Radar cross section on matlab
时间：04-06
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antenna project.pdf
i want to measure Radar cross section is based on the measurement results which I got in two exel files one is real and other is imaginary data . In this assignment . my teacher examined horn antenna and corner reflector and calculate rcs (Radar cross section) .
I have uploaded my assignment i am going through some problems in it in first part . it says thay plot a full signal from (0 to sampling freq.) i am wondering
what should be the sampling freq i should use in this assignment. and he also want us to calculate the operating freq. of radar using this plot .
can you please help me in solving this assingment . I have just 5 days left .
i am putting my assignment below so any one can read it .
Antenna Theory Project
Calculate radar cross section (RCS) based on the measurement results
22 October 2012
Introduction
The main task in the project is to calculate radar cross section (RCS) based on the measurement results in
reality. The purposes of this project are to help students to
- Get knowledge of equipments.
- Understand the measurement results in reality.
- Calculate based on the measurement results.
- Process the measurement results using Matlab.
Radar system
Radar is an abbreviation of Radio Detection and Ranging. It is a radio system using electromagnetic waves,
specifically radio waves, to detect objects and determine the ranges between this radio system and those
objects. Although the beginning experiments of Heinrich Hertz showing that radio waves could be reflected
from solid objects were carried out in 1886, the milestone for the development of radar did not occur until
World War II. Radar has a wide range of applications including those for civil and military purposes.
Detecting and ranging air, ground and sea targets are crucial applications of radar for military purposes.
Meanwhile, civilian applications of radar can be found in aviation, marine, monitoring and so forth. A basic
radar system includes one transmitter emitting radio waves called radar signals and one or more receiver(s)
capturing reflections from objects such as aircrafts, ships, vehicles and terrain. If a radar system utilizes one
transmitting antenna and one receiving antenna which are collocated, that radar system is called a mono-static system. A radar system will be called a bi-static system if its transmitting antenna and receiving
antenna are separated. For the mono-static case, the radar range R is calculated from the round trip
propagation time as
R= c*tau/2
(1)
where c is the propagation speed and equal to the speed of light c = 3×10
8m/s, and tau is the propagation
time of the radio waves back and forth. The relationship between the transmitted power Pt
and received
power Pr
of a mono-static radar system is represented by the radar equation
Pr/Pt = G*Ae*σ*(F)sqaure 4/ (2*pi)2 (R)sqaure 4
where G is the gain of the antenna, Ae is the effective area of the antenna, σ is RCS of the object, and F
indicates the antenna pattern. If a radar system operates in vacuum and without interference, the term F in
the numerator of (2) is set to one ( F = 1).
In an experiment performed at BTH, a mono-static SAR system is used. The mono-static SAR system is
built with a vector network analyzer [1], a horn antenna [2] and accessories. The system is shown in Fig. 1.
Fig. 1. Mono-static SAR system.
Corner reflector
A corner reflector is a reflector consisting of three mutually perpendicular, intersecting flat surfaces, which
reflects waves back directly towards the source, but shifted (translated). The three intersecting surfaces
often have square shapes. Radar corner reflectors made of metal are used to reflect radio waves from radar
sets. Radar corner reflectors are designed to reflect the microwave radio waves emitted by radar sets back
toward the radar antenna. This causes them to show a strong "return" on radar screens. A simple corner
reflector consists of three conducting sheet metal or screen surfaces at 90° angles to each other, attached to
one another at the edges, forming a "corner". These reflect radio waves coming from in front of them back
parallel to the incoming beam.
In the same experiment performed at BTH, we build a radar corner reflector with the dimension 30 cm × 30
cm × 30 cm. The reflector is shown in Fig. 2.
3
Fig. 2. Radar corner reflector.
The radar cross-section σ is assumed to be determined by
σ = pi*(a)square 4/3λ2
where a is the dimension of edge of the reflector and λ is the wavelength
Experiment
The aim of the same experiment performed at BTH is to estimate RCS of the radar corner reflector given in
Fig. 2. In the measurement, the radar antenna is steered to the corner reflector as shown in Fig. 3.
Fig. 3. Measurement setup.
4
The measurement results are processed S11. That means the original S11 (without processing) is first
transformed to time-domain using the transform function of the network analyzer, and then filtered to get
the response only from the radar corner reflector using the gating function of the vector network analyzer,
and finally transformed back to frequency-domain by turning off the transform function of the network
analyzer. The measurement results are saved in two CVS files, one is the real part of the data and the other
is the imaginary part. In each CVS files, the data is arranged in two columns, one is the frequency and the
other is amplitude. The CVS files can be downloaded in the project folder.
Tasks
a) Build the full signal spectrum (from 0 to sampling frequency) from the given measurement results
and plot it in logarithm scale using Matlab. To avoid the problem of log(0), the very low noise
level should be added. The axes must be in correct unit. Find the operating frequency of the radar
system.
b) Transform the signal spectrum to time-domain and plot it in logarithm scale using Matlab. The
axes must be in correct unit. Find the distance between the radar antenna and the radar corner
reflector based on the plot.
c) Verify the selected parameters including operating frequency, size of the edge of the reflector, far-field condition based on the found distance.
d) Determine RCS at different frequency and plot them as a function of the frequency.
e) Check if the RCS is matched with (3).
i want to measure Radar cross section is based on the measurement results which I got in two exel files one is real and other is imaginary data . In this assignment . my teacher examined horn antenna and corner reflector and calculate rcs (Radar cross section) .
