RADAR Chuck Hobson BA BSc (hons)

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RADARChuck Hobson BA BSc (hons)
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INTRODUCTION
This presentation starts with the early
beginnings of Radar in the United States and
Great Britain. It moves on from there to
describe various military and civilian radars,
how they work and what they look like. In keeping
with this, I shall first kick off with my own
early beginnings and how I fit into the
picture. I was born and raised in Pittsburgh
Pennsylvania, which is located at the heart of
the US steel and coal mining industries. My
early years were spent there during the Great
Depression. I graduated from High School at the
age of 17 in 1944. Like most young men in similar
circumstances at that time, I contemplated my
future, which included the military draft and a
life time working in Steel Mills. With such a
future to look forward to, I became very
depressed indeed. Then one morning while walking
in down town Pittsburgh I spotted a US Navy
recruitment poster in a Post Office window. My
spirits soared. US Navy wants young men in
Radar! I rushed into the Post Office where I
suddenly found myself confronted by a very
intimidating US Navy Chief Petty Officer.So you
want to join the Navy, he asked? I mentioned
the Radar poster and he said I would have to pass
a written test on mathematics and physics to get
into the Navys Radar school. I was really elated
as those were my favourite high school subjects.
I said I would like to take the test please. The
Chief said It was called The Captain Eddy Test,
which consisted of 80 questions, and that very
few ever passed it. He then handed me the test
paper and told me I had two hours to complete it.
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INTRODUCTION (continued)
I completed the test in an hour and 10 minutes
and handed it back to the Chief. He asked me,
Whats the matter, cant you answer the
questions? I told him I finished the test. He
marked it and graded it a pass. The chief then
handed me an official looking US Navy form and
told me to give it to the doctor in an adjoining
room. The physical exam took about 5 hours, It
was truly an ordeal. Having passed that I found
myself on my way to Boot Camp the following week
with a Seaman First Class rating (S1/c). After
surviving four weeks of accelerated boot
training, I went on to attend a suite of US Navy
technical schools. The first was called
Pre-Radio School. It was a gruelling four weeks
of mathematics. I managed that (30 survival
rate). From there I went on to the next level,
Primary Radio School for 3 months. It included
electronic theory, some higher math, and building
elementary receivers. After finishing and passing
that, I went on to the final level, Secondary
Radio School. That lasted six months. This
school included a lot of electronic theory, which
was taught in the mornings. The afternoons were
taken up with extensive hands on experience
Radar and Sonar sets, Communication gear, and
Navigation equipment. I graduated in the top 10
of the class and was awarded a second class petty
officer rating. (RT2/c) It was not because I had
a super brain, but because I was adicted to
electronics and completely immersed in my
studies. (The Nerd mode)
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INTRODUCTION (continued)
During the next 6 years I served aboard various
Naval ships and on shore stations repairing any
and all kinds of Naval Electronic Equipment. If
it contained vacuum tubes (valves) magnetrons and
klystrons, I had a go at it Fire Control, Air
and Surface Search Radars, HF/VHF/UHF
Transmitters and Receivers, Loran etc. That
experience along with the Navys
education/training in Radar set me up for life in
the field of Electronics. In the process I became
quite familiar with many kinds of Radars, which
is what this Radar presentation is all about. The
next slide shows a picture of the USN
Recruitment Poster I saw in Pittsburgh, a photo
of me taken in Boot Camp and and another of an
early US Navy Destroyer Escort. From there the
presentation goes strictly into Radar.
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MY BEGINNINGS
S1/c Chuck Hobson Jan. 1945
US Navy Recruiting Poster 1944
US Naval Destroyer Escort DE-316
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WHAT IS RADAR

• RADAR RAdio Detection And Ranging (American)
• RDF Radio Direction Finding (British)
• Doover Australian equivalent to thingamajig

• Radar transmits short high powered burst of RF
  energy
• RF energy travels towards aircraft at speed of
  light
• RF illuminated aircraft re-radiates signal back
  to Radar
• Radar measures RF energy round trip time (12.3µs
  per nm)

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RADAR USERS
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NOTES PAR Precision Approach Radar
ASDE Automated Surface Det Equipment
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HOW RADAR CAME ABOUT IN THE U.S.

