Strain Gage Measurement with AI-208 Using DASYLab and LabVIEW
Labview Based RCS Measurement System
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Transcript of Labview Based RCS Measurement System
1
EE 492 PROJECT
LABVIEW BASED
RCS MEASUREMENT SYSTEM
SUBMITTED BY:
İsmail YILDIZ – Göksenin BOZDAĞ
SUPERVISOR:
Asst. Prof. Dr. A.Sevinç AYDINLIK BECHTELER
Spring, 2010 – 2011
2
CONTENTS
ABSTRACT…………………………………………………………………………………....................... 3
A)INTRODUCTION………………………………………………………………………………………….. 4
1.RADAR CROSS SECTION……………………………………………………..……………………… 5
2.RCS OF SIMPLE OBJECTS…………………………………………………………………………….. 5
B)MEASUREMENT SYSTEM………………………………………………………………………………. 7
1.SETTING UP HARDWARE & REFERANCE OBJECTS……………………………………….. 10
2.BUILDING VIS.……………………………………………………………………………………………. 12
A)NETWORK ANALYZER SUB VIs………………………………………………………………. 12
B)TURN TABLE SUB VIs…………………………………………………………………………… 16
C)MEASURUMENTS…………………………………………………………………………………………. 19
1.CALIBRATION OF NETWORK ANALYZER……………………………………………………… 19
2.CALCULATION OF RCS VALUES…………………………………………………………………… 19
3.ANALYZING OF COLLECTED DATA………………………………………………………………. 23
D)CONCLUSION……………………………………………………………………………………………….. 26
E)REFERENCES…………………………………………………………………………………………………. 27
3
ABSTRACT
The ambition of the project is developing a bistatic radar cross section measurement system.
Hardware components of the system are used in remote mode and they are controlled by a
computer program written in LabView. All of the measurements are done in a anechoic
chamber. Finally, collected data is analyzed and radar cross section values of the objects are
calculated and graphed.
4
A)INTRODUCTION
Stealth technology is any technology that makes aircrafts, missiles, ships, submarines,
personnel etc. ideally invisible to radar, sonar and the other detection methods. This
technology without no doubt provide a great advantage who gets it. Thus, so many
researchers studies on this technology and so many companies and countries support and
invest in these researches.
In active sensor used detection systems such as radar, invisibility is not possible so main
purpose of these systems is decreasing detection distance. In other words ,decreasing
detection distance means that showing the objet smaller than its original size . The smallness
can be expressed as Radar Cross Section in square meter.
The ambition of the project is developing a “ Bistatic RCS Measurement System”. The system
is designed for indoor measurements for analyzing the rcs values of objects in terms of
frequency, position and polarization. We mainly used a network analyzer, a turn table, a
computer and two antennas with same specifications for setting up the system and all
measurements are done in anechoic chamber at İYTE wireless center.
5
1.RADAR CROSS SECTION
Radar Cross Section is the measure of a target's ability to reflect radar signals in the direction
of the radar receiver. It is a measure of the ratio of backscatter power per steradian (unit
solid angle) in the direction of the radar (from the target) to the power density that is
intercepted by the target. General formula is:
It is obviously seen that rcs is not a ratio of incident and scaterring waves. RCS value is the
answer of this question: How many square meter must be the object to get Ps power from
the Si density. We generally use dbsm (desibel square meter) unit for rcs to get more
understandable graphs .
1.RADAR CROSS SECTION of SIMPLE OBJECTS
Because of its pure radial symmetry, the perfectly conducting sphere is the simplest of all
three-dimensional scatterers. Despite the simplicity of its geometrical surface, however, and
the invariance of its echo with orientation, the RCS of the sphere varies considerably with
electrical size.
