Enviar pesquisa
Carregar
67 75
•
1 gostou
•
388 visualizações
Ijarcsee Journal
Seguir
Tecnologia
Denunciar
Compartilhar
Denunciar
Compartilhar
1 de 9
Baixar agora
Baixar para ler offline
Recomendados
Modeling, designing and structural analysis of ga n blue
Modeling, designing and structural analysis of ga n blue
eSAT Publishing House
Real Time Localization Using Receiver Signal Strength Indicator
Real Time Localization Using Receiver Signal Strength Indicator
Rana Basheer
Mr2521772184
Mr2521772184
IJERA Editor
241 250
241 250
Editor IJARCET
Af32216223
Af32216223
IJERA Editor
A1.2 r. k. verma
A1.2 r. k. verma
Yusor
Macro-Bending Loss of Single-Mode Fiber beyond Its Operating Wavelength
Macro-Bending Loss of Single-Mode Fiber beyond Its Operating Wavelength
TELKOMNIKA JOURNAL
Photonics @ IITM
Photonics @ IITM
Anil Prabhakar
Recomendados
Modeling, designing and structural analysis of ga n blue
Modeling, designing and structural analysis of ga n blue
eSAT Publishing House
Real Time Localization Using Receiver Signal Strength Indicator
Real Time Localization Using Receiver Signal Strength Indicator
Rana Basheer
Mr2521772184
Mr2521772184
IJERA Editor
241 250
241 250
Editor IJARCET
Af32216223
Af32216223
IJERA Editor
A1.2 r. k. verma
A1.2 r. k. verma
Yusor
Macro-Bending Loss of Single-Mode Fiber beyond Its Operating Wavelength
Macro-Bending Loss of Single-Mode Fiber beyond Its Operating Wavelength
TELKOMNIKA JOURNAL
Photonics @ IITM
Photonics @ IITM
Anil Prabhakar
167 169
167 169
Editor IJARCET
F05843238
F05843238
IOSR-JEN
Especificaciones sokkia 530 r
Especificaciones sokkia 530 r
banbannn26
5 mahjabin mobarak 7
5 mahjabin mobarak 7
Alexander Decker
28 35
28 35
Ijarcsee Journal
Hfc d coaxial fiber optic
Hfc d coaxial fiber optic
jose angel guzman lozano
116 121
116 121
Ijarcsee Journal
1 5
1 5
Ijarcsee Journal
35 38
35 38
Ijarcsee Journal
88 92
88 92
Ijarcsee Journal
20 26
20 26
Ijarcsee Journal
14 19
14 19
Ijarcsee Journal
58 64
58 64
Ijarcsee Journal
130 133
130 133
Ijarcsee Journal
44 49
44 49
Ijarcsee Journal
6 11
6 11
Ijarcsee Journal
41 45
41 45
Ijarcsee Journal
16 18
16 18
Ijarcsee Journal
Semester 1 seminar (roll no. 192606)
Semester 1 seminar (roll no. 192606)
Kush Singla
International Journal of Computational Engineering Research(IJCER)
International Journal of Computational Engineering Research(IJCER)
ijceronline
Am4301205207
Am4301205207
IJERA Editor
Stealth Radar
Stealth Radar
Pramod Devireddy
Mais conteúdo relacionado
Mais procurados
167 169
167 169
Editor IJARCET
F05843238
F05843238
IOSR-JEN
Especificaciones sokkia 530 r
Especificaciones sokkia 530 r
banbannn26
5 mahjabin mobarak 7
5 mahjabin mobarak 7
Alexander Decker
28 35
28 35
Ijarcsee Journal
Hfc d coaxial fiber optic
Hfc d coaxial fiber optic
jose angel guzman lozano
Mais procurados
(6)
167 169
167 169
F05843238
F05843238
Especificaciones sokkia 530 r
Especificaciones sokkia 530 r
5 mahjabin mobarak 7
5 mahjabin mobarak 7
28 35
28 35
Hfc d coaxial fiber optic
Hfc d coaxial fiber optic
Destaque
116 121
116 121
Ijarcsee Journal
1 5
1 5
Ijarcsee Journal
35 38
35 38
Ijarcsee Journal
88 92
88 92
Ijarcsee Journal
20 26
20 26
Ijarcsee Journal
14 19
14 19
Ijarcsee Journal
58 64
58 64
Ijarcsee Journal
130 133
130 133
Ijarcsee Journal
44 49
44 49
Ijarcsee Journal
6 11
6 11
Ijarcsee Journal
41 45
41 45
Ijarcsee Journal
16 18
16 18
Ijarcsee Journal
Destaque
(12)
116 121
116 121
1 5
1 5
35 38
35 38
88 92
88 92
20 26
20 26
14 19
14 19
58 64
58 64
130 133
130 133
44 49
44 49
6 11
6 11
41 45
41 45
16 18
16 18
Semelhante a 67 75
Semester 1 seminar (roll no. 192606)
Semester 1 seminar (roll no. 192606)
Kush Singla
International Journal of Computational Engineering Research(IJCER)
International Journal of Computational Engineering Research(IJCER)
ijceronline
Am4301205207
Am4301205207
IJERA Editor
Stealth Radar
Stealth Radar
