This chapter will discuss network measurements since the present work deals entirely with transmission lines and transmission line resonators. Also, because the sensors described in this work are intended to be connected directly to a network analyzer, understanding of these measurements is crucial to understanding of the operation and specifications of the sensors. However, in order to understand how a network analyzer can perform its task, it is important to understand how the various microwave quantities are defined and measured. We will therefore discuss some general methods of measurement and then link them to the network analyzer through the use of the S-parameters. We will discuss measurements in terms of the S-parameters since in the present work, we will only have recourse to measurements in transmission lines and cavity resonators and because the instrument we use to perform these measurements is a network analyzer.

Chapter Contents:

• 4.1 Introduction
• 4.2 N-Port networks
• 4.2.1 The scattering matrix and S-parameters
• 4.2.2 Generalized scattering parameters
• 4.2.3 Some properties of S-parameters
• 4.2.4 The ABCD-parameters and the transmission matrix
• 4.2.5 Relations between the various parameters
• 4.2.6 Shift of reference plane
• 4.2.7 Transformations between parameters
• 4.3 Use of the S-parameters for practical measurements
• 4.3.1 Matching of loads
• 4.3.2 Detection of resonance
• 4.3.3 Determination of losses
• 4.3.3.1 Reflection loss
• 4.3.3.2 Attenuation loss (transmission loss)
• 4.3.3.3 Insertion loss
• 4.3.3.4 Return loss
• 4.4 Other measurements
• 4.4.1 Frequency measurements
• 4.4.2 Wavemeters
• 4.4.3 Power measurements
• 4.5 Power sensors and detectors
• 4.5.1 Diode power sensors
• 4.5.2 Thermistors, bolometers, and thermocouples
• 4.5.3 Measurement of power density
• 4.6 Measurement of Q-factor of resonators
• 4.6.1 Q-Factors for series resonance
• 4.6.2 Q-Factors for parallel resonance
• 4.7 Measurement of impedance
• 4.8 Measurement of permittivity and loss tangent
• 4.9 Waveguide method of measurement
• 4.10 Cavity perturbation method
• 4.11 Other methods
• Bibliography

Inspec keywords: S-parameters; microwave detectors; transmission lines; cavity resonators; network analysers; microwave measurement

Other keywords: sensor; transmission line resonator; S-parameter; microwave measurement; network analyzer; cavity resonator

Subjects: Waveguide and microwave transmission line components; Network and spectrum analysers; Microwave measurement techniques; Sensing devices and transducers