The log-log plot of the figure shown below reveals the rapid rise in the RCS in the region
0<kr < 1, which is known as the Rayleigh region. The central region characterized by the
interference between the specular and creeping-wave contributions is known as the
resonance region .There is no clear upper boundary for this part of the curve, but a value
near kr = 10 is generally accepted. The region kr > 10 is dominated by the specular return
from the front of the sphere and is called the optics region. For spheres of these sizes the
geometric optics approximation πr2 is usually an adequate representation of the magnitude
of the RCS.
6
All measurements are done in optical region to get a constant rcs value. Used frequencies
are in the range of 8 -12 GHz and used reference object’s radius is 0,075 m. The ka values of
the our measurements are between 12.5664 and 18.8496. This range obviously satisfies the
optical region criteria.
Nose-on incidence lies at the center of
the patterns, and the sharp peaks near
the sides are the specular returns from
the slanted sides of the cone, also
called specular flashes. The RCS
formula for singly curved surfaces
given in the left side figure. It is used
to predict the amplitudes of the
specular flash within a fraction of a decibel.
B) MEASUREMENT SYSTEM
Our measurement system is based on LabView programming. It supplies us
control the necessary devices and process the collected data.
in an anechoic chamber that is a room to
sound or electromagnetic waves. The Figure
structure of the system.
Figure 1 (General Hardware
The network analyzer generates the signal with desired frequency ranges
points for the transmission and this signal is sent by the transmitter antenna (one of the
horn antennas). The other horn antenna that is used for receiver is
transmitter antenna and receives th
analyzer, we can easily measure S
is the ratio of ‘transmitted power wave at port2’ to ‘incid
objects are placed on a turn table and S21 values are measured with desired step size and
ranges. For each step, we get the data
operations are managed with the LabVi
7
B) MEASUREMENT SYSTEM
t system is based on LabView programming. It supplies us
devices and process the collected data. The measurements are made
anechoic chamber that is a room to be designed for stopping reflections of either
sound or electromagnetic waves. The Figure1 shown below is the general hardware
Figure 1 (General Hardware Structure)
The network analyzer generates the signal with desired frequency ranges
points for the transmission and this signal is sent by the transmitter antenna (one of the
horn antennas). The other horn antenna that is used for receiver is
transmitter antenna and receives the signal that is reflected from object.
we can easily measure S-parameters. For this measurement, we measure S21 that
is the ratio of ‘transmitted power wave at port2’ to ‘incident power wave at port1’. The
objects are placed on a turn table and S21 values are measured with desired step size and
ranges. For each step, we get the data and collected data is written in a text file.
ged with the LabView program set on a laptop.
t system is based on LabView programming. It supplies us to configure and
The measurements are made
for stopping reflections of either
shown below is the general hardware
The network analyzer generates the signal with desired frequency ranges and number of
points for the transmission and this signal is sent by the transmitter antenna (one of the
horn antennas). The other horn antenna that is used for receiver is placed near the
e signal that is reflected from object. Thanks to network
parameters. For this measurement, we measure S21 that
ent power wave at port1’. The
objects are placed on a turn table and S21 values are measured with desired step size and
and collected data is written in a text file. All of these
Figure 2 (LabView Front Panel
Figure 2 is “Front Panel” of the software and it is used as a user
start-stop degrees, step size for turn table; S-
configurations program is run. While program is running
8
Figure 2 (LabView Front Panel – User Interface)
the software and it is used as a user interface. User selects the visa address of each device and determines
-parameter, frequency range, number of points for network analyzer.
ram is running user can observe measured S-parameters for each step on the black boxes.
of each device and determines speed,
range, number of points for network analyzer. After determining all
for each step on the black boxes.
Figure 3 is “Block Diagram” of the software and it is called VI. All configuration, control, arithmetic and logic operations
diagram. We have some main subVIs and they also have their own
For this measurement, we have to control two main devices, turn table and network analyzer. While we operating these two devices together,
we have to be careful on two critical points. One of them is that two devices must work serially. Other one is there must be enough time
waiting between serialization. On the block diagram, we
9
Figure 3 (Labview Block Diagram)
Figure 3 is “Block Diagram” of the software and it is called VI. All configuration, control, arithmetic and logic operations
s and they also have their own several subVIs.
