introduction and classification to radar.pdf

radar system components

2. Pre-Radar Aircraft Detection –
Optical Systems
•Significant rangelimitation
–Attenuation byatmosphere
•Narrow field ofview
–Caused by very smallwavelength
•Clouds Cover limits operational
usefulness
–Worldwide -40-80% of thetime
Courtesy of NationalArchives.
IEEE New Hampshire Section
Radar Systems Course 2
Introduction10/1/2009
Courtesy of US Army SignalCorps.
Courtesy of UKGovernment

3. Pre-Radar Aircraft Detection –
AcousticSystems
Courtesy ofWikimedia
•Developed and used in first halfof
20
thcentury
•Attributes
–LimitedRange
approximately 10+miles
–Limited field ofview
–Ambient background noise
limited (weather,etc)
•Used with searchlights atnight
Courtesy of US Army SignalCorps.
Courtesy of US Army SignalCorps.
Japanese Acoustic DetectionSystem
IEEE New Hampshire Section
Radar Systems Course 3
Introduction10/1/2009
US Acoustic DetectionSystems

4. Sound Mirrors Dunge,
Kent,UK
Courtesy of si inWikimedia
•Used for aircraft detection (pre-World WarII)
•Short detection range (less than 15miles)
–Tactically useful for detecting slow WW1Zeppelins
–Not useful for detecting faster WW2 Germanbombers
Width ofAperture
200ft
30ft
20ft

5. How Radar Works-The
ShortAnswer!
•An electromagnetic wave is transmitted by theradar.
•Some of the energy is scattered when it hits a distanttarget
•A small portion of the scattered energy, the radar echo, is
collected by the radarantenna.
•The time differencebetween:
when the pulse of electromagnetic energy is transmitted,and
when the target echo isreceived,
is a measure of how far away the targetis.
c
=
2R
Courtesy ofNOAA
IEEE New Hampshire Section
Radar Systems Course 5
Introduction10/1/2009

6. Chain Home Radar
System
–Dipole Array on
Transmit
–Crossed Dipoles on
Receive
•AzimuthBeamwidth
–~100
o
•PeakPower
–350kW
•DetectionRange
IEEE New Hampshire Section
Radar Systems Course 6
Introduction10/1/2009
–~160 nmi onJU-88
GermanBomber
Chain Home
RadarParameters
•Wavelength
–10 to 15m
•Frequency
–20 to 30MHz
•Antenna
Typical Chain Home RadarSite
Courtesy of MIT Lincoln Laboratory
Used withpermission

7. The SCR 584 Fire-
ControlRadar
SCR-584
Wavelength 10 cm(S-Band)
Frequency 3,000 MHz
Magnetron 2J32
PeakPower 250kW
PulseWidth 0.8µsec
PRF 1707Hz
Antenna
Diameter 6 ft
Beamwidth 4°
AzimuthCoverage360°
MaximumRange 40mi
RangeAccuracy 75ft
AzimuthAccuracy0.06°
ElevationAccuracy0.06°
SCR-584Parameters
Courtesy of Department ofDefense
IEEE New Hampshire Section
Radar Systems Course 7
Introduction10/1/2009

8. The SCR 584 Fire-
ControlRadar
SCR-584 (40
th Anniversary of MIT RadLab)
Wavelength 10 cm(S-Band)
Frequency 3,000 MHz
Magnetron 2J32
PeakPower 250kW
PulseWidth 0.8µsec
PRF 1707Hz
Antenna
Diameter 6 ft
Beamwidth 4°
AzimuthCoverage360°
MaximumRange 40mi
RangeAccuracy 75ft
AzimuthAccuracy0.06°
ElevationAccuracy0.06°
SCR-584Parameters
Courtesy of MIT LincolnLaboratory
IEEE New Hampshire Section
Radar Systems Course 8
Introduction10/1/2009

9. Radar Proximity
Fuze
Modern
V-53
IEEE New Hampshire Section
Radar Systems Course 9
Introduction10/1/2009
Radar Proximity Fuze
Radar ProximityFuze
(Cutaway)
Circa1985
Courtesy of USNavy
Circa mid1940s
Operation of
Radar ProximityFuze
Must operate under very high g
forces
Micro transmitter in fuze emits a
continuous wave of ~200MHz
Receiverinfuzedetectsthe
Dopplershiftofthemoving
target
Fuze is detonated when Doppler
signal exceeds athreshold
Direct physical hit not necessary
for destruction oftarget
Radar Proximity Fuze Revolutionized AAA and ArtilleryWarfare
Courtesy of RobertO’Donnell

