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Results of L band multipath measurements at operational United States (U.S.) airports in support of the Microwave Landing System (MLS) Precision Distance Measuring Equipment (DME/P)

July 23, 1981
  |
Project Report
Author:
James E. Evans
…
Published in:
MIT Lincoln Laboratory Report ATC-109
Topic:
L-band
R&D area:
R&D group:

Summary

This report presents the results of a short duration L band multipath measurement program at five major U.S. airports (St. Louis, Tulsa, Wright Patterson Air Force Base, Philadelphia and Washington National) and one smaller airport (Quonset, RI) to better quantify the expected multipath environment for the Microwave Landing System (MLS) Precision Distance Measuring Equipment (DME/P). Specific objectives included: (1) Measurements of the principal multipath parameters (amplitude and time delay) with realistic aircraft/ground site locations at runways which had the major DME/multipath sources (large buildings) identified in previous analytical (simulation) studies. (2) Determination of whether significant DME/P multipath sources exist which had not been considered to date and (3) Comparison of the measured results with computer simulation results obtained with simplified airport models (such as have been used for DME/P system design to date). Particular emphasis was placed on the final approach region including the flare and rollout regions since these areas correspond to the most stringent DME/P accuracy requirements and, have not been utilized operationally with the current L band DME. All of the above objectives were achieved although in some cases the experimental data in the flare/rollout region was of poor quality due to low signal to noise ratio. The spatial region and time delay of specular multipath generally correlated well with expectations based on simple ray tracing. With the exception of Washington National, no significant (multipath to direct signal ratio (M/D >110 dB) multipath was encountered in operationally relevant areas which was not predicted. The quantitative predictions of the simple airport models agreed with the experimental data, although in some cases, (especially, near threshold) the measured M/D values were considerably higher than predictions.
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Summary

This report presents the results of a short duration L band multipath measurement program at five major U.S. airports (St. Louis, Tulsa, Wright Patterson Air Force Base, Philadelphia and Washington National) and one smaller airport (Quonset, RI) to better quantify the expected multipath environment for the Microwave Landing System (MLS)...

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Results of L band multipath measurements at operational United States (U.S.) airports in support of the Microwave Landing System (MLS) Precision Distance Measuring Equipment (DME/P)

L-Band air-to-air multipath measurements

September 6, 1977
  |
Project Report
Author:
Albert R. Paradis
Published in:
MIT Lincoln Laboratory Report ATC-77
Topic:
L-band
R&D area:
R&D group:

Summary

A series of air-to-air earth-scattered L-Band multipath measurements are described and experimental results presented. During these measurements RF pulses were transmitted between two instrumented general aviation aircraft flying coaltitude, diverging paths over a variety of terrain and water surfaces. Multipath data was collected over grazing angles ranging from ~5?? to ~75??. The objectives of these measurements were the: 1. Characterization of the multipath environment in which beacon based airborne collision avoidance (BCAS) equipment would operate. 2. Investigation of the merits and limitations of various degrees of antenna diversity in the rejection of multipath.
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Summary

A series of air-to-air earth-scattered L-Band multipath measurements are described and experimental results presented. During these measurements RF pulses were transmitted between two instrumented general aviation aircraft flying coaltitude, diverging paths over a variety of terrain and water surfaces. Multipath data was collected over grazing angles ranging from ~5?? to...

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L-Band air-to-air multipath measurements

Multipath parameter computations for the MLS simulation computer program

April 8, 1976
  |
Project Report
Author:
Jack Capon
Published in:
MIT Lincoln Laboratory Report ATC-68
Topic:
L-band
R&D area:
R&D group:

