A Telescope of Smart Design
The Giant Metrewave Radio Telescope (GMRT) is an array of thirty fully steerable parabolic dishes, each 45 metres in diameter. The facility is located about 80 km north of Pune, India. The antennas are arranged in a 'Y' configuration, with twelve dishes forming a compact central array about 1-by-1 kilometer in size, and the remaining eighteen spread out along three 14-kilometer-long arms. This layout gives the telescope a total baseline distance of up to 25 kilometers, allowing for both high-resolution imaging of small objects and the sensitivity to detect large, diffuse structures.
An important innovation in the GMRT's construction was the 'SMART' concept, which stands for Stretch Mesh Attached to Rope Trusses. Instead of a conventional heavy backup structure, the dish surface is made of a lightweight stainless steel wire mesh held in shape by a series of rope trusses. This design significantly reduced the weight and cost of the antennas, making it possible to build such a large array economically. The total collecting area is nearly 30,000 square meters. The telescope operates at several frequency bands between 150 and 1500 MHz, specializing in the metre-wavelength part of the radio spectrum.