Pramod Devireddy
Metamaterial
Metamaterial
Khalid Saeed Al-Badri
Radar target detection simulation
Radar target detection simulation
IJERA Editor
Basics on Radar Cross Section
Basics on Radar Cross Section
VICTOR MAESTRE RAMIREZ
G041034850
G041034850
IOSR-JEN
Enhancement of SNR for Radars
Enhancement of SNR for Radars
theijes
Lidar in-ieee-format
Lidar in-ieee-format
Vinay Bondirwad
A Preliminary Study of Radar - Anirudh Katyal
A Preliminary Study of Radar - Anirudh Katyal
UPES Dehradun
Microwave remote sensing
Microwave remote sensing
Mohsin Siddique
Chapter 1-generality
Chapter 1-generality
Rima Assaf
International Journal of Computational Engineering Research(IJCER)
International Journal of Computational Engineering Research(IJCER)
ijceronline
Id136
Id136
IJEEE
Laser ii 2 ppt
Laser ii 2 ppt
Bahir Dar university
Report on radar
Report on radar
pratibha007
Radar Cross Section reduction in antennas.pptx
Radar Cross Section reduction in antennas.pptx
josephine167719
I Cx Surveillance Tech Notes
I Cx Surveillance Tech Notes
Howard Borst
Radar remote sensing, P K MANI
Radar remote sensing, P K MANI
P.K. Mani
Semelhante a 67 75
(20)
Semester 1 seminar (roll no. 192606)
Semester 1 seminar (roll no. 192606)
International Journal of Computational Engineering Research(IJCER)
International Journal of Computational Engineering Research(IJCER)
Am4301205207
Am4301205207
Stealth Radar
Stealth Radar
Metamaterial
Metamaterial
Radar target detection simulation
Radar target detection simulation
Basics on Radar Cross Section
Basics on Radar Cross Section
G041034850
G041034850
Enhancement of SNR for Radars
Enhancement of SNR for Radars
Lidar in-ieee-format
Lidar in-ieee-format
A Preliminary Study of Radar - Anirudh Katyal
A Preliminary Study of Radar - Anirudh Katyal
Microwave remote sensing
Microwave remote sensing
Chapter 1-generality
Chapter 1-generality
International Journal of Computational Engineering Research(IJCER)
International Journal of Computational Engineering Research(IJCER)
Id136
Id136
Laser ii 2 ppt
Laser ii 2 ppt
Report on radar
Report on radar
Radar Cross Section reduction in antennas.pptx
Radar Cross Section reduction in antennas.pptx
I Cx Surveillance Tech Notes
I Cx Surveillance Tech Notes
Radar remote sensing, P K MANI
Radar remote sensing, P K MANI
Mais de Ijarcsee Journal
122 129
122 129
Ijarcsee Journal
109 115
109 115
Ijarcsee Journal
104 108
104 108
Ijarcsee Journal
99 103
99 103
Ijarcsee Journal
93 98
93 98
Ijarcsee Journal
82 87
82 87
Ijarcsee Journal
78 81
78 81
Ijarcsee Journal
73 77
73 77
Ijarcsee Journal
65 72
65 72
Ijarcsee Journal
52 57
52 57
Ijarcsee Journal
46 51
46 51
Ijarcsee Journal
36 40
36 40
Ijarcsee Journal
24 27
24 27
Ijarcsee Journal
19 23
19 23
Ijarcsee Journal
12 15
12 15
Ijarcsee Journal
134 138
134 138
Ijarcsee Journal
125 131
125 131
Ijarcsee Journal
114 120
114 120
Ijarcsee Journal
121 124
121 124
Ijarcsee Journal
104 108
104 108
Ijarcsee Journal
Mais de Ijarcsee Journal
(20)
122 129
122 129
109 115
109 115
104 108
104 108
99 103
99 103
93 98
93 98
82 87
82 87
78 81
78 81
73 77
73 77
65 72
65 72
52 57
52 57
46 51
46 51
36 40
36 40
24 27
24 27
19 23
19 23
12 15
12 15
134 138
134 138
125 131
125 131
114 120
114 120
121 124
121 124
104 108
104 108
Último
Corporate and higher education May webinar.pptx
Corporate and higher education May webinar.pptx
Rustici Software
Cloud Frontiers: A Deep Dive into Serverless Spatial Data and FME
Cloud Frontiers: A Deep Dive into Serverless Spatial Data and FME
Safe Software
Strategize a Smooth Tenant-to-tenant Migration and Copilot Takeoff
Strategize a Smooth Tenant-to-tenant Migration and Copilot Takeoff
sammart93
AWS Community Day CPH - Three problems of Terraform
AWS Community Day CPH - Three problems of Terraform
Andrey Devyatkin
Web Form Automation for Bonterra Impact Management (fka Social Solutions Apri...
