 Hi, I'm Tom with Gaurav Elmans and today we'll talk about beam efficiency. Antennas have many parameters and it can be often quite difficult to understand which ones are important and when. In Wisp industry, users often give a lot of importance to front to back ratio, which says how strong the back lobe is compared to the main lobe or side lobe level, which tells us what's the strength of the biggest side lobes. While both of these parameters have some information of value, what Wisp should really care about is beam efficiency. Beam efficiency tells us what portion of the total energy an antenna radiates is contained within the main lobe, where the main lobe is defined up to the first null of the radiation pattern. In other words, beam efficiency is a measure of side lobes of an antenna. For example, if the beam efficiency is 40%, it means the remaining 60% of the radiated energy goes into the side lobes. For a stable network, antennas for fixed wireless applications should perform well in the whole bandwidth of operation, which is why it makes sense to average beam efficiency over the whole bandwidth. In textbooks, beam efficiency is defined at a single frequency, but we took it to another level by averaging the beam efficiency over the whole bandwidth of operation and both polarizations of an antenna. This way, the beam efficiency as a parameter is much more robust because the higher the average beam efficiency is, the better the stability of antenna performance resulting in a stable network regardless of the channel you use. Beam efficiency gives you a complete information about the side lobes an antenna might have because, first, it considers the full 3D radiation pattern and second, it's averaged over the whole bandwidth of operation. In contrast, the front-to-back ratio or side lobe level is commonly defined based on a single slice of the radiation pattern at a single frequency point, giving the manufacturers a huge gray area to make your antennas look better by picking the bed snippet of the radiation pattern. Eventually, front-to-back ratio and side lobe level only define one of the many side lobes an antenna might have at a single frequency, which makes these parameters practically useless in real life. For more interesting topics from the Earth world, check out some of our older videos and don't forget to subscribe to our channel.