Chapter 3 — Vector Network Analyzer 3-6 VNA Measurements - 2-Port Gain Measurements
MS20xxA VNA Master UG 10580-00166 Rev. C 3-19
DMax
DMax is the maximum horizontal distance that can be analyzed. The Stop Distance can not
exceed D
max
. If the cable is longer than D
max
, then D
max
needs to be improved by increasing
the number of datapoints or by lowering the frequency span ( F). Note that the datapoints
can be set to 137, 275, or 551.
Suggested Span
If the frequency span is set to the suggested span, the Stop Distance will equal Dmax giving
the best fault resolution for the given conditions. With Stop Dist entered in meters, the
following relationship can be obtained:
2-Port Gain Measurements
Two power levels are available with 2-port measurements: High (0 dBm) and Low (-35 dBm).
The low power setting should be used when making direct gain measurements of amplifiers.
This will help to ensure that the amplifier is operating in the linear region. The High power
setting is ideal when characterizing passive devices but can also be used when making
relative gain or antenna-to-antenna isolation measurements in the field.
The Variable Bias Tee Option (Option 10) can be used to place between +12V and +24V on the
center conductor of the
RF In port. It is designed to deliver 500 mA at +12V and 250 mA at
+24V.
Also refer to “Bias Tee” on page 3-52 in the sweep menu section.
Example 1
This example describes an S21 measurement of an attenuator. Figure 3-13 displays the
results of this example when using the VNA measurement menu. The example is also valid in
the Field measurement menu. The difference between these two choices requires a different
soft key selection, as stated in 2.
Procedure
1. If a test port extension cable is to be used, then connect it to the RF Out connector on the
VNA Master.
2. Press the
Measurement function hard key and select S21 Transmission | Log Magnitude (VNA
menu) or
2-Port Gain (Field menu).
3. Press the
Shift key, then the Sweep (3) key.
4. Select the
Power soft key and set power to High.
5. Press the
Freq/Dist function hard key and set the Start Frequency and Stop Frequency.
6. Press the
Shift key, then the Calibrate (2) key.
7. Press the
Start Cal soft key and perform a 2-port OSL calibration at the connector or at
end of the extension cable. Follow the instructions on the display or refer to
“Calibration” on page 3-3 for more details.
D
max
Datapoints 1–()Fault Resolution×=
Suggested Span (Hz)
Datapoints 1–()1.5 10
8
× vp×()×
Stop Distance (meters)
--------------------------------------------------------------------------------------------=
10580-00166C.book Page 19 Thursday, February 21, 2008 12:52 PM
To Next Page
Loading...