, we have to control two main devices, turn table and network analyzer. While we operating these two devices together,
two critical points. One of them is that two devices must work serially. Other one is there must be enough time
between serialization. On the block diagram, we see these points clearly.
Figure 3 is “Block Diagram” of the software and it is called VI. All configuration, control, arithmetic and logic operations are done in the
, we have to control two main devices, turn table and network analyzer. While we operating these two devices together,
two critical points. One of them is that two devices must work serially. Other one is there must be enough time
10
1.SETTING UP HARDWARE & REFERANCE OBJECTS
Connection between laboratory instruments is supplied with GPIB cables. An USB GPIB is
used to connect laptop to instruments. Network analyzer and turntable controller are
connected to each other. USB side of USB GPIB is connected to laptop and the other side is
connected to one of the instruments. Some coaxial cables and many connectors are used.
Coaxial cables are supplied connection between instruments and antennas. Connectors are
used to connection between different types of inputs.
Fig.29 (Coaxial cable) Fig.30 (Connector) Fig.31 (Connector)
Figure 32 (Connection instrument and cable) Fig.33 (GPIB cable)
For the measurement, we used two horn antennas whos
two antennas are attached to a handmade wood board by side by side. Tripods metal parts
are covered with isolator. The network analyzer was located into the anechoic chamber
because of weak power and also it was covered with isolator. For adjusting
antennas directivity, we turned antennas symmetrically by using laser pointer.
Fig.34 (Antennas ar
During the project time, we could measure 4 types of objects;
1.) Sphere (steel-clad) with diameter 15cm
2.) Plate (brass) with 10X10cm size
3.) Plate (brass) with 15X15cm size
4.) Plate (steel) with 15X15
Fig.34 (Sphere (steel-clad) with diameter 15cm) Fig.34 (Plate (brass) with 10x10cm size)
11
For the measurement, we used two horn antennas whose specifications are the same. These
to a handmade wood board by side by side. Tripods metal parts
The network analyzer was located into the anechoic chamber
because of weak power and also it was covered with isolator. For adjusting
antennas directivity, we turned antennas symmetrically by using laser pointer.
Fig.34 (Antennas are ready for measurement)
During the project time, we could measure 4 types of objects;
clad) with diameter 15cm
with 10X10cm size
Plate (brass) with 15X15cm size
Plate (steel) with 15X15cm size
clad) with diameter 15cm) Fig.34 (Plate (brass) with 10x10cm size)
e specifications are the same. These
to a handmade wood board by side by side. Tripods metal parts
The network analyzer was located into the anechoic chamber
because of weak power and also it was covered with isolator. For adjusting the object and
antennas directivity, we turned antennas symmetrically by using laser pointer.
clad) with diameter 15cm) Fig.34 (Plate (brass) with 10x10cm size)
Fig.34 (Plate (steel) with 15x15
2. BUILDING VIs
a)Network Analyzer SubVI
Our network analyzer is Agilent/HP 8720D and its necessary visa drivers are found on the
library of National Instruments web
Network analyzer SubVI consists of two main section, configuration and control.
� Network Analyzer Configuration V
Figure 3 (
12
Fig.34 (Plate (steel) with 15x15cm size) Fig.34 (Plate (brass) with 15x15cm size)
SubVIs
analyzer is Agilent/HP 8720D and its necessary visa drivers are found on the
library of National Instruments web-site.
Network analyzer SubVI consists of two main section, configuration and control.
Network Analyzer Configuration VIs
Figure 3 (Network Analyzer Configuration VIs)
Fig.34 (Plate (brass) with 15x15cm size)
analyzer is Agilent/HP 8720D and its necessary visa drivers are found on the
Network analyzer SubVI consists of two main section, configuration and control.
