Sponsor (May-Aug 1957)

ABOUT VERY LOW FREQUENC PROPAGATION ! Smaller antennas, lower transmitter power, and relative freedom from atmospheric noise are reasons behind our communication services' gradual migration to the upper end of the frequency spectrum. Lying fallow and awaiting rediscovery has been the very low frequency band below :)i) kc. Now, because VLF offers a reliable means of Communicating over vast global distances, there is a marked revival of interest. It is now known that VLF has highly stable propagation characteristics which make it possible to transmit data to distant points with unusual fidelity and precision. Where greater accuracy is required, such as very long range radio navigation systems and international transmission of frequency standards, VLF pron to open doors to many new and important u ■ June Proceedings of the IRE gives you the facts about VLF This year, the Boulder Laboratories of the Nat ional Bureau of Standards and the IRE Professional Croup on Antennas and Propagation co-sponsored a Symposium at I'.oulder, Colorado, on the propagation of very low frequency radio waves. From the papers given at this important meeting the editors of Proceedings have chosen those of broadest interest for publication in the June. 1957, issue. Typical of the service offered members of IRE is this VLF report — to be used now and referred to for years to come. If you are not a member of Tin InstituU of Radio Engineers be sure to reserve a copy of the June Proceedings of tin IRE, today! Partial Contents of this VLF issue: "A Technique for the Rapid Analysis of Whistlers," by J. K. Grierson, Defense Reserve Board. Ottawa. Ontario. Canada. "VLF Radiation from Lightning Strokes," by E. L. Hill, School of Physics. University of Minnesota. "Some Recent Measurements of Atmospheric Noise in Canada," by C. A. McKerrow. Defense Reserve Board, Ottawa. Ontario, Canada. "Intercontinental Frequency Comparison by Very Low Frequency Radio Transmission," by J. A. Pierce, Croft Laboratory. Harvard. "The Mode Theory of VLF Ionospheric Propagation for Finite Ground Conductivity," by James R. Wait. National Bureau of Stardards, Boulder. Colorado. "The Geometrical Optics of VLF Sky Wave Propagation," by J. R. Wait & A. Murphy, National Bureau of Standards, Boulder, Colorado. "Characteristics of Atmospheric Noise from 1 to 100 Kc/s." by A. D. Watt & E. L. Maxwell, National Bureau of Standards. Boulder, Colorado. "The Present State of Knowledge Concerning the Lower Ionosphere." by A. H. Waynick. The Pennsylvania State University. "Noise Investigation at VLF by the National Bureau of Standards." by W. Q. Crichlow. National Bureau of Standards. Boulder, Colorado. "Reflection at a Shapely-Bounded Ionosphere," by I. W. Yebroff, Stanford University. "The Attenuation Versus Frequency Characteristics of VLF Radio Waves." by J. R. Wait. National Bureau of Standards. Boulder, Colorado. "The Waveguide Mode Theory of the Propagation of VLF Radio Waves." by K. G. Budden. University of Cambridge, England. PROCEEDINGS OF THE IRE 1 East 79th Street, New York 21, New York □ Enclosed is S3.00 Enclosed is company purchase order for the June, 1957, issue on VERY LOW FREQUENCY. Name Company Address City & State All IRE members will receive this June issue as usual. Extra copi( $1.25 each (only one to a men: er). The Institute of Radio Engineers 1 East 70th Street New York 21 . New York ,ii \.\ 1951 231