Stealth technology basics UPSC Prelims PYQ 2026

Which of the following statements with regard to stealth technology is/are correct?

Stealth objects have a very small radar cross-section and are coated with Radar Absorbing Material.
Stealth objects can be detected using specific frequencies.
Stealth objects are coated with metamaterials to increase the scattering of electromagnetic radiation.

Statement 1 is correct

Stealth objects are designed to have a very small Radar Cross-Section (RCS) so that they reflect minimal radar signals back to the radar receiver. They are also coated with Radar Absorbing Materials (RAM) that absorb electromagnetic waves and reduce radar reflection.

Statement 2 is correct

Stealth technology is not completely invisible to radar. Certain radar frequencies, especially low-frequency radars such as VHF and UHF bands, may detect stealth objects because stealth shaping and coatings are generally optimised against higher-frequency radar bands.

Statement 3 is incorrect

Metamaterials are generally researched and used to reduce or manipulate electromagnetic wave reflection and scattering, not to increase scattering. The objective of stealth technology is to minimise detectability by reducing the reflection of radar signals.

Metamaterials are artificially engineered materials designed to exhibit properties not found in naturally occurring materials, especially in their interaction with electromagnetic waves. Their properties depend more on their structure (arrangement of unit cells) than on their chemical composition. They can manipulate electromagnetic waves in unusual ways.
Properties of Metamaterials:
- Negative refractive index: It allows electromagnetic waves to bend in unconventional ways not seen in natural materials.
- Wave control capability: It enables precise manipulation of light, sound, or other waves.
- Structural dependence: It ensures that properties arise from engineered structure rather than composition.
- Customisability: It allows the design of materials for specific advanced technological applications