7.1.21 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 Editor schematic. 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 current measured. 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: