Accession Number : ADA017083

Title :   The Logan MLS Multipath Experiment.

Descriptive Note : Project rept.,


Personal Author(s) : Shnidman,D. A.

Report Date : 23 SEP 1975

Pagination or Media Count : 90

Abstract : The National Plan for a Microwave Landing System (MLS) has specified a carrier frequency for the system in the vicinity of 5.1 GHz. At that frequency, no multipath data taken at a major civilian airport existed. The purpose of this experiment was to obtain such data at Logan International Airport in order to ascertain: (1) which objects are the major causes of measurable multipath reflections and their levels relative to the direct signal (M/D level), (2) whether or not the reflections from these objects can be satisfactorily simulated by the Lincoln computer model and, if so, how complicated must that model be, and (3) if the characteristics of multipath provide a significant discriminant between the Doppler and scanning beam techniques. It was found in the experiment that regions where reflections were noted could be predicted from ray optics and diffraction. No measurable reflections were noted elsewhere. For the purpose of modeling for multipath, building surfaces could be characterized as a flat plate with a reflection coefficient determined by measurement if it were a complicated surface, or by the dielectric properties of the surface material, if a simple surface. The airplane reflection model was also found to agree well with measurements. (Author)

Descriptors :   *Microwave landing systems, *Microwave transmission, *Multipath transmission, Computerized simulation, Digital computers, Doppler effect, Target discrimination, Flat plate models, Reflectors, S band, Massachusetts

Subject Categories : Terminal Flight Facilities
      Air Navigation and Guidance
      Radiofrequency Wave Propagation

Distribution Statement : APPROVED FOR PUBLIC RELEASE