• THE EARLY BEGINNINGS
• U. S. Naval Research Lab

• 1934 1935 experimented with Pulsed Radar
• 1936 Demonstrated Pulse Radar 25 mile
  range (Air Search Radar)

• 1937 Installed 200MHz Radar on destroyer
  
• 1938 1945 Installed same radar on DDEs DDs
  CAs BBs Carriers and various other ships (SC
  series Air Search Radar)

Typical Destroyer mast
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HOW RADAR CAME ABOUT IN BRITAIN
THE EARLY BEGINNINGS

• 1933 Ionosphere sounding
  Experiments with HF
• 1934 Examined HF fading
  caused by aircraft.
• 1935 Deventry Experiments
  Demonstrated Feasibility
• 1935 developed demonstrated Pulsed Radar at
  Orfordness leading to construction of CH Radar
• 1936 1939 Built the CH Radar system

Chain Home Radar Transmitter Antennas
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THE TIZARD COMMITTEE
Scientific Survey of Air Defence Committee
Tizard Chairman Rector of Imperial College Rowe
Secretary Air Ministry Wimperis
Member Air Ministry Watts
Member Radio RS Supt.
This committees job was to. investigate new
technologies for defense against air attacks.
Their 1st task given to Watson Watts was
calculate the amount of RF energy needed to
disable the pilot and aircraft in flight?
His results shown it to be impractical.
Subsequently Arnold Wilkins was asked via Rowe
and Watts how he may help the Air Ministry with
their task. Hence, efforts to develop Radar
began. (This was in early 1935)
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ARNOLD WILKINS
Scientific Officer at the Radio Research Station
Expert on antennas the behaviour of radio
waves Conducted Deventy experiment Participated
in pulsed radar tests at Orfordness RRS known as
Home of the Invention of Radar Credit for
invention given to Sir Watson Watts
ARNOLD WILKINS (1907 1985)
1933 Wilkins familiar with pulsed RF
techniques Ionosphere sounding Noted flutter of
VHF (60MHz) signals from nearby
Aircraft Subsequently mentioned this to
Watts Joint Watts Wilkins memo presented to
Tizard Committee Led to Deventry Experiment,
Radar tests at Oxfordness CH Radar
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THE DEVENTRY EXPERIMENT
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THE DEVENTRY EXPERIMENT
Heyford Bomber
RAF Long Range Bomber Prototype Flown in
1930 Speed 229km/hr (142 mph) Range 1480km (920
Miles) Ceiling 6400m (21000 ft.)
Deventry Experiment Site
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ORFORDNESS

• Radar proposal by Watts and Wilkins accepted and
  go ahead given
• Highly secret work started Apr. 1935 at
  Orfordness an isolated place
• A very austere operation
• Test equipment 2 HF wave meters, 2 Avometers,
  misc. VM AMs
• Tech book Radio Amateur Handbook Wilkins other
  2 were Hams
• Erected two 75 wooden towers for Xmtr and 4
  others for Receivers
• Transmitter problems Flash over and pulse width
  Corona on ant.
• Committee appeared on site expecting results
  (June 1935)
• 50 metre freq. Used. Atmospheric noise problems.
• Echo from Valencia A/C observed at 27km
• Committee gave glowing report to Air Ministry
• Shifted to 22MHz (14m) atmospheric problem went
  away.
• Pulse width down from 50µs to 10µs

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CHAIN HOME (CH) RADAR

• Following Orfordness development work, a system
  of 20 CH radars were strung up along the south
  and east coasts of England just before World
  War Two.
• These radars gave the RAF a distinct advantage
  over the German Luftwaffe.

• These radars were able to detect incoming enemy
  bombers and provide the RAF with their range,
  direction and altitude (position)
• With this information the RAF could choose when
  and where, or simply not to engage the enemy
  bombers (A distinct tactical advantage)

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Map of Chain Home Radars
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CHAIN HOME (CH) RADAR

• Pulse type radar operating at 20 to 30MHz
  Transmitter peak power 350kW/750kW
• Large HF antennas strung up between two 100 metre
  high steel towers for transmitting

Transmitted very broad beam to illuminate all
aircraft in search area Receiving antennas (not
shown) provided azimuth and elevation data
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CHAIN HOME (CH) RADAR

• Second set of cross type antennas on 60m high
  towers for receiving.

