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

(a) 1 only
(b) 2 and 3 only
(c) 1 and 2 only ✓ UPSC's answer
(d) 1, 2 and 3

Why the answer is (c)

• Stealth aims to make an aircraft or ship hard to detect: faceted or blended shapes deflect radar energy away from the receiver and radar-absorbing materials (RAM) convert the rest to heat, giving a very small radar cross-section — statement 1 is correct.

• Stealth shaping is optimised against the X-band and similar high-frequency fire-control radars; longer-wavelength VHF/UHF radars, passive and bistatic radars, and infrared sensors can still detect stealth objects — statement 2 is correct.

• Statement 3 is wrong: metamaterial coatings are designed to absorb or cancel radar waves, i.e. to reduce scattering, not increase it.

• Stealth is therefore reduced detectability, not invisibility; the F-117 shot down over Serbia in 1999 by a modified long-wavelength radar is the classic example.

• Hence 1 and 2 only, option (c).

Why the other options are wrong

(a) 1 only: Statement 2 is also correct: long-wavelength and passive radars can detect stealth objects.
(b) 2 and 3 only: Statement 3 is wrong: metamaterials reduce, not increase, scattering.
(d) 1, 2 and 3: Statement 3 is wrong, so all three cannot be correct.

Asked in the GS Paper I of the UPSC Civil Services Preliminary Examination 2026, held on 24 May 2026. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.