Radar presentation

Seminar
Modern Academy

1. T H E R A D A R 4 1

2. Outline Introduction to radar . History . Basic Radar Principles . Components Of Radar System . Types Of Radar . Factors Effects on Radar . Stealth Technology . Advantages & dis-Advantages . Application . Conclusion .

3. INTRODUCTION RA DIO D ETECTION A ND R ANGING “R A D A R” 3

4. WORKING PROCESS OF RADAR Bats use a basic form of RADAR . They send sound waves that reflect of an object just as electric RADAR systems do.

5. HISTORY The history of RADAR starts with experiments by Heinrich Hertz in the late 19 th century. The first form of RADAR created by humans was the telemobilescope. Telemobilescope ( The first form of RADAR ) It was mainly used to detect ships to avoid collisions

6. Radar Frequency Bands

7. Principle of Operation Reflection of electromagnetic waves Measurement of running time of transmitted pulses

8. Determining Range With Pulse Radar c = 3 x 10 8 m/sec t is time to receive return divide by 2 because pulse traveled to object and back

9. Doppler Effect that the Doppler effect is the change in frequency that occurs when a source and a target are in relative motion. The Doppler affect can be used in a CW radar in order to determine velocity.

10. Doppler effect theory F d = 2V r λ F d = doppler shift V r = relative velocity of target with respect to radar.

11. A basic Radar System

12. Duplexer The duplexer is a waveguide switch It passes the transmitted high-power pulses to the antenna and the received echoes from the antenna to the receiver Duplexer switches automatically based on the timing control signal

13. Antenna System 15 Radiation from a directional source The energy is focused in a given directions This allows the energy to travel further, hence a gain, G, compared to the isotropic source

14. Antenna System Coastal Surveillance and Vessel Traffic System radars are usually fan or inverse-cosecant-squared beams fan beam pattern Inverse-cosecant-square beam pattern

15. TYPES OF RADAR RADAR PRIMARY SECONDARY CONTINIOUS WAVE PULSE MODULATE UNMODU-LATE MTI DOPPLER

16. Factors That Affect Radar Performance Signal Reception Receiver Bandwidth Pulse Shape Power Relation Beam Width Pulse Repetition Frequency Antenna Gain Radar Cross Section of Target Signal-to-noise ratio Receiver Sensitivity Pulse Compression Scan Rate Mechanical Electronic Carrier Frequency Antenna aperture

17. Material. Shape, Directivity and Orientation. Active Cancellation. Radar Absorbent Paint. Stealth Technology

18. Material Materials such as metal are strongly radar reflective and tend to produce strong signals. Wood and cloth (such as portions of planes and balloons used to be commonly made) or plastic and fibreglass are less reflective or indeed transparent to RADAR making them suitable for radomes . Even a very thin layer of metal can make an object strongly radar reflective. Submarines have extensive usage of rubber mountings to isolate and avoid mechanical noises that could reveal locations to underwater passive sonar arrays.

19. Shape, Directivity and Orientation The surfaces of the F-117A are designed to be flat and very angled. This has the effect that RADAR will be incident at a large angle (to the normal ray) that will then bounce off at a similarly high reflected angle; it is forward-scattered. The edges are sharp to prevent there being rounded surfaces. Rounded surfaces will often have some portion of the surface normal to the RADAR source. As any ray incident along the normal will reflect back along the normal this will make for a strong reflected signal. With purpose shaping , the shape of the target’s reflecting surfaces is designed such that they reflect energy away from the source.

20. Active Cancellation With active cancellation, the target generates a radar signal equal in intensity but opposite in phase to the predicted reflection of an incident radar signal . This creates destructive interference between the reflected and generated signals,resulting in reduced RCS.

21. Radar Absorbent Paint The SR-71 Blackbird and other planes were painted with a special "iron ball paint“. This consisted of small metallic-coated balls. RADAR energy is converted to heat rather than being reflected. One of the most commonly known types of RAM is iron ball paint. It contains tiny spheres coated with carbonyl iron or ferrite. Radar waves induce molecular oscillations from the alternating magnetic field in this paint, which leads to conversion of the radar energy into heat. The heat is then transferred to the aircraft and dissipated.

22. Interference Noise. Clutter. Jamming.

23. Radiation Hazards and Precaution SEA CLUTTER Sea clutter echoes are caused by reflection of the radar pulse against the sea waves. The reflection is specular and conditions for the pulse to return to the scanner are favorable near the ship. At longer ranges the beam will be deflected away from the ship. Marine radars are equipped with rejection systems to minimize the effect of sea clutter. This control is often named “Anti Clutter Sea” or “STC”.

24. Noise Signal noise is an internal source of random variations in the signal, which is generated by all electronic components. Noise typically appears as random variations superimposed on the desired echo signal received in the radar receiver. The lower the power of the desired signal, the more difficult it is to discern it from the noise (similar to trying to hear a whisper while standing near a busy road). Noise figure is a measure of the noise produced by a receiver compared to an ideal receiver, and this needs to be minimized. Noise is also generated by external sources, most importantly the natural thermal radiation of the background scene surrounding the target of interest. There will be also flicker noise due to electrons transit, but depending on 1/f, will be much lower than thermal noise when the frequency is high.

25. PPI Scope

26. Jamming Radar jamming refers to radio frequency signals originating from sources outside the radar, transmitting in the radar's frequency and thereby masking targets of interest. Jamming may be intentional, as with an electronic warfare (EW) tactic, or unintentional, as with friendly forces operating equipment that transmits using the same frequency range. Jamming is considered an active interference source, since it is initiated by elements outside the radar and in general unrelated to the radar signals.

27. ADVANTAGES OF MILITARY RADARS All-weather day and night capability. Multiple target handling and engagement capability. Short and fast reaction time between target detection and ready to fire moment. Easy to operate and hence low manning requirements and stress reduction under severe conditions . Highly mobile system, to be used in all kind of terrain Flexible weapon integration, and unlimited number of single air defence weapons can be provided with target data.

28. Time - Radar can take up to 2 seconds to lock on Radar has wide beam spread (50 ft diameter over 200 ft range ). Cannot track if deceleration is greater than one mph/second . Large targets close to radar can saturate receiver . Hand-held modulation can falsify readings. DISADVANTAGES

29. Application

30. FIELDS OF APPLICATION MILITARY REMOTE SENSING AIR TRAFFIC CONTROL LAW ENFORCEMENT AND HIGHWAY SECURITY AIRCRAFT SAFETY AND NAVIGATION SHIP SAFETY SPACE MISCELLANEOUS APPLICATIONS

31. MILITARY IMPORTANT PART OF AIR DEFENCE SYSTEM,OPERATION OF OFFENSIVE MISSILES & OTHER WEAPONS TARGET DETECTION, TARGET TRACKING & WEAPON CONTROL TRACKS THE TARGETS, DIRECTS THE WEAPON TO AN INTERCEPT AND ASSESS THE EFFECTIVENESS OF ENGAGEMENT ALSO USED IN AREA, GROUND & AIR SURVEILLANCE.

32. WEATHER OBSERVATION-T.V.REPORTING PLANETARY OBSERVATION BELOW GROUND PROBING MAPPING OF SEA ICE REMOTE SENSING

33. USED TO SAFELY CONTROL AIR TRAFFIC IN THE VICINITY OF THE AIRPORTS AND ENROUTE GROUND VEHICULAR TRAFFIC & AIRCRAFT TAXING MAPPING OF REGIONS OF RAIN IN THE VICINITY OF AIRPORTS & WEATHER AIR TRAFFIC CONTROL

34. RADAR IS FOUND ON SHIPS & BOATS FOR COLLISION AVOIDANCE & TO OBSERVE NAVIGATION, BUOYS WHEN THE VISIBILITY IS POOR SHORE BASED RADARS ARE USED FOR SURVEILLANCE OF HARBOURS & RIVER TRAFFIC SHIP SAFETY

35. CONCLUSION RADAR is used to find velocity, range and position of the object. LIDER is Advanced type of RADAR which uses visible light from LASER Technology will continue to grow, and RADAR will advance with it. Growth of RADAR technologies will be accompanied by a wider variety of applications. RADAR in the future will most likely be as common as cell phone applications are today.

36. Q/A .?