This book is based on the updated versions of a lively mixture of tutorials, topical papers, and scientific and technological contributions collected from the International URSI Symposium on Environmental and Space Electromagnetics held in Tokyo on 4-6 September, 1989. It was sponsored by the International Union of Radio Science (URSI) as an activity of Commission E (Chairman: present editor) preceding the URSI General Assembly in Prague, Czechoslovakia in 1990. The aim was an exchange of information and views to highlight the state of the art in radio science and interdisciplinary areas. Along this line, the editor has attempted to cover quite new, novel or unconventional subjects besides more traditional or conventional ones. Although a great many subjects have apparently been covered, this book has been edited so the reader can find some common concepts or views presented. On this basis, a group of many subjects can be treated in a unified fashion, and new ideas and views can be gained as a most valuable addition to current knowledge. This is one of the major features of this volume that cannot be found in any of the monographs or proceedings that cover a narrow range oflimited topics. Its broad scope does not stand for presentation in a superficial and shallow manner, but stands for a strong focus on the search for a common nature in basic concepts or views in apparently diverse subjects, and a focus on the advanced or innovatory nature of each contribution.