analysis of coaxial feeding and strip line feeding on … of coaxial feeding and strip line feeding...
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Analysis of Coaxial Feeding and Strip Line Feeding on the
Performance of the Square Patch Antenna
1B.T.P.Madhav, 1J.Chandrasekhar Rao, 1K.Nalini, 2N.Durga Indira
1 Assistant professor, Department of ECE, K L University, AP, India 2M.Tech Project Student, Department of ECE, K L University, AP, India
Abstract:
Microstrip patch antennas have different feeding
techniques. They can be divided based on power
transfer mechanism from feed line to patch. This
paper focuses on the design, model and simulation of
a microstrip patch antenna by applying two well
known and mostly used feeding techniques. Those
are coaxial feeding and the strip line feeding. The
proposed antenna is excited through these two
feeding techniques and the antenna design has been
executed and simulated using Ansoft’s HFSS.
Comparative study of simulated parameters like gain,
Bandwidth, directivity, Radiation pattern have been
done and presented in this paper.
1. Introduction:
Microstrip patch Antennas has various advantages
such as low profile, light weight, easy fabrication.
Feed line is used for excite to radiate by direct or
indirect contact. Microstrip patch antennas can be fed
in a variety of ways.1.Contacting 2.Non-Contacting.
In contacting method the RF power is fed directly to
the radiating patch using a connected element, they
are microstrip feed and coaxial feed.
In Non Contacting method, electromagnetic coupling
is done to transfer the power between the feed line
and the radiating patch, they are Aperture coupled
feed and Proximity coupled feed.
2. Feeding Techniques:
Microstrip line feed is one of the easier methods to
fabricate as it is a just conducting strip connecting to
the patch and therefore can be consider as extension
of patch. It is simple to model and easy to match by
controlling the inset position. The disadvantage of
this method is that as substrate thickness increases,
surface wave and spurious feed radiation increases
which limit the bandwidth.
In Coaxial feeding, the inner conductor of the coaxial
is attached to the radiation patch of the antenna while
the outer conductor is connected to the ground plane.
The main advantages of this method are easy to
fabricate, easy to match and low spurious radiation.
Aperture coupling consist of two different substrate
separated by a ground plane. On the bottom side of
lower substrate there is a microstip feed line whose
energy is coupled to the patch through a slot on the
ground plane separating two substrates. Top substrate
uses a thick low dielectric constant substrate, and the
bottom substrate uses high dielectric substrate. The
ground plane, which is in the middle, isolates the feed
from radiation element and minimizes interference of
spurious radiation for pattern formation and
polarization. The main advantage of this method is
allows independent of feed mechanism element.
Proximity coupling has the largest bandwidth, has
low spurious radiation. Length of feeding stub and
width-to-length ratio of patch is used to match.
Figure (1) coaxial feeding square patch antenna
B.T.P.Madhav et al, Int. J. Comp. Tech. Appl., Vol 2 (5), 1352-1356
IJCTA | SEPT-OCT 2011 Available [email protected]
1352
ISSN:2229-6093
Figure (2) Strip line feeding square patch antenna
Figure (1) shows the coaxial feeding microstrip
square patch antenna and Figure (2) shows the strip
line feeding microstrip square patch antenna. Both
these antennas are using RT-duroid substrate material
of dielectric constant 2.2.
3. Results and analysis
1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50Freq [GHz]
-30.00
-25.00
-20.00
-15.00
-10.00
-5.00
0.00
dB
(St(
1,1
))
Ansoft Corporation Patch_Antenna_ADKv1Return Loss
m 1
Curve Info
dB(St(1,1))Setup1 : Sw eep1
Name X Y
m1 3.4085 -27.5877
Figure (3a) Return loss Vs Frequency curve for
coaxial feeding antenna
The return loss curve for the square patch antenna by
using coaxial feeding is presented in figure (3a). The
operating frequency of the proposed antenna is
chosen at 3.4GHz which is used for the Wi-Fi
connectivity. From the figure (3a) we got the return
loss of -25.58dB at 3.4GHz.
The figure (3b) showing the return loss curve for the
square patch antenna designed using microstrip line
feeding. The return loss obtained from this curve is
about -14.15dB at 3.4GHZ.
