2INTRODUCTIONThis 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 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 Navy’s 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.
3INTRODUCTION (continued) I completed the test in an hour and 10 minutes and handed it back to the Chief. He asked me, “What’s the matter, can’t 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)
4INTRODUCTION (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 Navy’s 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.
5MY BEGINNINGS S1/c Chuck Hobson Jan. 1945 US Navy Recruiting Poster 1944US Naval Destroyer Escort DE-316
6WHAT IS RADAR RADAR: RAdio Detection And Ranging (American) RDF: Radio Direction Finding (British)Doover: Australian equivalent to thingamajigRadar transmits short high powered burst of RF energyRF energy travels towards aircraft at speed of lightRF illuminated aircraft re-radiates signal back to RadarRadar measures RF energy round trip time (12.3µs per nm)
7RADAR USERS.NOTES: PAR = Precision Approach Radar ASDE = Automated Surface Det Equipment
8HOW RADAR CAME ABOUT IN THE U.S. THE EARLY BEGINNINGSU. S. Naval Research Lab:1934 – 1935 experimented with Pulsed Radar1936 Demonstrated Pulse Radar mile range (Air Search Radar)1937 Installed 200MHz Radar on destroyer1938 – 1945 Installed same radar on DDE’s DD’s CA’s BB’s Carriers and various other ships (SC series Air Search Radar)Typical Destroyer mast
9HOW RADAR CAME ABOUT IN BRITAIN THE EARLY BEGINNINGS1933 Ionosphere sounding Experiments with HF1934 Examined HF fading caused by aircraft.1935 Deventry Experiments Demonstrated Feasibility1935 developed & demonstrated Pulsed Radar at Orfordness leading to construction of CH Radar1936 – 1939 Built the CH Radar systemChain Home Radar Transmitter Antennas
10Scientific Survey of Air Defence Committee THE TIZARD COMMITTEEScientific Survey of Air Defence CommitteeTizard Chairman Rector of Imperial CollegeRowe Secretary Air MinistryWimperis Member Air MinistryWatts Member Radio RS Supt.This committee’s 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)
11ARNOLD WILKINS Scientific Officer at the Radio Research Station Expert on antennas & the behaviour of radio wavesConducted Deventy experimentParticipated in pulsed radar tests at OrfordnessRRS known as Home of the Invention of RadarCredit for invention given to Sir Watson Watts**ARNOLD WILKINS (1907 – 1985)** 1933 Wilkins familiar with pulsed RF techniques Ionosphere soundingNoted flutter of VHF (60MHz) signals from nearby AircraftSubsequently mentioned this to WattsJoint Watts Wilkins memo presented to Tizard CommitteeLed to Deventry Experiment, Radar tests at Oxfordness & CH Radar
13THE DEVENTRY EXPERIMENT Heyford BomberRAF Long Range BomberPrototype Flown in 1930Speed 229km/hr (142 mph) Range 1480km (920 Miles) Ceiling 6400m (21000 ft.)Deventry Experiment Site
14ORFORDNESSRadar proposal by Watts and Wilkins accepted and go ahead givenHighly secret work started Apr at Orfordness an isolated placeA very austere operationTest equipment 2 HF wave meters, 2 Avometers, & misc. VM & AM’sTech book Radio Amateur Handbook: Wilkins & other 2 were “Hams”Erected two 75’ wooden towers for Xmtr and 4 others for ReceiversTransmitter 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 27kmCommittee gave glowing report to Air MinistryShifted to 22MHz (14m) atmospheric problem went away.Pulse width down from 50µs to 10µs
15CHAIN HOME (CH) RADARFollowing 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)
17CHAIN HOME (CH) RADARPulse type radar operating at 20 to 30MHz Transmitter peak power: 350kW/750kWLarge HF antennas strung up between two 100 metre high steel towers for transmittingTransmitted very broad beam to illuminate all aircraft in search areaReceiving antennas (not shown) provided azimuth and elevation data
18Second set of cross type antennas on 60m high towers for receiving. CHAIN HOME (CH) RADARSecond set of cross type antennas on 60m high towers for receiving.Cross Dipoles mounted on wooden towersAntennas were used to DF on reflections from aircraftDF was achieved by phasing cross dipoles with goniometersBeam was shifted left, right, up and down with goniometers calibrated in az. and el. Mechanical calculators converted elevation angle to altitude.
19LUFTWAFFE FLYING BELOW CH RADAR BEAM Chain Home Low (CHL) Radars added (Picked up Luftwaffe flying below CH radar beamsOperated at 180 – 210MHzAntenna broadside 32 dipole arrayHorizontal Beam width 200Antenna steered on pedal crank by WAAF“A” Scope display. PPI introduced in 1940Antenna rotated at ~ 1 to 2 rpm
20CHAIN HOME GCI RADAR ADDED GCI = Ground Control Intercept500MHz –600MHz GCI Radar introduced in 1942Peak Power 50kW PW 4µs Rep-Rate 500ppsAntenna beam width ~4.50 Hor. And Vert.On 200’ tower detect bombers flying 500’ at 120miles
21IDENTIFICATION FRIEND OF FOE IFF (Secondary Radar) PASSIVE REFLECTORMARK IMARK I IMARK I I IMARK XTHIS SLIDE IN WORK
23CW MICROWAVE TRANSMITTER (3cm 10GHz) CW DOPPLER RADARCW MICROWAVE TRANSMITTER (3cm 10GHz)Compares Transmitted Freq to reflected signal frequency from moving objects to get Doppler shift frequency. Radar sees only moving objectsAircraft: GCA operations. Approaching aircraft speed determined from Doppler shiftRoad Traffic: Police Radar. Traffic speed determined from Doppler shiftMeteorology: Sees moving cloud masses etc.
