This clause incorporates ANSI X3.263-1995, by reference, with the exceptions listed in 25.4. The ANSI standard states that the return loss at the AOI shall be above the limit line depicted in figure 25.1.6-1. Return loss, as defined in test 25.2.1, is the magnitude of the reflection coefficient expressed in decibels.
VI is the voltage in the incident wave.
I is the error in the reflection coefficient measurement. Table 1 shows e as a function of r. Figure 25.1.6-1 shows that the minimum conformant return loss is 10dB, which corresponds to a reflection coefficient of 0.32. As mentioned in test 25.2.1, return loss cannot be computed without a specified source impedance Z S . Z S is primarily resistive with a phase angle magnitude less than 3 o in the frequency range of 2MHz to 80MHz. This will force the parallel detection mechanism to configure the DUT for 100BASE-TX operation.