Detection Technology for IVHS, Volume II: Final Report Addendum

DTFH61-91-C-00076This addendum contains the results of analyses for an additional 39 runs. These runs were selected to be representative of the widest possible range of traffic and weather conditions that were encountered. The number of runs for each site analyzed in this addendum was chosen giving consideration to the amount of data collected at each particular site. The goal of the additional analysis was to study more results and thus, have a larger base by which to judge the performance of the technologies represented in the detector field tests. Understanding the operation of the detectors under test and the various layouts and configurations employed are an integral part of interpreting the results contained in this addendum. The necessary background information is contained in the Task L final report in Chapters 9 and 10 and is not reproduced in this addendum. Indeed, this volume is not intended to be a stand-alone document, but a complement to the work already published. The Detection Technology for IVHS project identified traffic parameters and their required accuracies for characterizing traffic flow in conventional and newer intelligent transportation systems (ITS), obtained state-of-the-art detectors, installed and evaluated them in three states having diverse climates, and studied the need and feasibility of establishing a national detector evaluation facility. The other report in this series is FHWA-RD-95-100, Volume I: Final Report

Modeling Micro-Porous Surfaces for Secondary Electron Emission Control to Suppress Multipactor

This work seeks to understand how the topography of a surface can be engineered to control secondary electron emission (SEE) for multipactor suppression. Two unique, semi-empirical models for the secondary electron yield (SEY) of a micro-porous surface are derived and compared. The first model is based on a two-dimensional (2D) pore geometry. The second model is based on a three-dimensional (3D) pore geometry. The SEY of both models is shown to depend on two categories of surface parameters: chemistry and topography. An important parameter in these models is the probability of electron emissions to escape the surface pores. This probability is shown by both models to depend exclusively on the aspect ratio of the pore (the ratio of the pore height to the pore diameter). The increased accuracy of the 3D model (compared to the 2D model) results in lower electron escape probabilities with the greatest reductions occurring for aspect ratios less than two. In order to validate these models, a variety of micro-porous gold surfaces were designed and fabricated using photolithography and electroplating processes. The use of an additive metal-deposition process (instead of the more commonly used subtractive metal-etch process) provided geometrically ideal pores which were necessary to accurately assess the 2D and 3D models. Comparison of the experimentally measured SEY data with model predictions from both the 2D and 3D models illustrates the improved accuracy of the 3D model. For a micro-porous gold surface consisting of pores with aspect ratios of two and a 50% pore density, the 3D model predicts that the maximum total SEY will be one. This provides optimal engineered surface design objectives to pursue for multipactor suppression using gold surfaces

Bounty Above, The

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Optimum space-time signal processing and parameter estimation /

Prepared for Air Force Cambridge Research Laboratories, Office of Aerospace Research, United States Air Force, Bedford, Massachusetts."Reprinted from the IEE Transactions on Aerospace and Electronic Systems, Vol. AES-4,No.3, pp.334-341, May 1968."Contract Monitor: John F. McIlvenna, Microwave Physics Laboratory.""Contract No. F19628-68-C-0082, Project No. 5635, Task No. 563506, Work Unit No. 56350601, Scientific Report No. 3.""June 1968."Includes bibliographical references (page 7)Mode of access: Internet

Radiation from slot-fed dielectric slabs /

The report contains analyses of the radiation characteristics of grounded dielectric slabs fed by slots in the groundplane. Two configurations are examined, one in which a semi-infinite slab covers the slot, a second in which a finite slab does not extend over the slot. The slots are parallel to the slab edges so that only TM mode propagation is considered. Integral equations are derived for the fields at the ends of the slabs and approximate solutions are obtained. Numerical results in the form of radiation patterns are given for the case of the semi-infinite slab. It is found that the feed pattern is very close to the space-wave that would exist if the slab were infinite, but differs from it in the region near the horizon. The results can be applied to studies of electronic scanning of finite arrays of slots in the presence of surface wave structures. Recommendations for further study are included. (Author)."Contract Monitor: Allan C. Schell, Microwave Physics Laboratory.""Contract No. F1628-72-C-0145.""December 1972.""Scientific Report No. 1."Includes bibliographical references (page 51).The report contains analyses of the radiation characteristics of grounded dielectric slabs fed by slots in the groundplane. Two configurations are examined, one in which a semi-infinite slab covers the slot, a second in which a finite slab does not extend over the slot. The slots are parallel to the slab edges so that only TM mode propagation is considered. Integral equations are derived for the fields at the ends of the slabs and approximate solutions are obtained. Numerical results in the form of radiation patterns are given for the case of the semi-infinite slab. It is found that the feed pattern is very close to the space-wave that would exist if the slab were infinite, but differs from it in the region near the horizon. The results can be applied to studies of electronic scanning of finite arrays of slots in the presence of surface wave structures. Recommendations for further study are included. (Author).Mode of access: Internet

Investigation of use of superimposed surface wave modes.

A novel method of achieving a matched radiating element in a phased array antenna over a wide scan angle has been investigated. This method has been applied in the design of an experimental linear array of 41 elements. Each radiating element consists of an open-ended waveguide driven by an end-on coaxial transition in conjunction with offset posts for the appropriate excitation of the two lowest order modes. The measured input VSWR over a 55 degree scan angle was less than 1.5 on this experimental linear array. This result agreed fairly well with the predicted value. In addition, no degradation on the array pattern due to edge effect was observed on the experimental array with all the elements matched over the 55 degrees scan range. (Author).Prepared for Air Force Cambridge Research Laboratories, Office of Aerospace Research, United States Air Force, Bedford, Massachusetts.Contract No,. AF19(628)-4984; Project No. 4600; Task No. 460002."25 February 1967."Includes bibliographical references (pages B1-2)A novel method of achieving a matched radiating element in a phased array antenna over a wide scan angle has been investigated. This method has been applied in the design of an experimental linear array of 41 elements. Each radiating element consists of an open-ended waveguide driven by an end-on coaxial transition in conjunction with offset posts for the appropriate excitation of the two lowest order modes. The measured input VSWR over a 55 degree scan angle was less than 1.5 on this experimental linear array. This result agreed fairly well with the predicted value. In addition, no degradation on the array pattern due to edge effect was observed on the experimental array with all the elements matched over the 55 degrees scan range. (Author).Mode of access: Internet

Study of application of antenna optimization techniques /

Contract AF no, AF19(628)-4358; Project No. 8683; Task NO. 868303; Work unit no. 86830301.Prepared for Air Force Cambridge Research Laboratories, Office of Aerospace Research, United States Air Force, Bedford, Massachusetts.AD 662 341."List of publications": pages 1-2.Final report (October 1964 to August 1967).Mode of access: Internet