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  • 1. Professional Development Short Course On: Propagation Effects for Radar & Comm Systems Instructor: G. Daniel Dockery ATI Course Schedule: ATI's Propagation Effects for Radar: 349 Berkshire Drive • Riva, Maryland 21140 888-501-2100 • 410-956-8805 Website: • Email:
  • 2. Propagation Effects for Radar and Communication Systems Course Outline 1. Fundamental Propagation Phenomena. Introduction to basic propagation concepts including reflection, refraction, diffraction and absorption. 2. Propagation in a Standard Atmosphere. Introduction to the troposphere and its constituents. Discussion of ray propagation in simple atmospheric conditions and explanation of effective-earth radius concept. 3. Non-Standard (Anomalous) Propagation. Definition of subrefraction, supperrefraction and various types of ducting conditions. Discussion of meteorological processes giving rise to these different refractive conditions. 4. Atmospheric Measurement / Sensing Techniques. Discussion of methods used to determine April 6-8 2009 atmospheric refractivity with descriptions of different Columbia, Maryland types of sensors such as balloonsondes, rocketsondes, instrumented aircraft and remote sensors. $1490 (8:30am - 4:00pm) 5. Quantitative Prediction of Propagation Factor "Register 3 or More & Receive $10000 each or Propagation Loss. Various methods, current and Off The Course Tuition." historical for calculating propagation are described. Several models such as EREPS, RPO, TPEM, TEMPER and APM are examined and contrasted. 6. Propagation Impacts on System Performance. General discussions of enhancements and degradations for communications, radar and weapon Summary systems are presented. Effects covered include radar This three-day course examines the atmospheric detection, track continuity, monopulse tracking effects that influence the propagation characteristics of accuracy, radar clutter, and communication interference radar and communication signals at microwave and and connectivity. millimeter frequencies for both earth and earth-satellite 7. Degradation of Propagation in the scenarios. These include propagation in standard, Troposphere. An overview of the contributors to ducting, and subrefractive atmospheres, attenuation attenuation in the troposphere for terrestrial and earth- due to the gaseous atmosphere, precipitation, and satellite communication scenarios. ionospheric effects. Propagation estimation techniques 8. Attenuation Due to the Gaseous Atmosphere. are given such as the Tropospheric Electromagnetic Methods for determining attenuation coefficient and Parabolic Equation Routine (TEMPER) and Radio path attenuation using ITU-R models. Physical Optics (RPO). Formulations for calculating 9. Attenuation Due to Precipitation. Attenuation attenuation due to the gaseous atmosphere and coefficients and path attenuation and their dependence precipitation for terrestrial and earth-satellite scenarios on rain rate. Earth-satellite rain attenuation statistics employing International Tele-communication Union from which system fade-margins may be designed. (ITU) models are reviewed. Case studies are presented ITU-R estimation methods for determining rain from experimental line-of-sight, over-the-horizon, and attenuation statistics at variable frequencies. earth-satellite communication systems. Example problems, calculation methods, and formulations are 10. Ionospheric Effects at Microwave presented throughout the course for purpose of Frequencies. Description and formulation for Faraday providing practical estimation tools. rotation, time delay, range error effects, absorption, dispersion and scintillation. 11. Scattering from Distributed Targets. Received Instructor power and propagation factor for bistatic and G. Daniel Dockery received the B.S. degree in physics monostatic scenarios from atmosphere containing rain and the M.S. degree in electrical or turbulent refractivity. engineering from Virginia Polytechnic 12. Line-of-Sight Propagation Effects. Signal Institute and State University. Since characteristics caused by ducting and extreme joining The Johns Hopkins University subrefraction. Concurrent meteorological and radar Applied Physics Laboratory (JHU/APL) measurements and multi-year fading statistics. in 1983, he has been active in the areas of modeling EM propagation in the 13. Over-Horizon Propagation Effects. Signal troposphere as well as predicting the impact of the characteristics caused by tropsocatter and ducting and environment on radar and communications systems. relation to concurrent meteorology. Propagation factor Mr. Dockery is a principal-author of the propagation and statistics. surface clutter models currently used by the Navy for 14. Errors in Propagation Assessment. high-fidelity system performance analyses at Assessment of errors obtained by assuming lateral frequencies from HF to Ka-Band. homogeneity of the refractivity environment. Register online at or call ATI at 888.501.2100 or 410.956.8805 Vol. 97 – 21
  • 3. Boost Your Skills 349 Berkshire Drive Riva, Maryland 21140 with On-Site Courses Telephone 1-888-501-2100 / (410) 965-8805 Tailored to Your Needs Fax (410) 956-5785 Email: The Applied Technology Institute specializes in training programs for technical professionals. Our courses keep you current in the state-of-the-art technology that is essential to keep your company on the cutting edge in today’s highly competitive marketplace. Since 1984, ATI has earned the trust of training departments nationwide, and has presented on-site training at the major Navy, Air Force and NASA centers, and for a large number of contractors. Our training increases effectiveness and productivity. Learn from the proven best. For a Free On-Site Quote Visit Us At: For Our Current Public Course Schedule Go To:
  • 4. OUTLINE • Part 1: Over-Sea Propagation • Part 2: Scalar Parabolic Equation (PE) Algorithms • Part 3: Over-Land Propagation • Part 4: 3-D Vector PE Modeling
  • 5. Part 1 Outline: Over-Sea Propagation • Introduction & Radar Equation • Surface Reflection • Multipath • Rough Sea Effects • Spherical Earth Diffraction & Radio Horizon • Physical Optics Models • Atmospheric Refractivity • Atmospheric Measurements • Evaporation Ducting • Synoptic Weather Factors • Sea Clutter • HF Propagation
  • 6. Radar Equation We begin by reviewing the basic monostatic radar range equation describing received power for a radar system: PGt Gr λ 2 PF 4σ RCS Pr = t (4π )3 r 4 L Where Pt = Transmitted power Gt = Transmit antenna gain Gr = Receive antenna gain λ = Radar wavelength PF = Pattern Propagation Factor r = Slant range from radar to target σRCS = Target radar cross section (RCS) L = Miscellaneous system losses
  • 7. Path Loss Another quantity frequently used to describe propagation effects is path loss (PL). The relation between PF and PL is λ2 PL = PF 2 (4π ) 2 r 2 This quantity is most useful for one-way communications problems, where the transmission equation can be written in terms of PL as λ2 Pr = PGt Gr PF 2 (4π r ) 2 t = PGt Gr PL t The results presented in this course will generally be presented in terms of PF2 or PF4.