Summary

A set of mathematical models and computer programs have been developed to characterize multipath propagation in an airport environment. When combined with system mathematical models, these models are intended to provide a firm technical basis for assessing the performance of candidate Microwave Landing Systems (MLS) in realistic airport environments. The two paramount issues in developing these models have been 1) validation based on actual field test data and 2) computer running time. The obstacles modeled include buildings and aircraft, as well as the ground which can cause both specular reflections and diffuse scattering. In addition, the shadowing effects due to runway humps, and aircraft, buildings approaching the line of sight between transmitter and receiver are included. Computational procedures are presented for obtaining the salient multipath parameters, i.e., relative magnitude, phase, directional angles, Doppler frequency, and time delay. Computer programs have been written for these algorithms using the Fortran programming language, with structured programming methods, such as Iftran, employed whenever possible. A presentation is given of computer validation data for the computational procedures. A comparison of these computer validation results with experimental field data demonstrates good agreement in all cases of interest. The computer running time for these computer programs is quite reasonable, e.g., it takes about five times longer than actual flight time to run a model of typical airport environment on an IBM 370 model 168.
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Summary

A set of mathematical models and computer programs have been developed to characterize multipath propagation in an airport environment. When combined with system mathematical models, these models are intended to provide a firm technical basis for assessing the performance of candidate Microwave Landing Systems (MLS) in realistic airport environments. The...

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Multipath parameter computations for the MLS simulation computer program

MLS multipath studies volume II: application of multipath model to key MLS performance issues

February 25, 1976
  |
Project Report
Author:
James E. Evans
…
Published in:
MIT Lincoln Laboratory Report ATC-63,II
Topic:
L-band
R&D area:
R&D group:

Summary

This report summarizes MLS multipath work carried out at Lincoln Laboratory from March 1974 to Sept. 30, 1975. The focus of the program is the development of realistic models for 1) the multipath in representative real world environments and 2) the multipath characteristic of candidate MLS techniques. These multipath and system models are used in a comprehensive computer simulation to predict the strengths and weaknesses of major MLS systems when subjected to representative real world environments. The report is organized into two volumes. Volume I describes the algorithms and validation of various portions of the program. In Volume II, the simulation (or selected portions thereof) is applied to key multipath related MLS issues. Mathematical models are given for the major MLS multipath sources (ground reflections, building and aircraft reflections, and shadowing by objects and humped runways), and it is shown that they agree (Doppler and scanning beam) considered in phase II of the U.S. MLS program are presented together with validation by comparison with theory and bench tests. Also presented are the results of a general study in motion averaging. The (validated) computer simulation (and portions thereof) is then applied to studying 1) the critical areas required by the TRSB system to avoid excessive reflection effects, 2) the expected TRSB performance of a specific TRSB system at Friendship International Airport (MD).
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Summary

This report summarizes MLS multipath work carried out at Lincoln Laboratory from March 1974 to Sept. 30, 1975. The focus of the program is the development of realistic models for 1) the multipath in representative real world environments and 2) the multipath characteristic of candidate MLS techniques. These multipath and...

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MLS multipath studies volume II: application of multipath model to key MLS performance issues

MLS multipath studies volume I: mathematical models and validation

February 25, 1976
  |
Project Report
Author:
James E. Evans
…
Published in:
MIT Lincoln Laboratory Report ATC-63,I
Topic:
L-band
R&D area:
R&D group:

Summary

This report summarizes MLS multipath work carried out at Lincoln Laboratory from March 1974 to Sept. 30, 1975. The focus of the program is the development of realistic models for 1) the multipath in representative real world environments and 2) the multipath characteristic of candidate MLS techniques. These multipath and system models are used in a comprehensive computer simulation to predict the strengths and weaknesses of major MLS systems when subjected to representative real world environments. The report is organized into two volumes. Volume I describes the algorithms and validation of various portions of the program. In Volume II, the simulation (or selected portions thereof) is applied to key multipath related MLS issues. Mathematical models are given for the major MLS multipath sources (ground reflections, building and aircraft reflections, and shadowing by objects and humped runways), and it is shown that they agree (Doppler and scanning beam) considered in phase II of the U.S. MLS program are presented together with validation by comparison with theory and bench tests. Also presented are the results of a general study in motion averaging. The (validated) computer simulation (and portions thereof) is then applied to studying 1) the critical areas required by the TRSB system to avoid excessive reflection effects, 2) the expected TRSB performance of a specific TRSB system at Friendship International Airport (MD).
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Summary

This report summarizes MLS multipath work carried out at Lincoln Laboratory from March 1974 to Sept. 30, 1975. The focus of the program is the development of realistic models for 1) the multipath in representative real world environments and 2) the multipath characteristic of candidate MLS techniques. These multipath and...

