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G0MDK 1 RADAR Chuck Hobson BA BSc (hons). G0MDK 2 INTRODUCTION This presentation starts with the early beginnings of Radar in the United States and Great.

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Presentation on theme: "G0MDK 1 RADAR Chuck Hobson BA BSc (hons). G0MDK 2 INTRODUCTION This presentation starts with the early beginnings of Radar in the United States and Great."— Presentation transcript:

1 G0MDK 1 RADAR Chuck Hobson BA BSc (hons)

2 G0MDK 2 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 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.

3 G0MDK 3 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)

4 G0MDK 4 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.

5 G0MDK 5 MY BEGINNINGS US Navy Recruiting Poster 1944 S1/c Chuck Hobson Jan US Naval Destroyer Escort DE-316

6 G0MDK 6 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)

7 G0MDK 7 RADAR USERS. NOTES: PAR = Precision Approach Radar ASDE = Automated Surface Det Equipment

8 G0MDK 8 HOW RADAR CAME ABOUT IN THE U.S – 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) THE EARLY BEGINNINGS U. S. Naval Research Lab: Typical Destroyer mast

9 G0MDK 9 HOW RADAR CAME ABOUT IN BRITAIN 1933 Ionosphere sounding Experiments with HF Examined HF fading caused by aircraft Deventry Experiments Demonstrated Feasibility developed & demonstrated Pulsed Radar at Orfordness leading to construction of CH Radar – 1939 Built the CH Radar system THE EARLY BEGINNINGS Chain Home Radar Transmitter Antennas

10 G0MDK 10 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 1 st 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)

11 G0MDK 11 ARNOLD WILKINS ARNOLD WILKINS (1907 – 1985) 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** ** 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 Scientific Officer at the Radio Research Station


13 G0MDK 13 THE DEVENTRY EXPERIMENT Heyford Bomber Deventry Experiment Site RAF Long Range Bomber Prototype Flown in 1930 Speed 229km/hr (142 mph) Range 1480km (920 Miles) Ceiling 6400m (21000 ft.)

14 G0MDK 14 ORFORDNESS 1.Radar proposal by Watts and Wilkins accepted and go ahead given 2.Highly secret work started Apr at Orfordness an isolated place 3.A very austere operation 4.Test equipment 2 HF wave meters, 2 Avometers, & misc. VM & AMs 5.Tech book Radio Amateur Handbook: Wilkins & other 2 were Hams 6.Erected two 75 wooden towers for Xmtr and 4 others for Receivers 7.Transmitter problems: Flash over and pulse width Corona on ant. 8.Committee appeared on site expecting results (June 1935) 9.50 metre freq. Used. Atmospheric noise problems. 10.Echo from Valencia A/C observed at 27km 11.Committee gave glowing report to Air Ministry 12.Shifted to 22MHz (14m) atmospheric problem went away. 13.Pulse width down from 50µs to 10µs

15 G0MDK 15 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)

16 G0MDK 16 Map of Chain Home Radars

17 G0MDK 17 CHAIN HOME (CH) RADAR 1.Pulse type radar operating at 20 to 30MHz Transmitter peak power: 350kW/750kW 2.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

18 G0MDK 18 CHAIN HOME (CH) RADAR 1.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.

19 G0MDK 19 LUFTWAFFE FLYING BELOW CH RADAR BEAM 1.Chain Home Low (CHL) Radars added ( Picked up Luftwaffe flying below CH radar beams 3.Operated at 180 – 210MHz 4.Antenna broadside 32 dipole array 5.Horizontal Beam width Antenna steered on pedal crank by WAAF 7.A Scope display. PPI introduced in Antenna rotated at ~ 1 to 2 rpm

20 G0MDK 20 CHAIN HOME GCI RADAR ADDED 1.GCI = Ground Control Intercept 2.500MHz –600MHz GCI Radar introduced in Peak Power 50kW PW 4µs Rep-Rate 500pps 4.Antenna beam width ~4.5 0 Hor. And Vert. 5. On 200 tower detect bombers flying 500 at 120miles