Cross Dipoles mounted on wooden towers
Antennas were used to DF on reflections from
aircraft DF was achieved by phasing cross dipoles
with goniometers Beam was shifted left, right, up
and down with goniometers calibrated in az. and
el. Mechanical calculators converted elevation
angle to altitude.
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LUFTWAFFE FLYING BELOW CH RADAR BEAM

• Chain Home Low (CHL) Radars added (1939 - 1940
• Picked up Luftwaffe flying below CH radar beams
• Operated at 180 210MHz
• Antenna broadside 32 dipole array
• Horizontal Beam width 200
• Antenna steered on pedal crank by WAAF
• A Scope display. PPI introduced in 1940
• Antenna rotated at 1 to 2 rpm

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CHAIN HOME GCI RADAR ADDED

• GCI Ground Control Intercept
• 500MHz 600MHz GCI Radar introduced in 1942
• Peak Power 50kW PW 4µs Rep-Rate 500pps
• Antenna beam width 4.50 Hor. And 7.50 Vert.
• On 200 tower detect bombers flying 500 at
  120miles

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IDENTIFICATION FRIEND OF FOE IFF (Secondary
Radar)

• PASSIVE REFLECTOR
• MARK I
• MARK I I
• MARK I I I
• MARK X

THIS SLIDE IN WORK
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BASIC RADAR TYPES
CW DOPPLER RADAR PULSED
RADAR PULSE DOPPLER RADAR
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CW DOPPLER RADAR
CW MICROWAVE
TRANSMITTER (3cm 10GHz) Compares Transmitted
Freq to reflected signal frequency from moving
objects to get Doppler shift frequency. Radar
sees only moving objects
Aircraft GCA operations. Approaching aircraft
speed determined from Doppler shift Road
Traffic Police Radar. Traffic speed determined
from Doppler shift Meteorology Sees moving
cloud masses etc.
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PULSED RADAR
PROVIDES Range - Azimuth- Elevation
Information USED FOR

• Surveillance Radar (Surface and air search)
  
• Precision Tracking Radar. Provides accurate
  Az El and Range information for
• a. Ground Control Approach GCA
• b. Military Fire Control and Gun Laying
  Radars
• Satellite Tracking Radar
  (Sat. have Transponders)

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PULSED RADAR SYSTEM

BASIC PULSED RADAR SYSTEM
Timer is sometimes regarded as a Synchronizer
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PULSED RADAR DISPLAYS
PPI PLAN POSITION INDICATOR

N
W
E
S

• PPI Scope Most popular display
• Provide maplike display in Azimuth and Range
• Polar coordinates Range centre outward
  Azimuth 0 to 3600

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US NAVY SC RADAR CONSOLE
Probably USN Radar Operators School
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REPORTING RADAR SIGNAL STRENGTH
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PULSED RADAR TRANSMITTER
RADAR TRANSMITTER (MAGNETRON)
PFN charges up to 12kV (dc resonance Choke L and
PFN C) Energy stored in PFN ½ V2C In this case
2 Joules. Thyratron discharges PFN in 2µs
which is stepped up to 27kV pulse 2 Joules of
energy used in 2µs represents 1.0MW pk pwr input
to Maggy With pulse rate 400pps, Duty Cycle
2/2500. Average pwr. 800W
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PULSED RADAR TRANSMITTER COMPONENTS
X BAND MAGNETRON (2J36)
HYDROGEN THYRATRON VX2511

VX2511 Pk I 350A Ave. I
350mA Max V 20kV Hold off Voltage
Pk I 12A Pk V 14kV Pk Pwr 17kW Freq. 9.1GHz
Used with 500kW Radars
L-Band Magnetron (5J26) tunable
Pk I 35A Pk V 27kV Pk Pwr
900kW Freq. 1.25GHz Z 800

