John M Tobias - Academia.edu (original) (raw)

Papers by John M Tobias

The copyright law of the United States (Title 17, United States Code) governs the making of photo... more The copyright law of the United States (Title 17, United States Code) governs the making of photocopies or other reproductions of copyrighted material. Under certain conditions specified in the law, libraries and archives are authorized to furnish a photocopy or other reproduction. One of these specified conditions is that the photocopy or reproduction is not to be "used for any purpose other than private study, scholarship, or research." If a, user makes a request for, or later uses, a photocopy or reproduction for purposes in excess of "fair use" that user may be liable for copyright infringement, This institution reserves the right to refuse to accept a copying order if, in its judgment, fulfillment of the order would involve violation of copyright law.

The findings in this report are not to be construed as an official Department of the Army positio... more The findings in this report are not to be construed as an official Department of the Army position, unless so designated by other authorized documents. The citation of trade names and names of manufacturers in this report is not to be construed as official Government endorsement or approval of commercial products or services referenced herein.

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Security Program Regulation, Chapter IX. For unclassified, limited documents destroy by any metho... more Security Program Regulation, Chapter IX. For unclassified, limited documents destroy by any method that will prevent disclosure of contents or reconataction of the document. PooE CO ON 17. SgaY .ASICTIU 3 SEIUTY .ASSOWCAT"O a9 VEIT CLASSWPCATION 20. UMITATION OP A@STUACT Unclassified Unclassifie Unlasiie UL ON 740-1 2154W Stndad Fonn 2" (Rev. 249) auWm w o M Accesion For NTIS CRA& DTIC TAB Unannounced 0 Justification By.

IEEE Transactions on Industry Applications, 1996

Alternative conductors for lightning protection applications favorable for use in mobile systems ... more Alternative conductors for lightning protection applications favorable for use in mobile systems have been tested to demonstrate high levels of protection against maximal lightning events. The method of determining the survivability of the down conductors was to expose each type of conductor to maximal lightning events generated by a large Marx capacitor bank. Each type of conductor was tested until mechanical failure occurred or until it survived four exposures to the lightning event. A test to determine the effect of physical damage on conductor performance was also conducted. A theory attributing interstrand or intraconductor magnetic forces, rather than ohmic heating, as the primary cause of conductor failure is proposed. Results indicate that two types of tested conductor exist which can provide protection against maximal lightning events, yet have properties that lend themselves to mobile appliration.

Optics Letters, Dec 1, 1999

Self-imaging was observed in simulations and in microwave experiments that were performed on a fa... more Self-imaging was observed in simulations and in microwave experiments that were performed on a face-centered cubic photonic crystal structure. The structure was composed of dielectric spheres that generally were smaller than the incident wavelength. Such self-imaging phenomena occurred along the direction of propagation and at distances smaller than the propagating wavelength.

Abstract : This report discusses design applications of lightning protection systems to military ... more Abstract : This report discusses design applications of lightning protection systems to military tactical/mobile communications equipment. New information from a recent test program discusses alternative, nonstandard materials for use that achieves levels of protection comparable to industry standards. Material specifications and assembly techniques are given for items validated by repeated exposure to 200,000-ampere simulated lightning current. The effects of lightning damage to system components is discussed. Design guidelines are presented addressing the specific problems encountered in tactical/mobile systems. Methods for predicting the probability of lightning strikes, and cost/risk analysis are considered to assist designers. Two case studies of existing systems are given to illustrate applications of the report recommendations. Data presented in the report provides tested advice to the communications system designer when industrial standards cannot be met because of overriding weight/mobility requirements.... Lightning protection, Lightning protection system design, Lightning.

IEEE Transactions on Industry Applications, Jul 1, 2004

The study of lightning protection system design encompasses nearly 300 years. Yet, many of the or... more The study of lightning protection system design encompasses nearly 300 years. Yet, many of the original sources for common design practices used today remain obscure. This paper traces the significant developments in lightning protection from the late 1700s to the modern day. Emphasis is placed on significant events in the history that have had direct consequences in the establishment of design practices for lightning protection. It is also demonstrated that many of the design practices used today were subject to significant scrutiny and empirical qualification. Our intent is to familiarize the student of lightning protection design with the original literature, testing, and other noteworthy contributions to the design of effective lightning protection systems.

Approved for public release; distribution is unlimited. iDTIC QUALITY rasPEOTED 3 REPORT DOCUMENT... more Approved for public release; distribution is unlimited. iDTIC QUALITY rasPEOTED 3 REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188 Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instruction, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send I comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to

Journal of the Optical Society of America B, 2002

Periodic intensity variations as a function of incident and azimuthal angles were observed upon r... more Periodic intensity variations as a function of incident and azimuthal angles were observed upon rotating a face-centered-cubic photonic crystal with respect to a linearly polarized microwave beam. These intensity variations also depended on the radiation frequency. We have studied propagating wavelengths that were smaller than, comparable with, and larger than the crystallographic pitches. It is suggested that the observed transmission variations arise from the combination of a periodic structure with transverse confinement of the propagating wave. Such diffraction configurations may permit spatial filtering techniques with subwavelength periodic structures.

Journal of the Optical Society of America, 2002

EXPERIMENTAL STUDIES OF WAVE PROPAGATION IN THREEDIMENSIONAL PHOTONIC CRYSTALS by John M. Tobias ... more EXPERIMENTAL STUDIES OF WAVE PROPAGATION IN THREEDIMENSIONAL PHOTONIC CRYSTALS by John M. Tobias Photonic crystals were proposed fifteen years ago. Propagation is selectively prevented through these crystals resulting in a photonic band gap, that is, a frequency region where light cannot propagate. These frequency bands are analogous to electronic band gaps in solid-state crystals. The optical properties of the photonic crystal in regions near the band gap remain relatively unexplored. Yet, there is significant evidence to suggest that this avenue of investigation can provide useful optical and microwave applications. Numerical studies have predicted that the effective permittivity near the photonic band gap approaches zero and becomes negative. Self-collimation of the propagating beam and ultrarefraction, where radiation is redirected through large angles in the crystal, are predicted. Although not considered as the ideal structure, the face centered cubic (fcc) opaline photonic is...

Abstract : This pamphlet is a guide to proper earth grounding methods and procedures for use with... more Abstract : This pamphlet is a guide to proper earth grounding methods and procedures for use with tactical systems. It describes different earth grounding systems and provides guidance on the proper methods for their installation. Earth grounding helps to protect personnel and equipment from electrical faults, power surges, and other surges and transients. Earth grounding also helps reduce circuit noise and other transmission interference that can degrade communications-electronics system performance. The instructions contained in this pamphlet, not often found in technical manuals, will help in setting up effective and safe earth grounding systems for tactical equipment and shelters.

IEEE Transactions on Industry Applications, 1996

Optics Letters, Dec 1, 1999

IEEE Transactions on Industry Applications, Jul 1, 2004

Journal of the Optical Society of America B, 2002

Journal of the Optical Society of America, 2002