The Paraboloidal Reflector Antenna in Radio Astronomy and Communication: Theory and Practice , Jacob W. M. Baars , Springer, New York, 2007. $169.00 (253 pp.). ISBN 978-0-387-69733-8, CD-ROM
Paraboloidal reflector antennas are ubiquitous in modern society. They appear in large numbers on or near urban residences, in rural areas, on communication towers, and on the premises of cable-television providers. Those small dishes serve communication functions, largely domestic television reception, for which they are deployed in the tens of millions. That particular application, however, is not what Jacob W. M. Baars aims to cover in his elegant The Paraboloidal Reflector Antenna in Radio Astronomy and Communication: Theory and Practice. He instead discusses the much larger, enormously more expensive, more sophisticated, and highly photogenic modern radio telescope used for cutting-edge research in radio astronomy. Baars has been centrally involved in the design and construction of several of the world’s major radio telescopes of the past three decades and thus is well qualified to treat his subject.
The book is physically attractive. Many of the radio telescopes under discussion are pictured in full color, and the mathematical notation is familiar and elegant, as is the text format. I was especially intrigued to learn that the entire book had been composed in Mathematica. The mathematical analyses are coupled with textual listings of the Mathematica routines used to compute the examples, and a CD-ROM with the routines, but not the Mathematica program, accompanies the book.
Despite the importance of the parabolic reflector antenna and its variants in modern communication technology and in scientific research, not many books have been written on the topic. Part of the reason for that may be because performance of small antennas for the consumer market is not critical, which makes the antennas easy to design. Another reason is that large radio telescopes and deep-space communication antennas have a large size-to-wavelength ratio, and thus classical geometrical optics and diffraction theory suffice for antenna performance analysis. Yet in both space-communication and astronomical applications, stringent requirements for high efficiency, low noise, and precise shaping of the received or radiated field have generated many sophisticated modifications of the basic paraboloid of revolution with a small receiving antenna at the focus. Consequently, a plethora of papers have been published, and Baars selects a number of the topics they cover—for example, the effects on antenna performance of axial and lateral defocusing, random errors in reflector surface accuracy, and intentional beam steering by lateral deviation of the receiving antenna—some for theoretical analysis and some for qualitative description.
Underlying those special topics is Baars’s attempt to offer a coherent analysis of the basic reflector antenna. For three decades I have taught the subject and find myself somewhat uncomfortable with his mathematical treatment, which is rather discontinuous and sometimes obscure. For example, he often skips large intermediate steps in a derivation. For a basic, first-principles pedagogical treatment, one might be better off consulting the classic Microwave Antenna Theory and Design (McGraw-Hill, 1949), edited by Samuel Silver; Willard Van Tuyl Rusch and Philip Potter’s Analysis of Reflector Antennas (Academic Press, 1970); Peter Wood’s Reflector Antenna Analysis and Design (Peter Peregrinus, 1980); or Brian Westcott’s Shaped Reflector Antenna Design (Research Studies Press, 1983).
Another matter of concern is a major flaw in the treatment of what is probably the most important relationship in the whole subject of aperture antennas, including paraboloids—the Fourier transform relation between the field in the aperture and the radiated field in the Fraunhofer region. In chapter 3, figure 3.9 and its caption are incompatible, and the accompanying text only adds to the confusion. Given this indication of perfunctory editing and proofreading, one hopes that no other, less obvious anomalies exist.
Overall, Baars’s text is a valuable addition to the literature on large reflector antennas. As an encyclopedia of modern, very large paraboloidal antennas, it has no equal, and the existing state of the art is well documented therein. Despite the book’s flaws, I believe it will become a standard reference.
