An Introduction to RF Stealth (Radar, Sonar and Navigation)

Description

This expanded, revised and updated new edition of Introduction to RF Stealth covers two major topics: Low Observables and Low Probability of Intercept (LO and LPI) of radars and data links, collectively sometimes called Stealth. Each chapter includes examples, student exercises and references. Worked simulations are available that illustrate the techniques described. Chapter 1 provides an introduction and history of RF/microwave LPI/LO techniques and some basic LPI/LO equations, expanded from the first edition with more information on new and current systems, including more on infrared and hypersonic missile signatures. Chapter 2 is a new chapter, covering radiation absorbing materials and shaping, focused on materials, meta-materials and detailed platform shaping and structures including ships. Chapter 3 covers interceptability parameters and analysis with corrections, updates and simulations. Chapter 4 covers current and future intercept receivers and some of their limitations with more information and tracking techniques. Chapter 5 surveys exploitation of both the natural and the threat environment with extensive threat table updates including Russian S300, S400, S500 and more information on cellular systems. Chapter 6 deals with LPIS waveforms and pulse compression with new material and simulations of new codes. Chapter 7 introduces some hardware techniques associated with LO/LPIS low sidelobe / cross section antenna and radome design with emphasis on active electronic scan arrays. Chapter 8 is a new chapter on RCS testing of subsystems and platforms. Cover Contents About the author Supplementary material Preface Organization of the book Acknowledgments 1 Introduction to stealth systems 1.1 Introduction 1.1.1 Introduction to survivability 1.1.2 Brief history of radar and ladar 1.1.3 Brief history of signature reduction 1.1.4 Great thoughts of stealth/LO technology 1.1.5 Brief history of LPI systems 1.1.6 LPIR program accomplishments 1.1.7 LPI modes demonstrated through test 1.1.8 LPIR program results summary 1.2 The stealth design challenge 1.2.1 The stealth approach 1.2.2 Balanced design 1.2.3 RCS and power management summary 1.3 Low probability of intercept systems: an introduction 1.3.1 Great thoughts of LPI systems design 1.3.2 Passive detection and intercept probability 1.3.3 Reduced detectability: effective radiated peak power 1.3.4 Reduced detectability: maximum signal uncertainty 1.3.5 LPI performance example 1.3.6 LPIS typical technology 1.3.7 LPI maximizes uncertainty 1.4 Basic LPI equations 1.4.1 Radar and beacon equations 1.4.2 Intercept power relations and LPIS figures of merit 1.4.3 Detection range versus intercept range equations 1.5 Introduction to RCS 1.5.1 Mathematical basis 1.5.2 RCS phenomenology 1.5.3 Estimating RCS 1.5.4 Edge diffraction 1.6 Introduction to signature balance 1.6.1 Radar threat 1.6.2 Infrared threat 1.6.3 Visual threat 1.6.4 Intercept threat 1.7 Exercises References 2 Introduction to materials and shaping 2.1 Introduction 2.2 Detailed RCS calculation 2.2.1 Plates or facets 2.2.2 Edges 2.2.3 Wedges 2.2.4 Dihedrals 2.2.5 Ogives 2.3 Radiation absorbing materials 2.3.1 Bulk RAM 2.3.2 Circuit analogs 2.3.3 Metamaterials 2.4 Blending 2.5 More complex shapes 2.6 Exercises References 3 Interceptibility parameters and analysis 3.1 Interceptability parameters 3.1.1 Interceptability footprints 3.1.2 Interceptor time response 3.1.3 Receiver sensitivity versus intercept probability 3.1.4 Power management 3.2 Interceptibility analysis 3.2.1 Intercept receiver sensitivity 3.2.2 Sidelobe intercept range 3.2.3 Interceptor detection probabilities 3.2.4 Interceptability time constraints 3.2.5 Interceptability frequency constraints 3.2.6 Antenna gain mismatch 3.2.7 Cumulative probability of intercept 3.3 Example mode interceptability calculations 3.3.1 Data link mode interceptability example 3.4 Footprint calculation 3.4.1 “Cookie cutter” footprints 3.4.2 More accurate footprints 3.5 Bistatics 3.5.1 Bistatic properties 3.5.2 Bistatic threats 3.6 Exercises References 4 Intercept receivers 4.1 Survey of current and future intercept receivers 4.2 Receiver types (similar to Schleher) 4.2.1 Crystal video receiver 4.2.2 Instantaneous frequency measurement 4.2.3 Scanning superheterodyne receivers 4.2.4 Channelized