  • 8. Multipath Geometry “Flat Earth” “Direct” Field r Source θ θ =-θg r2 Specularly Earth’s θg r1 Reflected Field Surface r’=r1+r2
  • 9. Multipath, 3 GHz, z = 20 m V-pol s 500 400 height (m) Altitude[m] 300 200 100 0 0 20 40 60 80 range [km] -30 -25 -20 -15 -10 -5 0 5 PF2 (dB)
  • 10. Multipath, 3 GHz, z = 20 m at height = 200 m s 10 0 -10 PF2 [dB] -20 -30 -40 -50 H-pol -60 V-pol 0 20 40 60 80 range [km]
  • 11. Earth Horizon Geometry Target Rh Source zob zs Earth
  • 12. Height (m) -50 -40 -30 -20 -10 0 10
  • 13. 4/3 earth horizon, zs = 20 m, V-pol 3 GHz 500 400 height [m] 300 200 100 0 0 20 40 60 80 100 range [km] -50 -40 -30 -20 -10 0 10
  • 14. 4/3 earth horizon, z = 20 m, V-pol at height = 200 m s 10 Horizon = 76.8 km 0 -10 PF2 [dB] -20 -30 10 GHz -40 3 GHz 1 GHz -50 500 MHz 0 20 40 60 80 100 range [km]
  • 15. Effective Earth Radius (k-factor) h ae h' eff is such that h=h' at each range when ray is drawn straight. Since keff ae ay curvature depends on refraction, eff also depends on refractive onditions.
  • 16. Propagation Conditions Horizontally Launched Rays Subrefraction Free Space dN/dz>0 dN/dz=0 Standard dN/dz=-39 Superrefraction dN/dz<-39 Ducting Ducting Threshold dN/dz<-157 dN/dz=-157 Earth
  • 17. Physical Optics Regions 4/3 earth horizon, z = 20 m, V-pol, 3 GHz at height = 200 m s 10 0 Diffraction -10 Region PF2 [dB] -20 Bold Interference Region Interpolation -30 Region -40 -50 0 20 40 60 80 100 range [km]
  • 18. Physical Optics – PE Comparison 3 GHz, 100-ft Antenna Altitude, V-Pol. Standard Atmosphere, 500 ft Altitude ropagation actor (dB) Range (nmi)
  • 19. TYPES OF REFRACTIVE CONDITIONS “Standard” Sub- Evaporation Surface Elevated Atmosphere refraction Duct Duct Duct h” Eart Altitude “4/3 0.2-2km Upward- Upward- Refracting Ducting 0-300 m 0-40m 50-500m Layer Layer M” = Modified Refractivity M M M M Altitude Little red = affect strongest on surface illumination sensors Range Atmospheric refraction has a large effect on system performance – The “standard atmosphere” assumption is often inadequate
  • 20. Strong Surface-Based Ducting Standard Atmosphere keff = 1.33 One-Way Propagation Factor F2 – S-Band – 50-foot Antenna – Narrow Beamwidth Sin(x)/x Pattern Measured Surface-Based Duct Profile
  • 21. Circulation Associated with Sea-Breeze < 3,000 feet Warm Dry Sinking Rising Air Due to Surface Heating Dry Hot Sea Breeze Cool Moist Land 15-25 nm 15-25 nm Water This situation results in the over-water conditions persisting some distance inland
  • 22. Advection Off Shore Off-Shore Flow Dry Hot Continental Air Cool Moist Marine Air Land 15-25 nm 15-25 nm Water This situation results in a surface duct increasing in height away from shore
  • 23. Helicopter Instrumentation Usual Aircraft: Bell Jet or Long Ranger Crew: Civilian Pilot & 2 APL Engineers Custom APL Instrumentation Compass “Slow” T, RH R Sea Temp “Fast” T,RH Pitot Static Sensor: Air speed
  • 24. Helicopter Vertical Profiles Instrumented Helicopter ~600 m Shipboard Radars 10 km
  • 25. Helo Data Sample collected September 2001 Near Camp Pendleton, CA STD Land
  • 26. Propagation Diagram • Measured Environment (first profile only) (all profiles)
  • 27. Clutter Power Equation Ignoring propagation effects, the monostatic radar equation for received clutter power by a pulsed radar may be written as PG 2 λ 2 f 4 ⎛ cτ ⎞ Pr = t 3 3 ⎜ o B σθ ⎟ (4π ) r ⎝ 2⎠ where G is the antenna gain assumed for both transmit & receive, f 4 is the two-way antenna pattern factor in the direction of the surface, c is the speed of light, θB is the azimuth beamwidth, and τ is the pulse width. This is the equation that has historically been inverted to estimate σo using data from clutter measurement campaigns. Thus, in empirically based models for σo, the propagation effects are embedded in the normalized cross section.
