VSWR Pretest | Sensor Operational Tests |
5-3 VSWR Pretest
The most common cause of power sensor failure is excess input power. Applying power exceeding the damage level shown on the label will damage the sensor’s sensing element resulting in impedance change. Input match will be degraded when element impedance is changed. If you suspect that a senor is damaged, you should start with an input match pretest.
The maximum VSWR values are listed in the Performance Specification section of this manual. The uncertainty of the VSWR test equipment will affect actual measurement values. See the following Table
Test Procedure
Follow the manufacturers S11 (or return loss) calibration procedure to perform calibration on a network analyzer. Connect the power sensor to the network analyzer test port and measure power sensor input match. Typically, matches are measured in terms of return loss in dB. Return loss and magnitude of the reflection coefficient conversion equations are as follows:
ρ=
RL =
RL = Return Loss in dB
ρ= Magnitude of the Reflection Coefficient
VSWR and magnitude of the reflection coefficient conversion equations are as follows: VSWR = (1 + ρ) / (1 – ρ)
ρ= (VSWR – 1) / (VSWR + 1) where
VSWR = Voltage Standing Wave Ratio
ρ= Magnitude of the Reflection Coefficient
Record the measured data into Table
Note: There are no
Table
| MS4624B Reflection | Maximum Reflection |
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Frequency | Coefficient Uncertainty | Coefficient | Actual Measurement |
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50 MHz to 2 GHz | 0.013 | 0.050 + 0.013 = 0.063 |
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2 GHz to 6 GHz | 0.020 | 0.100 + 0.020 = 0.120 |
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MA24106A UG |