I have uploaded my assignment i am going through some problems in it in first part . it says thay plot a full signal from (0 to sampling freq.) i am wondering
what should be the sampling freq i should use in this assignment. and he also want us to calculate the operating freq. of radar using this plot .
can you please help me in solving this assingment . I have just 5 days left .
i am putting my assignment below so any one can read it .
Antenna Theory Project
Calculate radar cross section (RCS) based on the measurement results
22 October 2012
Introduction
The main task in the project is to calculate radar cross section (RCS) based on the measurement results in
reality. The purposes of this project are to help students to
- Get knowledge of equipments.
- Understand the measurement results in reality.
- Calculate based on the measurement results.
- Process the measurement results using Matlab.
Radar system
Radar is an abbreviation of Radio Detection and Ranging. It is a radio system using electromagnetic waves,
specifically radio waves, to detect objects and determine the ranges between this radio system and those
objects. Although the beginning experiments of Heinrich Hertz showing that radio waves could be reflected
from solid objects were carried out in 1886, the milestone for the development of radar did not occur until
World War II. Radar has a wide range of applications including those for civil and military purposes.
Detecting and ranging air, ground and sea targets are crucial applications of radar for military purposes.
Meanwhile, civilian applications of radar can be found in aviation, marine, monitoring and so forth. A basic
radar system includes one transmitter emitting radio waves called radar signals and one or more receiver(s)
capturing reflections from objects such as aircrafts, ships, vehicles and terrain. If a radar system utilizes one
transmitting antenna and one receiving antenna which are collocated, that radar system is called a mono-static system. A radar system will be called a bi-static system if its transmitting antenna and receiving
antenna are separated. For the mono-static case, the radar range R is calculated from the round trip
propagation time as
R= c*tau/2
(1)
where c is the propagation speed and equal to the speed of light c = 3×10
8m/s, and tau is the propagation
time of the radio waves back and forth. The relationship between the transmitted power Pt
and received
power Pr
of a mono-static radar system is represented by the radar equation
Pr/Pt = G*Ae*σ*(F)sqaure 4/ (2*pi)2 (R)sqaure 4
where G is the gain of the antenna, Ae is the effective area of the antenna, σ is RCS of the object, and F
indicates the antenna pattern. If a radar system operates in vacuum and without interference, the term F in
the numerator of (2) is set to one ( F = 1).
In an experiment performed at BTH, a mono-static SAR system is used. The mono-static SAR system is
built with a vector network analyzer [1], a horn antenna [2] and accessories. The system is shown in Fig. 1.
Fig. 1. Mono-static SAR system.
Corner reflector
A corner reflector is a reflector consisting of three mutually perpendicular, intersecting flat surfaces, which
reflects waves back directly towards the source, but shifted (translated). The three intersecting surfaces
often have square shapes. Radar corner reflectors made of metal are used to reflect radio waves from radar
sets. Radar corner reflectors are designed to reflect the microwave radio waves emitted by radar sets back
toward the radar antenna. This causes them to show a strong "return" on radar screens. A simple corner
reflector consists of three conducting sheet metal or screen surfaces at 90° angles to each other, attached to
one another at the edges, forming a "corner". These reflect radio waves coming from in front of them back
parallel to the incoming beam.
In the same experiment performed at BTH, we build a radar corner reflector with the dimension 30 cm × 30
cm × 30 cm. The reflector is shown in Fig. 2.
3
Fig. 2. Radar corner reflector.
The radar cross-section σ is assumed to be determined by
σ = pi*(a)square 4/3λ2
where a is the dimension of edge of the reflector and λ is the wavelength
Experiment
The aim of the same experiment performed at BTH is to estimate RCS of the radar corner reflector given in
Fig. 2. In the measurement, the radar antenna is steered to the corner reflector as shown in Fig. 3.
Fig. 3. Measurement setup.
4
The measurement results are processed S11. That means the original S11 (without processing) is first
transformed to time-domain using the transform function of the network analyzer, and then filtered to get
the response only from the radar corner reflector using the gating function of the vector network analyzer,
and finally transformed back to frequency-domain by turning off the transform function of the network
analyzer. The measurement results are saved in two CVS files, one is the real part of the data and the other
is the imaginary part. In each CVS files, the data is arranged in two columns, one is the frequency and the
other is amplitude. The CVS files can be downloaded in the project folder.
Tasks
a) Build the full signal spectrum (from 0 to sampling frequency) from the given measurement results
and plot it in logarithm scale using Matlab. To avoid the problem of log(0), the very low noise
level should be added. The axes must be in correct unit. Find the operating frequency of the radar
system.
b) Transform the signal spectrum to time-domain and plot it in logarithm scale using Matlab. The
axes must be in correct unit. Find the distance between the radar antenna and the radar corner
reflector based on the plot.
c) Verify the selected parameters including operating frequency, size of the edge of the reflector, far-field condition based on the found distance.
d) Determine RCS at different frequency and plot them as a function of the frequency.
e) Check if the RCS is matched with (3).