Explain the difference in typical return loss performance between a UPC and an APC connector.

The difference in return loss performance between a UPC (Ultra Physical Contact) and an APC (Angled Physical Contact) connector stems from the way their end-faces are polished. Return loss, also known as optical return loss (ORL), is a measure of the amount of light reflected back towards the source from a connector or other optical component. A higher return loss value (expressed in dB as a negative number, so a larger absolute value is better) indicates less reflection and better signal quality. UPC connectors have a flat, slightly curved end-face that is polished to achi....