1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50Freq [GHz]
-35.00
-30.00
-25.00
-20.00
-15.00
-10.00
-5.00
0.00
dB
(St(
1,1
))
Ansoft Corporation Patch_Antenna_ADKv1Return Loss
m1
Curve Info
dB(St(1,1))Setup1 : Sw eep1
Name X Y
m1 3.4085 -14.1512
Figure (3b) Return loss Vs Frequency curve for
microstrip line feeding antenna
From the both the results of return loss for coaxial
feeding and strip line feeding we observed that a
considerable values obtained from both the cases
which is showing return loss less than -10dB. For the
coaxial feeding we go better result in compared with
the strip line feeding as per the return loss is
concerned.
0.20 0.40 0.60 0.805.002.001.000.500.20
5.00
-5.00
2.00
-2.00
1.00
-1.00
0.50
-0.50
0.20
-0.20
0.00-0.005.00 2.00 1.00 0.50 0.20
5.00
-5.00
2.00
-2.00
1.00
-1.00
0.50
-0.50
0.20
-0.20
0.00-0.00 0
10
20
30
40
5060
708090100110120
130
140
150
160
170
180
-170
-160
-150
-140
-130-120
-110-100 -90 -80
-70-60
-50
-40
-30
-20
-10
Ansoft Corporation Patch_Antenna_ADKv1Input ImpedanceCurve Info rms bandw idth(1, 0)
St(1,1))Setup1 : Sw eep1 0.7600 3.0391
Figure (4a) Input Impedance curve for coaxial
feeding antenna
Figure (4a) is giving the input impedance smith chart
for the square patch antenna operating at 3.4GHz.
The rms obtained from the coaxial feeded square
patch antenna is 0.766 and bandwidth enhancement
for this model is about 0.89%.
Figure (4b) is showing impedance matching curve of
the proposed antenna with strip line feeding. The rms
obtained for this case is about 0.7668 and the
bandwidth enhancement is about 0.91%.
B.T.P.Madhav et al, Int. J. Comp. Tech. Appl., Vol 2 (5), 1352-1356
IJCTA | SEPT-OCT 2011 Available [email protected]
1353
ISSN:2229-6093
0.20 0.40 0.60 0.805.002.001.000.500.20
5.00
-5.00
2.00
-2.00
1.00
-1.00
0.50
-0.50
0.20
-0.20
0.00-0.005.00 2.00 1.00 0.50 0.20
5.00
-5.00
2.00
-2.00
1.00
-1.00
0.50
-0.50
0.20
-0.20
0.00-0.00 0
10
20
30
40
5060
708090100110120
130
140
150
160
170
180
-170
-160
-150
-140
-130-120
-110-100 -90 -80
-70-60
-50
-40
-30
-20
-10
Ansoft Corporation Patch_Antenna_ADKv1Input ImpedanceCurve Info rms bandw idth(1, 0)
St(1,1))Setup1 : Sw eep1 0.7658 3.0995
Figure (4b) Input Impedance curve for micro strip
line feeding antenna
From these results we noticed that the rms and
bandwidth is higher for strip line feeding in
compared with the coaxial feeding.
-200.00 -150.00 -100.00 -50.00 0.00 50.00 100.00 150.00 200.00Theta [deg]
-30.00
-25.00
-20.00
-15.00
-10.00
-5.00
0.00
5.00
10.00
Y1
Ansoft Corporation Patch_Antenna_ADKv1ff_2D_GainTotalm1m2 Curve Info
dB(GainTotal)Setup1 : LastAdaptive
dB(GainTotal)_1Setup1 : LastAdaptive
Name X Y
m1 0.0000 8.4059
m2 4.0000 8.4713
Figure (5) gain of the antenna for coaxial and strip
line feeding
Figure (5) showing the gain of the antenna by using
the coaxial and strip line feeding mechanism. For the
coaxial feeded microstrip square patch antenna a gain
of 8.47dBi is obtained and for the strip line feeding a
gain of 8.40dBi is obtained. From figure (5) we can
conclude that the gain for the current model by using
both the feeding mechanisms is almost equal. The
difference in the gain between these two cases is
about 0.0654dB.
Figure (6a) Radiation pattern in phi direction for
coaxial feeding antenna
Figure (6a) giving the radiation pattern of the coaxial
feeded antenna in three dimensional view. For each
mode there are two orthogonal planes in the far-field
region. One designated as E-plane and other
designated as H-plane. The far-zone electric field lies
in the E-plane and the far-zone magnetic field lies in
the H-plane. The patterns in these planes are referred
to as the E and H plane patterns respectively.
