Prime Minister Narendra Modi with his Japanese counterpart Sanae Takaichi (L) in Delhi. (Photo: MEA)
New Delhi: India and Japan on Thursday formally inked an agreement for the joint development of the Unified Complex Radio Antenna – or UNICORN – mast, a sophisticated integrated communication system. Expected to sharpen the stealth profile of Indian Navy warships, the signing of agreement marks the first instance of the two countries co-developing and co-producing a piece of military hardware.
The two countries had signed memorandum of implementation (MoI) at Tokyo on November 15, 2024, at a ceremony held at the Indian embassy.
The MoI builds on the 2015 bilateral agreement on the transfer of defence equipment and technology between the two countries, but this is the first project under that framework to move beyond an exchange of technology and into genuine co-development.
For Tokyo, long cautious about exporting military systems, it represents a notable shift; for New Delhi, it offers a route into a class of naval technology it has not built indigenously so far.
Addressing the mediapersons along with his Japanese counterpart Sanae Takaichi, Prime Minister Narendra Modi said that the two nations will begin work towards joint development of defence technologies that help boost regional peace and maritime security.
“In the defence sector, we have signed an agreement today on the first co-development project between India and Japan. This project--involving the Naval Radio Antenna ‘UNICORN’ - will open a new chapter in our defence technology partnership. We will now jointly develop defence technologies that strengthen regional peace, maritime security, and the rules-based order,” Modi said.
What UNICORN does?
Conventional warships typically carry several exposed antennas – for radar, communications and electronic warfare – bolted onto a mast. Each of these surfaces adds to a ship’s radar cross-section, making it easier for an adversary to detect.
UNICORN does away with that arrangement by consolidating multiple antennas into a single enclosed radome mounted on one mast, cutting down the number of reflective surfaces a hostile radar can pick up.
Developed jointly by three Japanese firms – NEC Corporation, Sanwa Kogyo and the Yokohama Rubber Company – the system is already in service aboard Japan’s Mogami-class frigates. Its design stacks the antennas vertically inside a bar-shaped dome, moving components such as the tactical air navigation antenna from an exposed position at the top of the mast to a more sheltered spot lower down.
Industry estimates suggest the configuration can cut a ship’s radar cross-section by as much as half compared with a conventional mast arrangement.
A lightning diverter strip runs across the mast's surface as a safety measure, given the exposure of ships at sea to lightning strikes.
Beyond stealth, the system is also designed to reduce mutual interference between closely packed antennas, improve the range at which external radio signals can be detected, and simplify installation and maintenance – a consideration that matters over a warship's multi-decade service life.
The idea had been on the Indian Navy’s wish list for some years, alongside Japan’s ShinMaywa US-2 amphibian aircraft, another long-discussed but unresolved acquisition.
The UNICORN mast came up formally during the India-Japan 2+2 ministerial dialogue in August 2024, when the defence minister, Rajnath Singh, and the external affairs minister, S Jaishankar, discussed the technology with their Japanese counterparts.
On the Indian side, state-run Bharat Electronics Limited (BEL) will lead the development work, drawing on its experience with the Advanced Composite Communication System currently fitted on Indian Navy ships, while Japanese companies contribute materials expertise and antenna design know-how developed for the Mogami-class programme.
Strategic context
The pact fits into a broader pattern of India and Japan deepening defence-industrial ties as both countries watch China’s naval expansion in the Indo-Pacific with growing concern. Officials on both sides have also flagged further areas for collaboration, including underwater surveillance systems, unmanned platforms, ship maintenance, and extending defence support to third countries in the region.