10. World War 2 Air Defense
System
British 3.7” AAAGun
SCR-584 Fire ControlRadar
US 90 mm AAAGun
M9Predictor
When deployed on British coast, V-1 “kill
rate” jumped to 75%, when thisintegrated
system was fully operational in1944
Radar
Proximity
Fuze
Courtesy of Department ofDefense
IEEE New Hampshire Section
Radar Systems Course 10
Introduction10/1/2009
Courtesy of USArmy
Courtesy of USArmy
Courtesy
of
USNavy
Courtesy
of
USNavy

11. What radars measure

12. Pulsed
RadarTerminology andConcepts
Power
Duty cycle=
Average power = Peak power * Dutycycle
Pulse repetition frequency (PRF) =1/(PRI)
Peak
power
Time
Pulselength
Pulse repetition interval
(PRI)
Pulselength
Pulse repetitioninterval
Target
Return
Continuous wave (CW) radar: Duty cycle = 100% (alwayson)
IEEE New HampshireSection
Radar Systems Course 12
Introduction10/1/2009

13. Pulsed
RadarTerminology andConcepts
Power
Duty cycle=
Average power = Peak power * Dutycycle
Peak
power
Time
Pulselength100sec
1MW
Target
Return 1W
Pulse repetitioninterval
(PRI) 1msec
Pulselength
Pulse repetitioninterval
Pulse repetition frequency (PRF) =1/(PRI)
100kW
10%
1kHz
Continuous wave (CW) radar: Duty cycle = 100% (alwayson)
IEEE New HampshireSection
Radar Systems Course 13
Introduction10/1/2009

14. Radar
Observables
TransmittedSignal:
ReceivedSignal:
s
T(t)=A(t)exp(j2f
0t)
s
R(t)=A(t−)expj2(f
0+f
D)t
c
=
2R
0
=
2 Vf
0
=
2V
c 
f
D
TimeDelay DopplerFrequencyAmplitude
Depends on RCS, radar
parameters, range, etc.
R
0
Transmitted
Signal
Received
Signal
Target
Angle
Azimuth
and
Elevation
0
R(t)=R−Vt
V
IEEE New Hampshire Section
Radar Systems Course 14
Introduction10/1/2009

15. Doppler
Shift
0
c +V
2(R−VT)
B
t=T+
c +V
=
2R
0
A•Time when peak A arrives back at radar t
0
R
0
Transmitpulse
A B
V
Location at t =0
Location at t =t
•Time when peak B arrives back atradar
R
0
c +V
•This peak leaves antenna at time t = 0, when aircraft atR
0
•The peak A arrives at target at timet
•Aircraft moving with radial velocityV
•The period of the transmit pulse is T, and f
0 = 1/T and c = T =f
0
•Note:ct=R−Vt or t=
T
T
IEEE New Hampshire Section
Radar Systems Course 15
Introduction10/1/2009

16. Doppler Shift
(continued)

c
1−
c

•The period of the transmitted signal is T and the received echo
is T
R = T
B-T
Aor

1 +
V
f=f
c +V 
=f

=T
c−V
0 
V

c +V


0
c−V


T
RR
c/f 
=+
2 V
=+
2V
+2V
ff

V
=1 +
c
−
c
+. ..
1−
f
c/f
1 V
•ForV cthen
V
2
c
0
D
0
0R
+ Approachingtargets
-Recedingtargets
RadialVelocity
Christian Andreas Doppler
(1803 -1853)
IEEE New Hampshire Section
Radar Systems Course 16
Introduction10/1/2009

17. Radar
Observables
TransmittedSignal:
ReceivedSignal:
s
T(t)=A(t)exp(j2f
0t)
s
R(t)=A(t−)expj2(f
0+f
D)t
c
=
2R
0
=
2Vf
0
=
2V
c 
f
D
TimeDelay DopplerFrequencyAmplitude
Depends on RCS, radar
parameters, range, etc.
R(t)=R−Vt
0
Transmitted
Signal
Received
Signal
Target
Angle
Azimuth
and
Elevation
+ Approachingtargets
-Recedingtargets
IEEE New Hampshire Section
Radar Systems Course 17
Introduction10/1/2009

18. Different Radar wavelengths / frequencies

19. Radar FrequencyBands
Wavelength
10
9
10
13 10
15 10
1710
7
Frequency(Hz)
10
11 10
19
100m 1m 1cm 100µm 1 µm 10nm 1 Å 0.01Å
Gamma-rays
Microwave
X-rays
Ultraviolet
Visible
Light
Infra-red
Radio
TV
7 8UHF1
X-BandS-Band C-BandL-BandVHF
Ku
K
Ka
W
2 3 4 5 6
Allocated Frequency(GHz)
LogarithmicScales
9 10 1112
Linear Scale
Millimeter
Bands
MicrowaveBand
~3cm
~2m
~10cm
~5.5
cm~23cm~435
cm
IEEE New HampshireSection
Radar Systems Course 19
Introduction10/1/2009

