Introduction: A reference step-like pulse generator is described which has been developed at NBS. This generator can be used for accurately characterizing the step response of various kinds of trap ient recording equipment (oscilloscopes, waveform recorders, transient digitizers, etc.). Basic design principles are given as well as complete circuit diagrams and descriptions. An analysis of the output stage of the generator is presented together with the circuit models for developing a time-domain computer simulation program using extended- SCEPTRE. Preliminary specifications indicate that the NBS Reference Flat Pulse Generator provides a negative-going reference transition duration (90 to 10 percent) of 600 ps, *20 percent with baseline perturbations of less than *2 percent for less than 5 ns.

Pamphlet issued by the United States National Bureau of Standards discussing the reasons that the U.S. decided passed the Metric Conversion Act of 1975 and provides tables, illustrations, and formulas for converting between customary units and metric units of measuring weight, length, volume, and temperature. It also includes a discussion of how one might expect to use metric measurements in the marketplace, in the home, and at work.

From Introduction: "In this monograph, the background of the exponential reference atmosphere will be outlined and a set of radio ray tracings presented. These ray may be used for the solution of many problems involving refraction by means of the exponential reference atmosphere."

Report discussing optical wedge beam splitters and the basic theory for computing the ratio of the intensity of the incident beam to the intensity of any selected emerging beam and also for computing the direction of the emerging beam, assuming that the wedge angle, index of refraction, angle of incidence, and number of reflections are known.

From Abstract: "This publication contains information, useful to the hard of hearing, on several topics relating to hearing and hearing aids. This publication represents an extensive revision of NBS Circular 534, Hearing Aids. It includes new material based upon research conducted at the National Bureau of Standards during the intervening years."

Report giving tables of the specific heat, cp, and the enthalpy of 28 metals, 3 alloys, 8 other inorganic substances, and 8 organic substances in the temperature range, 1º to 300º K.

From introduction: In this report the following will he discussed: (1) design consideration of the broadband magnetic field sensor, (2) overall design of the magnetic field meter, (3) performance of the meter, (4) calibration and operating procedures, (5) alignment and adjustment procedures, and (6) summary and conclusions.

From Abstract: "This Monograph has been prepared to give an understanding of heat treatment principally to those unacquainted with this subject. This Monograph has been prepared to answer such inquiries and to give in simplified form a working knowledge of the basic theoretical and practical principles involved in the heat treatment of iron and steel."

From preface: STARPAC documentation is being published as a series of Technical Notes. This Note is the first in the series. It gives an overview of the STARPAC library, defines conventions used in the documentation, provides an example using STARPAC subroutines, and presents general background material. This Note includes information which is essential for using the STARPAC library, and users should be familiar with its contents before attempting to use any STARPAC subroutine.

From preface: This Note documents 16 subroutines for nonlinear least squares regression. Twelve of these compute the least squares estimates, performing either weighted or unweighted analysis with either numerically approximated or user-supplied (analytic) derivatives. The other four are user-callable subroutines for two procedures used within the estimation code: the first selects optimum step sizes for approximating the partial derivatives of the model; and the second checks the validity of a user-supplied derivative subroutine.

Report issued by the U.S. National Bureau of Standards discussing the System Management Facilities for IBM systems. As stated in the introduction, "the purpose of SMF, as stated in the IBM manual, is to provide the means for gathering and recording information that can be used for billing customers or evaluating system usage" (p. 1). This report includes tables, and illustrations.

Report presenting the technical background and basis for a new method of evaluating certain performance parameters which are common to all microwave systems. A unique feature of the new measurement concept is its elimination of the precision waveguide and connector requirements for an important class of measurement problems.

Parameters determined by a least-squares method for the reduced Simon equation and for a new, empirical melting equation.

From introduction: The fabrication of various iris-fed millimeterwave rectangular microstrip patch antennas is described. A model is proposed to describe the iris-fed antenna. Irises ranging in size from 15 percent of the area of the patch to the fully open waveguide are used to couple energy into the antenna. Resonance of the antenna is observed to be insensitive to the size of the iris for irises up to 115 percent of the size of the patch. A study is also made of th? relationship of coupling to the antenna as a function of position of the iris with respect to the transverse plane of the waveguide, the iris always being centered with respect to the patch. In general, the antenna has a VSWR in the waveguide feed on the order of 5:1 at resonance, except for the fully open waveguide which gives rise to a VSWR of 2.9:1 at resonance. Far-field antenna power patterns are observed to be quite broad with H-plane beamwidths on the order of 1300. Maximum antenna gain is seen to be 4.5 dBi with 3 dBi typical. An initial study is made of the microstrip patch antenna fed from a longitudinal waveguide wall. Results indicate that …

From Abstract: "This work traces the development of the Loran-C concept from its inception as a 100-kHz pulse hyperbolic navigation system to more recent times when it found a variety of applications to both timing and navigation."

