Hi, everybody. Welcome back. My name is Tyler McMinn with Aruba, a Hewlett Packard Enterprise company. This is the Aruba Mobility Essentials part one, our fifth video, talking about antennas. If you made it through the last video on data modulation, pat yourselves on the back, that was a tough one. This one, we're going to ease it up a little bit, I think most people know what an antenna is, we're just going to talk about some of the major types that you're going to experience out there, and you might wonder, "Hey, how come there's no antenna on this? Where's my antenna? Where is my plug?" This one's an internal one, we'll talk more about it here in just a bit, sit back and let's get going. All right, antennas, what an antenna does is it takes the radio signal, the radio impulses coming off of this little connector, and if it's external the antenna can either be attached directly to that connector and screw in, or you could use an antenna cable and place this antenna up on a ceiling, or outside the building, or something like that, with the access points safely housed, warm, and snug inside the building. You want to make sure that if you are going to look at purchasing an antenna, you always want to get an antenna from the manufacturer, many manufacturers will not warranty you using someone else's antenna. So if you want an ET phone home, put aluminum foil on an umbrella and sit out there in the woods, you may not get the sympathy of support if you call up the company and say, "I just made my own antenna, but I don't know why it's not working," and they be like, "Maybe it's because you made your own antenna." Anyway, what they do is the antenna takes this energy coming off of the radio minus any loss due to the electrons going across this copper, and it broadcasts that signal and radiates that energy out away from the antenna, and it does this based upon how the antenna is designed and built, they come in a lot of different shapes and sizes. But ultimately what they're designed to do, such as this dipole antenna, is they're designed to take what would normally be, if I didn't have an antenna, just to a point in space and time which you would have theoretically a perfect isotropic sphere like a perfect balloon expanding in all 360 degrees, and instead, it squishes that balloon so that it goes out in 360 degrees along this flat plane, the floor that you set the antenna in. If you hang this AP from the ceiling, and here's your floor, you've got the AP hung from the ceiling there, put a couple of dipole antennas in there pointing straight down, only straight down, then it would cover that floor space pretty well in all directions on that floor. But what it wouldn't do is bleed very much into the floor above, especially if you hook a metal plate there and it wouldn't typically bleed very far below. You got to be careful of your ceiling height, with these Aruba APs, generally we want the ceiling height to be less than 30 feet right around there, it's generally about the maximum 25 to 30 feet is a pretty safe. Then you usually get somewhat of a downward tilt if it's an internal antenna versus one of these external dipole antennas, but the goal is the same, you want to only cover the floor you're on and so you might say, "All right Tyler, what do I do about the floor below? What do I do about the floor above?" For the floor below, you put another AP with antennas or internal antennas, and you allow it to cover that floor, you let this upper AP here cover that floor, that's how we do it. Now you could offset these a little bit, you definitely want to make sure they're on different channels but all in all, that's not a bad design. We'll get more into design in a future video here. When antenna is connected to a receiver, takes the RF waves on the receiver side and directs an AC or an RF signal back to the receiver itself, it takes the radio waves in and then this signal is being received on the radio internally, or you have the antenna inside anyway, and you're just simply sending and receiving. This is a bit of a repeater or you might hear the term mesh setup here, normally the receiver is your laptop, or it's your phone, or it's your mobile device or something like that, but you could use this receiver as a client bridge where it plugs into a device like an old printer that has a network interface card but not a radio, it'd be a pretty expensive client bridge, lot of times what you'll do is you'll plug it in not to a printer, but you'll plug it into another switch in that side of the network. If I've got a building here and a building there, I'll now bridge my two buildings together. Pretty cool, right? It saves you from having to dig a trench and run fiber. So doing a wireless can overcome that. The basic antenna types, we have the internal versus external, of course, but even internal could be directional and external could be omnidirectional. The main antenna ties we're going to discuss, rather than internal versus external is omnidirectional and directional. Omnidirectional is what I just described. This is the signal radiating in all directions, but let's put a little asterisk there to say on the same plane or on the same floor because that's generally where you're going to see these being used. They're not used to go into the