The effect of ALS and ILS localizer on the MLS azimuth phased array antenna

As a radiating system operating in airports having hangers, buildings, the approach light system (ALS), and the Instrument Landing System (ILS), the MLS (Microwave Landing System) azimuth phased-array antenna will be subject to unwanted reflections (multipath) from these obstacles. It is important to determine these propagation errors as they are essential for siting the MLS antennas with the collocated ILS system and ALS light lanes. The scattering problem is formulated and solved, and the MLS guidance error is determined. In addition, the propagation error components of the path following error (PFE) are obtained and analyzed. The peak MLS guidance error and the PFE are functions of the ALS or ILS structure and their distances from the MLS azimuth antenna phased array. It is concluded that in order to keep these errors within the acceptable tolerances care must be taken in siting MLS phased-array with respect to the existing ILS localizer.<>