International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 3, Issue 7, July 2013)
Analysis of Electrical Parameters of Inset Fed Rectangular
Micro strip Patch antenna (RMPA) by Varying Inset Gap and
Inset Width
Swarna Pundir1, D. Arya2, Aruna Bansal3
1,3
M.Tech Student, IET Alwar, Electronics and Communication Department
Associate Professor, IET Alwar, Electronics and Communication Department.
2
Abstract-- This paper investigate the dependency of
electrical properties of inset fed rectangular microstrip patch
antenna (RMPA) by varying inset width and inset gap for
proper impedance matching to achieve efficient operation.
The design strategy is optimized for 2.4 GHz rectangular
shaped patch antenna using CST Micro stripes 2009 EMC
Edition. It has been observed the performance of patch
antenna depends more on inset gap between patch conductor
and inset fed line rather than inset length.
II. DESIGN P ROCEDURE
Before designing a Patch antenna we take consideration
of some basic facts like resonant frequency fr, kind of
model used for analysis, feeding method, shape and
dimensions of patch as well as substrate. So here the fr is
2.4 GHz ,Transmission line model is used because of ease
and gives good physical insight yet has less accurate and it
is more difficult to model coupling[6].Feeding method used
is recessed microstrip-line feed, shape considered is
rectangular patch on GML 1000 with dielectric constant εr
= 3.2 and thickness (t) of substrate is .762mm.
Keywords-- Inset- fed, Inset gap, Inset width, Inset fed Line,
Patch antenna, Resonance frequency
I. INTRODUCTION
III. DESIGN METHODOLOGY
A wireless communication system emphasis on
lightweight, compact and cost effective low profile
antennas for frequencies above100 MHz (ʎ ˂ 3m).
Microstrip patch antenna rises as a good candidate meeting
these requirements due to its versatility of possible
geometry and easy integrity with printed circuits. The
performance of
a patch antenna depends upon their
geometrical shape, physical dimensions and properties of
the material used. Including all this the location and type of
feed also plays a vital role for improving its performances.
The inset feed antenna provides a method of impedance
control with a planer configuration [1-2].It is found that a
shifted Cos2 function works well for the inset-fed patch [34]. The parameters of the shifted cosine function –squared
depend on the inset width for a given patch and substrate
geometry [5]. Bandwidth of a patch antenna is a linear
function of substrate thickness t and increasing t to increase
bandwidth result in greater surface wave, spurious radiation
and reduced directivity. In inset fed technique a notch is cut
on the edge of radiating patch to increase the matching for
better performance by controlling the input impedance
level.
This paper analyzes the variation of electrical properties
of a patch antenna with respect to inset width and inset gap
keeping the width of inset fed line constant.
While adopting the design strategy we try to keep the
return loss as minimum as possible. Design procedure is
conventional based on existing literature, choosing εr in
advance as dielectric of substrate are not easily available
which alongside also brings the thickness of the material
with itself.
IV. P ATCH ANALYSIS
Steps:
1. Calculate Width „W‟ [7]
√
2. Calculate εreff [9]
-1/2
εreff =
+
[
]
for Wp / h>1
3. Calculate ΔL i.e. normalized length[8]
= 0.412
126
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)
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International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 3, Issue 7, July 2013)
If we cut a notch on the patch and extend the inset fed
line, the input resistance of the fed line is that of where the
notch has been cut out of the patch, this gives a good
impedance matching for better result.
Here two parameters i.e. Inset gap width (notch width)
and the Inset fed (notch length) is varied keeping one of the
parameter constant at a time. Starting from the non
radiating edge notch width set to 00mm to0.34mm,
0.35mm and.5mm. Repeating it for the notch length from
the calculated value of 7.5mm ± 0.5mm.The variation is
kept in small steps as a minute change can also be easily
observed in this process rather than using bigger variations.
4. Calculate LP
=
- 2ΔL
√
5. For calculating notch width we use equation [10]
=
+
√
Rearranging the above equation for
=
√
6. Calculating
=
[11][12]
(
VI. RESULT AND D ISCUSSION
)
Summarizations of different model are shown in the
Table 2, showing
the effects on all the electrical
parameters of microstrip patch antenna. Figure _and _
shows the simulated variation in return loss (S11) and
bandwidth for model C, G and K. As input impedance of
inset fed patch antenna depends primarily upon the inset
length „d‟ and to some extend at the inset gap between
patch conductor and inset line. These result shows that the
resonance frequency ,return loss and bandwidth is to some
extend depends upon the inset gap ‟g‟ and less on inset
length ‟d‟. On comparing model no A, E, I with C,G,K, it is
easily seen that due to input impedance there is shift in S11
,bandwidth and resonance frequency . One can be precise
for a selective resonance frequency with
choosing a
proper width gap.
Tabulated values using above equations are shown in
Table 1.
Table 1:
Physical dimensions of microstrip patch antenna
Operating frequency
Dielectric constant
Length of the patch Lp
Width of the patch
Wp
Thickness (t) of the
Substrate
Model for Analysis
Substrate Length
Substrate Width
2.4GHz
3.2 (GML-1000)
34.75 mm
43.129 mm
.762mm
Transmission Line TLM
39.4 mm
47.7 mm
VII. CONCLUSION
For better analysis, input impedance of patch antenna
plays an important role as it will decide the performance of
an patch antenna. It can be easily concluded that impedance
matching depends more on inset gap rather than inset
length which in return affect the electrical parameters of a
microstrip antenna.
