 All right, once again, good morning everyone and I'm Tomasz Wonski and I'm a product manager at RF Elements and marketing manager at the same time. And my promise for today to you is that you will learn what beam efficiency is and why do we actually think it's the most important antenna parameter in Wisp Networks as well as you will also learn about the other antenna parameters that are usually thought or known for showing the ability of an antenna to deal with noise. So let's start. So the parameters that are usually considered relevant when speaking of the ability of an antenna to mitigate the interference are front-to-back ratio, side-loop levels or Etsy masks. And these you most likely know or at least heard about and the one we at RF Elements believe is the most important one in terms of noise suppression is beam efficiency. Beam efficiency is the ratio of the main-loop energy to the total energy an antenna radiates. Now it says how much of the total signal energy is contained in the main-loop, as simple as that. So the maximum beam efficiency value is 100%, which is an ideal situation. That's really the ideal goal we desire. And the smaller the beam efficiency is, the more side-lobes an antenna has. Since antenna side-lobes are the direct cause of problems in Wisp Networks, antennas with a lot of side-lobes should be avoided at all costs, really. The higher the beam efficiency of the antenna you use is, the better for your network and the end-users of your services in the end. Beam efficiency is an antenna parameter not only to know about, but actually also factor it in when you're deciding on how to deal with the interference issues you may have in your unlicensed networks. Now here is a practical example. So this is the radiation pattern of a generic parabolic dish. And if its beam efficiency is 40%, the remaining 60% of the energy goes everywhere else. In other words, side-lobes. And because any radiation outside the main-loop is a side-loop, well obviously it must go in the side-lobes. And note that all the side-lobes are highlighted here, so beam efficiency includes all the side-lobes an antenna has. And if you want to compare two antennas in terms of side-loop performance, beam efficiency makes it extremely simple. The higher number wins. In this example, the ultra horn on the left has beam efficiency 99%, so only 1% short of perfection. A generic dish antenna on the other hand has beam efficiency 40%, so the remaining 60% of the energy it radiates is in the side-lobes. 99% is clearly more than 40%, and that's why ultra horn is way better antenna in terms of noise suppression, in our opinion the best on the market to be honest. But to be fair, let's also have a look at the parameters you may already know. Front-to-back ratio is one of them and many manufacturers included in their data sheets, so let's have a small recap of front-to-back ratio. The conventional thinking about front-to-back ratio is that if front-to-back ratio is high, it means an antenna is good for dense collocation. So if the antennas are back-to-back and both have high front-to-back ratio, they will not interfere with each other. The reality is that high front-to-back ratio does not mean that antenna is good for dense collocation in every possible setting. It is simply a misunderstanding. It's important to really get this right, because the next time you have a conversation about front-to-back ratio, you can be sure that if anyone is saying that high front-to-back ratio means an antenna is great for collocation, you know that the person is either misinformed or simply didn't go deep enough with the topic. High front-to-back ratio means that the back-lobe is small. This is the lobe pointing in the opposite direction as the main lobe. It can also mean that the group of side-lobes around the back-lobe is small, depending on the definition or the way the front-to-back ratio was determined. The front-to-back ratio is very easy to understand. Looking at the radiation pattern of an antenna in this example, we show the pattern of a directional patch array. The front-to-back ratio is the difference between the gain of the main lobe and the gain of the back-lobe, which is pointing backwards. In practice, front-to-back ratio is often determined based on the strongest side-lobe. From a plus-minus-thirty-degree angle around the back-lobe because of possible manufacturing, assembly or material imperfections. And because of these imperfections, the back-lobe might not just be a single lobe, but can be divided and fractured into several minor lobes around that direction. Nevertheless, back-lobe is one of many side-lobes. Antennas used in the Wisp industry typically have. So if back-lobe is one out of many side-lobes, then it's probably not so important. This is the typical error in interpretation of front-to-back ratio. It doesn't say anything about all the other side-lobes. When two antennas are exactly back-to-back, which, let's be honest, is quite a rare kind of scenario, high front-to-back ratio can help to decrease the interference level the radios see. But, as I said before, typical antenna used in Wisp networks has a lot of side-lobes and the back-lobe itself can be quite complex at the same time. As soon as there are more links on a tower or in the or collocated antennas are not exactly back-to-back, you are looking at noise issues coming your way because of all the other side-lobes that these antennas have. High front-to-back ratio provides absolutely no protection in high noise environment. So for urban and suburban areas with other wireless links in the neighborhood or even on the same tower, front-to-back ratio is irrelevant. These other links may be yours or competitors. Either way, they're using very similar hardware to yours, meaning their antennas most likely also have many side-lobes that create noise, receive the noise and anything in