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PULSE DOPPLER RADARS
DISTINGUISHES BETWEEN FIXED MOVING TARGETS
Surveillance Radars (Surface and air search)
Precision Tracking Radars Relies heavily on
digital signal processing (dsp)
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PULSE DOPPLER RADARS
SIMPLIFIED WEATHER RADAR SYSTEM

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MOVING TARGET INDICATOR (MTI)
STALO Stable Local Oscillator
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MILITARY RADARS
BMEWS Radar Antenna
US Navy 10cm Radar Surface Search SG-1b
Navy Destroyer Escort Mast
USN Fire Control Radars
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US ARMY WW2 RADARS
AN/TPS-1B Range Azimuth Air Search
Radar Developed by Bell Telephone Labs
Produced
by the Western Electric Operated by crew of two

Detects
bombers alt 10k at 120 nm
AN/TPS-10A Height Finder Developed by MIT's
Radiation Lab Produced by Zenith
Operated by crew of 2
Detected bombers alt. 10k at 60 nm
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MILITARY RADAR STATION

L Band Search Radar Type
TPS-1B Freq. 1.2
1.3GHz Power output 500kW
Range 120nm Pulse
width 2µs RAF service
Type 60
X-Band Height Finder Type AN/TPS-10D.Freq
9230 - 9404 MHz.Power output 250kW
Range 60/120 miles. Pulse width
.5 2µsRAF service Type 61 Mk2
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GCA RADAR (Ground Control
Approach)
Gilfillan Freq 9,000
- 9,160 MHz Pulse Rep. Freq. (PRF) 1,500
Hz Pulse-width 0.18 to 0.6µs Peak Power 150
kW Displayed Range 40 nmi
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MILITARY HEIGTH FINDER
Military AN/FPS-6 Height Finder Frequency2600 -
2900 MHz (PRF)300 - 405Hz Pulse-width
(PW)2.0µs Peak Power2.0MW Displayed
Range300nm Range Resolution 1000ft  beamwidth 
3.2 degrees Az 0.9 El
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AIRPORT RADAR

Frequency 10GHz Antenna Rotates at 60 RPM
ASDE (Airport Surface Detection Equipment Scans
Airport Surface to Locate Vehicles and Aircraft
Limitation due to RF Multipath and Target ID
problems.
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AIRPORT RADAR

Digital Airport Surveillance Radar Primary Radar
Frequency 2.7 2.9GHz Peak Power
25kW Secondary Radar (IFF) Top Array Interrogator
Frequency 1030MHz Aircraft Transponder Freq.
1090MHz
Detects Aircraft and Weather Conditions in
Airport Vicinity Detection Range out to 60 Miles
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US NAVY RADAR
US Navy Air Search Radar SPS-49A (MID
1990s) Frequency 850 942MHz Antenna Size 8 X
24 ft. Stabilized in Pitch and Roll Beam width
3.30 Az 110 El Parabolic CSC2 Rotation Rate 6
or 12 rpm Peak Power 360kW



Development began in the 1970s by The US Naval
Research Lab Latest Version Determines radial
speed of each Target Uses Unique Digital Signal
Processing Developed by the NRL
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POLICE RADAR

K Band Speed Gun Range 3500 feet Locks on
Target 3 Digit MPH or kmH Display DECATUR 1250
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FLAT ARRAY ANTENNAS
Used in MIG29 Zhuk-ME radar Flat Slotted Array
Antenna Requires Mechanical Steering
Used in MIG29M2 NIIP BARS 29 Radar Phased Array
Electronic Steering Scans and Tracks Multiple
Targets Considerable Losses in Phase Scanning
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ACTIVE ELECTRONIC STEERED ARRAY
Array APG-81 AESA (X-Band) Picture Shows Grumman
Test Bed 2000 TR Modules (2,000 each) Total cost
of Antenna 2,000,000
AN/APG 79 AESA Radar Fitted on USN F/A-18E/F
Super-Hornet
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Thank you for viewing my Radar
Presentation I hope you found it informative
and enjoyableChuck Hobson G0MDK

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