Web Form Automation for Bonterra Impact Management (fka Social Solutions Apri...
Jeffrey Haguewood
"I see eyes in my soup": How Delivery Hero implemented the safety system for ...
"I see eyes in my soup": How Delivery Hero implemented the safety system for ...
Zilliz
Introduction to Multilingual Retrieval Augmented Generation (RAG)
Introduction to Multilingual Retrieval Augmented Generation (RAG)
Zilliz
Platformless Horizons for Digital Adaptability
Platformless Horizons for Digital Adaptability
WSO2
Strategies for Landing an Oracle DBA Job as a Fresher
Strategies for Landing an Oracle DBA Job as a Fresher
Remote DBA Services
How to Troubleshoot Apps for the Modern Connected Worker
How to Troubleshoot Apps for the Modern Connected Worker
ThousandEyes
Mcleodganj Call Girls 🥰 8617370543 Service Offer VIP Hot Model
Mcleodganj Call Girls 🥰 8617370543 Service Offer VIP Hot Model
Deepika Singh
[BuildWithAI] Introduction to Gemini.pdf
[BuildWithAI] Introduction to Gemini.pdf
Sandro Moreira
FWD Group - Insurer Innovation Award 2024
FWD Group - Insurer Innovation Award 2024
The Digital Insurer
Cloud Frontiers: A Deep Dive into Serverless Spatial Data and FME
Cloud Frontiers: A Deep Dive into Serverless Spatial Data and FME
Safe Software
Rising Above_ Dubai Floods and the Fortitude of Dubai International Airport.pdf
Rising Above_ Dubai Floods and the Fortitude of Dubai International Airport.pdf
Orbitshub
Boost Fertility New Invention Ups Success Rates.pdf
Boost Fertility New Invention Ups Success Rates.pdf
sudhanshuwaghmare1
Why Teams call analytics are critical to your entire business
Why Teams call analytics are critical to your entire business
panagenda
CNIC Information System with Pakdata Cf In Pakistan
CNIC Information System with Pakdata Cf In Pakistan
danishmna97
TrustArc Webinar - Unlock the Power of AI-Driven Data Discovery
TrustArc Webinar - Unlock the Power of AI-Driven Data Discovery
TrustArc
EMPOWERMENT TECHNOLOGY GRADE 11 QUARTER 2 REVIEWER
EMPOWERMENT TECHNOLOGY GRADE 11 QUARTER 2 REVIEWER
MadyBayot
Último
(20)
Corporate and higher education May webinar.pptx
Corporate and higher education May webinar.pptx
Cloud Frontiers: A Deep Dive into Serverless Spatial Data and FME
Cloud Frontiers: A Deep Dive into Serverless Spatial Data and FME
Strategize a Smooth Tenant-to-tenant Migration and Copilot Takeoff
Strategize a Smooth Tenant-to-tenant Migration and Copilot Takeoff
AWS Community Day CPH - Three problems of Terraform
AWS Community Day CPH - Three problems of Terraform
Web Form Automation for Bonterra Impact Management (fka Social Solutions Apri...
Web Form Automation for Bonterra Impact Management (fka Social Solutions Apri...
"I see eyes in my soup": How Delivery Hero implemented the safety system for ...
"I see eyes in my soup": How Delivery Hero implemented the safety system for ...
Introduction to Multilingual Retrieval Augmented Generation (RAG)
Introduction to Multilingual Retrieval Augmented Generation (RAG)
Platformless Horizons for Digital Adaptability
Platformless Horizons for Digital Adaptability
Strategies for Landing an Oracle DBA Job as a Fresher
Strategies for Landing an Oracle DBA Job as a Fresher
How to Troubleshoot Apps for the Modern Connected Worker
How to Troubleshoot Apps for the Modern Connected Worker
Mcleodganj Call Girls 🥰 8617370543 Service Offer VIP Hot Model
Mcleodganj Call Girls 🥰 8617370543 Service Offer VIP Hot Model
[BuildWithAI] Introduction to Gemini.pdf
[BuildWithAI] Introduction to Gemini.pdf
FWD Group - Insurer Innovation Award 2024
FWD Group - Insurer Innovation Award 2024
Cloud Frontiers: A Deep Dive into Serverless Spatial Data and FME
Cloud Frontiers: A Deep Dive into Serverless Spatial Data and FME
Rising Above_ Dubai Floods and the Fortitude of Dubai International Airport.pdf
Rising Above_ Dubai Floods and the Fortitude of Dubai International Airport.pdf
Boost Fertility New Invention Ups Success Rates.pdf
Boost Fertility New Invention Ups Success Rates.pdf
Why Teams call analytics are critical to your entire business
Why Teams call analytics are critical to your entire business
CNIC Information System with Pakdata Cf In Pakistan
CNIC Information System with Pakdata Cf In Pakistan
TrustArc Webinar - Unlock the Power of AI-Driven Data Discovery
TrustArc Webinar - Unlock the Power of AI-Driven Data Discovery
EMPOWERMENT TECHNOLOGY GRADE 11 QUARTER 2 REVIEWER
EMPOWERMENT TECHNOLOGY GRADE 11 QUARTER 2 REVIEWER
67 75
1.
