at 10.6 GHz and 13.5 GHz as shown in figure 14 of structure 3 of (4 *
3.06
2) square mm slot. Radiation pattern of figure 15 shows gain of 3.04 dB.
3.04
3.02
3.04
The table III shows the comparison results for different slots of Rectangle of area (4 * 2) mm, (4 * 1) mm, (4 * 0.5)
(4 x (4 x (4 x (7 x
2)mm 1)mm 0.5)mm 0.5)mm
Gain (dB)
mm and (7 * 0.5) mm in the patch. Figure 16, 17 and 18 shows the comparison chart for return loss, bandwidth and gain with frequency.
TABLE III. COMPARISON RESULTS FOR DIFFERENT RECTANGULAR SLOTS
20
10.6 13.5 10.45 13.35
10
0
10.4 13.35
10.3 13.25
Figure18: Gain Comparison chart
Slot Area (square
mm)
Gain (dB)
Resonant frequency
(GHz)
(fr1, fr2)
%BW (BW1,B
W2)
S11 (dB)
4 x 2
3.04
10.6, 13.50
9.8, 5.9
-18, -28
4 x 1
3.07
10.45, 13.35
9.56, 5.99
-22, -29
4 x 0.5
3.08
10.4, 13.35
9.61, 6.36
-23, -27
7 x 0.5
3.08
10.3, 13.25
9.70, 6.03
-23, -24
It is observed that the gain is above 3 dB for all geometries. A dual band is observed in each structure in the X and Ku band with minimum return loss.
-
-
COMPARATIVE ANALYSIS OF ALL STRUCTURES:
Bandwidth and Gain are the two important antenna performance parameters. It is observed that antenna has two resonant frequencies for structure 2 and structure 3.
-10
-20
(4 x 2)mm (4 x 1)mm (4 x 0.5)mm (7 x 0.5)mm
-18
Gain is above 2 dB. Comparative results are more clearly shown by table IV below. Comparison of structure 2 with the basic patch of structure 1 shows a good improvement in the return loss from -18.5 dB to -32 dB with a dual band at
9.65 GHz and 13.3 GHz. Comparison of Structure 3 with
-30
-40
-22 -23 -23
-28 -29 -27
fr1 s11(f1) fr2 s11(fr2)
6
9.7
9.61
13.25
14
12
10
8
6
4
2
0
Figure16: Return loss and frequency chart for Structure 3
13.5
13.35
13.35
10.65
9.8
10.45
9.56
10.4
10.3
5.9
5.9
6.3
(4 x 2)mm (4 x 1)mm (4 x (7 x
0.5)mm 0.5)mm
fr1 % BW1 fr2 % BW2
5
8.78.6
10
Figure 17: % Bandwidth and frequency chart for Structure 3
-24
structure 1 shows dual band at frequency 10.6 GHz and
13.50 GHz with return loss of -18 dB and -28 dB.
TABLE IV. COMPARISON RESULTS FOR ALL STRUCTURES
Arrangement
Gain (dB)
Resonant freq.
(GHz)
S11 (dB)
Bandwidth (%)BW
Structure 1
2.15
8.7
-18.5
8.6
Structure 2
(r=1.5mm)
3.2
9.65
-32
9.3
13.3
-13
4.1
Structure 3 Slot area=(4*2) sq
mm
3.04
10.6
-18
9.8
13.50
-28
5.9
15
13.3
13.5
Structure 1
Structure 2
Structure 3
fr1 BW1 fr2 BW2
0
5.9
9.8
9
10.65
.659.3
4.1
Figure 19: % Bandwidth and frequency comparision chart
20
10
0
-10
-20
-30
-40
8.7
9.65
13.3
10.6
13.5
fr1 S11 (fr1) fr2 S11 (fr2)
2.15
-32
-18.5
-13
Structure 2
Structure 1
Figure 20: Return loss and frequency Comparison chart
3.5
3
2.5
2
1.5
1
0.5
0
3.2
3.04
Structure 1 Structure 2 Structure 3
Gain
Figure 21 : Gain Comparison chart
Figure 19, 20 and 21 shows the comparison chart for return loss, bandwidth and gain with frequencies for all three structures.
