by Girish Linganna

The Defence Metallurgical Research Laboratory (DMRL) has made a noteworthy achievement in creating homegrown fused silica Radomes for missiles. Radomes are essential enclosures that safeguard radar antennas and greatly influence the effectiveness of missiles.

Fused silica is the ideal material for radomes because of its exceptional electromagnetic and mechanical properties, along with its ability to withstand sudden temperature changes. The significant breakthrough achieved by the DMRL involves the development of a cost-effective and efficient method to produce Radomes using indigenous raw materials.

By effectively mastering cold isostatic pressing (CIP) technology, the laboratory can now produce these crucial components with high success rates and the desired properties. CIP is a technique that involves applying high pressure from all directions to compress powdered materials evenly. This process helps in shaping the material and creating a dense, uniform structure with improved strength and properties.

The CIP technology utilizes high pressure to compress powdered fused silica, shaping it according to requirements. Through a process called sintering, the material is then transformed into a strong and compact structure.

DMRL’s research was aimed at optimizing various factors, such as powder characteristics, binders, sintering reagents and process parameters. This was done to achieve in the final radome product the desired microstructure and ‘amorphous’ structure, which refers to a material that lacks a defined, ordered arrangement of atoms. It appears more like a random, disordered solid, which can provide favourable properties, such as transparency and improved mechanical strength.

The radomes produced through CIP-sintering of silica demonstrate an optimal combination of density, electromagnetic properties and mechanical strength, which make them well-suited for challenging missile purposes.

The DMRL has filed for a patent for the CIP technology it used to produce silica Radomes. The Radomes have also undergone successful integration with RF-seekers and have been thoroughly tested to assess their performance.

These tests have shown their compatibility and effectiveness. This accomplishment signifies a major stride towards self-sufficiency in missile technology and reinforces India’s defence capabilities.

Role of Radomes: Shielding Antennas

A Radome is a cover that protects radar systems or antennas. Made from special materials, it ensures that radar signals can pass through with minimal interference. Radomes guard antennas from bad weather and can also conceal them from view.

When placed at the front of a missile, a Radome must be tough enough to protect the sensitive RF antenna from air and environmental pressures. It also has to withstand the aerodynamic forces and heat generated during flight, while allowing radio waves to pass through effortlessly.

Missile Radome Materials: Key Properties

For advanced missile Radome designs, the materials should have the following properties:

High Melting Point: This ensures the material can withstand extreme heat without melting. It is crucial for maintaining the integrity of the Radome during high-speed flight.

 

Strong Tensile Strength: This property allows the material to endure significant stress without breaking, making the Radome structurally durable.

 

High Fracture Toughness: This means the material can resist cracking and breaking even under impact. It helps the Radome survive harsh conditions, such as rain and dust collisions.

 

Low Coefficient of Thermal Expansion (CTE): This reduces the extent by which the material expands or contracts with temperature changes. A low CTE prevents thermal stress that caused structural failure to the Radome.

 

Stable, Low Dielectric Constant At Radio Frequencies: This ensures that the material allows radio waves to pass through with minimal interference. It is vital so that the radar system can perform effectively

 

Resistance To Erosion: This property helps prevent damage from environmental factors, such as rain and dust. It prolongs the lifespan and reliability of the Radome in rough conditions

The author of this article is a Defence, Aerospace & Political Analyst based in Bangalore