
ES User’s Guide
3-73
Making Measurements
Measuring Impedance using the Smith Chart
Measuring Impedance using the Smith
Chart
The amount of power reflected from a device is directly related to the
impedances of both the device and the measuring system; for example,
the value of the complex reflection coefficient
Γ
is equal to 0 only when
the device impedance and the system impedance are exactly the same.
Each value of
Γ
uniquely defines a device impedance.
The Smith chart is a tool used to map the complex reflection coefficient
Γ
to the DUT's impedance. In a Smith chart, the complex impedance plane
is reshaped to form a circular grid, from which the series resistance and
reactance can be read (R + jX). (See
Figure 3-33, “Interpreting the Smith
for more information on the Smith chart.) Marker features on the
analyzer display the resistance in units of ohms, and the reactance as an
equivalent capacitance or inductance in units of farads or henrys.
This section uses an example measurement to describe how to measure
the input impedance of an insertable bandpass filter like the one that
was supplied with your network analyzer. An S
11
measurement is
demonstrated in this example, but the same general concepts apply for
an S
22
measurement.
TIP
An optimum calibration is critical for achieving best measurement
accuracy. Refer to
Chapter 6, “Calibrating for Increased Measurement
for detailed information about all of the various aspects of
calibration.
Summary of Contents for HP 8712ES
Page 8: ...viii ES User s Guide ...
Page 17: ...ES User s Guide 1 1 1 Installing the Analyzer ...
Page 34: ...1 18 ES User s Guide Installing the Analyzer Preventive Maintenance ...
Page 35: ...ES User s Guide 2 1 2 Getting Started ...
Page 52: ...2 18 ES User s Guide Getting Started Performing the Operator s Check ...
Page 53: ...ES User s Guide 3 1 3 Making Measurements ...
Page 135: ...ES User s Guide 4 1 4 Using Instrument Functions ...
Page 159: ...ES User s Guide 4 25 Using Instrument Functions Using Markers Figure 4 15 Delta Marker Mode ...
Page 165: ...ES User s Guide 4 31 Using Instrument Functions Using Limit Testing Figure 4 16 Limit Lines ...
Page 224: ...4 90 ES User s Guide Using Instrument Functions Using an External VGA Monitor ...
Page 225: ...ES User s Guide 5 1 5 Optimizing Measurements ...
Page 246: ...5 22 ES User s Guide Optimizing Measurements Measuring Devices with Long Electrical Delay ...
Page 247: ...ES User s Guide 6 1 6 Calibrating for Increased Measurement Accuracy ...
Page 281: ...ES User s Guide 7 1 7 Front Rear Panel ...
Page 306: ...7 26 ES User s Guide Front Rear Panel Line Module ...
Page 307: ...ES User s Guide 8 1 8 Hardkey Softkey Reference ...
Page 410: ...8 104 ES User s Guide Hardkey Softkey Reference Z ...
Page 411: ...ES User s Guide 9 1 9 Specifications ...
Page 469: ...ES User s Guide 10 1 10 Safety and Regulatory Information ...
Page 475: ...ES User s Guide 10 7 Safety and Regulatory Information Regulatory Information ...
Page 476: ...10 8 ES User s Guide Safety and Regulatory Information Regulatory Information ...
Page 477: ...ES User s Guide 11 1 11 Factory Preset State and Memory Allocation ...