ISSN: 2277 –
9043 International Journal of Advanced Research in Computer Science and Electronics Engineering Volume 1, Issue 5, July 2012 RADAR CROSS SECTION PREDICTION FOR DIFFERENT OBJECTS USING MAT LAB AND RADAR CROSS SECTION (RCS) REDUCTION R.Radha Krishna, Assoc.Prof, R.Murali Krishna, R.Gopi Krishna, D.Sekhar _____________________________________________________________________ ABSTRACT----Radar Cross Section (RCS) depends on the characteristic dimensions of the object compared to the radar wave length. The Radar Cross Section of the target determines the power density returned to the radar for a particular power density incident on the target. The cross section is more dependent on the target shape than its physical size. The radar antenna captures a portion of echo energy incident on it. Radar Cross Section fluctuates as a function of radar aspect angle and frequency. Using the MAT LAB Programming, Prediction of Radar cross section `σ` for simple shapes of targets like Sphere, Ellipsoid and Circular Flat Plate. The methods of controlling radar cross section and penalties of implementing these methods are discussed. The four basic techniques for reducing radar cross section (target shaping, radar absorbing materials, passive cancellation, and active cancellation) are summarized with their advantages and disadvantages. Keywords: Active cancellation, Echo energy, Passive cancellation, Radar Cross Section 1. INTRODUCTION 3. RADAR CROSS SECTION (RCS) In this Paper, the phenomenon of target 3.1. Introduction scattering and methods of RCS calculation are examined. Target RCS fluctuations due to aspect The term Radar cross section (RCS) is a measure angle, frequency, and polarization are presented. of power scattered in a given direction when a Target scattering matrix is developed. Radar cross target is illuminated by an incident wave from section characteristics of some simple and complex Radar More precisely it is the limit of that ratio as targets are also introduced. the distance from scatterer to point where the scattered power is measured approaches infinity. 2. RADAR FUNDAMENTALS 2 lim E scat RADAR is a contraction of the words RAdio R E inc Detection And Ranging. E scat 2 H scat 2 RADAR is an Electromagnetic system for the 4 R 2 2 4 R 2 2 detection and location of objects. Radar operates by E inc H inc transmitting a particular type of waveform and detecting the nature of the signals reflected back from objects Where σ is Radar Cross Section in sq. meters The Radar Range Equation- The radar range equation relates the range of the radar to the E scat is scattered electric field characteristics of the transmitter, receiver, antenna, target and the environment. E inc is field incident at the target R is the distance to the target from the Radar Antenna. -EM scattered field: is the difference between the total field in the presence of an object and the field that would exist if the object were absent. Manuscript received June 15, 2012. - EM diffracted field: is the total field in the Radha Krishna Rapaka, Assoc.Prof. in ECE Department,Swarnandhra College of Engineering presence of the object. 2 .a &Technology., (e-mail: radhakrishnarapaka@gamil.com). Narsapur,India, 9490346661. -when 1 (the Rayleigh region), the Murali Krishna Rapaka, ECE Department,SCET (e-mail: muralirapaka@gamil.com).Narsapur,India, 8790837227. Gopi Krishna Rapaka, ECE Department, JITS(e-mail: scattering from a sphere can be used for modeling gopi.ece123@gamil.com).Narsapur,India, 9963438298. D.Sekhar,ECE Department, SCET(e-mail: raindrops. sekhoo007@gamil.com).Narsapur,India, 9491018701. 67 All Rights Reserved © 2012 IJARCSEE
2.
