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Probing the Sky with Radio Waves

From Wireless Technology to the Development of Atmospheric Science

By the late nineteenth century, engineers and experimental scientists generally knew how radio waves behaved, and by 1901 scientists were able to manipulate them to transmit messages across long distances. What no one could understand, however, was why radio waves followed the curvature of the Earth. Theorists puzzled over this for nearly twenty years before physicists confirmed the zig-zag theory, a solution that led to the discovery of a layer in the Earth’s upper atmosphere that bounces radio waves earthward—the ionosphere.
In Probing the Sky with Radio Waves, Chen-Pang Yeang documents this monumental discovery and the advances in radio ionospheric propagation research that occurred in its aftermath. Yeang illustrates how the discovery of the ionosphere transformed atmospheric science from what had been primarily an observational endeavor into an experimental science. It also gave researchers a host of new theories, experiments, and instruments with which to better understand the atmosphere’s constitution, the origin of atmospheric electricity, and how the sun and geomagnetism shape the Earth’s atmosphere.  
This book will be warmly welcomed by scholars of astronomy, atmospheric science, geoscience, military and institutional history, and the history and philosophy of science and technology, as well as by radio amateurs and electrical engineers interested in historical perspectives on their craft.

384 pages | 3 halftones, 68 line drawings | 6 x 9 | © 2013

Earth Sciences: History of Earth Sciences

History: History of Technology

Physical Sciences: History and Philosophy of Physical Sciences


“The advent of global radio communications marked the beginning of three decades of intense theoretical and experimental studies of the ionosphere. Yeang’s work is a philosophically sophisticated examination of the interplay between theory and practice in the early years of radio science. Definitive experiments in the 1920s intentionally bounced radio waves off the ionosphere to probe its structure, and Yeang fits the history of the complex evolution of ionospheric studies into the wider contact of active sensing. . . . Highly recommended.”


“Chen-Pang Yeang’s book is the major contribution to our knowledge of how physical theory and electrical experimentation worked together to explain the movement of radio waves beyond the horizon—a compelling question in the years following Marconi’s famous experiment of 1901. Yeang clearly explains how ‘direct evidence’ for the existence of the ionosphere was ultimately provided and reminds us of how important work in classical physics continued into the exciting era of relativity and quantum mechanics. What he describes is a rare mix of physics and electrical engineering encountering the ‘field sciences.’”

A. David Wunsch, University of Massachusetts Lowell

Probing the Sky with Radio Waves offers us a fine example of the ‘mutual shaping’ of science and technology. Those interested in a thoughtful, technically adept history of the discovery of the ionosphere will not be disappointed. Yet this book offers much more. Chen-Pang Yeang deftly draws out the diverse international array of local cultures that made the discovery possible: mathematical, theoretical, and experimental physicists; civilian, military, and corporate engineers; inventors and radio amateurs. The story is a fascinating one, and Yeang—coupling the history and philosophy of science—is an able narrator.”

Suman Seth, Cornell University

Table of Contents

Chapter 1: Introduction: From Propagation Studies to Active Sensors
     From Propagation Studies to Active Sensing: Experiment and Theory
          Field Experiments and Direct Evidence
          Epistemic Status of Theories
     Where This Book Fits In
     Outline of Chapters
     A Note on Units

PART I: Conceiving Long-Range Propagation, 1901-19

Chapter 2: Theorizing Transatlantic Wireless with Surface Diffraction
          European Theoretical Physicists and Wave Propagation
     Surface Diffraction Theory in Britain and France
          Macdonald’s Initiative
          Rayleigh’s Coup
          Poincaré’s Formula
          Nicholson’s Numbers
     Surface Diffraction Theory in Germany
          Antenna Directivity and Zenneck’s Surface Waves
          Sommerfeld’s Refinement of Surface Waves
Chapter 3: The U.S. Navy and the Austin-Cohen Formula
     A Naval Wireless Laboratory
     The Experiment
     The Formula
Chapter 4: Synthesis with Atmospheric Reflection
     Surface Diffraction after Austin-Cohen
          The German Story
          A New Experiment
          The British Response
     Atmospheric Reflection Theory
          Kennelly-Heaviside Layer
          Eccles’s Ionic Refraction
     Watson’s Synthesis and Its Acceptance
          The 1918 and 1919 Papers
          Consolidating the Watson-Austin-Cohen Paradigm

PART II: Discovering the Ionosphere, 1920-26

Chapter 5: Radio Amateurs Launch the Short-Wave Era
     American Radio Amateurs in the Early Twentieth Century
     Fading Experiments
          Standard Experimental Procedure and Data Format
     Setting the Stage for Transatlantic Experiments
     Transatlantic Experiments
          The First Trial
          The Second Trial
          The Third Trial
          The Two-Way Test and the Fourth Trial
Chapter 6: From the Skip Zone to Magneto-Ionic Refraction
     Discovering the Skip Zone and Short-Wave Data
          Albert Hoyt Taylor and the U.S. Naval Research Laboratory
          Discovery of the Skip Zone
          More Comprehensive Range Data at High Frequencies
     Magneto-Ionic Theory for Short Waves
          Eccles’s Ionic Refraction Theory
          Larmor’s Ionic Refraction Theory
          Effects of Geomagnetism: Nichols, Schelleng, and Appleton
          Explaining the Skip Zone: Taylor and Hulburt
Chapter 7: British Radio Research and the Moments of Discovery
          Direct Evidence, Sounding-Echo Experiments, Operational Realism
          A British System of Radio Ionospheric Research
     Direction Finding, Wave Polarization, and the Ionosphere
          Loop Direction Finders and Their Problems
          Thomas Eckersley’s Work on Polarization
          National Physical Laboratory, Radio Research Board, and Reginald Leslie Smith-Rose    
          Smith-Rose and Barfield’s Experiment
     Frequency-Change Experiments and Discovering the Ionosphere
          Edward Victor Appleton
          The Frequency-Change Experiment
          Smith-Rose and Barfield Try Again
          Improving Direction Finding as a By-product
Chapter 8: Pulse Echo, CIW, and Radio Probing of the Ionosphere
     Pulse-Echo Experiments in the United States
          Carnegie Institution of Washington, Gregory Breit, Merle Tuve
          Pulsed Radio Sounding of the Ionosphere
          The Meaning of Height
     The Ionosphere has a Structure
          Appleton’s Program of Ionospheric Sounding
          The Discovery of the F Layer

PART III: Theory Matters, 1926-35

Chapter 9: Consolidating a General Magneto-Ionic Theory
     Generalizing the Magneto-Ionic Theory
          Appleton and Altar’s Derivation
          Lassen’s Derivation
          Goldstein’s Derivation
     Measuring Polarization in Both Hemispheres
          A Polarimetric Experiment
          More Polarization Research in Both Hemispheres
     A Mathematical Inquiry into the General Magneto-Ionic Theory
Chapter 10: Handling Microphysics
     The Lorentz Correction
          Origin of the Concept
          Douglas Hartree and the Lorentz Correction in Ionic Refraction
          A Microphysical Controversy without Microphysics
          Where Was the Empirical Evidence?
     The Quasi-Elastic Force
          Measuring the Dielectric Constant of Ionized Air
          A Propagation Theory from Tabletop Experiments
          Anatomy of a Debate
          Death of a Theory

PART IV: Conclusion

Chapter 11: A New Way of Seeing the World
          From Wave Propagation Studies to Ionosphere Probing
           A Case History for Active Sensing


Atmospheric Sciences Librarians International: ASLI Choice Award
Honorable Mention

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