World Journal of Engineering and Technology, 2013, 1, 1-8
doi:10.4236/wjet.2013.11001 Published Online May 2013 (http://www.scirp.org/journal/wjet)
1
Analysis and Design of an Obstacle Detection Radar
Transceiver for ISM Band
Bimal Garg, Dauood Saleem
Department of Electronics Engineering, Madhav Institute of Technology and Science, Gwalior, India.
Received April 13th, 2013; revised April 18th, 2013; accepted April 25th, 2013
Copyright © 2013 Bimal Garg, Dauood Saleem. This is an open access article distributed under the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
ABSTRACT
Authors designed an obstacle radar transceiver for ISM band. This work is focused on rectangular microstrip transceiver
integrated with innovative metamaterial structure at a height of 3.276 mm from the ground plane. Two rectangular mi-
crostrip transceiver is designed for transmitting and receiving purpose. This work is mainly focused on increasing the
potential parameters of rectangular microstrip transceiver. RMT along with the proposed innovative metamaterial
structure is designed to resonate at 2.259 GHz. Simulation results showed that the impedance bandwidth of the RMT is
improved by 575%, return loss is reduced by 391% and efficiency is improved by 28% by incorporating the proposed
innovative metamaterial structure. For verifying that the proposed innovative metamaterial structure possesses negative
values of Permeability and Permittivity within the operating frequency range, Nicolson-Ross-Weir method (NRW) has
been employed. An op-amp and comparator is used to compare the return loss of transmitting and receiving RMT. An
indicator is used to indicate difference of return loss and power of transmitting and receiving rectangular microstrip
transceiver. For all simulation purpose, computer simulation technology-microwave studio (CST-MWS) software has
been used.
Keywords: Rectangular Microstrip Transceiver (RMT); Industrial; Scientific and Medical Radio Band (ISM);
Permittivity; Permeability; Nicolson-Ross-Weir (NRW) Approach
1. Introduction
Technology supporting safe driving, an information col-
lection infrastructure for sensing road conditions and
supplying key information on road conditions to vehicles
comprises an important theme for consideration. Devel-
opment efforts are currently underway to come up with a
practical infrastructure of this type. The information col-
lection infrastructure is expected to detect current posi-
tions and velocities of obstacles on roads, such as things
that have been dropped, or that have fallen on the road,
standing or running vehicles. This technology is essential
for constructing Smart way. The author has adopted a
thematic rather than a chronological approach in Figure
1.
Advanced cruise assist highway system (AHS Smart-
way, intelligent road) is an infrastructure that realizes
Smart cruise with advanced safety vehicle (ASV Smart
Car, intelligent vehicle) and smart gateway [1] (Intelli-
gent communications). More specifically, this road is
equipped with a variety of information facilities and an
administration system to apply the facilities to ITS ser-
vices. The smart cruise systems are explained in Figures
2 & 3.
Figure 1. Thematic approach of a rectangular microstrip
transceiver.

Analysis and Design of an Obstacle Detection Radar Transceiver for ISM Band
2
Figure 2. Smart Cruise Systems.
Figure 3. Service s provided by Smartway .
Now, what will driving be like in an environment
where smart way and smart car begin to exchange infor-
mation? Let’s try to imagine a drive someday when this
system is in place.
The radio detection and ranging (RADAR) use rec-
tangular microstrip transceiver to extract information
about the target’s position. Radar systems transmit sig-
nals in form of electromagnetic waves from the transmit-
ter. The signal travels from the source to the target where
it is reflected back to the receiver. The difference in the
parameters of the transmitted signal and the received
signal are then used to extract information about the tar-
get. Information that may be obtained includes position,
speed, height and size of target. The distance to the target
is obtained from the time lapse between the received and
the transmitted signal. The size of target is directly pro-
portional to the power of the received signal. For receiv-
ing and transmitting purpose the authors used two iden-
tical rectangular Microstrip transceivers. This is shown in
Figure 4.
Rectangular microstrip transceiver is designed on a di-
electric substrate, which is composed of a radiating tran-
sceiver on one side and ground plane on the other side as
shown in Figure 5.
These are low profile, lightweight, low cost transceiv-
ers. In spite of having a lot of advantages these trans-
ceivers have some drawbacks like narrow-bandwidth,
low gain, high return loss etc. [2]. To overcome trans-
ceivers drawbacks several researches have been done on
rectangular microstrip transceiver. In this area of re-
search, Victor Veselago [3-4] introduced the theoretical
concept of metamaterials. According to the theory of
Veselago, these are generally artificial materials used to
provide properties, which are not found in readily avail-
able materials in nature [5]. For improving the perform-
ance of microstrip transceiver J.B. Pendry and his col-
leagues [6] added more information. They proved that
the array of metallic wires can be used to obtain negative
permittivity and split ring resonators for negative per-
meability. On the basis of this information D. R. Smith
and his colleagues [7] fabricated a structure in 2001,
which was a composition of split ring resonator and thin
wire. It had been observed that the structure proposed by
them possessed the negative values of permittivity and
permeability simultaneously and was named as LHM
[8-9].
In this work “Rectangle surrounded by circles and
hexagonal” innovative metamaterial structure has been
introduced for reducing the return loss and ameliorating
the bandwidth and efficiency of the RMT. Metamaterial
Figure 4. Radar System using rectangular microstrip tran-
sceiver.
Figure 5. Rectangular microstrip transceiver.