20. Standard Radar Bands* & TypicalUsage
VHF 30 –300MHz
UHF 300 MHz –1GHz
L-Band 1 –2GHz
S-Band 2 –4GHz
C-Band 4 –8GHz
X-Band 8 –12GHz
Ku-Band 12 –18GHz
K-Band 18 –27GHz
Ka-Band 27 –40GHz
W-Band 40 –100+GHz
HF 3 –30MHz
Search
Radars
Courtesy of MIT Lincoln Laboratory
Used withpermission
.
UHF -VHF
ALTAIR
UHF
UEWR –Fylingsdales,UK
IEEE New HampshireSection
Radar Systems Course 20
Introduction10/1/2009
Courtesy ofspliced
.
GNU
*From IEEE Standard521-2002

21. Standard Radar Bands* & TypicalUsage
HF 3 –30MHz
VHF 30 –300MHz
UHF
L-Band
300 MHz –1GHz
1 –2GHz
S-Band 2 –4GHz
C-Band 4 –8GHz
X-Band
Ku-Band
8 –12GHz
12 –18GHz
K-Band 18 –27GHz
Ka-Band 27 –40GHz
W-Band 40 –100+GHz
*From IEEE Standard521-2002
Tracking
Radars
Courtesy of MIT Lincoln Laboratory
Used withpermission
C-Band
MOTRMQP-39
Courtesy of Lockheed Martin
Used withpermission
X
.
-Band
HaystackRadar
.
IEEE New HampshireSection
Radar Systems Course 21
Introduction10/1/2009

22. IEEE New HampshireSection
Radar Systems Course 22Introduction
10/1/2009
Standard Radar Bands* &
TypicalUsage
HF 3 –30MHz
VHF 30 –300MHz
UHF
L-Band
S-Band
300 MHz –1GHz
1 –2GHz
2 –4GHz
C-Band 4 –8GHz
X-Band
Ku-Band
K-Band
8 –12GHz
12 –18GHz
18 –27GHz
Ka-Band 27 –40GHz
W-Band 40 –100+GHz
*From IEEE Standard521-2002
Search &Track
Radars
L-Band
TPS-77
S-Band
AEGISSPY-1
C-Band
PatriotMPQ-53
Courtesy of US MDA
Used withpermission.
Courtesy of Lockheed Martin
Used withpermission.
Courtesy of US Navy
Used withpermission.

23. Standard Radar Bands* & TypicalUsage
HF 3 –30MHz
VHF 30 –300MHz
UHF 300 MHz –1GHz
L-Band 1 –2GHz
S-Band 2 –4GHz
C-Band 4 –8GHz
X-Band 8 –12GHz
Ku-Band 12 –18GHz
K-Band 18 –27GHz
Ka-Band 27 –40GHz
W-Band 40 –100+GHz
Missile
Seekers
*From IEEE Standard521-2002
IEEE New HampshireSection
Radar Systems Course 23
Introduction10/1/2009
Courtesy of US Army.
Used withpermission.

24. Standard Radar Bands* & TypicalUsage
HF
VHF
UHF
3 –30MHz
30 –300MHz
300 MHz –1GHz
L-Band 1 –2GHz
S-Band
C-Band
X-Band
2 –4GHz
4 –8GHz
8 –12GHz
Ku-Band 12 –18GHz
K-Band
Ka-Band
W-Band
18 –27GHz
27 –40GHz
40 –100+GHz
Range
Instrumentation
Radars
Courtesy of MIT Lincoln Laboratory
Used withpermission
.
Reagan TestSite
Kwajalein
*From IEEE Standard521-2002
IEEE New HampshireSection
Radar Systems Course 24
Introduction10/1/2009