13
Network analyzer configuration VIs consists of 4 subVIs. After the initialization, we set up a
wait block because turn table must stop totally. Then, network analyzer go on processing
such as set format, set meas and set sweep.
Figure 4 (Inner parts of the Initialization subVI)
Figure 5 (Inner parts of the Set Format subVI)
14
Figure 6 (Inner parts of the Set Meas subVI)
Figure 7 (Inner parts of the Set Sweep subVI)
15
� Network Analyzer Control VIs
Figure 8 (Network Analyzer Control VIs)
Network analyzer configuration VI consists of one subVI that is collect data. Lower part of
the figure shows the measured data on the screen. Upper side of the figure shows the
frequency, S21 values and degree are written in a text file.
NOTE: The device driver can be found on the web site of National Instruments at the
LabVIEW developer zone.
b)Turn Table SubVI
Our turntable is a product of Innco Systems, Germany. A controller called CO 2000 and
produced by Innco systems is used for controlling the turntable. CO 2000 controller has a
GPIB port so we use this port for communication. It’s default GPIB address is 7
number is used in the program.
Two main subVIs are generated. One of them is for configuration, the other one is for
manipulation.
� Turntable Configuration VI
Left side of VI includes controls and the right side includes indicators/connection
choose the GPIB address of turntable for VISA session control. Start, Stop and Step size are
entered by user in degree and user enters the turning speed of turntable in a range from 1
to 8. When we look at the right side, we see a VISA resource
us which visa address is used in the vi.
direction of turntable (clockwise or counter clockwise). Start, stop and step size buffers show
the values of initially determine
Figure 17 (inner part of turntable configuration VI, it has also four different subVIs)
16
SubVIs
Our turntable is a product of Innco Systems, Germany. A controller called CO 2000 and
produced by Innco systems is used for controlling the turntable. CO 2000 controller has a
GPIB port so we use this port for communication. It’s default GPIB address is 7
number is used in the program.
Two main subVIs are generated. One of them is for configuration, the other one is for
Turntable Configuration VI
Left side of VI includes controls and the right side includes indicators/connection
choose the GPIB address of turntable for VISA session control. Start, Stop and Step size are
entered by user in degree and user enters the turning speed of turntable in a range from 1
to 8. When we look at the right side, we see a VISA resource name out, this indicator shows
us which visa address is used in the vi. TF (True-False) case helps us determining the
direction of turntable (clockwise or counter clockwise). Start, stop and step size buffers show
the values of initially determined.
Figure 17 (inner part of turntable configuration VI, it has also four different subVIs)
Our turntable is a product of Innco Systems, Germany. A controller called CO 2000 and
produced by Innco systems is used for controlling the turntable. CO 2000 controller has a
GPIB port so we use this port for communication. It’s default GPIB address is 7 and this
Two main subVIs are generated. One of them is for configuration, the other one is for
Left side of VI includes controls and the right side includes indicators/connection nodes. We
choose the GPIB address of turntable for VISA session control. Start, Stop and Step size are
entered by user in degree and user enters the turning speed of turntable in a range from 1
name out, this indicator shows
False) case helps us determining the rotation
direction of turntable (clockwise or counter clockwise). Start, stop and step size buffers show
Figure 17 (inner part of turntable configuration VI, it has also four different subVIs)
Figure 18 (initialize VI of turntable configuration VI)
Figure 19 (Speed Control subVI of turntable configuration VI)
17
Figure 18 (initialize VI of turntable configuration VI)
Figure 19 (Speed Control subVI of turntable configuration VI)
Figure 19 (Speed Control subVI of turntable configuration VI)
Figure 20 (This subVI
� Turntable control VI
This VI is used for only counter clockwise turning when star degree is less than stop
degree.
Figure 21 (
Note: All of the string commands can be found between the pages 35 and 43 in the service
manual of Innco Systems.
