 Hi, I'm Mr. T with R of Elements. Radiation efficiency is one of the basic antenna parameters you should know about. Before we go into the topic though, comment, like and consider subscribing to our channel if you find our videos useful. Radiation efficiency is closely tied to antenna gain and tells us what part of the RF signal energy delivered to the antenna is radiated into free space. It spans values from 0 to 100%, where 100% would be the ideal. In reality, because of the material and manufacturing imperfections, we can only approach its value. There are three main components of the signal power loss decreasing antenna radiation efficiency – reflection loss or mismatch, conductor loss and dielectric loss. The main cause within antenna structure itself varies depending on antenna type. The full metal antennas are affected mainly by their conductor loss, while the PCB based antennas by dielectric loss. The reflection loss is caused by the impedance mismatch of the antenna input port and the cable feeding it. The bigger the difference, the more power is reflected from the antenna port decreasing the antenna radiation efficiency. Check our older Inside Wireless episode for more details on this topic. Electrical currents flowing through the metal antenna parts with particular resistance cause some of the RF signal power to be lost in the metal. In practice, it depends on the antenna type, size and operating frequency what the conductor loss will be, but for most antennas the conductor loss increases with frequency due to increasing skin effect and at very high frequencies higher surface roughness further amplifies conductor loss. Materials such as PCB substrate on which antennas are often etched have so called lost tangent, which is a measure of how strongly particular material absorbs the power of the RF signal passing through it resulting in the heating of the material. In practice, it is hard to compute or separate the conductor and dielectric loss, but they can be determined experimentally. To determine the radiation efficiency of an antenna, we can express the losses as efficiencies, being inversely proportional to the losses with values from 0 to 100%, where the 100% would be the ideal value for each of them. Antenna radiation efficiency that relates the gain and directivity is defined as the product of combined conductor and dielectric loss, because these two components are tied to the materials an antenna is made of. This is the official definition of antenna efficiency according to the IEEE standards. For more information about gain, check our previous video through the link in the corner or in the video description. This gain does not include the losses arising from impedance or polarization mismatch. This gain includes the impedance mismatch on top of the material losses and considers the chain of the feed and transmission line and the antenna together. Ideally, antenna radiation efficiency would be 100%, meaning gain would be equal to directivity and all the power at the antenna ports is radiated into free space and none is lost in the materials. But since real-world materials always introduce some loss, we can only approach this value. The same goes for the realized gain. There is always some mismatch between a feeding cable and an antenna, so realized gain is always smaller than the absolute gain. And what do you think? Let us know in the comments what antenna radiation efficiency is sufficient in your industry. If you think our videos are useful, consider subscribing to our channel and hit that like button.