Stealth technology aims to make aircraft and ships invisible to radar detection. It works by reducing radar cross-sections through smooth shapes and radar-absorbing materials. Various radars try to detect stealth objects, such as bistatic radar using multiple transmitters, low-frequency radar, and phased array radar operating in L-band. Radars can also use infrared and sonar. Stealth radars aim to not be detected through frequency agility, noise jamming, and employing AESA which is harder to jam.

1. STEALTH RADAR
G RAM PRABU
DEVIREDDY PRAMOD REDDY
KARRI V R DINESH KUMAR REDDY

2. Introduction
What is Stealth Technology?
• Stealth – movement that is quiet and careful in order not to be seen
or heard (in general), not detectable by radar.
• Radars associated with stealth
1. Radars detecting objects in stealth mode
2. Radars operating in stealth mode

3. How is stealth achieved?
• Reduce RCS of the object by changing its shape.
• Smooth edges with flat surfaces, Round wing tips
• Radar absorbing materials (RAM)
Commonly used material – Iron Ball Paint
• Heat trails from engines reduced to prevent
IR detection
• Noise from engines reduced and travels in
subsonic speeds to prevent sonic boom.

4. Stealth Planes and Ships
US stealth copter RAH -66

5. Radars to detect Stealth objects
• Bistatic Radar: Multiple transmitters and emitters are used because energy is
scattered in many directions and needs to be captured effectively.
• Low Frequency Radar:
• uses frequency lower than 1 GHz
• Radar absorbing materials absorb frequency from
2.5 – 13 GHz with an efficiency of 95%
Advantages:
• Cost effective,
• high range
Disadvantages:
• Large size
• Doppler unambiguities

6. Low Frequency Radar - continued
• Block diagram:

7. Radars to detect Stealth objects
• Phased Array Radar operating in L-band:
• Consists hundreds or thousands of such blocks each radiating
in same phase

8. Phased Array Radar- continued
• Advantages:
Portable
Inexpensive to build in mass production
• Disadvantages:
Signal processing difficulty
Prior knowledge of range and target angle is needed

9. Radars to detect Stealth objects
• Infra Red receivers used to detect chemical and physical signatures of
exhaust gas plume particularly heat from engines.
• Exhaust plume has other characteristics that are detectable, and when
coupled with absence of heat it is certainly a stealth aircraft.
• SONAR (Sound Navigation and Ranging) is used along with these radars for
better results.
• Usually multiple types of radars are used for stealth detection.
• Signals from communication satellites and telephone towers are used by
radar receivers to detect objects (advanced transmitter-less radar).

10. Some Counter Stealth Radars

11. Radars operating in stealth mode
• Radars that are not detected by other Radars i.e., radars that cannot be jammed
are called as radars operating in stealth mode.
• What is Radar deception and jamming?
Radar jamming and deception (Electronic countermeasure) is the intentional
emission of radio frequency signals to interfere with the operation of a radar by saturating
its receiver with noise or false information.
• Types of Jamming
• Mechanical
• Electronic

12. Radar Jamming
• Mechanical Jamming: by devices which reflect radar energy back to
the radar.
• Chaff – metallic strip to reflect different frequency waves.
• Corner reflectors – multiple sided reflecting objects.
• Decoys – flying objects to deceive a radar by creating clutters.
• Electronic Jamming: Jammers radiate energy signal towards radiating
radar.
• Spot Jamming – single frequency jammer of high power used.
• Sweep Jamming – Multiple frequency & high power at different times.
• Barrage Jamming – Multiple frequencies simultaneously, but less effective.
• Base Jamming – Main radar jammed in case of multiple radars.
• Pulse Jamming – Noise pulses generated to deceive the receiver

13. DRFM Jamming
• Digital radio frequency memory is an electronic method for digitally capturing
and retransmitting RF signal.
• Properties changed are :
• Delay in transmitted pulses
• Frequency variation
• Creates a false range targets to the
radar
• Creates Doppler(velocity) errors.
• Blip Enhancement

14. Counter measures used in stealth radars
• Constantly changing the operating frequency.
• Covering the outgoing signal with random noise, makes it more
difficult for a jammer to figure out the frequency that a radar is
operating on.
• Employing an effective operator who is skilled in signal processing.
• Active electronically scanned array (AESA) radars are innately harder
to jam and can operate in Low Probability of Intercept (LPI) .
• A quantum radar system would automatically detect attempts at
deceptive jamming.

15. Active Electronically Scanned Array
• Active phased array radar
• Transmitter and receiver (transceiver) functions are composed of
numerous small solid-state transmit/receive modules (TRMs).
• Spreads the signal emissions out, across a band of
frequencies.
• Produce numerous simultaneous sub beams that
it can recognize due to different frequencies and
can track a large no. of targets.
• Multiple frequencies generated at once.

16. Active Electronically Scanned Array
• Advantages:
• Low probability of intercept.
• High jamming resistance.
• Limitation:
• The highest Field of View (FOV) for a flat phased array antenna is currently
120°.

17. References
• www.wikipedia.org
• www.defensemedianetwork.com
• www.foia.cia.gov
• www.whale.to
• www.dailymail.co.uk
• www.researchinventy.com
• www.defense-update.com
• www.army.mil
• www.marines.mil
• Books:
• Advantages of Bistatic radar
• Introduction to radar systems

18. THANK YOU