Analysis and Design of an Obstacle Detection Radar Transceiver for ISM Band 3
substrate size variation may affect the microstrip trans-
ceiver parameters so that variations in metamaterial sub-
strate have not been done. Along with these outcomes, it
has been observed that, this structure satisfies the double
negative property within the operating frequency range.
2. Rectangular Microstrip Transceiver
Designing Procedure and Simulation
Results of RMT with & without
Innovative Metamaterial Structure
The RMT parameters are calculated from the formulae
given below.
A. Desired Parametric Analysis [10- 1 1]
Calculation of Width (W)
00
12
12 1
2rrr
r
C
wf
f




2
(1)
where
c = free space velocity of light
εr = Dielectric constant of substrate
The effective dielectric constant of the rectangular mi-
crostrip transceiver.
11 1
22 12
1
rr
eff h
w













(2)
The actual length of the transceiver (L)
2
eff
LL L (3)
where
2
eff
reff
C
Lf

 (4)
Calculation of Length Extension


0.3 0.264
0.412
0.258 0.8
eff
eff
w
Lh
w h
h











(5)
The Rectangular Microstrip transceiver is designed on
FR-4 lossy substrate with εr = 4.3 and height from the
ground plane d = 1.6 mm. The Length and width of RMT
are L = 30 mm, W = 36 mm respectively, which are cal-
culated from the formulae discussed in parametric analy-
sis section. For cut width, cut depth, length of transmis-
sion line and width of the feed, some specific values have
been chosen to obtain the resonating frequency of the
proposed rectangular microstrip transceiver at 2.259 GHz.
These values can be varied to change the resonating fre-
quency. The parameter specifications of rectangular mi-
crostrip transceiver are mentioned in Table 1.
Figure 6 shown below represent dimensional structure
of rectangular microstrip transceiver at a resonant fre-
quency 2.259 GHz whose specifications for designing
are mentioned above.
In this paper the proposed innovative metamaterial
structure is introduced to form the superstate of a rec-
tangular microstrip transceiver. The required specifica-
tions of this design are shown in the Figure 7.
Table 1. Rectangular Microstrip Transceiver Specifications.
Parameters Dimensions Unit
Dielectric Constant (εr)4.3 -
Loss Tangent (tan∂) 0.02 -
Thickness (h) 1.6 mm
Operating Frequency 2.259 GHz
Length (L) 30 mm
Width (W) 36 mm
Cut Width 5 mm
Cut Depth 11 mm
Path Length 20 mm
Width Of Feed 2.7 mm
Figure 6. Rectangular microstrip transceiver at 2.259 GHz.
Figure 7. Design of proposed innovative metamaterial struc-
ture.

