Professional Development Short Course On:
Propagation Effects for Radar & Comm Systems
G. Daniel Dockery
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Propagation Effects for Radar and Communication Systems
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
3. Non-Standard (Anomalous) Propagation.
Definition of subrefraction, supperrefraction and
various types of ducting conditions. Discussion of
meteorological processes giving rise to these different
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.
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The Applied Technology Institute specializes in training programs for technical professionals. Our courses keep you
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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.
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• Part 1: Over-Sea Propagation
• Part 2: Scalar Parabolic Equation (PE)
• Part 3: Over-Land Propagation
• Part 4: 3-D Vector PE Modeling
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
Another quantity frequently used to describe propagation effects
is path loss (PL). The relation between PF and PL is
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
Pr = PGt Gr PF 2
(4π r ) 2
= PGt Gr PL
The results presented in this course will generally be
presented in terms of PF2 or PF4.
θ =-θg r2 Specularly
Earth’s θg r1 Reflected
Multipath, 3 GHz, z = 20 m V-pol
0 20 40 60 80
-30 -25 -20 -15 -10 -5 0 5
Multipath, 3 GHz, z = 20 m at height = 200 m
0 20 40 60 80
4/3 earth horizon, z = 20 m, V-pol at height = 200 m
Horizon = 76.8 km
-40 3 GHz
-50 500 MHz
0 20 40 60 80 100
Effective Earth Radius (k-factor)
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
Horizontally Launched Rays
Subrefraction Free Space
Ducting Ducting Threshold
Physical Optics Regions
4/3 earth horizon, z = 20 m, V-pol, 3 GHz at height = 200 m
Interference Region Interpolation
0 20 40 60 80 100
Physical Optics – PE Comparison
3 GHz, 100-ft Antenna Altitude, V-Pol.
Standard Atmosphere, 500 ft Altitude
TYPES OF REFRACTIVE CONDITIONS
“Standard” Sub- Evaporation Surface Elevated
Atmosphere refraction Duct Duct Duct
0-300 m 0-40m 50-500m
M” = Modified Refractivity M M M M
red = affect
strongest on surface
Atmospheric refraction has a large effect on system performance –
The “standard atmosphere” assumption is often inadequate
Circulation Associated with Sea-Breeze
< 3,000 feet
Warm Dry Sinking
Rising Air Due to
This situation results in the over-water conditions
persisting some distance inland
Advection Off Shore
Dry Hot Continental Air
Cool Moist Marine Air
This situation results in a surface duct increasing
in height away from shore
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:
Helicopter Vertical Profiles
Helo Data Sample collected
September 2001 Near Camp Pendleton, CA
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
(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.
Part 3 Outline:
Propagation Over Terrain
• Primary Terrain-related Effects
• Propagation Modeling Approaches
• Modeling Propagation Over Terrain With
• Refractivity Characteristics
• Land Clutter
Part 4 Outline:
3-D Vector PE Modeling
• 3-D Scalar PE Approaches (Brief Summary)
• 3-D Vector PE Modeling
• Modeling Propagation Over Terrain
• RCS Calculations (Brief Summary)
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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.
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• 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.
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eliminating employee travel time and expenses.
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We suggest you look at ATI course descriptions in this catalog and on the ATI website.
Visit and bookmark ATI’s website at http://www.ATIcourses.com for descriptions of all
of our courses in these areas:
• Communications & Computer Programming
• Radar/EW/Combat Systems
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I suggest that you read through these course descriptions and then call me personally, Jim
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you can expect in results and future capabilities.
Our training helps you and your organization
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