Figure (6b) Radiation pattern in phi direction for
microstrip line feeding antenna
For the TM01 mode the contributions to the far fields
are from the magnetic surface current densities on the
side walls containing the radiating edges. The
direction of magnetic currents that the E-plane is the
y-z plane (Phi=900) and the H-plane is the x-z plane
(Phi=00). Fig (6a) and fig (6b) are giving radiation
pattern in phi direction for coaxial feeded and strip
line feeded antennas.
B.T.P.Madhav et al, Int. J. Comp. Tech. Appl., Vol 2 (5), 1352-1356
IJCTA | SEPT-OCT 2011 Available [email protected]
1354
ISSN:2229-6093
Figure (7a) Radiation pattern in Theta direction for
coaxial feeding antenna
Figure (7b) Radiation pattern in Theta direction for
microstrip line feeding antenna
Figure (7a) and figure (7b) are giving the radiation
pattern in theta direction for both the cases in three
dimensional views. From these two figures we
observed that the radiation pattern is broader in both
directions and the radiation efficiency is acceptable
for the entire region.
1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50Freq [GHz]
0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00
90.00
100.00
VS
WR
t(co
ax_
pin
_T
1)
Ansoft Corporation Patch_Antenna_ADKv1XY Plot 1
m 1
Curve Info
VSWRt(coax_pin_T1)Setup1 : Sw eep1
Name X Y
m1 3.4940 1.4114
Figure (8a) VSWR Curve for coaxial feed antenna
Figure (8a) and figure (8b) giving the VSWR curve
Vs frequency for both the feeding techniques. The
VSWR obtained from the coaxial feeded square patch
antenna is about 1.414 and for the strip line feeded
antenna the VSWR is 1.441 at 3.4 GHz. Both these
values are maintaining the standardization with 2:1
VSWR ratio.
1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50Freq [GHz]
0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00
90.00
100.00
VS
WR
t(co
ax_
pin
_T
1)
Ansoft Corporation Patch_Antenna_ADKv1XY Plot 1
m 1
Curve Info
VSWRt(coax_pin_T1)Setup1 : Sw eep1
Name X Y
m1 3.4940 1.4413
Figure (8b) VSWR Curve for strip line feed antenna
S.NO Antenna
parameters
Coaxial
feeding
Microstrip line
feeding
1 Max U 0.0061713 w/sr 0.0056694 w/sr
2 Peak Directivity 7.0357 7.1399
3 Peak gain 7.0328 7.1268
4 Peak realized gain 7.0128 6.7931
5 Radiated power 0.011023w 0.0099786w
6 Accepted power 0.011027w 0.0099969w
7 Incident power 0.011059w 0.010488w
8 Radiation efficiency
0.9996 0.99816
9 Front to back ratio 110.15 112.81
Table (1) Antenna Parameters
Maximu
field data
values
Coaxial feeding Microstrip line feeding
rE field Value
(v)
At Phi
(deg)
At
Theta
(deg)
Value
(v)
At
Phi
(deg)
At
Theta
(deg)
Total 2.1571 90 4 2.0676 90 4
X 0.8345 20 32 0.2736 25 32
Y 2.1519 90 4 2.0625 90 4
Z 0.9649 90 42 0.91348 90 42
Phi 2.1409 180 0 2.0538 180 0
Theta 2.1571 90 4 2.0675 90 4
LHCP 1.563 150 12 1.476 140 8
RHCP 1.5625 30 10 1.4784 40 8
Table (2) Maximum field data
B.T.P.Madhav et al, Int. J. Comp. Tech. Appl., Vol 2 (5), 1352-1356
IJCTA | SEPT-OCT 2011 Available [email protected]
1355
ISSN:2229-6093
Conclusion:
The proposed square patch antenna is designed by
considering coaxial feeding and strip line feeding and
their output parameters are presented in this paper. In
both the cases the results showing the good
impedance matching between the input and the
output. The gains obtained from these cases are
8.40dBi and 8.47dBi respectively for coaxial feeding
and strip line feeding. The other antenna parameters
and maximum field data is shown in table (1) & table
(2) which are almost identical to each other. The strip
line feeding is preferable because of impedance
mismatching with the case of coaxial feeding.
Coaxial feeding requires number of trial and error
methods for getting impedance bandwidth perfectly.
Whereas for the strip line feeding impedance related
problems can be almost avoided.
Acknowledgements:
The authors like to express their thanks to
the management of K L University and the
Department of Electronics and Communication
Engineering for their continuous support and
encouragement during this work.
References:
[1] B.T.P.Madhav, K.Praveen Kumar, N.Srinivas Sri Chaitanya,
P.Rakesh Kumar, N.V.K.Ramesh, B.Nagaraju Nayak,
Comparative Analysis of Shorting Pin and Shorting Plate Models
for Size Reduction in the Microstrip Patch Antennas,
International Journal of Communication Engineering
Applications-IJCEA, http://technicaljournals.org ISSN: 2230-
8504; e-ISSN-2230-8512Vol 02, Issue 04; July 2011
[2] B.T.P.Madhav, K.V.L.Bhavani, P.Poorna Priya, Y.Joseph
Manoj Reddy, N.Srinivas Sri Chaitanya, N.Krishna Chaitanya,
ANALYSIS OF ORTHOGONAL FEED DUAL FREQUENCY
RECTANGULAR MICROSTRIP PATCH ANTENNA FOR S-
BAND APPLICATIONS, International Journal of Advances in
Engineering Research http://www.ijaer.com/ (IJAER) 2011, Vol.
No. 1, Issue No. V, June ISSN: 2231-5152
[3] P.J.Soh, M.K.A.Rahim, A.Asrokin & M.Z.A.Abdul Aziz,
Design, Modeling, and performance comparison of feeding
techniques for a microstrip patch antenna. Journal Teknologi, 47
(D) Dis.2007: 103-120 universiti technologi Malaysia.
[4] M. Irsadi Aksun, Shun-Hen Chuang, Senor Member, IEEE
AND Yuen Tze LO, Life Fellow, IEEE. On slot- coupled
microstrip antennas and their applications to CP operation-theory
and experiment. IEEE transactions on Antenna & Propagation,
vol.38, no.8, August 1990.
[5] V.R.Anitha, S. Narayana reddy. Design of an 8x1 square
microstrip patch antenna array. International Journal of Electronic
Engineering Research, vol.1, (2009) 71-77.
[6] Kazi Tofayel Ahmed, Md. Bellal H0ssain, Md. Jassed
Hossain. Designing a high bandwidth patch antenna and
comparison with the formed patch antennas. Canadian Journal on
Multimedia and Wireless networks, vol 2, no.2, April 2011.
[7] Jagadish.M.Rathod, Member IACSIT, IETE (I), IE (I), BES
(I). Comparative study of microstrip patch antenna for wireless
communication application. International Journal of Innovation,
Management & Technology, vol.1, n0.2, June-2010, ISSN:
2010-0248.
[8] Kazuhiro Kitatani, Sadahiko Yamamoto. Coaxial feed-type
microstrip patch antenna with variable antenna height.
Electronics and Communications in Japan (Part I:
Communications), Volume 87, Issue 2, pages 10–16, February
2004.
[9] D.D.Sandu, O.Avadanei, A.Ioachima, G.Banciua, P.Gasner.
Microstrip Patch Antenna with dielectric substrate. Journal
Optoelectronics and Advanced Materials Vol. 5, No. 5, 2003.
[10] Zhi Ning Chen; Chia, M.Y.W. Center-fed microstrip patch
antenna. Antennas and Propagation, IEEE Transactions on Issue Date: March 2003 Vol: 51 Issue:3.
Author’s Details:
B.T.P.Madhav was born in India, A.P, in
1981. He received the B.Sc, M.Sc, MBA, M.Tech degrees
from Nagarjuna University, A.P, India in 2001, 2003, 2007,
and 2009 respectively. From 2003-2007 he worked as
lecturer and from 2007 to till date he is working as
Assistant Professor in Electronics Engineering. He has
published more than 45 papers in International and
National journals. His research interests include antennas,
liquid crystals applications and wireless communications.
J. Chandrasekhar Rao was born in India,
A.P in 1985. He received his B. Tech, M.Tech degrees in
ECE. He currently working as Assistant professor in ECE
department of K L University. He has 3 national and 1
International conference paper, and one international
journal paper. His research interests include satellite
communications, antennas, and image processing.
B.T.P.Madhav et al, Int. J. Comp. Tech. Appl., Vol 2 (5), 1352-1356
IJCTA | SEPT-OCT 2011 Available [email protected]
1356
ISSN:2229-6093