The development of centimetre AI

The system of interception devised to observe, engage and destroy enemy night bombers is known as ground-controlled interception (GCI). The aircraft involved are fitted with an airborne radar for airborne interception (AI) to help them in intercepting the enemy aircraft. The early Marks of AI used a 1.5 m carrier wavelength and had some problems. The early AI radar sets had a very limited range (less than the altitude of the fighter) and were susceptible to jamming by the enemy. This problem led to the development of AI radar sets operating on shorter centimetre wavelengths (S-, X- and K-bands) which had a much greater range and were much less susceptible to jamming by the enemy. The paper describes centimetre AI, and the theory of the system is given. An analysis and discussion of the operational results is also given.