James R. Wait

Bio: James R. Wait is an academic researcher. The author has contributed to research in topics: Electromagnetic radiation & Wave propagation. The author has an hindex of 1, co-authored 1 publications receiving 1379 citations.

Electromagnetic Waves in Stratified Media

Abstract: This book [1] was written at an important point in the development of applications of electromagnetic (radio) waves to communications, navigation, and remote sensing. Such applications require accurate propagation predictions for a variety of path conditions, and this book provides the theoretical basis for such predictions. The book is based on fundamental research in electromagnetic wave propagation that James R. Wait performed in the Central Radio Propagation Laboratory (CRPL) of NBS from 1956 to 1962. The mathematical theory in the book is very general, and the “stratified media” models are applicable to the earth crust, the troposphere, and the ionosphere. The frequencies of the communication, navigation, and remote sensing applications treated in this book range all the way from extremely low frequencies (ELF) to microwaves. The mathematical theory of electromagnetic wave propagation is based on Maxwell’s equations [2], formulated by James Clerk Maxwell in the 1860s. Experimental propagation studies in free space [3] and over the earth [4] also go back over 100 years. Research in radio science, standards, and measurements began in NBS in the early 1900s, and the long history of radio in NBS has been thoroughly covered by Snyder and Bragaw [5]. CRPL was moved to Boulder in 1954, and Wait joined the organization in 1955. The mathematics of electromagnetic wave propagation in stratified (layered) media is very complicated, and progress in propagation theory in the early 1900s was fairly slow. Wait’s book [1] included the most useful theory (much of which he developed) and practical applications that were available in 1962. A hallmark

Electromagnetic scattering and radiation by surfaces of arbitrary shape in layered media. I. Theory

Abstract: An accurate and general procedure for the analysis of electromagnetic radiation and scattering by perfectly conducting objects of arbitrary shape embedded in a medium consisting of an arbitrary number of planar dielectric layers is developed. The key step in this procedure is a formulation of the so-called mixed-potential electric field integral equation (MPIE) that is amenable to an existing advanced solution technique developed for objects in free space and that employs the method of moments in conjunction with a triangular-patch model of the arbitrary surface. Hence, the goal is to immediately increase analysis capabilities in electromagnetics, yet remain compatible with the large existing base of knowledge concerning the solution of surface integral equations. Three alternative forms of the MPIE in plane-stratified media are developed, and their properties are discussed. One of the developed MPIEs is used to analyze scatterers and antennas of arbitrary shape that penetrate the interface between contiguous dielectric half-spaces. >

Light Antennas in phototactic algae.

Abstract: INTRODUCTION ..............6.............573 The Problem: Detecting Light Direction in the Native Environment ..... .... 574 The Solution: a Directional Antenna Designed to Match the Environment of the Organism .......................................................... 576 ANTENNA STRUCTURES .................................................... 579 Optical Principles 580 Absorption ............................................................... 581 Scattering 581 Refraction 581 Reflection and interference ............................................... 581 Wave guide optics ........................................................ 583 Dichroism ................................................................ 584 Tracking Antenna Designs .................................................. 584 Chlorophyceae: multilayer quarter-wave stack antennas .................. 584 Chlorophyceae: variations in design .... .................................. 588 Dinophyceae: quarter-wave stack antennas and lens antennas ........... 590 Cryptophyceae: dielectric slab wave guide antennas ...................... 592 Euglenophyceae: absorbing screens and dichroic crystal detectors ....... 592 Chrysophyceae, Xanthophyceae, and Phaeophyceae: absorbing screens and paraflageliar swelling ................................................. 593 Eustigmatophyceae: absorbing screens and paraflagellar buttons ........ 594 Prymnesiophyceae (Haptophyceae) ....................................... 595 Discussion 595 ANTENNA PROPERTIES DETERMINED FROM BEHAVIOR ................. 596 Threshold: Receptor Pigment Concentration 596 Receptor pigment content of various algae ..... 598 Action Spectra: Identity of Photoreceptor Pigment and Mechanisms of Producing Directivity .................................................... 600 Threshold action spectrum ............................................... 601 Finite-response action spectra ............................................ 601 Algae with layered eyespots ...... 601 (i) Volvox ............................................................. 601 (ii) Chlamydomonas 602 (iii) Platymon as ........................................................ 602 Dinoflagellates ... ... ..... 603 Cryptomonas ............................................................. 603 Euglena .............................................................. 604 Intensity-Response Curve: Identity of Receptor Pigment, Mechanisms of Producing Directivity, and Pigment Regeneration Rate ................... 604 Chlamydomonas action spectra and regeneration rate .................... 606 Polarized Light: Characterization of the Dichroic Crystal Detector in Euglena 607 Discussion of Receptor Pigments ........... ... ... 608 ANTENNA FUNMCION IN PHOTOTAXIS ........ 609 Signal Production: Scanning by Cell Motion .. .... 609 Signal Processing 6............12 Response: Tracking the Light Direction 6.............................. 61 Chknmydomonas ........................ .. 616 Microthamniun 617 Eugklna ........... ........... .. .. .. 617 Dinoflageliates ..................................... 617 Colonial algae .. ... ........ .. .. ..... 617 Discussion 619 PROSPECTS AND CONCLUSIONS ........................... 619

Applications of the interaction of microwaves with the natural snow cover

Abstract: (1987). Applications of the interaction of microwaves with the natural snow cover. Remote Sensing Reviews: Vol. 2, No. 2, pp. 259-387.

Theory for passive microwave remote sensing of near‐surface soil moisture

Abstract: The theory of microwave thermal emission from a nonscattering half-space medium is developed for application to regions with nonuniform subsurface soil-moisture and temperature variations. A coherent stratified model is presented which is valid for nonuniform temperature profiles and rapidly varying moisture profiles, under which conditions the commonly used emissivity and radiative-transfer approaches become inaccurate. For naturally occurring profiles the stratified model gives more accurate results than the other approaches at frequencies below about 4 GHz. Experimental results from ground-based radiometric observations of a controlled target area compare systematically with brightness temperatures predicted from the theoretical model to within approximately 10 K. Results of dielectric-constant measurements of the sand are given at seven frequencies in the microwave range and for moisture contents in the range from 0% to 30% by volume. By using this model, the thermal microwave emission spectrum is computed for a number of representative moisture and temperature profiles in the frequency range from 0.25 to 25 GHz.

Subionospheric VLF signal perturbations possibly related to earthquakes

Abstract: A likely VLF subionospheric signal effect related to seismic activity was first reported by Hayakawa et al. [1996a, b] in association with the great Kobe earthquake. We have analyzed similar data during periods around 10 other great earthquakes (magnitude M>6) in order to understand the main features of such an effect. The following characteristics emerged from our analysis: The effect appears as a transient oscillation with a 5- to 10-day period, which is initiated a few days before a large earthquake and decays over a few days to weeks after it. It is mainly related to crustal earthquakes. It appears when resonant atmospheric oscillations with periods in a range of 5–11 days exist before the earthquake. The seismic influence on the VLF signal is probably explained by the generation of long-period gravity waves during the earthquake process and their intensification at heights of 70–90 km.