Analysis and Design of an Obstacle Detection Radar Transceiver for ISM Band
4
Rectangular microstrip transceiver with proposed me-
tamaterial is shown below in Figure 8. It shows the ac-
curate position of metamaterial structure over the rec-
tangular microstrip patch antenna. It is more significant
that metamaterial structure get accurate position over the
patch antenna to radiate in proper order elsewhere some
variations in measured results take place from simulation
results.
Return loss S11 and Impedance Bandwidth of Rectan-
gular Microstrip transceiver is shown in Figure 9. The
designed antenna resonates at 2.259 GHz. The bandwidth
of the antenna can be said to be those range of frequent-
cies over which the return loss is greater than −10 dB
(corresponds to a VSWR of 2). Thus the bandwidth of
antenna can be calculated from return loss versus fre-
quency plot. The Impedance bandwidth of the simulated
patch antenna is 13.8 MHz and resonant frequency is
2.259 GHz.
Return loss S11 and Impedance Bandwidth of Rectan-
gular microstrip transceiver with proposed metamaterial
structure is shown in Figure 10. The bandwidth of the
Figure 8. Rectangular microstrip transceiver with proposed
innovative metamaterial structure.
Figure 9. Simulation of Return loss S11 and impedance
bandwidth of Rectangular microstrip transceiver.
Figure 10. Simulation of Return Loss S11 and impedance
bandwidth of RMT with proposed metamaterial structure.
antenna can be said to be those range of frequencies over
which the return loss is greater than −10 dB (corresponds
to a VSWR of 2). The bandwidth of the simulated patch
antenna is 93.2 MHz and resonant frequency is 2.259
GHz (2.1913 - 2.2845 GHz). More negative is the return
loss; more is the coupling and therefore more will be the
directivity and gain of the proposed antenna in particular
direction.
From Figures 9 & 10 it has been observed that the re-
turn loss has significantly reduced by 40.24 dB and
bandwidth has increased by 79.4 MHz by incorporating
proposed metamterial structure with RMT. These results
are showing that there is amelioration in return loss by
391% and in bandwidth by 575% of RMT by incorpo-
rating proposed innovative metamaterial structure.
The radiation pattern of a transceiver is generally its
most basic requirement because it determines the distri-
bution of radiated energy into the space. Gain depends on
directivity and directivity is totally depends on the shape
of the radiation patterns of a transceiver. The Radiation
Pattern of the RMT operating at 2.259 GHz is shown in
Figure 11. This shows that the directivity is 6.993 dBi
and efficiency is −4.984 dB i.e. 31.73%, whereas Figure
12 shows that the directivity of the RMT with the pro-
posed innovative metamaterial structure that is 7.116 dBi
and efficiency is −3.91 dB i.e. 40.64%. These results are
showing that there is amelioration in efficiency by 28%
and in directivity by 2% of RMT by incorporating pro-
posed innovative metamaterial structure. Figures 13 &
14 show that power used by transceiver with & without
proposed metamaterial structure.
Figures 15 & 16 show the E-field and H-field pattern
of the proposed rectangular microstrip transceiver along

Analysis and Design of an Obstacle Detection Radar Transceiver for ISM Band 5
Figure 11. Radiation Pattern of a Rectangular microstrip
transceiver.
Figure 12. Radiation Pattern of RMT with proposed meta-
material structure.
Figure 13. Power Pattern of a Rectangular microstrip tran-
sceiver.
Figure 14. Power Pattern of RMT with proposed metama-
terial structure.
Figure 15. E-Field of RMT with proposed metamaterial
structure.
Figure 16. H-Field of RMT with proposed metamaterial
structure.
with metamaterial respectively at the operating frequency
2.259 GHz, which gives the information about distribu-

Analysis and Design of an Obstacle Detection Radar Transceiver for ISM Band
6
tion of E-field and H-field by the antenna. The magni-
tude of main lobe for E-field and H-field are 17.6 dBV/m
and −33.9 dBA/m respectively and angular width of both
fields are 84.9 degree.
Smith charts define a very important characteristic for
a transceiver as it provides valuable information about
impedances at different frequency point so that decision
about the impedance matching can be taken. From Fig-
ures 17 & 18 it is clear that the RMT with the proposed
innovative metamaterial structure provides better impe-
dance matching at 2.259 GHz, when compared to RMT
alone.
3. Nicolson-Ross-Weir (NRW) Approach
The values of permittivity and permeability affect the
potential parameters like return loss and radiation pattern
of a transceiver, this is the reason why these values are
calculated. For obtaining the values of permeability and
permittivity different methods can be used, some of them
Figure 17. Smith chart of Rectangular microstrip trans-
ceiver.
Figure 18. Smith chart of RMT with proposed metamaterial
structure.
are Nicolson-Ross-Weir (NRW), NIST iterative, Non-
iterative and Short circuit techniques. In this work
Nicolson-Ross-Weir (NRW) technique [12-13] has been
used to obtain the values of permittivity and permeability
as this is a very popular technique to convert S-parame-
ters due to the fact that this technique provides easy as
well as effective formulation and calculation. All these
methods discussed above required S-parameters for ob-
taining the values of permeability & permittivity. Here in
this work for extracting the S-Parameters, proposed me-
tamaterial structure is placed between the two waveguide
ports [14-16] at the left and right hand side of the X axis
as shown in Figure 19. In Figure 19, Y-Plane is defined
as Perfect Electric Boundary (PEB) and Z-Plane is de-
fined as the Perfect Magnetic Boundary (PMB), which
creates internal environment of waveguide. The simu-
lated S-Parameters are then exported to Microsoft Excel
Program for verifying the Double-Negative properties of
the proposed metamaterial structure [17-19].
B. Equations used for calculating permittivity and
permeability using NRW approach [20-22].