23 G0MDK 23 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.

24 G0MDK 24 PULSED RADAR 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) PROVIDES: Range - Azimuth- Elevation Information USED FOR:

25 G0MDK 25 PULSED RADAR SYSTEM BASIC PULSED RADAR SYSTEM Timer is sometimes regarded as a Synchronizer

26 G0MDK 26 PULSED RADAR DISPLAYS PPI Scope: Most popular display Provide maplike display in Azimuth and Range Polar coordinates: Range centre outward Azimuth 0 to PPI: PLAN POSITION INDICATOR N WE S

27 G0MDK 27 US NAVY SC RADAR CONSOLE Probably USN Radar Operators School


29 G0MDK 29 PULSED RADAR TRANSMITTER RADAR TRANSMITTER (MAGNETRON) PFN charges up to 12kV (dc resonance Choke L and PFN C) Energy stored in PFN = ½ V 2 C 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 00W With pulse rate = 400pps, Duty Cycle = 2/2500. Average pwr. = 800W

30 G0MDK 30 PULSED RADAR TRANSMITTER COMPONENTS HYDROGEN THYRATRON VX2511 VX2511 Pk I 350A Ave. I 350mA Max V 20kV** ** Hold off Voltage Used with 500kW Radars X BAND MAGNETRON (2J36) Pk I 12 A Pk V 14kV Pk Pwr 17kW Freq. 9.1GHz L-Band Magnetron (5J26) tunable Pk ~ I 35A Pk V 27kV Pk Pwr ~900kW Freq.~ 1.25GHz Z = 800

31 G0MDK 31 PULSE DOPPLER RADARS DISTINGUISHES BETWEEN FIXED & MOVING TARGETS Surveillance Radars (Surface and air search) Precision Tracking Radars Relies heavily on digital signal processing (dsp)


33 G0MDK 33 MOVING TARGET INDICATOR (MTI) STALO: Stable Local Oscillator

34 G0MDK 34 MILITARY RADARS US Navy 10cm Radar Surface Search SG-1b BMEWS Radar Antenna Navy Destroyer Escort Mast USN Fire Control Radars

35 G0MDK 35 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

36 G0MDK 36 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 : MHz. Power output: 250kW Range: 60/120 miles. Pulse width :.5 & 2µs RAF service Type 61 Mk2

37 G0MDK 37 GCA RADAR (Ground Control Approach) Gilfillan Freq: 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

38 G0MDK 38 MILITARY HEIGTH FINDER Military AN/FPS-6 Height Finder Frequency: MHz (PRF): Hz Pulse-width (PW):2.0µs Peak Power:2.0MW Displayed Range:300nm Range Resolution: 1000ft beamwidth: 3.2 degrees Az 0.9 El

39 G0MDK 39 AIRPORT RADAR ASDE (Airport Surface Detection Equipment Scans Airport Surface to Locate Vehicles and Aircraft Limitation due to RF Multipath and Target ID problems. Frequency 10GHz Antenna Rotates at 60 RPM

40 G0MDK 40 AIRPORT RADAR Detects Aircraft and Weather Conditions in Airport Vicinity Detection Range out to 60 Miles 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

41 G0MDK 41 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 Az 11 0 El Parabolic CSC 2 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 ==================================================================================================

42 G0MDK 42 POLICE RADAR K Band Speed Gun Range 3500 feet Locks on Target 3 Digit MPH or kmH Display DECATUR $1250

43 G0MDK 43 FLAT ARRAY ANTENNAS Used in MIG29M2 NIIP BARS 29 Radar Phased Array Electronic Steering Scans and Tracks Multiple Targets Considerable Losses in Phase Scanning Used in MIG29 Zhuk-ME radar Flat Slotted Array Antenna Requires Mechanical Steering

44 G0MDK 44 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

45 G0MDK 45 Thank you for viewing my Radar Presentation I hope you found it informative and enjoyable Chuck Hobson G0MDK. Comments

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