This paper deals with the collision avoidance radar based antenna performance characteristics. This antenna can be placed inside the vehicle and it receives the signals from the base station and warns the driver accordingly. If any accident occurs to that vehicle, then that information is also passes to substation for help. The proposed antenna is designed on liquid crystal substrate and all its output parameters are simulated and presented in this work.
Trang 1Collision Avoidance Radar Operated LC Substrate based MSP Antenna in Vehicular Systems
1
1 Department of ECE, K L University, Guntur DT, AP, India 2
Head of the ECE Department, DJR IET, Gudavalli, AP, India
Email: madhav.mtech@gmail.com
Abstract: Road safety and precautionary measurement based instruments became part and parcel of the modern
vehicular systems Collision avoidance helps to prevent the vehicles from accidents and from unnecessary collision
while the driving When vehicle is moving with high speed and if any obstacle suddenly appears, it is very difficult to
control the vehicle If we design a system with the support of base station then we can warn the driver about the
accident occurred nearer to his way and about traffic jams etc This paper deals with the collision avoidance radar
based antenna performance characteristics This antenna can be placed inside the vehicle and it receives the signals
from the base station and warns the driver accordingly If any accident occurs to that vehicle, then that information
is also passes to substation for help The proposed antenna is designed on liquid crystal substrate and all its output
parameters are simulated and presented in this work
Keywords: Collision Avoidance, LC Substrate, MSP Antenna
1 Introduction:
Collision Avoidance System is a technology which
helps in avoiding vehicle collisions Various factors
to be taken in to consideration are Velocity of the
vehicle, direction of travel, acceleration of the
vehicle, steering angle and Yaw – rate The system
identifies a potential collision and gives warning
signal to the driver of the automobile This system is
a real – time system in which the radar to sends a
sonar signal It identifies any kind of obstacles in the
track of the vehicle Sensors are placed in the vehicle
to identify or sense the speed of the vehicles on either
side Antennas are used on the vehicle to send and
receive the signals [1-3]
The Collision Avoidance System identifies a
threat of collision well in advance depending on the
distance The distance may be user defined during the
process of design A warning signal is issued to
caution the driver to avoid the collision If the
situation goes out of control of the driver, another
system can be enforced to take the control over the
vehicle to avoid collision or mitigate the collision as
a final option which can be called an over – ride
system
In case of warning, the radar senses the obstacle in
the track followed by the vehicle and estimates the
distance Depending on the distance it warns the
driver [4] This warning can be issued by a warning
system which alerts the driver like alarm or an LED
After issue of the warning signal, the Collision
Avoidance depends on the response time or the
reaction time of the driver and the time taken for the
vehicle to decelerate or brake
The reaction time of the driver depends on various factors like the condition of the driver, reflexes of the driver, his attitude and behavior, his habits, his work stress of the day and his moods The braking time depends on the condition of the vehicle, brake efficiency, the traction of tyres and the kinematics of both the vehicles under collision [5-6]
Sensors are placed in the vehicle to identify or sense the speed of the vehicles on either side The sensors may be color video cameras and the ERIM
3-D laser range finder The major disadvantage of these systems is these are generally not very well suited for
a quick reaction to unexpected obstacles Especially
in the case of collision avoidance, a sensor is needed that can supply the relevant information fast with little data processing overhead and interact with actuators at the level of the vehicle controller
Sensors that satisfy these requirements are for example sonars, infrared sensors, pulsed 1-D laser range finders or microwave radar Compared to light based sensors Sonars have the advantage that they
do not get confused by transparent or black surfaces
On the other hand, the wavelength of ultrasound is much larger than the wavelength of lights Therefore, unless the transducer faces the reflector surface in a normal direction, only rough surfaces or edges can reflect sound waves Outdoor surfaces almost always have a type of surface roughness that enables sonar to detect the object It was therefore decided to use sonar sensors for the collision avoidance system of the vehicle [7-8]
The position of the vehicle is estimated relative to some initial point The distance travelled is provided
Trang 2by an optical encoder on the drive shaft and vehicle
orientation in 3-D space is provided by the gyroscope
of an inertial navigation system The measurements
are combined to give the x-y position and orientation
of the vehicle with respect to the world coordinates
Figure (1) Collision avoidance communication system
Figure (2) Nearer view of the system fitted in bayonet
2 Properties of Liquid crystals:
LCs is an anisotropic material showing both
properties of a crystal and a liquid All further
explanations are related to nematic LCs which shows
up to now the best dielectric properties at microwave
and millimeter-wave frequencies LC can be
processed around 300°C, has excellent electrical
properties, very low moisture absorption, light
weight, mechanical stiffness, thermal stability (CTE
= 0 to 30 ppm/°C), chemical resistance Depending
on the temperature, LC phase exists in a mesophase
between a crystalline solid and an isotropic liquid In
this state, the material can flow like a liquid but at the
same time, molecules have orientational order The
size of the molecule is typically a few nanometers
For this configuration, the electrical parameters of the
LCs are defined as ε┴ and tan δ┴ The molecules can
be rotated parallel to the RF field by applying a
voltage between the conductors in order to create an
electrostatic field in the LCs, thus changing the value
of the permittivity and loss tangent to ε║ and tan δ║
respectively
3 Results and Discussion:
Freq [GHz]
-35.00 -30.00 -25.00 -20.00 -15.00 -10.00 -5.00 0.00
Ansoft Corporation Return Loss Patch_Antenna_ADKv1
m 1
Curve Info dB(St(1,1)) Setup1 : Sw eep1 Name X Y
m1 23.8191 -34.7835
Figure (3) Return loss Vs Frequency Return Loss is a parameter which indicates the amount of power that is “lost” to the load and does not return as a reflection Figure (3) shows the return loss curve of the proposed antenna A return loss of -34.78dB is obtained at the desired frequency and it is acceptable return loss of <-10dB The input impedance of an antenna is defined as “the impedance presented by an antenna at its terminals or the ratio of the voltage to the current at the pair of terminals or the ratio of the appropriate components
of the electric to magnetic fields at a point” Hence the impedance of the antenna can be written as Zin =
Rin + jXin.Where Zin is the antenna impedance at the terminals, Rin is the antenna resistance at the terminals, Xin is the antenna reactance at the terminalsFigure (4) shows the input impedance smith chart rms of 0.74 and bandwidth enhancement of 0.87% is attained from the current model
5.00 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
10 30 50 70 90 100 120
140
160
180
-170
-150
-130 -110 -90 -80 -60 -40 -20
Ansoft Corporation Input Impedance Patch_Antenna_ADKv1
Curve Info rms bandw idth(1, 0) St(1,1)) Setup1 : Sw eep1 0.7458 21.1832
Figure (4) Smith chart Gain is a measure of the ability of the antenna to direct the input power into radiation in a particular direction and is measured at the peak radiation intensity Figure (5) shows the gain curve and a typical gain of 17.71dB is obtained from the current antenna The gain value is showing very high compared to the normal antenna The high gain can
be obtained with array models but here with single patch itself we obtained higher gain
-200.00 -150.00 -100.00 -50.00 0.00 50.00 100.00 150.00 200.00
Theta [deg]
-30.00 -20.00 -10.00 0.00 10.00 20.00
Ansoft Corporation ff_2D_GainTotal Patch_Antenna_ADKv1
dB(GainTotal) Setup1 : LastAdaptive dB(GainTotal)_1 Setup1 : LastAdaptive
Name X Y m1 12.0000 17.7160
Figure (5) gain
Trang 3Figure (6) rE-phi in 3D view Besides the reflection and mutual coupling
coefficients, the far-field radiation pattern is one of
the most important parameters in antenna design
Figure (6) and (7) shows the radiation pattern of the
antenna in phi and theta directions in three
dimensional views
Figure (7) rE-theta in 3D view
Figure (8) LHCP Curve in 3D View The directivity is indicated by both the distance from
the origin in the particular direction (defined by the
angles of azimuth phi and the zenith angle theta) and
the directivity surface color Figures (8) and (9) show
the directivity for the left and right circularly
polarized components of the receive antenna
far-field
Figure (9) RHCP Curve in 3D View
The axial ratio quantifies the polarization quality for
a circularly polarized antenna Circular polarization is specified by its sense (left-hand or right-hand) and by its axial ratio The axial ratio is the ratio of the maximum to minimum response to a linear signal of any orientation and is commonly expressed in dB
Figure (10) shows the axial ratio of the antenna in three dimensional view The inherently antenna radiates elliptically polarized waves Linear polarization being a particular case of it The elliptical polarization is characterized by three quantities: axial ratio, tilt angle and the sense of rotation
Figure (10) Axial Ratio in 3D View For linear polarization, the axial ratio is zero or infinite while the tilt angle gives its orientation
Circular polarization is obtained for unit axial ratio, where the tilt angle losses its meaning Thus the quality of circularly polarized wave is determined by the axial ratio
Figure (11) Polarization in 3D View Directivity is a measure of the concentration of radiation in the direction of the maximum Directivity and gain differ only by the efficiency, but directivity
is easily estimated from patterns Figure (12) shows the directivity of the antenna in 3D view
Figure (12) Directivity in 3D View
Trang 410.00 15.00 20.00 25.00 30.00 35.00 40.00
Freq [GHz]
0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00
90.00
Ansoft Corporation XY Plot 1 Patch_Antenna_ADKv1
m 1
Curve Info VSWRt(coax_pin_T1) Setup1 : Sw eep1 Name X Y
m1 23.8191 1.0371
Figure (13) VSWR Vs Frequency VSWR is a measure of impedance mismatch between
the transmission line and its load The higher the
VSWR, the greater is the mismatch The minimum
VSWR which corresponds to a perfect impedance
match is unity Figure (13) shows the VSWR Vs
frequency curve and VSWR of 1.03 is obtained from
the current model
4 Conclusion:
High gain antenna was designed and simulated for
collision avoidance radar based operation for
vehicular systems This antenna will be worthwhile
for getting information from base station and with the
help of advanced circuitry for desired operation
Maximum gain of 17dB and bandwidth up to 0.87%
enhancement can be obtained from the current model
All the parameters presented in this work are
showing the applicability of this antenna in the
collision avoidance system With the help of other
intelligence circuitry the speed of the vehicle and
breaks can be controlled
5 Acknowledgments:
The authors like to express their thanks to the
management of KLU and Department of ECE for
their support and encouragement during this work
Further, VGKM Pisipati acknowledges the financial
support of Department of Science and Technology
through the grant No.SR/S2/CMP-0071/2008
References:
[1] “A New Threat Assessment Measure for Collision
Avoidance Systems” by Yizhen Zhang, Erik K Antonsson
and Karl Grote (°c 2006 California Institute of Technology
Patent Pending, Serial # 60/798,516 All rights reserved.)
[2] “Sonar based Outdoor Vehicle Navigation and Collision
Avoidance” by Dirk Langer and Charles Thorpe The
Robotics Institute Carnegie Mellon University Pittsburgh,
PA 15232 (IROS '92)
[3] Economou, L & Langley, J (1998) Circular microstrip
patch antennas on glass for vehicle applications IEE
Proceedings Microwaves, Antennas and Propagation, 145
(5), pp.416-420
[4] Hoare, E & Hill, R (2000) System requirements for
automotive radar antennas In: IEEColloquium on Antennas
for Automotives pp.1/1-111
[5] “Collision Avoidance for Vehicle-Following Systems”
by Stefan K Gehrig and Fridtjof J Stein IEEE TRANSACTIONS ON INTELLIGENT TRANSPORTATION SYSTEMS, VOL 8, NO 2, JUNE
2007
[6] Low, L., Langley, R., Breden, R & Callaghan, P
(2006) Hidden Automotive Antenna Performance and Simulation IEEE Transactions on Antennas and Propagation, 54 (12), pp.3707-3712
[7] Sulic, E., Pell, B., John, S., Gupta, R., Rowe, W., Ghorbani, K & Zhang, K (2010) Deformation Evaluation
of Embedded Antennas in Vehicular Components In:
Proceedings of the World Congress of Engineering 2010
London, UK, pp.2389-2394
[8] Toriyama, H., Ohe, J., Kondo, H & Yotsuya, H (1987) Development of printed-on glass TV antenna system for
car In: 37th IEEE Vehicular Technology Conference, 1987
pp.334-342
Authors Biography
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 55 papers in International and National journals
His research interests include antennas, liquid crystals applications and wireless communications
Prof VGKM Pisipati was born in India, A.P, in
1944 He received his B.Sc, M.Sc and PhD degrees from Andhra University Since 1975 he has been with physics department at Acharya Nagarjuna University
as Professor, Head, R&D Director He guided 22 PhDs and more than 20 M.Phils His area of research
Trang 5includes liquid crystals, nanotechnology and liquid
crystals applications He visited so many countries
and he is having more than 260 International research
publications He served different positions as
academician and successfully completed different
projects sponsored by different government and
non-government bodies He is having 5 patents to his
credit
Prof Habibulla khan born in India, 1962
He obtained his B.E from V R Siddhartha Engineering
College, Vijayawada during 1980-84 M.E from C.I.T,
Coimbatore during 1985-87 and PhD from Andhra
University in the area of antennas in the year 2007.He is
having more than 20 years of teaching experience and
having more than 20 international, national
journals/conference papers in his credit.Prof Habibulla
khan presently working as Head of the ECE department at
K.L.University He is a fellow of I.E.T.E, Member IE and
other bodies like ISTE His research interested areas
includes Antenna system designing, microwave
engineering, Electro magnetics and RF system designing
P Syam Sundar received his B.Tech from JNTU College
of Engineering, Ananthapur in 1999 and M.Tech from
JNTU College of Engineering, Ananthapur in 2006 He
currently working as Associate Professor in the department
of ECE at K L University, Vaddeswaram, Guntur DT His
field of interest includes digital communication, antennas
and signal processing He is having one International
Journal Paper Publication
Mr Kommani Vijaya Prasad,
Professor & HOD, Department of ECE, DJR
Institute of Engineering & Technology, is a well
experienced teacher of Engineering for the past 15
years He holds his B.E from Osmania University,
M.Tech form JNTU University and professional
Diploma in information technology His student &
Teacher experience have created a lot of interest in
him for research Thus he is very interested in the
areas Computer Networks, Communications, Linear
IC Application and VLSI Design He is a life
member of ISTE
K.Balaji was born on 14-12-1963 in India
He did his B.Tech in 1988 from VRSEC and M.S from Bits Pilani in 1994 He is having 22 years of Teaching experience and currently he is working as Associate professor in the Department of ECE, K L University His research area includes Antennas and Communication systems