ISSN: 2277 –
9043 International Journal of Advanced Research in Computer Science and Electronics Engineering Volume 1, Issue 5, July 2012 Geometrical Theory of Diffraction (GTD), Physical Theory of Diffraction (PTD), and Method of Equivalent Currents (MEC). Interested readers may consult Knott or Ruck (see References) for more details on these and other approximate methods. 3.4. RCS Dependency on Aspect Angle and Frequency Radar cross section fluctuates as a function of radar aspect angle and frequency. The spacing between the two scatterers is 1 meter. The radar Fig:3.1(a) Radar cross section of the sphere aspect angle is then changed from zero to 180 a= radius, λ = wavelength degrees, and the composite RCS of the two 2 .a -when 1 the σ approaches the optical scatterers measured by the radar is computed. cross section πa2. RCS can be expressed as Because in the far field either E or H is sufficient to describe the EM wave. Radar Cross Section is a function of Position of transmitter relative to target Position of receiver relative to target Target geometry and material composition Figure: 3.1(b) RCS dependency on aspect angle. Angular orientation of target relative to (a) Zero aspect angle, zero electrical spacing. transmitter and receiver (b) Aspect angle, electrical spacing. Frequency or wavelength Transmitter polarization Receiver polarization. Having gone through the introductory part of Radar Fig. 3.2 shows the composite RCS Cross Section, let us, now discuss the importance corresponding to this experiment. This plot can be of Radar Cross Section for Naval Targets. reproduced using MATLAB function “rcs_aspect.m”. As indicated by Fig. 3.1(b), RCS 3.2. Importance of Radar Cross-Section Prediction for Naval Targets is dependent on the radar aspect angle There are five basic reasons for why the RCS measurements are conducted. They give brief knowledge of the following. They are Acquire understanding of basic scattering phenomena Acquire diagnostic data Verify the system performance Build a database Satisfy a contractual requirement. Due to the above reasons Radar Cross Section measurement has gained a lot of importance. Figure: 3.2. Illustration of RCS dependency on 3.3. Methods of RCS prediction aspect angle. Two categories of RCS prediction methods are MATLAB Function “rcs_aspect.m” available: exact and approximate. Exact methods of RCS prediction are very Its syntax is as follows: [rcs] = rcs_aspect complex even for simple shape objects associated (scat_spacing, freq) with the exact RCS prediction, approximate methods become the viable alternative. The majority of the approximate methods are valid in the optical region, approximate methods are Geometrical Optics (GO), Physical Optics (PO), 68 All Rights Reserved © 2012 IJARCSEE
3.
ISSN: 2277 –
9043 International Journal of Advanced Research in Computer Science and Electronics Engineering Volume 1, Issue 5, July 2012 The material in this section covers two Next, to demonstrate RCS dependency on topics. First, a review of polarization fundamentals is presented. Second, the concept of target frequency, consider the experiment shown in Fig: scattering matrix is introduced. 3.3. Fig: 3.4 and Fig: 3.5 show the composite RCS 4. RCS OF SIMPLE OBJECTS versus frequency for scatterer spacing of 0.1 and 4.1. Introduction 0.7 meters. This section presents examples of backscattered radar cross section for a number of simple shape objects. When compared to the optical region approximation, is overwhelming. Most formulas presented are Physical Optics (PO) approximation for the backscattered RCS measured by a far field radar in the direction (θ,φ) as illustrated in Fig.4.1. Figure: 3.3. Experiment setup which demonstrates RCS dependency on frequency; dist = 0.1, or 0.7 m. Figure: 4.1. Direction of antenna receiving backscattered waves. 4.2. Sphere Figure: 3.4. Illustration of RCS dependency on The PP backscattered waves from a sphere are frequency. LCP, while the OP backscattered waves are negligible. The normalized exact backscattered RCS for a perfectly conducting sphere is a Mie series given by Where r is the radius of the sphere, k = 2π/λ. λ is the wavelength Jn, is the spherical Bessel of the first kind of order n, Hn(1)and is the Hankel function Figure: 3.5. Illustration of RCS dependency on of order n, and is given by frequency. From those two figures, RCS fluctuation as a function of frequency is evident. Little frequency change can cause serious RCS fluctuation when the In Fig. 3.9, three regions are identified. First is scatterer spacing is large. MATLAB Function “rcs_frequency.m” the optical region (corresponds to a large sphere). [rcs] = rcs_frequency (scat_spacing, frequ, In this case, freql) RCS Dependency on Polarization 69 All Rights Reserved © 2012 IJARCSEE
4.
