Tools of Radio Astronomy

This is a book describing the tools that a radio astronomer needs to pursue his trade. These tools consist, on one hand, of the radio telescopes and the various kinds of receivers needed to analyse the cosmic radio signals, and on the other, of the physics of the radiation mechanisms responsible for both the continuous and line radiation. The book grew out of a one year graduate course that I gave repeatedly at the Ruhr University at Bochum. I hope, however, that this text will also be useful for all scientists that use data and results obtained by radio astro nomical means and will help them to understand both their strong points and characteristic drawbacks. Finally, this book may occasionally save some scien tists working in the field of radio astronomy from long searches in the literature when questions concerning their tools occur. Although the students whom this course was addressed to had a rather thor ough background knowledge of physics, a characteristic difficulty often turned up when the material tools (Chaps. 4-7) were discussed. Obviously there is a difference between how a subject is treated in a genuine physics book and the way it is dealt with in a text intended for engineers - one example is the way in which four-terminal networks are used. I have tried to explain everything using concepts that are familiar to both astrophysicists and general physicists.