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MLS multipath studies volume I: mathematical models and validation

Model aircraft L-band beacon antenna pattern gain maps

May 16, 1975
  |
Project Report
Author:
Douglas W. Mayweather
Published in:
MIT Lincoln Laboratory Report ATC-44
Topic:
L-band
R&D area:
R&D group:

Summary

This document presents L-band antenna patterns for a variety of general aviation and air carrier aircraft; these pattern were based on scale-model measurements. The antenna patterns are described by aircraft-coordinate-referenced elevation vs azimuth gain-contour maps. This method of presentation conveniently displays the effects of aircraft configuration on antenna patterns and allows one to observe the changes in a pattern that result from a change in wheel, flap, or antenna location.
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Summary

This document presents L-band antenna patterns for a variety of general aviation and air carrier aircraft; these pattern were based on scale-model measurements. The antenna patterns are described by aircraft-coordinate-referenced elevation vs azimuth gain-contour maps. This method of presentation conveniently displays the effects of aircraft configuration on antenna patterns and...

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Model aircraft L-band beacon antenna pattern gain maps

Scale model pattern measurements of aircraft L-band beacon antennas

April 4, 1975
  |
Project Report
Author:
Kimball J. Keeping
…
Published in:
MIT Lincoln Laboratory Report ATC-47
Topic:
L-band
R&D area:
R&D group:

Summary

This report describes the techniques and apparatus used to measure the directional patterns of aircraft ATC transponder antennas (L-Band) using digital techniques and magnetic tapes for data storage. Algorithms involved in data normalization, cross-polarization correction and coordinate conversations are discussed. Some typical applications of the data are illustrated with actual computer outputs obtained from the model measurements.
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Summary

This report describes the techniques and apparatus used to measure the directional patterns of aircraft ATC transponder antennas (L-Band) using digital techniques and magnetic tapes for data storage. Algorithms involved in data normalization, cross-polarization correction and coordinate conversations are discussed. Some typical applications of the data are illustrated with actual...

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Scale model pattern measurements of aircraft L-band beacon antennas

An analysis of aircraft L-band beacon antenna patterns

January 15, 1975
  |
Project Report
Author:
Gary J. Schlieckert
Published in:
MIT Lincoln Laboratory Report ATC-37
Topic:
L-band
R&D area:
R&D group:

Summary

Radiation patterns are examined for L-Band beacon antennas mounted on aircraft ranging from small, single-engine, general aviation aircraft to the Boeing 747. The data analyzed consists of antenna gain values taken in two degree steps over a spherical surface centered at the antenna location. Data from three representative scale model aircraft are studied in detail and show the effects of various airframe structural members on the radiation lobing patterns and the relative performance of antennas located at a number of positions on each scale model aircraft. Significant observations were that: -Landing gear and flaps complicate the lobing structure but do not introduce many more low gain values. -In general, antennas mounted forward of the leading edge of the wing and on fuselage bottom centerline (not too close to nosewheel) provide the best overall performance. -As an aircraft maneuvers, antenna performance degrades in direct relationship with the severity of the roll or pitch.
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Summary

Radiation patterns are examined for L-Band beacon antennas mounted on aircraft ranging from small, single-engine, general aviation aircraft to the Boeing 747. The data analyzed consists of antenna gain values taken in two degree steps over a spherical surface centered at the antenna location. Data from three representative scale model...

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An analysis of aircraft L-band beacon antenna patterns
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