The 2001 URSI International Symposium on Electromagnetic Theory was held in Victoria, Canada, May 13–17th, 2001. This was the seventeenth symposium in a series of triennial meetings. The Symposium was sponsored by the Canadian National Committee of URSI and organized by the National Research Council of Canada. It is one of the major activities of Commission B Fields and Waves of the International Union of Radio Science (URSI) and is a well-established event in the electromagnetic community covering a wide variety of the most recent advances in electromagnetic theory and its many diverse applications.
 The Symposium covers the entire range of Commission B scientific activities including beam superposition, scattering and diffraction, integral equations, time domain methods, waves in complex and random media, inverse scattering and imaging, antennas for mobile communications, periodic structures, guided waves, numerical methods, interactions of electromagnetic waves with biological tissues, and new mathematical techniques. The Symposium attracts leading international experts in electromagnetics and offers a unique opportunity to interact and share new ideas, information and developments.
 This present special section of Radio Science is comprised of full-length papers selected from 236 papers presented at the meeting. Papers considered for inclusion in this special section were recommended by session chairs or technical program committee members. From these recommendations, the final selection of papers was made by the Special Section Editors, and authors were then invited to submit manuscripts. In keeping with the usual Radio Science policy, all papers were reviewed before the final decisions were made for publication.
 We wish to express our appreciation to the local organizing committee, the technical program committee and the session chairs for their advice and recommendations. We also thank the reviewers for their time and efforts and the authors for their timely work which contributed greatly to the success of the Symposium and of this special section of Radio Science.
 The venues for the symposia and special sections of Radio Science which contain selected papers are the following:
- 1953 Montreal, Quebec, Canada (microwave optics)
- 1956 Ann Arbor, Michigan
- 1959 Toronto, Ontario, Canada
- 1962 Copenhagen, Denmark (electromagnetic theory and antennas)
- 1965 Delft, Netherlands
- 1968 Stresa, Italy
- 1971 Tbilisi, USSR
- 1974 London, England
- 1977 Stanford, California
- 1980 Munich, Germany (Radio Science, 16(6), 1981)
- 1983 Santiago de Compostella, Spain (Radio Science, 19(5), 1984)
- 1986 Budapest, Hungary (Radio Science, 22(6) 1987)
- 1989 Stockholm, Sweden (Radio Science, 26(1–2) 1991)
- 1992 Sydney, Australia (Radio Science, 28(5–6) 1993)
- 1995 St. Petersburg, Russia (Radio Science, 31(6) 1996)
- 1998 Thessaloniki, Greece (Radio Science, 35(2) 2000)
- 2001 Victoria, Canada