Every optical satellite has the same weakness: put a cloud in front of it, wait for nightfall, or hide under a forest canopy, and it goes blind. For a country that spends months under monsoon cloud and guards borders wrapped in dense foliage, that blindness is a strategic problem. In Kolkata, a small team led by the man who built India’s first radar eye in space is fixing it — with a radar that sees straight through clouds, darkness and leaves.
Sisir Radar is building India’s first privately developed L-band synthetic aperture radar (SAR) satellite, a spacecraft designed, engineered and built in India that will deliver high-resolution, all-weather imagery for national security, disaster response, agriculture and climate resilience.
The man who gave India its first radar eye
Sisir Radar was founded by Dr Tapan Misra, who spent nearly four decades at the Indian Space Research Organisation, where he served as director of the Space Applications Centre and led the development of India’s RISAT radar imaging satellites. He is joined by chief executive Soumya Misra and chief technology officer Urmi Bhambhani Misra, and the company works out of Newtown, Kolkata.
That lineage matters. Radar imaging is not a technology you pick up from a textbook — it is a discipline of waveforms, antennas and signal processing refined over missions. Sisir Radar’s bet is that this deep, mission-hardened expertise, carried into a startup, can give India a sovereign radar capability that no longer depends on anyone else’s satellites.
Why L-band, and why it is hard
Most private SAR companies around the world work in X-band, a higher frequency that delivers sharp images but cannot see through vegetation or into the ground. Sisir Radar chose the harder path: L-band and P-band, longer wavelengths that penetrate clouds, rain, smoke and foliage, and even probe shallow ground.
As Misra puts it, India’s geographical nuances demand the ability to see not just through clouds but through vegetation, for military and civilian applications alike — and at lower frequencies, getting high resolution is conventionally challenging. Cracking that challenge is the company’s core achievement: the company says its L-band SAR delivers 0.75-metre resolution and its P-band SAR 2.5-metre resolution, which it describes as 10 times better than prevailing global standards in these bands.
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The payoff is a radar that keeps watching when everything else stops: borders in the monsoon, forests hiding illegal activity, flood zones under cloud, and tunnels below the ground along sensitive frontiers.
SATSAR-Alpha-LP: the satellite taking shape
The company’s flagship programme is SATSAR-Alpha-LP, a constellation of L- and P-band SAR satellites built around an unfurlable reflector antenna, optimised for size, weight and power so it can ride on a variety of satellite platforms. The company lists stripmap, spotlight, wideswath and ScanSAR imaging modes, single, dual and full polarimetry, repeat-pass interferometry, and a 300–500 km operating altitude with a 25–128 km swath in L-band.
Data from the satellites will be processed by Sisir Radar’s proprietary SAR processor, built to squeeze sub-metre resolution out of the long-wavelength returns, and served through Trinetra, the company’s software platform that turns raw radar data into readable, decision-ready intelligence.
The programme is already moving from prototype to orbit. Sisir Radar has partnered with XDLINX Space Labs to launch India’s first private L-band SAR satellite, and XDLINX is preparing a 190 kg-class satellite carrying a multi-spectral optical and SAR payload for a SpaceX Transporter mission in late 2026.
Proven first on a drone
Before going to orbit, Sisir Radar proved its radar in the air. In June 2023 the company test-flew Rabbit SAR, its software-defined drone SAR, at Sonarpur near Kolkata — a 14 kg system with six antennas that the company says delivered 1-metre resolution in L-band. Its X-band drone SAR has since reached 0.4 by 0.3 metre resolution, which the company describes as the finest of any Indian SAR system to date.
That airborne pedigree is why the company has already won two iDEX challenges to build specialised SAR satellites for the Indian Air Force, and why its radar work spans platforms from drones and aircraft to satellites.
More than one kind of seeing
Radar is the headline, but Sisir Radar’s sensing bench runs wider. Its ground-penetrating radar systems, mountable on drones, unmanned ground vehicles or handheld units, offer deep subsurface imaging for IED detection, mineral exploration, archaeological surveys and infrastructure monitoring. Its drone-based hyperspectral imaging system processes data across more than 50 spectral bands for agriculture, environmental monitoring and mineral identification.
Across all of it runs the same philosophy: build the full stack in India, from waveform design and on-board processing to ground systems and analytics, anchored in Indian intellectual property.
The backing behind the build
In December 2025, Sisir Radar raised $7 million in a Series A round led by 360 ONE Asset, with Shastra VC — its seed-round lead investor — also participating. The funding, the company says, accelerates its move from prototypes to orbital assets and expands its research and development pipeline.
Abhishek Nag, head of early-stage venture capital at 360 ONE Asset, called space-based L- and P-band SAR “core sovereignty infrastructure” for any nation serious about border security, maritime awareness and climate resilience, and described Sisir Radar as a full-stack radar company, from waveform design to analytics, backed by domestic capital.
Why this one is worth watching
India has long bought its sharpest eyes from others or waited on government missions. Sisir Radar is building a private, Indian radar eye that never blinks — through cloud, through night, through leaves and into the ground. If its L-band satellite flies as planned, India will join a very small club of nations that can watch their own territory, in any weather, with their own radar. That is a quiet capability with very loud consequences, and it is being built in Kolkata.
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