between through the rest of the side-lobes. Another parameter I want to mention is side-lobe level. In practical life, its effect is similar to that of the front-to-back ratio. So let's have a look at the details of that. Side-lobe level is the difference between the gain of the strongest side-lobe and the main-lobe. It is more useful than front-to-back ratio because it at least points out the strongest side-lobe, which says a bit about antenna performance in high noise areas, but just a little bit really. If side-lobe level is high, the strongest side-lobe is close to having the gain of the main-lobe, making it a very poor antenna for WISP networks. The issue with side-lobe level is that it does not talk about all the side-lobes an antenna has. Again, side-lobe level is defined by the strongest side-lobe, which again is only one side-lobe out of many and defined at a single frequency as well. Since the side-lobes are changing with frequency, the noise level also changes with them. So despite you know what the strongest side-lobe is at a single frequency, it is not very useful in the bigger picture, since simply switching the channel, everything changes. Side-lobe level is therefore a very similar metric to front-to-back ratio. It tells you what the strongest side-lobe is at one frequency, but nothing about the rest of the side-lobes throughout the useful bandwidth of an antenna, which is the biggest issue with these metrics. In WISP networks all side-lobes of an antenna matter. So to sum it up, not all antenna parameters are practically useful for WISP networks. It simply depends on the context an antenna is used in. In the end, it is up to the users and actually mainly the manufacturers to responsibly look at each antenna parameter and evaluate, honestly evaluate whether it is useful in the framework of WISP networks or not. The conclusion for front-to-back ratio and side-lobe level clearly says that these two are really not so important. They tell a very limited part of the story of the side-lobes. And if you're wondering why WISP antenna manufacturers use them and show them in their data sheets and on, my guess would be it's simply a remnant of the times when these parameters were the only ones that were easy to determine and calculate without enough computational power. You may also know about the Etsy Masks, which to a degree also serve as a parameter that says how well antennas perform in terms of noise. So yeah, let's have a look at those. It is important to clarify that Etsy Masks consider two main cuts of antenna radiation pattern, the azimuth and elevation. They consider two slices of the 3D radiation pattern. So again, rather incomplete, like completely incomplete, so to say, measure from the point of view of the whole 3D radiation pattern and all the side-lobes that matter in WISP networks. Etsy Masks are observed at three frequency points. So an improvement, right? So the beginning, the middle and the end of the spectrum an antenna works in. Nevertheless, the rest of the spectrum, which is rather wide in the case of WISP networks, is not included in Etsy Masks definition. So again, not very robust measure. So how does one get to the Etsy Masks and how do they look like? Starting with the polar plot, you may know from the antenna data sheets, redrawing it and redrawing it on an XY axis or XY plot. Etsy Masks are the blue dashed line, which says that the radiation pattern should stay below the mask so that an antenna can be declared compliant with a given Etsy NOR. If the radiation pattern does not stay below the mask, the antenna is not compliant, which is the case for this example. The masks are easy to understand and to their credit, they do consider the whole 360-degree circle of a radiation pattern, but unfortunately only two cuts of the whole 3D radiation pattern at three frequency points of the whole spectrum an antenna may work in. So vast majority of the spectrum and the radiation pattern is simply not included. Which is why in terms of interference suppression in WISP networks, even these Etsy Masks are really not that much of a useful parameter. So whenever you see an antenna being compliant with a particular Etsy NOR, know that it does not really bring much added value in terms of noise suppression in WISP networks. At our development, as a company, we are convinced about doing the right thing for the customer and the industry at the same time. So we investigated the textbooks ourselves and found about beam efficiency, which is the most complete measure of side loops out there, if it's used well. And when I say the most complete, I'm not just using empty overstatements or simplifications. And by the time we're done with the following slides, I promise you will understand why. So beam efficiency is the answer to the question of side loops. So despite you might have never heard about beam efficiency before, at our development, we do what we believe is the best for the customer, even if it means bringing something not considered or established before, which might be different from what other manufacturers may be saying. Beam efficiency is a ratio of the energy in the main loop to the total energy on antenna radiates, making it a perfect and complete measure of side loops. So how is beam efficiency obtained? Beam efficiency of an antenna can be determined through a measurement in an unequally chamber, like the one in the image. The antenna is attached to a rotary stage, which rotates it into axes, and it can measure the radiation pattern of an antenna, the full 3D radiation pattern. And based on the measurement, we can calculate beam efficiency. Alternatively, if the model of an antenna is precise, or let's say an antenna is simple enough, we can use simulation software to do the same thing, obtaining the radiation pattern. And based on that, we can calculate beam efficiency. So if beam efficiency is 