Robert A. (Agilent Technologies, USA) Witte 
Spectrum and Network Measurements [PDF ebook] 

This book covers the theory and practice of spectrum and network measurements in electronic systems. Intended for readers who have a background in electrical engineering and use spectrum or network analyzers to characterize electronic signals or systems, this classic volume successfully consolidates the pertinent theory into one comprehensive treatment of frequency domain measurements. Witte”s thorough coverage of critical concepts, such as Fourier analysis, transmission lines, intermodulation distortion, signal-to-noise ratio and S-parameters enables the reader to understand the basic theory of signals and systems, relate it to measured results, and apply it when creating new designs.