-
CONCLUSION
-
In this paper a new low profile broadband antenna operating at X and Ku band has been proposed. A rectangular patch with different slots in different position is taken to achieve good performances like gain and percentage band width. This design provides several advantages. The first one is the gain of antenna structure 2 and structure 3 is more than 2 dB. The second is that the patch antenna has dual band operating at X and Ku band. The overall patch size is small of 7.5*10.5 square mm and helps in feeding the antenna with coaxial feed. Finally the proposed structure is simple and can be fabricated easily. This antenna can be employed for Broadband Wireless communication systems.
REFERENCES:
-
A. Harrabi, T. Razban, Y. Mahe, L. Osman, and A. Gharsallah, Wideband patch antenna for X-band applications, Progress in Electromagnetics Research Symposium, Sweden, pp. 1043-1046, 2013.
Structure 3
-
A. Kayalvizhi; P. Geetha Prasanna, Multi band operating antenna for Wi-Fi, WiMAX and radar application, Pages: 1017 – 1020, IEEE Conference Publications, 2015.
-28
-18
-
V B Romodin, V I Oznogikhin and V V Kopylov, Log Periodic Microstrip Array, IEEE-Conference Mia-Mep9, 1999.
-
Monika Surana, O P Sharma, Analysis of Triple Band Rectangular Patch Antenna Loaded with Pairs of L shaped Slots, International Journal of Computer Application, Vol 111, No 12, pp 36-41, February 2015.
-
A. Gupta, R. K. Gangwar and S. P. Singh, Three Element Dual Segment Triangular Dielectric Resonator Antenna for X-Band Applications, Progress In Electromagnetics Research C, vol. 34, pp. 139-150, 2013.
-
M. Samsuzzaman, M.T. Islam, N. Misran, M.A. Mohd Ali, Dual Band X Shape Microstrip Patch Antenna for Satellite Applications, International Conference on Electrical Engineering and Informatics, ICEEI 2013, vol. 11, pp. 12231228, 2013.
-
M. Venkata Narayana, A.Vikranth, I. Govardhani, Sd. Khaja Nizamuddin, Ch. Venkatesh A Novel Design of a Microstrip Patch Antenna with an End Fire Radiation for SAR Applications International Journal of Science and Technology, Volume 2 No.1, pp 126-130, January 2012.
-
Govardhani.Immadi, M.S.R.S Tejaswi, M.Venkata Narayana, N.Anil Babu, G.Anupama , K.Venkata Ravi teja Design of Coaxial fed Micro strip Patch Antenna for 2.4GHz BLUETOOTH Applications Journal of Emerging Trends in Computing and Information Science VOL. 2, NO. 12, pp 686-690, December 2011.
-
M. Samsuzzaman and M. T. Islam, Inverted S-shaped compact antenna for X-band applications, The Scientific World Journal, pp. 1-11, 2014.
-
A. Srilakshmi, N. V. Koteswararao and D. Srinivasarao, X band printed microstrip compact antenna with slots in ground plane and patch, Recent Advances in Intelligent Computational Systems (RAICS), pp. 851-855, Sep 2011.
-
John D Kraus, Ronald J Marhefka, Ahmad S Khan , Antenna & Wave Propagation, Fourth edition, TMH India.
-
Anshu Toshniwal, O. P. Sharma, Analysis of multiband Square Microstrip Patch Antenna Loaded with a pair of Horizontal and Vertical Slits, International Journal of Advanced research in Electrical, Electronics and Instrumentation Engineering, Vol. 5, Issue 4, pp 3049-3057, April 2016.
-
Balanis, Antenna Theory Analysis and Design, third Edition, Wiley India.
-
Tapan Nahar, O.P.Sharma, Bandwidth Enhancement of Corporate fed Bowtie Antenna Array operating in L band by changing the substrate maerial and ground plane length, International Journal of Computer Application (IJCA), Vol.107, Issue 4, pp 16-19, Dec. 2014.