Why in the news?

  • With the procurement of a range of advanced air defence (AD) radars, the Indian Army has begun the process of plugging gaps in its air defence network along the northern and western borders.

Radar Technology

  • What is it?:
    • Radar stands for Radio Detection and Ranging.
    • It is an electromagnetic system used for detecting, locating, tracking, and recognizing objects at considerable distances.
  • Working Principle:
    • A transmitter generates radio waves.
    • Antenna directs these waves toward the target.
    • Target reflects a portion of the wave energy (echo).
    • The receiver captures the echo and processes it to determine range, velocity, distance.
  • Components:
    • Transmitter: Produces radio frequency pulses.
    • Antenna: Radiates and collects electromagnetic energy.
    • Duplexer: Switches antenna between transmitter and receiver.
    • Receiver: Amplifies and processes returned signals.
    • Display/Processor: Shows target info (range, speed, azimuth, elevation).
  • Types:
    • Continuous Wave (CW) Radar: Measures velocity using Doppler shift.
    • Pulse Radar: Determines range by measuring time delay.
    • Primary Radar: Detects objects using reflected signals.
    • Secondary Radar: Requires a transponder on the target (used in aviation).
    • Phased Array Radar: Uses multiple antennas, electronically steered beams.
    • Synthetic Aperture Radar (SAR): High-resolution imaging (used in satellites, remote sensing).
    • Over-the-Horizon Radar: Long-distance detection by ionospheric reflection.
  • Application:
    • Defence & Security:
      • Early warning systems, missile guidance, fire control.
      • Border surveillance, anti-drone systems.
    • Civil Aviation:
      • Air Traffic Control (ATC).
      • Weather radars for flight safety.
    • Space & Remote Sensing:
      • ISRO satellites (e.g., RISAT, NISAR with NASA).
      • Terrain mapping, earth observation, disaster monitoring.
    • Weather Forecasting:
      • Doppler Weather Radars (DWR) for cyclone, monsoon tracking.
    • Maritime Navigation:
      • Collision avoidance, ship navigation, coastal monitoring.
    • Civil Uses:
      • Speed detection by traffic police.
      • Ground Penetrating Radar (GPR) for archaeology, construction.
  • Indian Initiatives:
    • INDRA Radar series (by DRDO) for air surveillance.
    • Arudhra & Ashwini Radars (3D surveillance).
    • Revathi Radar (naval applications).
    • Rohini Radar (air defence).
    • NISAR (2024 launch) – joint ISRO-NASA SAR satellite for earth monitoring.
    • IMD’s Doppler Weather Radars – for cyclone and rainfall prediction.
  • Advantages:
    • Works day & night; not dependent on sunlight.
    • Penetrates through clouds, fog, rain (all-weather).
    • Detects objects at long range.
  • Limitation:
    • Limited resolution compared to optical sensors.
    • Vulnerable to jamming & stealth technology.
    • High energy consumption and cost.