Radio Astronomy Techniques

Outline of the chapter. The first two parts of this chapter, concerned respectively with receivers and aerials, represent a selection from a vast field of radio technology. lt is true that the material has been selected for its relevance to radio astronomy, but it remains a body of information on practice in radio technology which is current in connection with quite other fields than radio astronomy. lt will be recognized as such by the expert in radio and will appear to him to be profoundly specialized in places and shallow to the point of omission in others. But parts li and III have not been written primarily for the expert in radio, they have been written for the physicist or astronomer, engaged in radio astronomy, who would benefit from a collected and orderly exposition of those parts of radio technique which are especially relevant to his work. Whilst the compilation consisted merely in selection, it is felt that the result will serve a valuable end, as the corpus from which the selection has been made is too ex-, tensive for one not specifically grounded in radio to use efficiently without guidance.

This book presents lecture materials from the Third LOFAR Data School, transformed into a coherent and complete reference book describing the LOFAR design, along with descriptions of primary science cases, data processing techniques, and recipes for data handling.

This textbook presents the established sciences of optical, infrared, and radio astronomy as distinct research areas, focusing on the science targets and the constraints that they place on instrumentation in the different domains. It aims to bridge the gap between specialized books and practical texts, presenting the state of the art in different techniques.

This is a textbook for undergraduate courses on radio astronomy. Written by an active professor and researcher in the field, it begins by explaining why conducting observations at radio frequencies is so important, then reviews essential physics concepts corresponding to a sophomore-level curriculum or higher.

Reflector antennas are widely used in the microwave and millimeter wavelength domain. Radio astronomers have developed techniques of calibration of large antennas with radio astronomical methods. These have not been comprehensively described. This text aims to fill this gap. It takes a practical approach to the characterisation of antennas. All calculations and results in the form of tables and figures have been made with Mathematica by Wolfram Research. The reader can use the procedures for the implementation of his own input data. The book should be of use to all who are involved in the design and calibration of large antennas, like ground station managers and engineers, practicing radio astronomers and graduate students in radio astronomy and communication technology.

This book presents lecture materials from the Third LOFAR Data School, transformed into a coherent and complete reference book describing the LOFAR design, along with descriptions of primary science cases, data processing techniques, and recipes for data handling.

1. 1. Short History of Solar Radio Astronomy Since its birth in the forties of our century, solar radio astronomy has grown into an extensive scientific branch comprising a number of quite different topics covering technical sciences, astrophysics, plasma physics, solar-terrestrial physics, and other disciplines. Historically, the story of radio astronomy goes back to the times of James Clerk Maxwell, whose well known phenomenological electromagnetic field equations have become the basis of present-time radio physics. As a direct consequence of these equations, Maxwell was able to prognosticate the existence of radio waves which fifteen years later were experimentally detected by the famous work of Heinrich Hertz (1887/88). However, all attempts to detect radio waves from cosmic objects failed until 1932, which was mainly due to the early stage of development of receiving techniques and the as yet missing knowledge of the existence of a screening ionosphere (which was detected in 1925). Therefore, famous inventors like Thomas Edison and A. E. Kennelly, as well as Sir Oliver Lodge, were unsuccessful in receiving any radio emission from the Sun or other extraterrestrial sources. Another hindering point was that nobody could a priori expect that solar radio emission should have something to do with solar activity so that unfortunately by chance some experiments were carried out just at periods of low solar activity. This was also why Karl Guthe Jansky at the birth of radio astronomy detected galactic radio waves but no emission from the Sun.