Newtons4th PSM1700 User Manual

PSM1700 PsimetriQ user manual
16-8
16.7 Return loss
Return loss is a measure of impedance mismatch in signal
transformers that are terminated with the design load
resistance.
The secondary winding is terminated with the appropriate
load resistance and the primary is energised via a source
resistance that is equal to the resistance that should be
reflected back from the secondary (load resistance *
(turns ratio)
2
). The impedance looking into the primary is
measured.
If z is the complex impedance measured at the primary,
and R is the source resistance then the return loss is given
by:
return loss = | z + R | / | z - R |
Return loss is usually expressed in dB:
= 20 log (| z + R | / | z - R |) dB
As a figure of merit, a higher value of return loss indicates
a better transformer.
The circuit arrangement for return loss is the same as that
for inductance measurement except that the secondary is
terminated with the appropriate load resistance.
As the value of the load source resistance, R, is used in the
computation, it is important that this value be entered via
the MODE menu.

Newtons4th PSM1700 Specifications

General

Brand	Newtons4th
Model	PSM1700
Category	Measuring Instruments
Language	English