REFRENCES
[1]
[2]
Fig .1 shows the patch design with inset-fed located along the width.
V. S IMULATION S TRATEGY
[3]
Simulation is carried in a way to find out the effect of
variation in inset-fed gap and inset fed length on the
electrical parameters of patch antenna. Feed line with a
fixed width is extended up to the edge of the patch.
127
L.I.Basilio,M.A.Khayat,J.T.Williams and
S.A. Long, “The
Dependence of the Input Impedance on Feed Position of Probe and
Microstrip Line-fed Patch Antenna,”IEEE Trans.Antenna and
Propagation,Vol.AP-49,pp.45-47,Jan.2001.
T.Samaras,A.Kouloglou ,and J.N.Sahalos, “A note on the impedance
variation with feed position of a rectangular microstrip antenna,
”IEEE Antennas and Propagation Magazine,vol.46,pp.9092,April2004.
Y.Hu,E.J.Lundgren,D.R Jackson, J.T. Williams and S.A. Long, ”A
study of the Input Impedance of the Inset –fed Rectangular
Microstrip antenna as a function of notch depth and width,”2005
AP-S International Symposium, Washington DC, July 2005.
International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 3, Issue 7, July 2013)
[4]
[5]
[6]
[7]
Y.Hu, D.R. Jackson ,J.T.williams , and S.A.Long,”A Design
approach for inset-fed rectangular microstrip antennas,” AP-S
International Symposium,pp.1494 july2006.
M.A.Matin, A.I.Sayeed ,”A Design for Inset-fed Rectangular
Microstrip Patch Antenna,” Wseas Transactions on Communication
,Issue 1,Vol.9,Jan 2010.
E.H Van Lil and A.R Van De Capelle ,”Transmission –Line Model
for
Mutual
Coupling
Between
Microstrip
Antennas,”
IEEETrans.Antennas
Propagat.,Vol
AP-32,No.8,pp816821,Aug1984.
I.J Bahl and P Bhartia, Microstrip Antenna, Artech House,
Dedham.M.A, 1980.
[8]
T.A.Milligan,Modern Antenna Design, McGraw-Hill Book Co.,
New York ,1985
[9] C.A.Balanis, Advanced Engineering Electromagnetics,John Wiley &
Sons, New York,1989
[10] M.A.Matin, A.I.Sayeed,,A Design Rule for Inset-fed Rectangular
Microstrip Patch Antenna,,WSEAS Trans. on Communication, Issue
1,Vol.9,Jan 2010.
[11] A.G.Derneryd,”A Theoretical Investigation of the Rectangular
Microstrip Antenna Element,”IEEE Trans.Antenna Propagat.,
Vol.AP-26,No.4,pp532-535 ,July1978
[12] K.R.Carver and J.W.Mink,”Microstrip Antenna Technology,”IEEE
Trans. Antenna Propagat., Vol.AP-29, No.1, pp2-24, Jan 1981
Simulation Analysis
Table 2
Summarization of simulated result
Inset Feed
Patchl
No.
Inset
Gap
Inset
Length
g
(mm)
d
(mm)
Return Loss in
dB
W
(mm)
Lf
(mm)
Resonance
frequency
(GHz)
A.E
R.E
(dB)
(dB)
Directivity
in
( dBi)
Gain
in
( dBi)
Band Width
In
% age
2
2
5B
4B
3B
2B
00
.34
.35
.5
7
7
7
7
-13.261
-25.383
-24.591
-22.560
2.374
2.394
2.394
2.413
65.266
69.307
69.338
68.571
71.881
69.677
69.725
69.530
6.199
6.174
6.175
6.164
4.346
4.582
4.585
4.526
2.358
3.592
3.550
3.522
2
2
5
4
3
2
00
.34
.35
.50
7.5
7.5
7.5
7.5
-13.416
-22.641
-22.635
-21.029
2.373
2.401
2.402
2.406
65.098
69.344
69.748
69.073
71.796
69.686
69.748
69.784
6.195
6.171
6.173
6.166
4.330
4.587
4.587
4.559
2.444
3.498
3.538
3.408
2
2
5A
4A
3A
2B
00
.34
.35
.5
8
8
8
8
-13.427
-17.132
-17.039
-15.580
2.373
2.396
2.397
2.398
65.155
68.162
68.217
67.683
71.898
69.582
69.654
69.649
6.196
6.169
6.173
6.172
4.336
4.505
4.512
4.477
2.444
3.338
3.380
3.439
Simulated Result
Fig 2: return loss for patch 3A
Fig 2A: radiation patern for patch 3A
128
International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 3, Issue 7, July 2013)
Fig 3: return loss for patch 3B
Fig 3A: radiation patern for patch 3B
Fig 4: return loss for patch 3
Fig 4A: radiation patern for patch 3
Fig 5: return loss for patch 5
Fig 5A: radiation patern for patch 5
Fig 6: return loss for patch 5A
Fig 6A: radiation patern for patch 5A
129
International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 3, Issue 7, July 2013)
Fig 7: return loss for patch 5B
Fig 7A: radiation patern for patch 5B
130