This book describes the various devices used in radio communication and broadcasting to achieve high selectivity filtering and coupling. After providing 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, bandpass and pass-reject duplexers, multicouplers, circulators, low-noise amplifiers, helix resonators, and much more.