1.
Professional Development Short Course On:
Propagation Effects for Radar & Comm Systems
Instructor:
G. Daniel Dockery
ATI Course Schedule: http://www.ATIcourses.com/schedule.htm
ATI's Propagation Effects for Radar: http://www.aticourses.com/propogation_effects_radar.htm
349 Berkshire Drive • Riva, Maryland 21140
888-501-2100 • 410-956-8805
Website: www.ATIcourses.com • Email: ATI@ATIcourses.com
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 www.ATIcourses.com or call ATI at 888.501.2100 or 410.956.8805 Vol. 97 – 21
3.
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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
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]
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.
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
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
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.
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.
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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.
• Our on-site programs can save your facility 30% to 50%, plus additional savings by
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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:
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• 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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