1-44
Making Measurements
Measuring Electrical Length and Phase Distortion
3. Substitute a thru for the device and perform a response calibration by pressing:
4. Reconnect your test device.
5. To better view the measurement trace, press:
Notice that in Figure 1-34 the SAW filter under test has considerable phase shift within only a 2 MHz
span. Other filters may require a wider frequency span to see the effects of phase shift.
The linearly changing phase is due to the device's electrical length. You can measure this changing
phase by adding electrical length (electrical delay) to compensate for it.
Figure 1-34 Linearly Changing Phase
6. To place a marker at the center of the band, press and turn the front panel knob, or enter a
value from the front panel keypad.
7. To activate the electrical delay function, press .
This function calculates and adds in the appropriate electrical delay by taking a 10% span about the
marker, measuring the , and computing the delay as the negative of
/frequency.
Alternatively, press and turn the front panel knob to increase
the electrical length until you achieve the best flat line, as shown in Figure 1-35.
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