The solution of transmission-line problems by use of the circle diagram of impedance

In modern microwave technique transmission lines find wide application both for the interconnection of component pieces of equipment, such as oscillators and receivers and aerial systems, and as inductive and capacitive circuit elements within these pieces of equipment. In the former they are normally several wavelengths long, but in the latter only fractions of a wavelength. The analysis of their behaviour has been greatly facilitated by the development of a circle diagram technique, the theory and application of which are discussed. This is followed by a discussion of the fundamental principles underlying the transmission-line equations on which this technique is based, and of the meaning to be attached to the word ¿impedance¿ at very high frequencies in respect of terminating attachments to lengths of transmission line. In particular, attention is given to the physical possibility of producing a non-reflecting termination, on one aspect of which there appears to have been widespread misunderstanding.