Chapter 17 - Microwave Instrumentation and Measurements

Abstract

This chapter deals with microwave instrumentation and measurements. Scattering parameters include S-parameter measurements that are complex quantities containing both amplitude and phase information. There are two measurement techniques that are used in the industry. One measures both the amplitude and phase of the S-parameters, and the other measures only the amplitude. The first instrument is called a vector network analyzer, and the second a scalar network analyzer. Vector analyzers are mostly used in design and development work, whereas the scalar analyzers are in wide use as production test equipment. The chapter discusses scalar analysis and its associated uncertainties. It is also noted that S-parameters are intuitive and there is a phase angle associated with each S-parameter. A typical test setup for a scalar network analyzer consists of a signal source, a sweeper that is a directional element that separates the transmitted and reflected signals, a detector, and an oscilloscope or power meter. The oscilloscope contains a logarithmic video amplifier that essentially converts the detected signals into a logarithmic output to be displayed on the oscilloscope.