ISSN: 2277 –
9043 International Journal of Advanced Research in Computer Science and Electronics Engineering Volume 1, Issue 5, July 2012 Second is the Rayleigh region (small sphere). In this case, The region between the optical and Rayleigh regions is oscillatory in nature and is called the Mie or resonance region. Figure 4.3(a) Ellipsoid. When, the ellipsoid becomes roll symmetric. Thus, the RCS is independent of φ, and Eq. is reduced and for the case when a= b= c. MATLAB Function “rcs_ellipsoid.m” Figure : 4.2(a) Normalized backscattered RCS for [rcs] = rcs_ellipsoid (a, b, c, phi) a perfectly conducting sphere. Where Figure: 4.2(b) Normalized backscattered RCS for a perfectly conducting sphere using semi-log scale. The backscattered RCS for a perfectly conducting sphere is constant in the optical region. For this reason, radar designers typically use Figure: 4.3(b) Ellipsoid backscattered RCS versus spheres of known cross sections to experimentally. aspect angle, φ = 45° . 4.3 Ellipsoid 4.4 Circular Flat Plate An ellipsoid centered at (0, 0, 0) is shown Fig. 4.4(a) shows a circular flat plate of radius, in Fig. 4.3. It is defined by the following equation: centered at the origin. Due to the circular symmetry, the backscattered RCS of a circular flat plate has no dependency on φ. The RCS is only aspect angle dependent. For normal incidence (i.e., zero aspect angles) the backscattered RCS for a circular flat plate is One widely accepted approximation for the ellipsoid backscattered RCS is given by -------4.35 70 All Rights Reserved © 2012 IJARCSEE
5.
ISSN: 2277 –
9043 International Journal of Advanced Research in Computer Science and Electronics Engineering Volume 1, Issue 5, July 2012 This chapter evaluates methods of controlling RCS and the penalties in implementing these methods. There are four basic techniques for reducing radar cross section: (1) target shaping, (2) radar absorbing materials, (3) passive cancellation, and (4) active cancellation. Reduction methods are generally limited to a small spatial region. The platform design process must address how much RCS reduction is required based Figure: 4.4(a) Circular flat plate. on the platform’s mission, and the additional cost For non-normal incidence, two approximations of manufacturing and maintenance. for the circular flat plate backscattered RCS for any linearly polarized incident waves are 5.2 The Four Basic Techniques of RCSR The following sections provide a summary of ----------4.36 each RCSR technique. 5.2.1. Shaping Traditionally, shaping is considered the first step of RCS control. The Lockheed F-117A (Figure 5.1) --4.37 is an example of heavily applied surface faceting. Where k =2π/λ/, and J1(β) is the first order Edges are parallel so that the majority of the edge spherical Bessel function evaluated at β . The RCS effects are collectively directed away from corresponding to Eqs. 4.37through4.35 is shown in important viewing angles. The Northrop B-2 also Fig.4.4 (b) These plots can be reproduced using uses some faceting, especially on the trailing edges MATLAB function “rcs_circ_plate.m” . of the wing. In planform (Figure 5.2), the straight edges are dominant. MATLAB Function “rcs_circ_plate.m” For more “boxy” structures such as ships and ground vehicles, dihedral and trihedral corners, and [rcs] = rcs_circ_plate (r, freq) “top hats” (right circular cylinders with axes perpendicular to a flat plane) are the major RCS contributors. The amount of bulkhead tilt is a trade- off between RCSR performance and cost. Figure: 4.4(b) Backscattered RCS for a circular flat plate. 5. RADAR CROSS SECTION REDUCTION (RCSR) TECHNIQUES 5.1 Introduction For military RCS reduction is necessary because of the following reasons: To make ships / objects less detectable by the enemy radar To increase the effectiveness of Chaff Figure: 5.1. Planform of the Lockheed F-117. (Counter Measure) To make classification of Targets difficult to the Radar 71 All Rights Reserved © 2012 IJARCSEE
6.
ISSN: 2277 –
9043 International Journal of Advanced Research in Computer Science and Electronics Engineering Volume 1, Issue 5, July 2012 is not practical to devise a passive cancellation treatment for each of these sources. Note that there is a gray area between the technologies of absorbing materials and passive cancellation. For example, a layer of lossy dielectric coating applied to a target could fall into either category. 5.2.4. Active Cancellation Active cancellation involves the process of modifying and retransmitting the received radar signal. Obviously, this requires a challenging task for the system, as the frequency increases the work Figure: 5.2: The B-2 Spirit was one of the first becomes much more difficult aircraft to successfully become 'invisible' to radar. There are two levels of cancellation: 1.Fully active: The cancellation network receives, amplifies, and retransmits the threat signal such that it is out of phase with the static RCS of the target. The transmitted signal amplitude, phase, frequency and polarization can be adjusted to compensate for changing threat parameters. 