Radar Guidance
Semi-active radar guidance is widely used in surface-to-air and air-to-air missile systems. Its working principle is that the missile itself does not emit radar signals but relies on ground or airborne radar to illuminate the target. The missile is guided by receiving the radar signals reflected from the target. The advantages of this method are that the missile's head can be designed smaller and lighter, and it has strong anti-jamming capabilities. Semi-active guidance requires a radar to track and illuminate the target and a data link to provide a stable reference signal for the missile. If only one radar is used, pulse Doppler radar is commonly adopted. The missile's seeker uses narrow-band filters to track the target's reflected signals, suppressing the direct signals from the illuminator with different Doppler shifts and radar clutter signals. Since the semi-active missile's seeker is passive and uses narrow-band Doppler tracking, its anti-jamming performance is far superior to command guidance.
Active radar-guided missiles carry their own radar transmitting and receiving devices, allowing them to independently detect and track targets. The advantage of this method is the "fire-and-forget" capability, enabling the launch platform to maneuver immediately after firing the missile, avoiding enemy counterattacks. Most anti-ship missiles use active radar terminal guidance, and more air-to-air and surface-to-air systems are adopting active radar-guided seekers, eliminating the need for additional target illuminators. Due to the diameter limitation of the missile body, the antenna aperture power product is relatively small, thus limiting its range. For long-distance operations, semi-active or command guidance technologies are required for mid-course guidance.
Composite radar guidance combines the advantages of semi-active and active guidance. Typically, semi-active guidance is used in the mid-course, switching to active guidance in the terminal phase to improve missile accuracy and anti-jamming capabilities.
Electro-optical Guidance
Laser guidance includes laser beam riding and laser semi-active homing guidance. Laser beam riding guidance is suitable for short-range operations, where the missile's tail receives laser signals and flies along the center of the beam. Laser semi-active homing guidance receives the laser signals reflected from the target at the missile's front end, featuring narrow beam and pulse coding anti-jamming characteristics, suitable for longer-range attacks. Infrared-guided missiles are guided by passively receiving the target's thermal radiation, suitable for attacking aircraft, helicopters, tanks, and ships. Infrared-guided missiles usually use cooled detectors, capable of detecting the target's thermal radiation in different wavelength ranges. TV guidance uses a television camera to capture the target's image, with image processing technology for target recognition and tracking, suitable for precise strikes under visible light conditions.
Composite Guidance
Composite guidance systems combine the advantages of radar and electro-optical guidance, using multi-mode sensors for target detection and tracking. Multi-mode composite guidance systems can leverage the advantages of various sensors in different combat stages, enhancing the missile's all-weather combat capability and anti-jamming performance. In air-to-air combat, the common combination is forward-looking infrared for target detection, laser ranging, followed by launching radar or infrared-guided missiles. In ground-based air defense/anti-tank systems, radio frequency radar, infrared, and laser sensors are typically integrated to achieve high-precision target detection and tracking. The combination and application of the above precision guidance methods can significantly improve missile accuracy and operational effectiveness, meeting the modern warfare demands for efficient and precise strikes.