18
Figure 20 (This subVI makes turntable to go to desired degree)
is used for only counter clockwise turning when star degree is less than stop
Figure 21 (Counter Clockwise turning subVI)
Note: All of the string commands can be found between the pages 35 and 43 in the service
makes turntable to go to desired degree)
is used for only counter clockwise turning when star degree is less than stop
Note: All of the string commands can be found between the pages 35 and 43 in the service
19
C) MEASUREMENTS
RCS measurement can be divided into outdoor and indoor according to the different field.
The outdoor measurement is easily influenced by weather. It is difficult to get high
resolution and accurate results. On contraries, the indoor measurement can provide a
controlled electromagnetic circumstance, and researchers can work in a comfortable place.
Moreover, more accurate results can be gained with less cost. It also save one third of time
in comparison of the outdoor measurement. We did all measurements in the anechoic
chamber of İYTE- Wireless Center and the measurement system has been explained in the
previous part. 1. CALIBRATION OF NETWORK ANALYZER
Network analyzer must be calibrated to get accurate and stable results. For calibration, we used “Agilent 3.5mm Economic Calibration Kit” and two connectors.
Firstly, calibration menu button is pushed, calibration kit type and full two port calibration
tab are chosen. One of these ports is forward the other one is reverse port. We use an open
circuit, a short circuit and 50Ω load for both reverse and forward ports. Then we connect
these ports with the broadband load. Then, omit isolation tab is chosen from main
calibration menu. After these operations finish, analyzer calculates the coefficients in a few seconds. Finally, Save/Recall button is pushed to save the calibration.
For recalling a saved calibration, we push Save/Recall button again and chose the wanted calibration.
2. CALCULATION OF RCS VALUES
Measured values (S21) does not directly give exact rcs values because this measured values
contain both noise and rcs of chamber . Therefore; to get exact rcs values we must subtract the
noise and reduce the effect of rcs of chamber from measured values. According to this claim,
RCS values can be calculated by the formula given below:
where, σdBsm is the RCS of target, σdBsm is the RCS of scaling, S21,S’21 are the measured value
of target and scaling.
20
PLATE 15X15 E-PLANE
Frequency Measured S21 Values Measured S21 Values Measured S21 Values Average Values
(GHz) (dBsm) (dBsm) (dBsm) (dBsm)
8 -36,586 -36,412 -36,773 -36,59
8,5 -35,944 -34,74 -34,905 -35,2
9 -34,28 -34,024 -34,103 -34,14
9,5 -34,637 -33,808 -34,082 -34,18
10 -35,109 -33,922 -34,31 -34,45
10,5 -35,18 -33,521 -33,76 -34,15
11 -32,962 -31,924 -32,315 -32,4
11,5 -33,172 -32,233 -32,647 -32,68
12 -34,48 -33,074 -33,923 -33,82
PLATE 10X10 E-PLANE
Frequency Measured S21 Values Measured S21 Values Measured S21 Values Average Values
(GHz) (dBsm) (dBsm) (dBsm) (dBsm)
