2.20 RLOS - Return Loss
The Return loss test measures the impedance mismatch between the
transformer and a transmission line of a specified impedance. RLOS is
calculated from a measurement of the complex impedance and the specified
impedance. This test is suitable for audio & telecommunication
transformers and checks the effective input impedance of the transformer
in the application.
The load resistor is assumed to be on the fixture, but not shown on the
It is switched in circuit using an OUT test that must be inserted in the
program before the RLOS test.
(The relay patterns associated with inserting and removing fixture
resistors have deliberately not been included in the RLOS test dialogue
for two reasons: a) it would make the dialogue too complicated, and b) it
is not always necessary - e.g. in the case of a fixture where the resistor
is permanently fitted in circuit).
The test voltage is applied to the input winding, and the voltage and
From the measured results, and the reference impedance value (specified
by the user in the test dialogue), the return loss is calculated.
The impedances used are complex, where: -