India Japan UNICORN mast pact puts BEL at the centre of Japan's stealth antenna

The India Japan UNICORN mast agreement has crossed from intent into a working co-development project, the first time New Delhi and Tokyo have agreed to build a piece of military hardware together rather than trade one across a counter. Bharat Electronics Limited will manufacture the integrated mast in India, with Japanese firms supplying the design and the core technology.

Prime Minister Narendra Modi announced the step alongside Japanese Prime Minister Sanae Takaichi at the 16th India-Japan Annual Summit in New Delhi. "In the defence sector, we have signed an agreement today on the first co-development project between India and Japan," Modi told reporters at the joint press statement, calling the Naval Radio Antenna UNICORN project a new chapter in the two countries' defence technology partnership.

What the two governments signed

According to Japan's Ministry of Foreign Affairs, the inaugural project under the arrangement covers the development and licensed production of the UNICORN, short for Unified Complex Radio Antenna, a shipborne communications mast built by Japan's NEC Corporation. Japan provides the design and the core technologies. India takes on system integration, localisation and production under the Make in India framework.

This is not a purchase dressed up as partnership. Until now, defence cooperation between the two sides ran through joint exercises and staff talks. The India Japan UNICORN mast deal is the first project to move past a technology exchange and into genuine co-development, and it sits on top of the 2015 bilateral agreement on the transfer of defence equipment and technology. The two governments had signed the memorandum of implementation in Tokyo in November 2024, clearing the path to what was announced this month.

Why BEL sits at the centre of the India Japan UNICORN mast build

Bharat Electronics Limited will lead the manufacturing and integration work at home, drawing on the years it has spent fitting communication systems onto Indian warships. Although NEC developed the original mast, India intends to fit its own sensors and antennas into the structure before it goes to sea. That matters. A licensed build carrying only Japanese internals would leave the Navy tied to a foreign supply chain for every future upgrade, and an Indian sensor fit does not.

The work also feeds a wider push to build more of the Navy's kit at home, from radios to marine gas turbine generators for frontline ships. The integrated mast is expected to replace the communication and sensor masts used across the fleet, phased in over time rather than swapped overnight. India had chased the technology for years before the deal firmed up.

What sits inside the mast

UNICORN, also known as NORA-50, folds a warship's scattered antenna farm into one enclosed structure. Inside are an omnidirectional surveillance radar antenna, electronic support measures antennas, Wi-Fi and Link 16 antennas, UHF transmit and receive antennas, an identification friend-or-foe system, VHF and UHF communication antennas, a tactical navigation system and a lightning conductor. Consolidating all of that into a single mast cuts the number of aerials bolted onto a ship's superstructure.

How it changes a warship's signature

Fewer exposed antennas mean a smaller radar cross-section. A conventional superstructure bristling with separate aerials throws back a large radar return, which lets hostile sensors pick out and track the ship at range. Pulling those emitters inside one shaped enclosure lowers that return and makes the platform harder to detect. It tidies up maintenance and frees deck space too, but stealth is the draw.

From Mogami frigates to the Indian fleet

UNICORN was developed jointly by NEC Corporation, Sampa Kogyo K.K. and The Yokohama Rubber Co., Ltd. for Japan's Mogami-class frigates. NEC, as prime contractor, handled hardware integration and the tactical navigation piece. Sampa Kogyo brought the antenna work and years of maintenance experience. Yokohama Rubber produced the frequency selective radome that lets signals pass through while holding the radar return down. Each firm carried a distinct slice of the job, and the split is roughly the one India now inherits.

The system came together across 2015 and 2016. Serial production started in 2018. The first mast went onto a Mogami-class frigate in 2019, and Japan's navy has run the type at sea since. That track record is what gave Tokyo the confidence to send the technology abroad, a deliberate loosening for a country long wary of exporting finished military kit.

For the Indian Navy, the pact opens a class of naval technology the domestic industry has not built on its own, and it lands as new stealth frigates like the soon to be commissioned INS Mahendragiri join the fleet. Officials on both sides have flagged more ground to cover together, including underwater surveillance systems, unmanned platforms and ship maintenance. For now those remain talking points, with the UNICORN mast the first item on the list to move from an agreement into a signed programme.