Introduction - Anritsu MS2024B Manual

Chapter 9 — Distance Domain
9-1

Introduction

This chapter describes the Distance Domain feature in the Vector Network Analyzer. General
descriptions, key concepts, and examples are presented for distance measurements for both
coaxial and waveguide media. The Distance Domain was previously Option 501, but is now
standard in newer firmware. The firmware revision must be equal to or greater than the
following versions to have Distance Domain as a standard feature:
MS20xxC V1.14
MS20xxB V1.18
S412E V1.11
9-2 Distance Domain Measurements
The Distance Domain feature provides the ability to transform the native frequency domain
data (that is measured by the Vector Network Analyzer) into distance domain information.
Some typical applications are: help in determining the location of impedance discontinuities,
distance-to-fault (DTF) in cables, characterizing antennas, isolating and analyzing a desired
response in a one-port or two-port network.
The relationship between the frequency-domain response and the distance-domain response
of a network is described mathematically by the Fourier transform. The Vector Network
Analyzer makes measurements in the frequency domain, then transforms that data into its
distance-domain response, which can be displayed. This computational technique benefits
from the wide dynamic range of the instrument (and its measurement data) and from the
error correction of the frequency-domain data.
The transformation technique that is used by the Vector Network Analyzer (in most cases) is
the chirp-Z transform of the available frequency domain data for that parameter. Because the
transform simply treats the frequency domain values as input data, any S-parameter can be
transformed. The chirp-Z transform is (in a macro sense) very similar to the Fast Fourier
Transform with the exception that the output range can be variable. This permits you to zoom
in on a specific range of interest for the data display.
Two of the fundamental properties of distance-domain conversion are resolution and
maximum (alias-free) range. Resolution is the ability to resolve one discontinuity from
another. Resolution is limited by the frequency span of the measurement. Maximum range
defines how far you can see discontinuities on the media you are measuring. Beyond the
maximum range, the data just repeats itself, and you start seeing the same discontinuities
from closer ranges. The maximum range is determined by the frequency step size.
For more details about distance domain fundamentals, refer to the following application
notes:
• Reflectometer Measurements — Revisited - Anritsu Application Note 11410-00214
• Distance to Fault - Anritsu Application Note 11410-00373
Vector Network Analyzer MG PN: 10580-00289 Rev. K 9-1