25. Descriptive classifications of radars
Military, civilian, other

26. Classification Systems for Radars
By Function
Surveillance
Track
Fire Control – Guidance
Discrimination
By Mission
Air Traffic Control
Air Defense
Ballistic Missile Defense
Space Surveillance
Airborne Early Warning (AEW)
Ground Moving Target Indication (GMTI)
By Name
Pave Paws (FPS-115)
Cobra Dane(FPS-108)
Sentinel (MPQ-64)
Patriot (MPQ-53)
Improved Hawk (MPQ-48)
Aegis (SPY-1)
ALCOR
Firefinder (TPQ-37)
TRADEX
Haystack
Millstone
By Antenna Type
Reflector
Phased Array (ESA)
Hybrid-Scan
By Range
Long Range
Medium Range
Short Range
By Frequency
VHF-Band
UHF-Band
S-Band
C-Band
X-Band
K
U
-Band
K
A
-Band
Other
Solid State
Synthetic Aperture (SAR)
MTI
GMTI
By Platform
Ground
Ship
Airborne
Space
By Waveform Format
Low PRF
Medium PRF
High PRF
CW (Continuous Wave)
By Waveform
Pulsed CW
Frequency Modulated CW L-Band
Phase Coded
Pseudorandom Coded
By Military Number
FPS-17
FPS- 85
FPS-118
SPS-48
APG-68
TPQ-36
TPQ-37
MPQ-64

27. Depending on the desired
information, radar sets have
different qualities and
technologies. One reason for
thesedifferent qualities and
techniques, radar sets are
classified in:

28. Classification of Radar systems (1)
Radar Set

29. Primary Radar
•Primary Radar sets emit high-
frequency signals that are reflected at
targets. In contrast to secondary
radars, primary radars receive their
own emitted signals as echoes. The
resulting echo signals are received
and evaluated

30. Secondary
Radar
•With these radar sets, the aircraft must
be equipped with a transponder
(transmitting responder) and receive a
coded signal from the radar interrogator.
The active response is generated in the
transponder, which is then also coded and
sent back to the secondary radar. The run
time is also used as a measure of the
distance, as with primary radar. This reply
contains much more information (e.g.
altitude, identification or technical
problems on board, e.g. radio failure…)
than that can be achieved with primary
radar.

31. Pulse Radar

32. Continuous Wave Radar
•Continuous Wave Radar (CW radar) sets
transmit a high-frequency signal
continuously. The echo signal is received
and processed permanently. One has to
resolve two problems with this principle:
•prevent a direct connection of the
transmitted energy into the receiver
(feedback connection),
•
•assign the received echoes to a time system
to be able to do run time measurements.
Transmitter
Receiver

33. CW Doppler Radar
•Is an Unmodulated Continuous Wave Radar
•The continuous wave radar evaluates the phase
difference φ between the transmitted signal and the
received signal. The magnitude of this phase
difference is the ratio of the distance traveled by the
electromagnetic wave to the wavelength of the
transmitted signal, multiplied by the degree division
of the full circle (2·π).

34. Direct conversion receiver(Homodyne)
•A Doppler radar for speed
measurements is very simple. The
entire circuit of the transmitter and
receiver can be manufactured with
semiconductor components on a
substrate as an integrated component.
This component is usually called a
transceiver (a portmanteau of the
words transmitter and receiver). In
many cases, this transceiver is already
equipped with the required antennas.
Usually, these are patch antennas
realized on a double-sided printed
circuit board or (with larger
bandwidths) horn radiators.

36. Radar Devices
•Antenna
•Transmitter
•Receiver
•Duplexer
•Radar Scope(Display)
•Signal Processor

37. Radar Devices

38. Antennas
Characteristic values of antennas
•Antenna gain and directivity
•Antenna pattern
•Half power beamwidth
•Beam solid angle
•Sidelobe-attenuation
•Forward / Reverse ratio
•Effective antenna area (aperture)
•Band width

39. Antenna gain and directivity
•Due to the special design of the antenna, the
radiation density can be concentrated in certain
spatial
directions. A measure of the directivity of a
lossless antenna is the antenna gain. It is closely
associated with
the directivity of the antenna. In contrast to the
directivity, which only describes the directional
properties of
the antenna, the antenna gain also takes into
account the efficiency of the antenna. It,
therefore, indicates
the actual radiated power.

40. Antenna pattern
•The antenna pattern is a graphical
representation of the spatial distribution
of the radiated energy of an antenna.
Depending on the application, an
antenna should only receive from a
certain direction, but should not pick up
signals from other directions (e.g. TV
antenna, radar antenna), on the
other hand, the car antenna should be
able to receive transmitters from all
possible directions.

41. Half power beamwidth
•The half power beamwidth is the
angular range of the antenna pattern in
which at least half of the maximum power
is still radiated
Beam solid angle
•It is a rather theoretical value but can be
approximated for antennas with very large
directivity and
small sidelobes:
ΩA ≈ Θaz·Θel where:
Θ Θaz = horizontal half power-beamwidth
el = vertical half power-beamwidth

42. Effective antenna area (aperture)
•the maximum power that can be obtained from a
receiving antenna is proportional to the power density
of the plane wave incident at the receiving location.

43. Radar Scope Beam solid angle