Q. Which of the following statements with regard to stealth technology is/are correct?
I. Stealth objects have a very small radar cross-section and are coated with Radar Absorbing Material.
II. Stealth objects can be detected using specific frequencies.
III. Stealth objects are coated with metamaterials to increase the scattering of electromagnetic radiation.
Select the answer using the code given below:
1. (a) 1 only
2. (b) 2 and 3 only
3. (c) 1 and 2 only
4. (d) 1, 2 and 3

Answer : C

Explanation:

Statement 1 is correct: Stealth technology is specifically aimed at reducing the Radar Cross Section (RCS) of an aircraft, and the use of radar-absorbing materials (RAM) is a common technique to achieve this.
Statement 2 is correct: RAMs cannot absorb the whole spectrum of radar, but absorption can be made possible in some particular frequency ranges through proper tuning of the morphology and composition of the materials. This means stealth objects remain detectable using specific frequencies at which the RAM is less effective.
Statement 3 is not correct: Metamaterials used in stealth technology are designed to reduce the scattering and reflection of radar waves from surfaces of objects, not increase it.

Sources:

https://taylorandfrancis.com/knowledge/Engineering_and_technology/Military_engineering/Stealth_technology/

https://www.sciencedirect.com/topics/materials-science/radar-absorbing-material

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5532238/