TABLE OF CONTENTS Ian Instone
Network analysers are very complex instruments so it is important to define terms such as calibration to avoid confusion. The two dictionary definitions of calibration that can be applied to network analysers are 'to mark (a gauge) with a scale of readings' [1], and 'to correlate the readings of (an instrument, etc.) with a standard to find the calibre of [1]. Unfortunately neither of these expressions defines the term calibration as it is applied to network analysers, instead they relate better to verification which is the process where the network analyser's measurements are compared with those performed in a higher level laboratory.
Calibration in the network analyser sense is the process by which the errors within the instrument are compensated for, whereas verification checks that the resultant corrections have been properly assessed and applied. The extent of calibration used will depend on the desired measurement accuracy and the type of network analyser employed. To a large extent the available time will influence the type of calibration. There are two basic types of network analyser, both of them having their own advantages and limitations.
The scalar network analyser usually consists of a source, display/processor and a transducer. Earlier scalar network analysers rarely included a receiver, instead they normally employ wide band diode detectors that have the advantage of being able to make measurements over a very wide frequency range at high speed (Figure 12.1). Because this type operates over...
