THE LOGAN MLS MULTIPATH EXPERIMENT

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)

• Corporate Authors:

  Lincoln Laboratory

  Massachusetts Institute of Technology
  Lexington, MA  United States  02173

  Federal Aviation Administration

  Systems R&D Service, 800 Independence Avenue, SW
  Washington, DC  United States 
• Authors:
  • Shnidman, D A
• Publication Date: 1975-9-23

Media Info

• Pagination: 90 p.

Subject/Index Terms

• TRT Terms: Digital computers; Doppler effect; Microwave landing systems; Microwaves; Multipath transmission; Reflectorized materials; S band; Simulation; Structural plates; Tracking systems; Transmission techniques
• Geographic Terms: Massachusetts
• Old TRIS Terms: Flat plate models; Microwave transmission; Target discrimination
• Subject Areas: Materials;

Filing Info

• Accession Number: 00093408
• Record Type: Publication
• Source Agency: National Technical Information Service
• Report/Paper Numbers: ATC-55 Proj. Rpt., FAA-RD-75-130
• Contract Numbers: F19628-76-C-0002,, DOT-FA74WAI-461
• Files: NTIS, USDOT
• Created Date: Dec 29 1976 12:00AM