Technical paper issued by the Bureau of Standards over radio-frequency resistance in radio reception. As stated in the introduction, "the purpose of this paper is to present data on the radio-frequency resistance and inductance of coils within the range of frequencies used in radiotelephone broadcasting" (p. 651). This paper includes tables, and illustrations.

Report discussing a search conducted for stable, oil-soluble, organic compounds of metals (and other elements) for use in the spectrographic analysis of petroleum products. Compounds having suitable physical properties have been selected as standards. Methods are given for preparation of the compounds and for the spectrographic and chemical analysis of the chosen standards. Procedures are described for the preparation of stable solutions thereof in petroleum oils.

Report discussing the VLF, ELF propagation in the earth-ionosphere waveguide emphasizing the total field found by summing all modes which contribute appreciably. Solutions are given and calculations are made for a homogeneous isotropic ionosphere, a homogeneous ionosphere with a constant radial magnetic field imposed, and an ionosphere with a magnetic field of arbitrary dip angle.

From Abstract: "This treatise is a source document containing information on helium resources, production, conservation, thermodynamic properties, liquefaction and refrigeration techniques, transportation and storage of liquid and safety requirements. It also contains a discussion of uses for liquid and cold gas in cryoelectronics, superconductivity, bubble chambers, cryopumping and missile and space systems."

From abstract: "Guide for those who design, specify, use, and test military automatic test equipment containing sensors."

Report presenting a diagrammatic method for solving angular momentum recoupling problems. It is shown that a few graphical elements with a set of rules for their use lead to the solution of many types of recoupling problems in an intuitive and systematic way. Several examples are given together with exercises to develop the reader's facility with the method.

From introduction: A new method for determining the radiation characteristics of leakage from electronic equipment for interference studies is described in this report. Basically, an unintentional leakage source is considered to be electrically small, and may be characterized by three equivalent orthogonal electric dipole moments and three equivalent orthogonal magnetic dipole moments. When an unknown source object is placed at the center of a transverse electromagnetic (TEM) cell, its radiated energy couples into the fundamental transmission mode and propagates toward the two output ports of the TEM cell. With a hybrid junction inserted into a loop connecting the cell output ports, one is able to measure the sum and difference powers and the relative phase between the sum and difference outputs. Systematic measurements of these powers and phases at six different source object positions, based on a well-developed theory, are sufficient to determine the amplitudes and phases of the unknown component dipole moments, from which the detailed free-space radiation pattern of the unknown source and the total radiated power can be determined. Results of simulated theoretical examples and an experiment using a spherical dipole radiator are given to illustrate the theory and measurement procedure.

Abstract: Selected publications of the National Bureau of Standards technical staff in the field of electricity were first compiled in 1962 as a volume of the NBS Precision Measurement and Calibration Series (Electricity and Electronics, Handbook 77, Volume I); this compilation was extended in 1968 by the compilation of an additional volume in the Precision Measurement and Calibration Series (Electricity-Low Frequency, NBS Special Publication 300, Volume 3). The present volume, a further extension of these earlier compilations of selected publications in the field of electricity, includes 66 more recent papers by NBS authors and 16 abstracts of closely related papers by authors from other organizations. In view of the expansion of measurement technologies used in electricity and electromagnetism it has been necessary to reduce the range of topics for the selection of papers in the new compilation. In this connection an emphasis has been placed upon the realization and maintenance of fundamental electrical units and the related scientific advances, particularly in quantum physics. However, in the interest of completeness, three appendices also provide up-to-date bibliographies of publications by NBS authors in different areas of electromagnetism. (This book is a sequel to NBS Handbook 77-Vol. 1(1961) and NBS SP 300-Vol. 3 …

From Abstract: "Comparisons with other intensity measurements in individual spectra indicate that the National Bureau of Standards spectral-line intensities may have average errors of 20 percent, but first of all they provide uniform quantitative values for the seventy chemical elements commonly determined by spectrochemists. These data are presented by element in part I, and all 39,000 observed lines are given in order of wavelength in part II."