This book describes the various devices used in radio communication and broadcasting to achieve high selectivity filtering and coupling. After providing a background in the basics of microwave theory and more detailed material – including a special chapter on precision and errors in measurement – the reader will find detailed descriptions, manufacturing processes, and, for the most useful instances, a number of worked-through formulas, which will allow engineers and technicians to design circuits or components for filtering or coupling applications. Content is covered in this format across a broad range of fields including coaxial cavities, combline filters, band-pass and pass-reject duplexers, multicouplers, circulators, low-noise amplifiers, helix resonators, and much more.