R&S FSH
Measuring forward and reflected power
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Measuring forward and reflected power
The Directional Power Sensors R&S FSH-Z14 and R&S FSH-Z44 are connected between the source
and the load and measure the power flow in both directions, i.e. from the source to the load (forward
power) and from the load to the source (reflected power). The ratio of forward to reflected power
indicates how well a load is matched to the source. This ratio is referred to as return loss or voltage
standing wave ratio (VSWR).
The Directional Power Sensors R&S FSH-Z14 and R&S FSH-Z44 are of non-symmetrical design, i.e.
they must be connected such that the forward arrow (1
2) on the sensor points to the load
(corresponding to the direction of forward power).
The directional power sensors are controlled and powered via a special serial interface. The sensor
cable is to be connected and screwed to the POWER SENSOR connector on the R&S FSH. The
sensor is to be connected between the source and the load.
Directional Power Sensor
R&S FSH-Z14 / R&S FSH-Z44
Source
Load
Power Sensor
connector
When measuring high powers, strictly observe the following instructions to prevent damage to the
sensor or hazard to persons:
•
The permissible continuous power at the input of the directional power sensor must in
no case be exceeded (see diagram on the rear of the sensor).
•
Make sure that the RF power is switched off before connecting the sensor.
•
Make sure that the RF connectors are tightly screwed.
Failure to comply with these instructions may cause injuries like burns to the skin or may
damage or even destroy the equipment used.
