Anritsu 0701012, MA24106A manual Test Procedure, Vswr Pretest Sensor Operational Tests

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 5-2 for an example of how measurement system uncertainty can affect the Expected Maximum Reflection Coefficient when using the Anritsu MS4624B Vector Network Analyzer.

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= 10–RL/20

RL = –20logρwhere

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 5-2 under the Actual Measurement column. The Actual Measurement should be smaller than the Maximum Reflection coefficient. The Maximum Reflection Coefficient is equal to the measurement system uncertainty added to the sensor’s reflection coefficient specification. If the Actual Measurement reflection coefficient is larger than the Maximum Reflection Coefficient, then the power sensor may be defective. If the actual reflection coefficient is significantly larger than the maximum values in Table 5-2, then the sensor is damaged and it is not necessary to perform further testing.

Note: There are no user-serviceable parts inside the power sensors. Contact your local Anritsu Service Center and return defective sensors with a detailed description of the observed problem.

Table 5-2.Pretest Measurement Result

	MS4624B Reflection	Maximum Reflection
Frequency	Coefficient Uncertainty	Coefficient	Actual Measurement
50 MHz to 2 GHz	0.013	0.050 + 0.013 = 0.063
2 GHz to 6 GHz	0.020	0.100 + 0.020 = 0.120

5-2 MA24106A UG