How to [safely] land a plane using antennas and engineering

Abstract

Since the 1930s pilots have been able to know their relative position with respect to the runway thanks to antennas and clever engineering: the ILS (Instrumental landing system) was born. The ILS was (and still is) a robust means to drive from ground any aircraft on the correct landing path, without any knowledge of the aircraft presence or position. We will review how a 90 year old technology is still the most reliable and widespread solution to relay this information, and how its spatially-dependent modulation is achieved by means of antenna arrays in the UHF and VHF bands. We will also discuss in more detail how some of these array systems operate, with a mix of theory and practice, reviewing some of the solutions that Thales designs, installs and maintains all over the world.