8 -42,541 -42,885 -43,488 -42,97
8,5 -43,785 -43,446 -44,068 -43,77
9 -43,09 -42,356 -42,333 -42,59
9,5 -40,882 -39,448 -39,654 -40
10 -40,619 -39,832 -40,418 -40,29
10,5 -42,962 -41,671 -42,32 -42,32
11 -40,477 -38,201 -38,525 -39,08
11,5 -39,337 -37,619 -37,968 -38,31
12 -38,326 -37,068 -37,544 -37,65
PLATE 10X10 H-PLANE
Frequency Measured S21 Values Measured S21 Values Measured S21 Values Average Values
(GHz) (dBsm) (dBsm) (dBsm) (dBsm)
8 -41,129 -41,086 -41,444 -41,22
8,5 -46,499 -46,704 -45,982 -46,39
9 -38,711 -38,784 -39,756 -39,08
9,5 -41,7 -41,647 -41,553 -41,63
10 -38,434 -38,409 -38,46 -38,43
10,5 -40,039 -40,11 -40,509 -40,22
11 -37,159 -37,243 -37,615 -37,34
11,5 -37,646 -37,567 -38,43 -37,88
12 -42,867 -42,849 -42,407 -42,71
21
EMPTY E-PLANE
Frequency
(GHz)
Measured S21 Values
(dBsm)
Measured S21 Values
(dBsm)
Measured S21 Values
(dBsm)
Average Values
(dBsm)
8 -48,7848 -48,3674 -50,2043 -49,119
8,5 -46,8128 -46,1737 -46,49
9 -51,5067 -50,9618 -51,7687 -51,41
9,5 -57,7815 -63,8642 -60,02
10 -46,5181 -46,6762 -47,4534 -46,88
10,5 -44,5964 -44,3754 -44,48
11 -51,5033 -51,3084 -49,9068 -50,91
11,5 -53,7737 -57,2195 -55,01
12 41,7938 -41,7178 -42,5419 -42,02
PLATE 15X15 H-PLANE
Frequency
(GHz)
Measured S21 Values
(dBsm)
Measured S21 Values
(dBsm)
Measured S21 Values
(dBsm)
Average Values
(dBsm)
8 -34,36 -33,933 -34,122 -34,14
8,5 -35,146 -34,937 -35,192 -35,09
9 -33,076 -32,525 -32,764 -32,79
9,5 -34,879 -34,462 -34,452 -34,6
10 -32,827 -32,321 -32,243 -32,46
10,5 -32,594 -32,151 -32,413 -32,39
11 -31,551 -31,156 -31,025 -31,24
11,5 -32,498 -31,691 -32,123 -32,11
12 -35,299 -34,696 -34,813 -34,94
22
PLATE 15X15 E-PLANE
Frequency
(GHz)
Calculated S21 Values
(dBsm)
Measured Average
S21 Values(dBsm)
Measured Average Empty
S21 Values(dBsm)
X=Measured S21-Empty S21
(dBsm)
X-Calculated S21
(dBsm)
8 6,5521 -36,59 -49,119 12,53 5,98
8,5 7,0817 -35,2 -46,49 11,29 4,21
9 7,5782 -34,14 -51,41 17,27 9,69
9,5 8,0478 -34,18 -60,02 25,84 17,79
10 8,4933 -34,45 -46,88 12,43 3,94
10,5 8,9171 -34,15 -44,48 10,33 1,41
11 9,3212 -32,4 -50,91 18,51 9,19
11,5 9,7073 -32,68 -55,01 22,33 12,62
12 10,0769 -33,82 -42,02 8,2 -1,88 PLATE 10X10 E-PLANE
Frequency Calculated S21 Values Measured Average Measured Average Empty X=Measured S21-Empty S21 X-Calculated S21
(GHz) (dBsm) S21 Values(dBsm) S21 Values(dBsm) (dBsm) (dBsm)
8 -0,4885 -42,97 -49,119 6,15 6,64
8,5 0,0381 -43,77 -46,49 2,72 2,68
9 0,5345 -42,59 -51,41 8,82 8,29
9,5 1,0042 -40 -60,02 20,02 19,02
10 1,4497 -40,29 -46,88 6,59 5,14
10,5 1,8735 -42,32 -44,48 2,16 0,29
11 2,2775 -39,08 -50,91 11,83 9,55
11,5 2,6636 -38,31 -55,01 16,7 14,04
12 3,0333 -37,65 -42,02 4,37 1,34
COMPARE PLATE 10X10 AND 15X15 E
Frequency
(GHz)
Z1=X-Calculated S21
for 10x10 (dBsm)
Z2=X
for 15x15 (dBsm)
8 6,64
8,5 2,68
9 8,29
9,5 19,02
10 5,14
10,5 0,29
11 9,55
11,5 14,04
12 1,34
According to our measurements exact values and calculated values are almost same. The
difference is ±1dbsm and this difference is caused from not being provided far
conditions.
