Why can active radar-guided missiles be jammed or fooled by decoys?

Active radar-guided missiles are vulnerable to jamming and decoys because they rely on self-contained radar systems to track targets via emitted signals. This reliance on active emissions creates specific weaknesses that can be exploited through electronic warfare:1

• Noise Jamming: Hostile systems can flood the missile's receiver with noise, increasing the signal interference and degrading its ability to detect the actual target.2
• False Target Generation: Jammers can introduce deceptive signals into the receiver, tricking the missile into identifying the interference as a legitimate target.2
• Chaff: By releasing large quantities of tiny metallic strips, an aircraft can create a cloud that generates strong radar echoes, masking the real target or creating multiple false targets to confuse the missile's guidance.23
• Decoys: These are objects designed to mimic the radar signature of a real target. By presenting several potential targets, decoys force the missile to distinguish between the actual threat and the deceptive signal, often causing it to lose lock or track the wrong object.23

Because the missile depends on these emissions to compute its intercept trajectory, any method that obscures or mimics the reflected energy effectively compromises its guidance.14