India’s Ministry of Defence is advancing its Surface Wave Over-the-Horizon (SW-OTH) Radar project into the trial phase, marking a major milestone in indigenous long-range maritime surveillance technology.

The system employs high-frequency (HF) surface-wave propagation, allowing radar signals to bend and travel along the curvature of the sea, thereby detecting vessels far beyond the line-of-sight limitations of conventional coastal radars.

The current configuration under development uses a bi-static architecture, positioning the transmitter and receiver at separate coastal sites. This design enhances operational flexibility by minimizing mutual interference, reducing system vulnerability, and enabling optimally oriented geometry for wide coastal and oceanic coverage. It also allows advanced clutter suppression algorithms to isolate genuine maritime targets from sea-state reflections and other environmental noise.

Subsystem development has been completed, encompassing transmitter chains, receiver front-ends, signal processing units, and digital beamforming modules. Preparations for large-scale antenna installation are now in progress, with integration and calibration activities planned to follow. These steps will pave the way for comprehensive sea-trial campaigns to validate detection ranges, target-tracking stability, and performance across varying sea and atmospheric conditions.

Once operational, the indigenous SW-OTH radar will form a cornerstone of India’s maritime domain awareness grid, covering vital sea lanes, chokepoints, and exclusive economic zones (EEZ). It will provide persistent tracking data to cue naval aviation assets, surveillance drones, coastal missile batteries, and surface combatants, ensuring layered coastal defence and early warning capabilities.

Beyond its operational impact, the program strengthens India’s strategic autonomy in radar technology, contributing directly to self-reliance goals under Atmanirbhar Bharat. By establishing a homegrown ecosystem for HF radar design, fabrication, and integration, the project reduces dependence on imported over-the-horizon sensors and enhances the nation’s capacity for network-centric maritime operations within an indigenous command-and-control framework.

IDN (With Agency Inputs)