24PULSED 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 GCAb. Military Fire Control and Gun Laying RadarsSatellite Tracking Radar (Sat. have Transponders)
25BASIC PULSED RADAR SYSTEM Timer is sometimes regarded as a Synchronizer
26PPI: PLAN POSITION INDICATOR PULSED RADAR DISPLAYSPPI: PLAN POSITION INDICATORNWESPPI Scope: Most popular displayProvide maplike display in Azimuth and RangePolar coordinates: Range centre outward Azimuth 0 to 3600
27US NAVY SC RADAR CONSOLE Probably USN Radar Operator’s School
29PULSED 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 pulse2 Joules of energy used in 2µs represents 1.0MW pk pwr input to MaggyWith pulse rate = 400pps, Duty Cycle = 2/ Average pwr. = 800W
30PULSED RADAR TRANSMITTER COMPONENTS X BAND MAGNETRON (2J36)HYDROGEN THYRATRON VX2511VX Pk I 350A Ave. I 350mA Max V 20kV**** Hold off VoltagePk I 12A Pk V 14kV Pk Pwr 17kW Freq. 9.1GHzUsed with 500kW RadarsL-Band Magnetron (5J26) tunablePk ~ I 35A Pk V 27kV Pk Pwr ~900kW Freq.~ 1.25GHz Z = 800
31Surveillance Radars (Surface and air search) Precision Tracking Radars PULSE DOPPLER RADARSDISTINGUISHES BETWEEN FIXED & MOVING TARGETSSurveillance Radars (Surface and air search)Precision Tracking RadarsRelies heavily on digital signal processing (dsp)
32PULSE DOPPLER RADARSSIMPLIFIED WEATHER RADAR SYSTEM
33MOVING TARGET INDICATOR (MTI) STALO: Stable Local Oscillator
34MILITARY RADARS BMEWS Radar Antenna US Navy 10cm Radar Surface Search SG-1bNavy Destroyer Escort MastUSN Fire Control Radars
35US ARMY WW2 RADARSAN/TPS-1B Range & AzimuthAir Search RadarDeveloped by Bell Telephone Labs Produced by the Western Electric Operated by crew of two Detects bombers alt 10k at 120 nmAN/TPS-10A Height FinderDeveloped by MIT's Radiation Lab Produced by Zenith Operated by crew of Detected bombers alt. 10k at 60 nm
36MILITARY RADAR STATION X-Band Height Finder Type: AN/TPS-10D. Freq : MHz. Power output: 250kW Range: 60/120 miles Pulse width : .5 & 2µs RAF service Type 61 Mk2L Band Search Radar Type: TPS-1B Freq. 1.2 – 1.3GHz Power output 500kW Range: 120nm Pulse width: 2µs RAF service Type 60
38MILITARY HEIGTH FINDER Military AN/FPS-6 Height FinderFrequency: MHz(PRF): HzPulse-width (PW):2.0µsPeak Power:2.0MWDisplayed Range:300nmRange Resolution: 1000ft beamwidth: 3.2 degrees Az 0.9 El
39AIRPORT RADAR Frequency 10GHz Antenna Rotates at 60 RPM ASDE (Airport Surface Detection EquipmentScans Airport Surface to Locate Vehicles and AircraftLimitation due to RF Multipath and Target ID problems.
40AIRPORT RADAR Digital Airport Surveillance Radar Primary Radar Frequency 2.7 – 2.9GHzPeak Power 25kWSecondary Radar (IFF) Top ArrayInterrogator Frequency 1030MHzAircraft Transponder Freq. 1090MHzDetects Aircraft and Weather Conditions in Airport VicinityDetection Range out to 60 Miles
41US NAVY RADAR US Navy Air Search Radar SPS-49A (MID 1990’s) Frequency 850 – 942MHzAntenna Size 8 X 24 ft.Stabilized in Pitch and RollBeam width 3.30 Az 110 ElParabolic CSC2Rotation Rate 6 or 12 rpmPeak Power 360kW==================================================================================================Development began in the 1970’s by The US Naval Research LabLatest Version Determines radial speed of each TargetUses Unique Digital Signal Processing Developed by the NRL
42POLICE RADAR K Band Speed Gun Range 3500 feet Locks on Target 3 Digit MPH or kmH DisplayDECATUR $1250
43FLAT ARRAY ANTENNAS Used in MIG29 Zhuk-ME radar Flat Slotted Array AntennaRequires Mechanical SteeringUsed in MIG29M2 NIIP BARS 29 RadarPhased Array Electronic SteeringScans and Tracks Multiple TargetsConsiderable Losses in Phase Scanning
44ACTIVE ELECTRONIC STEERED ARRAY Array APG-81 AESA (X-Band)Picture Shows Grumman Test Bed2000 TR Modules ($2,000 each)Total cost of Antenna $2,000,000AN/APG 79 AESA RadarFitted on USN F/A-18E/F Super-Hornet
45Thank you for viewing my Radar Presentation I hope you found it informative and enjoyable Chuck Hobson G0MDKComments