3. ANALYZING OF COLLECTED DATA
All measurements are done at X
values according to position, frequency and polarization.
peak at 0 degree for plate and does not change for the sphere
independent of frequency.
We observed our measurement on graphs that were drawn according to 1 degree step size
from -90 degree to 90 degree as we see below.
This figure shows us angle dependency of RCS where two antennas were H plane. We can
observe that while RCS of sphere
23
COMPARE PLATE 10X10 AND 15X15 E-PLANE
Z2=X-Calculated S21
for 15x15 (dBsm)
Constant or RCS of Chamber
(Average Z1&Z2)(dBsm)
5,98 -6,31
4,21 -3,45
9,69 -8,99
17,79 -18,41
3,94 -4,54
1,41 -0,85
9,19 -9,37
12,62 -13,33
-1,88 0,27
According to our measurements exact values and calculated values are almost same. The
1dbsm and this difference is caused from not being provided far
3. ANALYZING OF COLLECTED DATA All measurements are done at X-Band (8-12GHz) and more than ten times
values according to position, frequency and polarization. We expect that RCS value will be
peak at 0 degree for plate and does not change for the sphere because the
We observed our measurement on graphs that were drawn according to 1 degree step size
90 degree to 90 degree as we see below.
hows us angle dependency of RCS where two antennas were H plane. We can
of sphere is almost constant, plate has a peak at 0 degree for 11 GHz.
Constant or RCS of Chamber
(Average Z1&Z2)(dBsm)
Deviation ((Z1-Z2)/2)
(dBsm)
0,33
0,76
0,7
0,62
0,6
0,56
0,18
0,71
0,95
According to our measurements exact values and calculated values are almost same. The
1dbsm and this difference is caused from not being provided far-field
ten times to get average
We expect that RCS value will be
the RCS of a sphere is
We observed our measurement on graphs that were drawn according to 1 degree step size
hows us angle dependency of RCS where two antennas were H plane. We can
k at 0 degree for 11 GHz.
Here, we compared two different sized plates that are 15x15 and 10x10 for 11 GHz. We can
obviously see that RCS value changes according to size of the object and plate with large size
has higher RCS values that small sized one.
This figure shows us how RCS value changes according to different polarization. White graph
represents E plane measurement where both two antennas are horizontal position. Red
graph represents H plane measurement whe
plane RCS values are almost same because of the directivity and gain specifications of used
antennas.
24
Here, we compared two different sized plates that are 15x15 and 10x10 for 11 GHz. We can
obviously see that RCS value changes according to size of the object and plate with large size
her RCS values that small sized one.
This figure shows us how RCS value changes according to different polarization. White graph
represents E plane measurement where both two antennas are horizontal position. Red
graph represents H plane measurement where two antennas are vertical position. E and H
values are almost same because of the directivity and gain specifications of used
Here, we compared two different sized plates that are 15x15 and 10x10 for 11 GHz. We can
obviously see that RCS value changes according to size of the object and plate with large size
This figure shows us how RCS value changes according to different polarization. White graph
represents E plane measurement where both two antennas are horizontal position. Red
re two antennas are vertical position. E and H
values are almost same because of the directivity and gain specifications of used
We try to observe the effect of different polarized antennas
and other one is H plane. The RCS value is lowest at 0 degree because E cross H gives 0 and
for other degrees, RCS can change because plate is not perpendicular to antennas directivity
and there should be some cosine values. T
Our ambition for this figure is that whether RCS value is increasing or not if frequency
increases. We see zoomed form of the figure at the right and clearly see that RCS value
increases if frequency increases.
