Correct Option
The correct option is 1 and 2 only.
[as per provisional answerkey]
Explanation
Stealth technology, also known as Low Observable (LO) technology, is a sub-discipline of military tactics and passive electronic countermeasures. It aims to make personnel, aircraft, ships, submarines, and missiles less visible or even invisible to radar, infrared, sonar, and other detection methods.
- Statement 1 is Correct: Stealth is achieved through a combination of physical shape and specialized coatings. The Radar Cross-Section (RCS) is a measure of how detectable an object is by radar. Stealth aircraft use faceted surfaces or complex curves to deflect radar waves away from the source. Additionally, they are coated with Radar Absorbing Materials (RAM), which convert incident electromagnetic energy into heat, thereby reducing the reflected signal.
- Statement 2 is Correct: No object is completely invisible to all forms of detection. While stealth aircraft are optimized against high-frequency radars (like X-band used for fire control), they can often be detected by low-frequency radars (such as L-band or VHF/UHF). These long-wavelength radars can trigger "resonance" effects where the wavelength is comparable to the size of the aircraft's structural features, making the stealth shaping less effective.
- Statement 3 is Incorrect: While metamaterials are an area of active research for future stealth applications, the statement regarding their function is scientifically inaccurate in this context. Stealth technology aims to minimize or absorb scattering towards the receiver, or redirect it away. Increasing the scattering of electromagnetic radiation would generally increase the probability of detection by multi-static radar systems or increase the overall electronic signature of the craft.
Key Takeaway:
Stealth technology relies on reducing the Radar Cross-Section (RCS) through geometric shaping and Radar Absorbing Materials (RAM), but it remains vulnerable to detection by low-frequency radar systems.