receivers 4.2.5 Transform intercept receivers 4.2.6 Hybrid or cueing receivers 4.2.7 Software-defined radios 4.2.8 Intercept receiver processing 4.2.9 Cross correlation processing 4.2.9.1 Wigner–Ville distribution 4.2.9.2 Quadrature mirror filtering 4.2.9.3 Cyclostationary spectral analysis 4.3 Interceptor measurement accuracy 4.3.1 Frequency measurement 4.3.2 Pulse amplitude and width measurement 4.3.3 Time of arrival and PRI measurement 4.3.4 Angle of arrival measurement 4.3.4.1 Amplitude angle of arrival 4.3.4.2 Phase angle of arrival 4.3.5 Range estimation 4.4 Intercept receiver threat trends 4.4.1 Typical response threats – elastic threat (after Gordon) 4.4.2 Corresponding specification of LPIS emissions 4.4.3 Typical response threats—radiometric 4.4.4 Typical response threats – correlation 4.5 LPIS versus interceptor 4.5.1 Screening jamming 4.5.2 Spoofing 4.6 Typical deployed intercept receivers 4.7 Exercises References 5 Exploitation of the environment 5.1 Atmospheric attenuation 5.2 Clutter Rain Doppler spread 5.3 Terrain masking 5.4 Electronic order of battle 5.4.1 Radar and EW intercept EOB 5.4.2 Radar emitter EOB 5.4.3 Electronic countermeasures EOB 5.5 RF Spectrum masking 5.5.1 Example ambient spectra 5.5.2 Estimating ambient spectra 5.5.3 Estimating ambient pulse density 5.6 Example scenario analysis 5.6.1 Classification usable sensitivity 5.6.2 Monte Carlo simulations 5.7 Typical deployed emitters 5.8 Exercises References 6 Stealth waveforms 6.1 Waveform criteria 6.2 Frequency diversity 6.2.1 Simultaneous transmit and receive cross talk 6.2.2 Low noise adaptive multifrequency generation 6.2.3 Detection by multifrequency waveforms 6.3 Power management 6.4 Pulse compression 6.4.1 Linear FM/chirp 6.4.2 LPI performance loss incurred by use of chirp 6.4.3 Stretch processing 6.4.4 Pulse compression waveform sidelobe measures 6.5 Discrete phase codes 6.5.1 Barker codes 6.5.2 Frank and digital chirp codes 6.5.3 Complementary codes 6.5.3.1 Complementary code overview 6.5.3.2 Type II complementary codes 6.5.3.3 Polyphase complementary codes 6.5.3.4 Polyphase codes 6.5.3.5 Self-noise performance of complementary codes 6.6 Hybrid waveforms 6.6.1 Hybrid spread spectrum stretch (S-cubed) 6.6.2 Hybrid spread spectrum stretch processing 6.6.3 Waveform and processing parameters 6.7 Noise propagation in pulse compressors 6.8 Waveform summary 6.9 Analog to digital conversion Saturation, quantization and optimum signal level [30] 6.10 Exercises References 7 Stealth antennas and radomes 7.1 Introduction 7.2 Antenna parameters 7.2.1 Fundamental definitions (adapted from Skolnik and Silver) 7.2.2 Antenna radiation pattern and aperture distribution 7.3 Single radiators 7.3.1 The electric dipole (adapted from Radiation Laboratories) 7.3.2 The magnetic dipole or small loop 7.3.3 Slot radiators (Adapted from Blass) 7.3.3.1 Small rectangular slot in infinite ground plane 7.3.3.2 Near half-wave radiating slot in infinite ground plane 7.3.3.3 Slot near field 7.3.4 Broadband radiators 7.4 Antenna arrays 7.4.1 Simple apertures 7.4.2 Sidelobe reduction functions 7.4.3 Error induced antenna pattern degradation 7.4.4 Arrays of elements 7.5 Electronically scanned arrays 7.5.1 Single beam antennas 7.5.2 Multibeam antennas 7.5.3 Active electronic scan antennas 7.5.4 AESA antenna example 7.5.5 AESA bandwidth and pulse compression 7.5.6 AESA exciter 7.5.7 AESA unique noise contributions 7.6 Multichannel receivers 7.6.1 Receiver noise sources: thermal noise 7.6.2 Thermal noise example 7.7 Antenna scattering 7.7.1 Basic notions 7.7.2 Estimating antenna RCS 7.7.3 Estimating AESA RCS 7.7.4 Estimating errors due to circuit variations 7.8 Low RCS radomes 7.8.1 Introduction 7.8.2 Antenna and radome integration 7.8.3 General formulas 7.8.4 Composite radomes 7.8.5 Thick frequency-selective layers 7.8.6 Edge treatment 7.8.7 Coordinate rotations 7.8.8 Radome and antenna RCS 7.9 Exercises References 8 Passive observables testing 8.1 Introduction 8.2 Indoor ranges 8.3 Inverse synthetic aperture radar (ISAR) 8.4 Typical RCS range performance 8.5 Ground to air RCS testing 8.6 Air to air RCS testing 8.7 Ship ISAR from aircraft 8.8 Exercises References Appendices Appendix of Chapter 1 Appendix of Chapter 2 Appendix of Chapter 3 Appendix of Chapter 4 Appendix of Chapter 5 Appendix of Chapter 6 Appendix of Chapter 7 Appendix of Chapter 8 Glossary Index