40%, this amounts to the power that goes into the main loop. So the remaining 60% must therefore be in the side loops. No question there. And note that all the side loops are highlighted. So beam efficiency really includes all the side loops of an antenna, not just one or a slice of the radiation pattern, but the whole package, the full 3D data, which is what makes beam efficiency a complete measure of side loops. Everything is included. And you can calculate beam efficiency for any antenna out there. Here you see the radiation pattern of a typical sector antenna. If beam efficiency is 58%, the rest of the energy, meaning the 42%, must be in the side loops. This clearly tells you why the patch array sector antennas are really not so good for unlicensed WISP networks, for the most part. 42% of the signal they radiate and receive is noise. Now WISPs use quite a wide chunk of the spectrum. But in antenna textbooks, beam efficiency is defined at a single frequency and for a single polarization. Now this is the case for most textbook parameters actually. And it makes perfect sense to always consider any antenna parameter in the whole useful bandwidth. Antenna works in not just the single frequency point. And since WISPs use their antennas in a wide frequency band, it only makes perfect sense that an antenna should perform well in the whole bandwidth in all important aspects, including beam efficiency. Which is why we decided to actually average beam efficiency over the whole useful bandwidth and on top of that for both polarizations. And the effect of this averaging is that it turns this textbook beam efficiency definition in a much more robust and reliable measure of the silo performance than the single frequency and single polarization definition. Or anything else out there really. The vast majority of antennas used for sector coverage with networks are either patch arrays or horns. And the patch arrays have many frequency dependent silo. So their beam efficiency values are somewhere on the scale of 60%, depending on the manufacturing and the design quality. The RF element horns, both symmetrical and asymmetrical, have beam efficiency between 90 and 95%. Now you can see other horns in this comparison as well. And this is to help you understand that it takes a considerable effort to design a horn antenna such that its beam efficiency is high. The stable and zero silo performance is not a given as soon as you have a horn. So be careful with that. But we do put a lot of effort into design of our antennas. Likewise with the point-to-point antennas. The patch arrays are again at the bottom of the beam efficiency performance due to the many frequency dependent silo's collecting and transmitting the noise hurting any and every wisdom network out there. And dishes are somewhat better. And generally the bigger the is, the better the beam efficiency becomes if the antenna is carefully designed and well manufactured on top of that. Now with any antenna though, the compromises accepted at the design stage unfortunately cannot be compensated by manufacturing quality since the real world results are at best approaching the results which we get from the simulation. What is interesting here though is the ultra horn. Its beam efficiency is 99%. Now let that sink in for a second. Over the whole bandwidth of operation in both polarizations, the beam efficiency of ultra horn is practically perfect. Only 1% of the RF signal goes into silo. So if you ever wonder if ultra horn was worth the extra cash compared to a dish with similar gain, you have a very clear answer here. With 99% beam efficiency, it is the best performing antenna on the market in terms of noise suppression. And the good thing is, you can use ultra horn not only for point of point but also for point of multi-point coverage. And with the option of tilting the antenna down, you can actually dynamically adjust the coverage. So it's really a very versatile tool and the best tool in terms of noise suppression. Beam efficiency tells you everything about silo performance. The higher the beam efficiency is, the better an antenna performs, period. So forget about front of a ratio, silo level or etsy masks and really focus on beam efficiency of an antenna when dealing with noise. Not only is it the most complete measure of silo, but it is also extremely robust measure of silo because of the averaging over the frequency, band and both polarizations. And a word of caution here. The average beam efficiency is our own internal standard, our development standard we set up for ourselves. So if anyone is telling you their antenna has high beam efficiency as well, ask them if it's averaged over the whole useful bandwidth and both polarizations to make sure the comparison is fair. Since it rarely happens that a wireless link is situated in a completely isolated place, the interference is present practically everywhere. The noisier the environment, the more important beam efficiency of an antenna you use becomes because the higher the beam efficiency, the better noise isolation. And recently you can also hear claims from other antenna manufacturers saying for example, well this sector patch or antenna works like horn in terms of avoiding the noise or similar statements. And to these claims, I would just ask a single question. What is the average beam efficiency of that antenna? Now if the beam efficiency of that antenna is of similar values, then I would stay quiet and say, yes, I agree. But otherwise if the beam efficiency is anything below 90%, you can be sure that they're really not the same and the claims of the manufacturers are probably more of a marketing fluff than anything else. And in the following section, I will tell you about the practical implications and consequences of using an antenna with high beam efficiency. And we can sum up the effect of high beam efficiency antennas into one