2. Semiactive: No boost in threat signal energy is provided by the cancellation network, but passive adjustable devices in the network allow the reradiated signal to compensate for limited changes Figure: 5.3. Planform of the Northrop B-2 . in the threat signal parameters. 5.2.2. Radar Absorbing Materials The demands for a fully active system are almost always so severe as to make it impractical. The radar absorbing materials reduce the energy It requires a transmitter and antennas that cover the reflected back to the radar by means of absorption. anticipated threat angles, frequencies, incident Radar energy is absorbed through one or more of power densities, and polarization. Knowledge of several mechanisms, which may involve the the threat direction is required, as well as the dielectric or magnetic properties of the materials. In target’s own RCS. A semiactive system is not as summary, the requirements of a RAM for use in complicated in terms of hardware, but the use of RCS reduction are: (1) the absorbing material adjustable devices still requires bias lines, should have adequate frequency response, (2) it controller units, and a computer with the should work for two orthogonal polarizations, and appropriate data bases. (3) it should work with the specified aspect angle characteristics [4]. To choose a RAM that simultaneously satisfies all of these requirements, 6. THE PENALTIES OF RCSR and yet is physically realizable is difficult, if not The first and unavoidable penalty of RCSR is impossible. Considerations of weight and the additional cost. The others are: reduced environment (e.g., temperature, rain, snow, etc.) payload, added weight, required high maintenance, play an important role in deciding the thickness of and reduced range or other operational limitations. any RAM coating. The mission of the platform and the severity of the 5.2.3. Passive Cancellation threat environment will determine the required RCSR and drive the trade-off study. Passive cancellation refers to RCS reduction by RCSR is just one aspect of the entire platform introducing a secondary scatterer to cancel with the design which is affected by other sensors and reflection of the primary target. This method is also signatures (infrared, acoustic, visual, etc.). An known as impedance loading. optimum design must be devised in order to The basic concept is to introduce an echo source maximize the objectives of the platform. whose amplitude and phase can be adjusted to In this paper the four basic RCSR techniques cancel another echo source. This can be were presented. Of the four, the use of shaping and accomplished for relatively simple objects, radar absorbing material design are the most used provided that a loading point can be identified on to date. the body. 7. RESULTS In addition to this, typical weapons platforms are hundreds of wavelengths in size and have MAT LAB Simulated Results dozens, if not hundreds of echo sources. Clearly, it 1. Aspect Angle Vs RCS in dBsm 72 All Rights Reserved © 2012 IJARCSEE
7.
ISSN: 2277 –
9043 International Journal of Advanced Research in Computer Science and Electronics Engineering Volume 1, Issue 5, July 2012 Frequency is 3GHz ; Scatter spacing is 0.5 m Fig:7.1 Aspect Angle Vs RCS in dBsm Fig:7.5 Frequency Vs RCS in dBsm 2. Aspect Angle Vs RCS in dBsm 6. Sphere: Sphere circumference Vs RCS Frequency is 10GHz ;Scatter spacing is 0.5 m Fig: 7.6(a) Sphere circumference Vs RCS Fig:7.2 Aspect Angle Vs RCS in dBsm 3. Aspect Angle Vs RCS in dBsm Frequency is 10GHz ;Scatter spacing is 1.0 m Fig: 7.6(b) Sphere circumference Vs RCS Fig:7.3 Aspect Angle Vs RCS in dBsm 4. Frequency Vs RCS in dBsm 7. Ellipsoid: RCS versus aspect angle. Frequency is 1GHz; Scatter spacing is 0.1 m a =0 .15; b =0.20; c=0.95 Fig:7.4 Frequency Vs RCS in dBsm Fig: 7.6(c) RCS and aspect angle 5. Frequency Vs RCS in dBsm 8. Ellipsoid: RCS versus aspect angle. Frequency is 1GHz; Scatter spacing is 1.0 m a = 0.20;b =0.50;c=0.90 73 All Rights Reserved © 2012 IJARCSEE
8.
ISSN: 2277 –
9043 International Journal of Advanced Research in Computer Science and Electronics Engineering Volume 1, Issue 5, July 2012 targets like Sphere, Ellipsoid, Circular Flat Plate are obtained. The RCS variation as a function of frequency is obtained for two scatters and are presented in Figures when the scattering spacing is more, RCS is highly oscillatory. While RCS is less oscillatory for lower scattering spacing. The RCS fluctuates as a function of frequency is evident. The importance of radar cross section reduction was discussed, and the major RCSR Fig: 7.8 RCS and aspect angle techniques summarized. . 