What is return loss

While it is true that poor return loss means that an antenna cannot radiate: It is NOT true that good return loss guarantees effective antenna radiation. Unfortunately, every week, we see antennas in our lab that radiate poorly, yet have a good return loss.

Knowing not assuming your radiation efficiency is one of the many benefits of antenna testing. Sometimes the problem is that internal losses radiation inefficiency in an antenna can also create good return loss, since the lost energy is not being reflected returned to the transmitter. But how do we tell if our good return loss is due to radiation desired or internal absorption undesirable?

The most accurate way is to have the antenna evaluated by an antenna testing service, and verify its radiation efficiency. Good radiation efficiency is the ultimate goal for most antennas not just good return loss. There are two other indications of poor radiation efficiency that can be checked on a test bench:.

Are you ready for antenna insights? Partner with an antenna testing service and get results. In this article, we will discuss what an acceptable measurement parameter return loss is and how it affects performance and functionality. The measurement of the amount of light reflected back toward the source is called return loss , and it is expressed in decibels dB.

This measurement parameter is always a positive number, and a high return loss is a favorable measurement parameter that generally correlates to a low insertion loss. Similarly, reflectance, which is also a measurement parameter that expresses reflection in decibels, is a negative number, and if it is excessive, it is not a favorable measurement parameter.

Return loss is the loss of signal power due to signal reflection or return by a discontinuity in a fiber-optic link or transmission line. This impedance mismatch can be with a device inserted in the line or with the terminating load.

Incidentally, if you increase the return loss, it will correlate to a lower SWR. Return loss is a measurement parameter that expresses how well a device or line matches. A high return loss is advantageous as it will result in a lower insertion loss. Typically, we represent Voltage Standing Wave Ratio as a ratio of a specific number in comparison to 1. Return loss is the measurement of the reflected wave or signal strength traveling or returning back to a transmitter from an antenna.

However, the forward wave, or incident wave, travels from a radio transmitter to an antenna. There is also a reverse wave or reflected wave reflected from an antenna or even another connectivity element back to a radio transmitter. Reflections propagate back and forth in a line, but most assessments only consider the effects of the initial reflection because the back and forth energy attenuates until it is untraceable.

Generally, a higher return loss value is preferable. Furthermore, a higher return loss value signifies less reflection in the wires. For this reason, we desire a loss in this instance, and a high return loss is preferable.

Furthermore, we can summarize that return loss, which we also express in decibels is the ratio of incident power to reflected power. Therefore, we can see how the two types of loss measurement parameters help to accurately gauge the overall efficiency of a measurable signal and component within a system or in a through path. Determining insertion loss and return loss in high speed circuits requires understandings of component relationships.

In conclusion, when we combine the measurement parameters of both insertion loss and return loss, we can more accurately assess efficiency and performance. Furthermore, it can determine if there are impedance mismatches at the pins of the receiver and transmitter as well as the vias, connectors, and various other discontinuities. In short, the overview that these two parameter measurements provide is an essential assessment tool in understanding signal performance.

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For circuit board designs that perform well and can be manufactured without errors, follow these PCB component placement tolerances. Home » Blog » Insertion Loss vs. Return Loss: Signal Transmission and Reflection. What is Insertion Loss? What is Return Loss?