Aperture Antennas and Diffraction Theory

by E.V. Jull

Overview

Two powerful techniques for the analysis of aperture antennas are now used. One is based on the convenient Fourier transform relationship between aperture field and far-field radiation pattern. Here this relationship is derived from the plane wave spectrum representation of the aperture fields. In the near field of the aperture, Fourier transforms become Fresnel transforms. Far-field patterns may be predicted from near-field measurements by treating the near field as the aperture plane. In its application this method is basically the Kirchhoff approximation of diffraction theory. It is accurate for the forward fields of large antennas but cannot provide the lateral and back radiation.

The other method is based on aperture edge diffraction and called the geometrical theory of diffraction. It is developed from an asymptotic approximation to rigorous diffraction theory. Inherently more accurate and more widely applicable, it is especially useful in the calculation of antenna radiation in the lateral and rear directions. However, at present it fails in some situations where the Kirchhoff method succeeds, for example the axial fields of paraboloidal reflectors. In this sense the two methods are complementary and often both are required in antenna analysis. Application of the two methods to the calculation of the pattern, gain and reflection coefficient of some common antenna types is shown and comparisons are made with experiment.

Product Details

ISBN-13:	9780906048528
Publisher:	The Institution of Engineering and Technology
Publication date:	06/30/1981
Series:	Electromagnetic Waves , #10
Pages:	184
Product dimensions:	6.14(w) x 9.21(h) x (d)

About the Author

Edward V. Jull was born in Calgary, Alberta, Canada in 1934. He received the B.Sc. degree in engineering physics from Queen's University, Kingston, Ontario, in 1956. From 1957-59 he held an Athlone Fellowship at UniversityCollege, London and received the Ph.D. degree in electrical engineering in 1960. He was awarded a D.Sc. (Eng.) from the Universityof London in 1979.

In 1956-57 and 1961-72 he was with the Division of Radio and Electrical Engineering of the National Research Council, Ottawa working on antennas and electromagnetic diffraction theory. During 1963-65 he was a guest researcher at the Laboratory of Electromagnetic Theory of the Technical Universityof Denmark and the Microwave Institute of the Royal Institute of Technology, Stockholm. In 1972 he joined the Department of Electrical Engineering of the Universityof British Columbia, Vancouver. During 1979-80 he was on leave and back at the National Research Council, Ottawa, as a visiting scientist.

Professor Jull was a joint winner in 1965 of the Bolljahn Memorial Award of the IEEE Antennas and Propagation Society. He has been chairman of Canadian Commission VI for the International Union of Radio Science (URSI) and is currently chairman of the Canadian National Committee for URSI. He is an associate editor of Radio Science.

Table of Contents

• Chapter 1: Introduction
• Chapter 2: Plane waves from apertures
• Chapter 3: Fourier transform representation of aperture patterns
• Chapter 4: Near-field radiation patterns
• Chapter 5: Aperture gain
• Chapter 6: Applications of aperture theory to antennas
• Chapter 7: Diffraction by conductors with sharp edges
• Chapter 8: Geometrical theory of diffraction by edges
• Chapter 9: Applications of geometrical diffraction theory to antennas
• Appendixes