2
2
2. 1
..1
r
cv
di v


 (6)



1
1
2. 1
.. 1
r
cv
di v



 (7)
1112
VS S
1

 (8)
2211
VS S
1

 (9)
where
εr = Permittivity
μr = Permeability
c = Speed of Light
ω = Frequency in Radian
d = Thickness of the Substrate
i = Imaginary coefficient
V1 = Voltage Maxima
V2 = Voltage Minima
Figure 19. Proposed metamater ial structure between the tw o
waveguide ports.

Analysis and Design of an Obstacle Detection Radar Transceiver for ISM Band 7
For satisfying Double Negative property, the values of
permeability and permittivity should be negative within
the operating frequency range. The obtained values of
these two quantities from the MS-Excel Program are
given in Tables 2 & 3, whereas Figures 20 & 21 show
the graph between permeability vs. frequency and per-
mittivity vs. frequency respectively.
The Tables generated for permittivity and permeability
by using MS-Excel Software was too large, the Tables 2 &
3 show the negative value of permeability and permittivity
only in the frequency range 2.2499998 - 2.2649999 GHz.
Table 2. Sampled values of permeability at 2.259 GHz cal-
culated on ms excel software.
Frequency
[GHz] Permeability [µr] Re [µr]
2.2499998 −270.798587153409 - 112.375651867994i −270.8
2.2529995 −262.790056026946 - 112.871815587582i −262.8
2.256 −254.894924191312 - 113.10786541182i −254.9
2.2590001 −246.989518964166 - 113.062410329303i −247
2.2620001 −238.951915332999 - 112.766063352027i −239
2.2649999 −230.684613628889 - 112.297165820145i −230.7
Table 3. Sampled values of permittivity at 2.259 GHz calcu-
lated on ms excel software.
Frequency
[GHz] Permittivity [εr] Re [εr]
2.2499998 −0.171922033221022 - 0.305191106496656i−0.172
2.2529995 −0.163397846483344 - 0.314433432234842i−0.163
2.256 −0.15445152683498 - 0.322675792751677i −0.154
2.2590001 −0.144420186288391 - 0.330172859997875i−0.144
2.2620001 −0.132763848247536 - 0.337457889150417i−0.133
2.2649999 −0.119185974821689 - 0.345248387298907i−0.119
Figure 20. Permeability versus Frequency Graph.
Figure 21. Permittivity versus Frequency Graph.
Further an additional arrangement is done for detection
of obstacle, an op-amp IC-741 and comparator ICLM339MX
is used to compare the return loss of transmitting and
receiving RMT. An indicator IC-PT2395 is used to indi-
cate difference of return loss and power of transmitting
and receiving rectangular microstrip transceiver.
4. Conclusion
On the basis of the simulation results it is observed that
the return loss obtained at the design frequency for the
RMT with proposed innovative metamaterial structure is
−50.50 dB and bandwidth is 93.2 MHz. By simulating
both the transceiver on CST-MWS, the return loss has
significantly reduce by 391%, the bandwidth has im-
proved by 575% and efficiency is improved by 28% as
shown in Figures 9-12. Smith Charts [23-25] in Figures
17 & 18 of both the transceiver shows the impedance at
simulated frequency. This is remarkable improvement in
ISM band, when compared to the results of RMT alone.
It is clearly observed that the return loss, bandwidth, ef-
ficiency and directivity has improved significantly by
incorporating the proposed metamaterial structure at
3.276 mm layer from the ground plane of the transceiver.
By using the NRW method in MS-Excel Software, the
negative permeability & negative permittivity have been
proved. The tables for permeability & permittivity gen-
erated by the MS-Excel Software were too large, be-
tween the simulated frequency ranges 1 - 3 GHz. There-
fore, Tables 2 & 3 show the negative values of perme-
ability & permittivity of the limited samples only in the
frequency range 2.2499998 - 2.2649999 GHz. The Fig-
ures 20 & 21 show the negative values of permeability &
permittivity of the proposed innovative metamaterial
structure. Along with these improvements this structure
satisfies double negative property within the simulated
frequency range. By investigation it is found that there is
difference between return loss and measured power of
transmitter and receiver when an obstacle comes between
transmitter and receiver. We set a false alarm condition

Analysis and Design of an Obstacle Detection Radar Transceiver for ISM Band
8
and used a comparator to measure the difference between
input and output signal.
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