25
effect of different polarized antennas where one of them is E plane
The RCS value is lowest at 0 degree because E cross H gives 0 and
for other degrees, RCS can change because plate is not perpendicular to antennas directivity
and there should be some cosine values. The result of this measurement is shown above
Our ambition for this figure is that whether RCS value is increasing or not if frequency
increases. We see zoomed form of the figure at the right and clearly see that RCS value
increases.
where one of them is E plane
The RCS value is lowest at 0 degree because E cross H gives 0 and
for other degrees, RCS can change because plate is not perpendicular to antennas directivity
measurement is shown above.
Our ambition for this figure is that whether RCS value is increasing or not if frequency
increases. We see zoomed form of the figure at the right and clearly see that RCS value
26
D) CONCLUSION
The importance of stealth technology has been increasing due to the its 'great advantage
day by day . Having information about RCS values that is the indicator of this technology is
as important as having the technology. So many commercial RCS measurement systems are
designed by researchers at both companies and universities. For determining the rcs values
of objects we are also designed and constructed a bistatic radar cross section measurement
system.
In this project, we only measured RCS of reference objects and generated a calibration
table at X-band for horizontal and vertical polarizations because of the many physical
problems such as need of a high frequency power amplifier or professional antenna holders
and pressure of time. We had only one term for constructing the system. On the other
hand, according to our data analyze, our results are acceptable and reliable due to the ±1
dbsm difference between theoretical RCS values and measured values.
Finally, calibration tables that are got thanks to this project can/must be used for measuring
for more complex objects. We can decrease the sensitivity of the system by using a power
amplifier and a professional antenna holder. Software of the system can make be more
useful by integrating measurement and data analyze interfaces.
27
E) REFERENCES
� Books
1. BISHOP, ROBERT H. , LABVIEW STUDENT EDITION 6I, NATIONAL INSTRUMENTS
2. SKOLNIK, MERRILL I,RADAR HANDBOOK, SECOND EDT. MC GRAW HILL
3. KNOTT, E. F., SHAEFFER, J. F., TULEY, M. T., 2004, RADAR CROSS SECTİON (2nd
EDITION), SCITECH PUBLISHING
4. BALANIS, CONSTANTIN A., ANTENNA THEORY AND DESIGN, THIRD EDITION, WILEY-
INTERNATINAL
� Papers
1. C.F. HU, J.D. XU, N.J. Lİ, L.X. ZHANG, LOW FREQUENCY RCS MEASUREMENT SYSTEM
IN ANECHOIC CHAMBER,CHINA MARCH 2010
2. HP 8720D OPERATION MANUAL
3. AGILENT ANTENNA AND RCS MEASUREMENT CONFIGURATIONS USING PNA
MICROWAVE NETWORK ANALYZERS
4. ANTENNA MEASUREMENTS, RCS MEASUREMENTS AND MEASUREMENTS ON
PULSEDIİGNALS WITH VECTOR NETWORK ANALYZERS R&S ZVM, R&S
ZVK,APPLİCATİON NOTE
5. ANECHOIC CHAMBER MEASUREMENT IMPOROVEMENT, MICROWAVE JOURNAL,
MARCH 2006
6. ERGİN, A. ARİF, GÖRÜNMEZLİK TEKNOLOJİLERİ, IDEF’07 NO:120
7. B. K. CHUNG, H. T. CHUAH AND JONATHAN W. BREDOD A MICROWAVE ANECHOIC
CHAMBER FOR RADAR-CROSS SECTION MEASUREMENT, IEEE ANTENNAS AND
PROPAGATION MAGAZINE, VOL. 39, NO. 3, JUNE 1997
8. AYANLI, HALİT, DEVELOPMENT OF A GRAPHICAL USER INTERFACE (GUI)
APPLICATION FOR RADAR CROSS SECTION (RCS) PREDICTION OF ARBITRARILY
SHAPED OBJECTS, M.S. THESIS, 2007
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� Web-Sites 1. http://zone.ni.com/dzhp/app/main (NI LabVIEW Developer Zone) 2. Radar Cross Section, http://www.earth2.net/parts/mugu/rcs.pdf