Text preview for : an_1287-3.pdf part of HP an 1287-3 HP Publikacje an_1287-3.pdf
Back to : an_1287-3.pdf | Home
Applying Error Correction
to Network Analyzer
Measurements
Application Note 1287-3
Table of Contents
Page
Introduction 2
Sources of Errors
and Types of Errors 3
Types of Error Correction 4
One-Port Calibration 4
The Effects of Adapters 5
Two-Port Error Correction 6
Electronic Calibration 7
Estimating Measurement
Uncertainty 8
Performing a Transmission
Response Calibration 10
Enhanced-Response Calibration
for Transmission
Measurements 11
Full Two-Port Calibration 12
TRL Calibration 12
Calibrating Noninsertable
Devices 13
The Swap-Equal-Adapter
Method 13
Adapter-Removal Calibration 14
2
Introduction Only perfect test equipment would not need correction. Imperfections exist
in even the finest test equipment and cause less than ideal measurement
results. Some of the factors that contribute to measurement errors are
repeatable and predictable over time and temperature and can be removed,
while others are random and cannot be removed. The basis of network
analyzer error correction is the measurement of known electrical
standards, such as a through, open circuit, short circuit, and precision
load impedance.
The effect of error correction on displayed data can be dramatic (Figure 1).
Without error correction, measurements on a bandpass filter show
considerable loss and ripple. The smoother, error-corrected trace produced
by a two-port calibration subtracts the effects of systematic errors and
better represents the actual performance of the device under test (DUT).
This application note describes several types of calibration procedures,
including the popular short-open-load-through (SOLT) calibration
technique, and through-reflect-line (TRL). The effectiveness of these
procedures will then be demonstrated in the measurement of high-
frequency components such as filters. Calibrations will also be shown for
those cases requiring coaxial adapters to connect the test equipment, DUT,
and calibration standards.
Figure 1.
Response versus
Measuring filter insertion loss
Two-Port
Calibration CH1 S21&M log MAG 1 dB/ REF 0 dB
CH2 MEM log MAG 1 dB/ REF 0 dB
Cor
After two-port calibration
After response calibration
Uncorrected
Cor
x2 1 2
START 2 000.000 MHz STOP 6 000.000 MHz
3
Sources and Types of All measurement systems, including those employing network analyzers,
Errors can be plagued by three types of measurement errors: