ST Radar

 The GU Stratospheric-Tropospheric Radar



The Gauhati University ST Radar is an advance system with cutting edge indigenous technology in VHF band with open configuration (Antennas, Transmit/Receive Module Modules and Cables), where active phased array concept has been used. It is a coherent pulsed Doppler radar operating in the Doppler Beam Swinging (DBS) mode. It consists of 576 antenna elements arranged in a circle with square grid. Each antenna is connected with its own T/R Module to generate high quality wind data (wind speed and its direction) with high spatial and temporal resolution on continuous basis.

Guwahati is considered to be the gateway to the North-Eastern region of India which is dominated with intriguing dynamical and meteorological aspects such as wind structures, cloud morphology, monsoon troughs,  tropospheric temperature, boundary layer characteristics and different small and large scale variabilities associated with atmospheric background oscillations. So, the Gauhati University ST-Radar system will provide a deep insight into synoptic processes and mesoscale systems with high vertical and temporal resolutions over North-Eastern region. This region is also considered as a special zone to study solar terrestrial energy dynamics, meet with the flow of wind through four corridors carrying sea salt and aerosols from Bay of Bengal and China. Along with these factors, the regional orographic structure has made North-Eastern region a very rich atmospheric natural laboratory which is yet to be explored.  The forecasting and nowcasting of the atmospheric phenomena in North-Eastern region will be very helpful to various sectors viz; meteorology, agriculture, civil aviation, disaster management etc. It will be extensively utilised by the universities and research laboratories in the North-Eastern region as well as rest of the country, and will also be produced skilled manpower in the field of atmospheric research and RF technology.

Radar is an excellent and indispensable experimental tool to measure different physical parameters related to earth’s atmosphere, weather patterns, atmospheric winds, waves, turbulance, temperature pressure etc. These physical parameters are used for basic atmospheric research, weather forecasting and disaster management. To study the lower atmospheric dynamics over the North-Eastern region, a state of the art Stratosphere-Troposphere (ST) Radar has been designed  and installed at Gauhati University, Guwahati (26.10N, 91.70E, ~ 50 m above MSL) for operating at frequency of 212.5 Mhz in collaboration with SAMEER, Mumbai. The project is funded by Ministry of Electronics and Information Technology, Government of India and Government of Assam.


 Specifications of the system

  • Type of the Radar system: 576 elements Active Phased Array with T/R Modules
  • Operating frequency: 212.5 MHz
  • Bandwidth: 4MHz
  • Antenna element: Four element Yagi-Uda antenna
  • Antenna element gain: 7.9 dBi
  • Height coverage: 0.5 to 20 km
  • Range gates: 256 (programmable)
  • Mode of operation: DBS
  • Height resolution: ~ 75m to 300m (Programmable)
  • Antenna area: 572 m2 (aperture diameter 27m)
  • Effective aperture: 522 m2
  • Array beam width: ~ 3.20 nominal
  • Antenna array gain: 34.5 dBi nominal
  • Off zenith angle: 00 to 200  in steps of 10 (programmable)
  • Azimuth angle: 00 to 3600 in steps of 10 (programmable)
  • Pulse width: 0.5 to 64 μs
  • Modulation: Binary Phase Shift Keying (BPSK) coded compression
  • Code: Complimentary code/Barker code
  • Baud: 0.5 to 4 μs
  • Pulse Repetition Frequency (PRF): 250 Hz to 5 kHz
  • TRM peak power: 400 W (typical per element)
  • Total peak power: 230.4 kW
  • Duty ratio: Up to 10% (Max)
  • Peak power and effective Aperture Product (PAP): ~ 1.2 × 10 8 Wm2
  • Receiver noise figure:  3.0 dB

The GU ST-Radar is situated atop of a small hill in the Gauhati University Campus. The folllwing images show the radar from different angles. It started functioning in October, 2019.

It was conceptualised and initiated by Prof Minakshi Devi, a Professor at the Department of Physics and former Head of the Department of Physics at Gauhati University.





Biman Jyoti Medhi [In-Charge]
MSc (Gauhati) PhD (Gauhati & IIA Bangalore) Postdoctoral Fellow (ARIES Nainital)
ISM-Dust, Polarisation, Star Formation, Open Star Cluster, Atmosphere

Research Scientist

Manoj Saikia
MSc (Gauhati) PhD (Gauhati)
Atmospheric Physics, Aerosols, Green House Gas, Climate Change, Remote Sensing
Samiran Patgiri
MSc (Gauhati)
Electronics, Signal Processing, Atmospheric Physics, Remote Sensing, Earthquake Science

Scientific Officer

Alaka Medhi
MSc (Gauhati) PhD (Gauhati)
Electronics, Atmospheric Physics, System Design
Subrat Das
MSc (Gauhati) PhD (Gauhati)
Data processing, Atmospheric Study