statement, higher throughput. So in a sector with no other links in the area, you don't mind the siloes, but as the number of sectors grows, their siloes cause the noise floor to rise. And higher noise floor equals lower SNR the radios are working with and eventually lower throughput. The beam efficiency of patch array sectors is on the order of 60% as we saw. So the remaining 40% of the energy is in the siloes that collect and transmit interference to other links within yours but also competitors networks, obviously. So low beam efficiency equals lower throughput and consequently more unsatisfied customers and constant issues with your network and that keeps you unnecessarily busy. Low beam efficiency of these antennas works in a very similar way. It's really the same thing, but not different really. The siloes collect the noise from its surroundings and transmit it to all neighbouring links again. So whether it's a backhaul link or a distant narrow sector, the beam efficiency around 40% means low throughput in high noise areas and on top of that susceptibility of these links to anything that's happening in the surroundings, like if someone puts up a new link you instantly see the result on your network performance. Now replacing the low beam efficiency patch array sector by horn antennas with beam efficiency up to 99% the noise level in the urban and high density areas is effectively avoided because high beam efficiency means no side loops and no side loops means no interference the final effect is high throughput and network stability. Addressing the most pressing problem of WIST networks is much more straightforward. Now only one advice here use antennas with high beam efficiency. High beam efficiency equals to high throughput and that equals eventually to happy customers of your WISP and a joyful life as an internet service provider. It actually frees you it gives you the freedom and time to you can switch from running around servicing the defaulty and problematic links or talking to angry customers to actually start thinking about how can I expand my business how can I do even better and that's really something that's invaluable and the radio manufacturers are actually also trying to help with the noise naturally so the GPS synchronization ensuring that the radios in your network transmit and receive at the same time protects you from self interference but not from the side loops of the competitors and tenants beam efficiency ensures that you do not have to worry about interference at all it does not receive it so you don't need to try to deal with it in the first place so beam efficiency is a very practical antenna parameter where before the discussion about the side loops was limited to many versus little or yes versus no beam efficiency provides a number from 0 to 100% and it's super easy to compare side loop performance of antenna so now you know that front of a ratio or side loop level are parameters that are really not so important not useful in the wisp industry because they only consider one side loop or one loop out of many antenna might have so beam efficiency on the other includes all the side loops which makes it very useful metric all the side loops removes any ambiguity you can be sure that this metric is reliable always ask whether a parameter is a single frequency or wideband in wisp industry wideband is simply a must because the spectrum is shared by many and therefore wideband performance is vital and our filament addition to the beam efficiency definition is to average it over both polarization and the whole antenna bandwidth so you cannot do better than that it's really the most one can do in terms of how well or how useful this parameter can be so beam efficiency is the ultimate measure to judge antennas by in wisp industry and it is a tool in your hands eventually to make better decisions for your business so please use it and asking for it ask for it you know you're looking for doesn't have it in the data sheet to make it easy for our customers we added beam efficiency over antennas into all our data sheets we are a transparent manufacturer and want to provide our customers the information that's important and if by any chance you need to explain to someone very quickly what beam efficiency is and why it matters feel free to direct them to our inside wireless video series on our youtube channel it's these two particular episodes that do a fantastic job explaining beam efficiency within minutes and another youtube playlist we have is called Wisp Traveler where we went to different places around the world as you can see and interviewed our customers asking them what was their experience with our antennas so if you don't take it from us that our antennas are great which is natural of course you have to check or you have to first test it out or maybe lean on the experience of your peers which is why we recorded these videos and be assured these are not staged videos you can actually even contact these people personally and find out for yourself we also have an online community so we're definitely very active on facebook on the many Wisp related forums and we also have our RF elements English page and RF elements Africa, RF elements Espanol and what else I think that was in Asia we also have RF elements Asia which are the support groups where you can actually contact our salesman ask them about the availability or anything related to our products or ask a technical question anything goes really and we also have RFELab.com which is our user forum again a lot of questions have been asked already so you can search through those or simply add your own question if you have something specific something pressing that you need to answer so it's probably time to wrap up this webinar it was a pleasure to have you here and I'm looking forward to any other webinars you might be joining so have a good day and bye bye