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 :

Option C is the correct answer.

Statement 1 is correct: Stealth technology, or Low Observable Technology, aims to render military vehicles virtually invisible to enemy radar. This is fundamentally achieved by minimizing the object's Radar Cross Section (RCS). Engineers accomplish this through specialized geometric shaping—which deflects radar waves away from the receiver—and by coating the object with Radar Absorbing Materials (RAM). RAM typically contains carbon-based composites or magnetic ferrites that absorb incident electromagnetic energy and dissipate it as heat, drastically reducing the reflected radar signal.

Statement 2 is correct: Stealth aircraft are not perfectly invisible; their geometric shaping is primarily optimized against high-frequency radar bands (such as the X-band) used for weapons targeting and fire control. However, stealth objects can often be detected using specific low-frequency radars operating in the VHF and UHF bands. The longer wavelengths of these low-frequency radars interact differently with the aircraft's structure, causing resonance scattering. This effectively bypasses the geometric stealth features designed for shorter wavelengths, allowing early-warning detection.

Statement 3 is incorrect: While metamaterials—artificially engineered sub-wavelength structures—are increasingly researched for advanced stealth applications, their purpose is to decrease or suppress electromagnetic scattering, not increase it. Metamaterials can be designed with a negative refractive index to bend electromagnetic waves around an object (creating a "cloaking" effect) or to actively cancel out scattered waves via destructive interference. Increasing the scattering of radiation would raise the object's RCS, defeating the entire purpose of stealth by making it highly visible to enemy sensors.

Takeaway: Stealth relies on minimizing radar returns through deflective shaping, RAM, and metamaterials. However, it remains a frequency-dependent compromise, leaving assets vulnerable to specific low-frequency radar detection.