9. Circular flat plate REFERENCES RCS of a circular flat plate of radius’ r’ [1] G.T. Ruck, D.E.Barrick, W.D.Stuart and Frequency in X-Band=12GHz;Radius(r ) = 0.5 m C.K.Krichbaum” Introduction to Radar Cross- Section Measurements”, Proc.IEEE, vol.53. [2] H. Ling, R. Chou, and S.W. Lee, “Shooting and Bouncing Rays: Calculating the RCS of an arbitrarily shaped cavity,” IEEE Trans. Antennas Propagation, vol.37, pp.194-205, Feb. 1989. [3] Hans C.Strifrs and Guillermo C.Gaunaurd,”Scattering of Electromagnetic Pulses by Simple-Shaped Targets with Radar Cross Fig:7.9 RCS and aspect angle Section Modified by a Dielectric Coating”,IEEE Tansactions on Antennas and 10. Circular flat plate Propagation,Vol.46,No.9. RCS of a circular flat plate of radius’ r’ [4] Lorant A.Muth, “Calibration Standards and Uncertainties in Radar Cross Section Frequency = X-Band=12GHz ;Radius(r ) = 0.25 m Measurements”, National Institute of Standards and Technology, Boulder,CO80303. [5]E.F. Knott,”A progression of high-frequency RCS prediction techniques,”Proc.IEEE,vol.73,pp.252-264,Feb. 1985. [6] R.A. Ross,”Radar cross section of rectangular flat plates as a function of aspect angle,” IEEE trans. Antennas Propagation.,vol.Ap-14,pp.329- Fig: 7.10 RCS and aspect angle 335, May 1996. [7] V. H. Weston, “Theory of Absorbers in Scattering,” IEEE Transactions on Antennas and 11. Truncated Cone (Frustum) Propagation, Vol. AP, No. 4, September 1963. [11] J.Rheinstein, “Scattering of Electromagnetic r1= 2; r2= 4; h= 8; freq= 9.5GHz ; indicator = 0 waves from dielectric coated conducting spheres”, IEEE Trans.Antennas Propagation.,vol.12, pp.334- 340, May1964. [12] Prof. G.S.N.Raju,” Radar Engineering and Fundamentals of Navigational Aids”, I.K.International Publications, New Delhi, 2008. [13] Radar Systems Analysis and Design Using MATLAB, Bassem R. Mahafza [14] MATLAB Simulations for Radar Systems Design by Bassem R. Mahafza and Atef Z. Fig: 7.11 RCS and aspect angle Elsherbeni [15] Eugene F. Knott, John F. Shaeffer, Michael T. 8. CONCLUSIONS Tuley, Radar crossection (2nd Edition), Artech House , London, 1992. Using the MAT LAB Programming, Prediction [16] Merrill I.Skolnik,”Introduction to Radar of Radar cross section of some simple shapes of Systems”, Tata Mc Graw-Hill,New Delhi. 74 All Rights Reserved © 2012 IJARCSEE
9.
ISSN: 2277 –
9043 International Journal of Advanced Research in Computer Science and Electronics Engineering Volume 1, Issue 5, July 2012 [17] Ruck,G.T.,Barrick,D.E.Stuart,W.D., and R.Gopi Krishna received the B.E. in electronics and Communication Krichbaum,C.K.”Radar Cross Section Hand engineering from Andhra University, Book”,Volume 2. India , in 2009.He joined JITS [18] “Federation of American Scientist Official Engineering college as a faculty in Website “(www.fas.org), 22 June 2003. Department of Electronics and communication Engineering, AP, India [19] Asoke Bhattacharyya, D.L. Sengupta, “Radar In 2009. Now he is pursuing M.Tech Cross Section Analysis & Control”, Artech House, (Embedded systems) at B.V.C Engineering College, From JNT 1991. University, AP, India.His research interests include radar, [20] B. C. Hoskin, A. A. Baker, “Composite Microprocessors and Embedded systems. Materials for Aircraft Structures”, AIAA, 1986. .D.Sekhar received the B.E. and [21] David C. Jenn, “Radar and Laser Cross M.Tech. degrees in electronics and Section Engineering”, AIAA, 1995. or’s Communication engineering from Andhra Universit and JNT University, India , in 2000 and 2010 respectively. In Photo 2007, he joined Swarnandhra College of BIOGRAPHIES Engineering and Technology as a faculty in Department of Electronics R.Radha Krishna received the B.E. and and communication Engineering, AP, India. His research M.Tech. degrees in electronics and interests include antennas, radar, optical communication and Communication engineering from electromagnetics. He is a Associate member of Institution of Andhra University, India, in 2003 and Electronics and Telecommunication Engineers (IETE). 2009 respectively. In 2004, he joined Swarnandhra College of Engineering and Technology as a faculty in or’s or’s Department of Electronics and communication Engineering, AP, India. His research interests include antennas, radar, optical communication and Photo Photo electromagnetics. He has published 3 research papers in conferences. He is a Associate member of Institution of Electronics and Telecommunication Engineers (IETE) He is a GATE-2007 qualified and UGC NET-Dec.2011 qualified. R.Murali Krishna received the B.Tech. and M.Tech. degrees in electronics and Communication engineering from JNT University, India , in 2007and 2011 respectively. In 2007, he joined Swarnandhra College of Engineering and Technology as a faculty in or’s Department of Electronics and communication Engineering, AP, India. His research interests include Electronic Devices, radar, VLSI design. He has Photo published 1 research papers in conferences. He is a Associate member of Institution of Electronics and Telecommunication Engineers (IETE). 75 All Rights Reserved © 2012 IJARCSEE
Baixar agora