  • 28. Sea Clutter Geometry Monostatic Pulsed Radar zs cτ /2 θg cτ secθg /2 θB rθB
  • 29. SPANDAR Sea Clutter Date Date
  • 30. HF Propagation Mode Diagram Ionosphere Sky Wave Ground Wave Surface Wave Earth
  • 31. Ionosphere Effects Summary Effect Freq. 0.5 1 GHz 3 GHz 10 GHz Dep. GHz Faraday Rotation (deg) 1/f2 432 108 12 1.1 Propagation Delay (µsec) 1/f2 1 0.25 0.028 0.0025 Excess Range Delay (m) 1/f2 300 75 8.3 0.75 Refraction (‘ or “) 1/f2 <2.4’ <0.6’ <4.2” <0.36” RMS Dir. Of Arrival (“) 1/f2 48” 12” 1.32” 0.12” Absorption (auroral/polar) ~1/f2 0.2 0.05 0.006 5x10-4 (dB) Absorption (mid-latitude) 1/f2 <0.04 <0.01 <0.001 <10-4 (dB) Dispersion (psec/Hz) 1/f3 0.004 0.0005 1.9x10-5 5x10-7 Scintillation (dB) >20 ~10 ~4 TEC=1.86x1018 m-1 ; B=0.43 Gauss ; Angle through ionosphere=30 deg
  • 32. Part 2 Outline: Scalar PE Algorithms • Summary of Modeling Approaches • Vector & Scalar Wave Equations • Parabolic Wave Equations • Numerical Solution Approaches • Basic and Mixed Fourier Split Step Solutions • Source Modeling • Surface Roughness • Validation Examples
  • 33. Part 3 Outline: Propagation Over Terrain • Introduction • Primary Terrain-related Effects • Propagation Modeling Approaches • Modeling Propagation Over Terrain With PE Models • Refractivity Characteristics • Land Clutter
  • 34. Part 4 Outline: 3-D Vector PE Modeling • Introduction • 3-D Scalar PE Approaches (Brief Summary) • 3-D Vector PE Modeling • Modeling Propagation Over Terrain • RCS Calculations (Brief Summary)
  • 35. Boost Your Skills with On-Site Courses Tailored to Your Needs The Applied Technology Institute specializes in training programs for technical professionals. Our courses keep you current in the state-of-the-art technology that is essential to keep your company on the cutting edge in today’s highly competitive marketplace. For 20 years, we have earned the trust of training departments nationwide, and have presented on-site training at the major Navy, Air Force and NASA centers, and for a large number of contractors. Our training increases effectiveness and productivity. Learn from the proven best. ATI’s on-site courses offer these cost-effective advantages: • You design, control, and schedule the course. • Since the program involves only your personnel, confidentiality is maintained. You can freely discuss company issues and programs. Classified programs can also be arranged. • Your employees may attend all or only the most relevant part of the course. • Our instructors are the best in the business, averaging 25 to 35 years of practical, real- world experience. Carefully selected for both technical expertise and teaching ability, they provide information that is practical and ready to use immediately. • Our on-site programs can save your facility 30% to 50%, plus additional savings by eliminating employee travel time and expenses. • The ATI Satisfaction Guarantee: You must be completely satisfied with our program. We suggest you look at ATI course descriptions in this catalog and on the ATI website. Visit and bookmark ATI’s website at for descriptions of all of our courses in these areas: • Communications & Computer Programming • Radar/EW/Combat Systems • Signal Processing & Information Technology • Sonar & Acoustic Engineering • Spacecraft & Satellite Engineering I suggest that you read through these course descriptions and then call me personally, Jim Jenkins, at (410) 531-6034, and I’ll explain what we can do for you, what it will cost, and what you can expect in results and future capabilities. Our training helps you and your organization remain competitive in this changing world. Register online at or call ATI at 888.501.2100 or 410.531.6034