Microwave and Radar Engineering

11

Microwave Measurements

11.1 INTRODUCTION

The measurement parameters and techniques used for analyzing the circuits (or networks) are different at low and microwave frequencies. At low frequencies, the entire circuit is affected by the voltage and current waves at the same time. Thus the circuit elements are lumped. It is convenient to measure current and voltage and to use them to calculate power at low frequencies. However, at high frequencies, it is convenient to describe a given network in terms of voltage waves and current waves rather than voltage and current, because they vary with position in a transmission line (or waveguide). At microwave frequencies, most of the quantities measured are relative, not absolute as in low-frequency ...