ceiling or into the floor, they're meant to be 360 degrees of euros. Stay on Florida number 2 and walk around. You'd be able to get a signal no matter which way you went from that access point. A directional antenna by contrast, focuses the energy not just above or below, but it takes the energy from a certain direction as well and funnels it in an arc, as narrow as you want, up to 10 degrees or even less than some cases, or as broad as you want, up to a 180 degrees if that's what you want to do. This could be a flat panel type of antenna where it goes off a 180 degrees off of there. It could be a Yagi antenna, looks like a little swordfish and that could narrow it down to 30 degrees or 60 degrees in some cases or even less, to a satellite dish or a parabolic antenna where it could be as narrow as just a few degrees across. The benefit of using a more narrow beam and focusing it is that you get a much stronger amplitude in that direction, because all that energy that would have covered your entire second floor is now being focused to just a few degrees across, where you can get some cases tens of kilometers before you need to put another dish on the other side. You always want to use the same antenna if you're doing these point-to-point links like this. If I were to put a laptop tens of kilometers away, it would receive the signal. The problem is when the laptop goes to transmit, the laptop is going to peter out pretty quickly there, and you're not going to pick up that signal very well. It's generally recommended that you match whatever you're transmitting on to whatever you're receiving on, if you're doing these building to building transmissions. When you go to look at these antennas, you can tell what the estimated coverage is going to be, on the antenna documentation. They'll have two main factors here: the H-Plane called the Azimuth, and the E-Plane called the elevation. The Azimuth is as if you were like a bird, that's a bird, flying across and if you were to look down at the top of this building where this access point, and you can see through the roof here, you would see that access point and this is what the broadcast would look like. So if you were a bird that could see radio waves and see through walls, a little bit of imagination there. But nonetheless, that's what your Azimuth is. That's where your H-Plane coverage is. This is not a directional, this is probably like a 325 or something like that. Internal antennas that's just melted directly on the ceiling, flat against the ceiling, so it's upside down and it's arcing maybe 30 degrees down, but primarily it's 360 degrees from that point along the floor. If you were looking at the E-Plane, that's as if you were standing in the same room as the AP and you could see radio, you would see how high into the ceiling this thing was going, and how low into the floor that this coverage was going. Generally, a metal plate here would bounce a lot of this down as well. But that's the basic E-Plain view. How much elevation up and how much down does this radio wave cover for you? Another way to look at this is the Azimuth showing your floor coverage with a panel or a directional antenna. This is a 60-degree coverage. It's recommended to give a good clean signal within this 60 degree arc. You can see there's a little bit of bleed or spill, but as you get outside of that 60 degrees, your signal drops dramatically, which is what you want. You want the signal to be basically unusable on either side or behind or around, but instead, very good in that particular direction. This could be used to achieve greater distances, or it could be used for security reasons where you mount this against the wall and you don't want people driving up in their car, that's a car, and sitting there listening to your radio or trying to hack into your network there. Same thing for the E-Plane or the elevation side. How high into the ceiling and how low into the floor would it go? So that is our quick overview on antennas and how they basically are viewed at the enterprise level. Again, there's a lot more when we get into outdoor deployments and point-to-point between buildings and things like that. But I'll show you our 3D seven later on here in a future video, where it's a quick, easy solution if you are looking at bridging a couple buildings together. Predominantly though inside the building, inside your house, you might want to look at how you're deploying your own access points. If you're finding that, somebody thought it'd be cool to mount it against the wall, make sure your antennas are pointing straight up or straight down. You get very frustrated sometimes, when I'll see antennas pointing straight out. What that really does is it creates this sideways doughnut of coverage here where the signal is really weak or nonexistent, to where the device we're actually pointing at, but very strong above your ceiling and in your basement. If you don't have a basement or a second floor, then that's just waste in RF here. A better solution would have been to just do a directly up or directly down antenna angle and allow it to do its job in that direction. Hopefully, that brings some insight into antenna placement and deployment. I hope you guys enjoyed that little video. The next one, we're going to be covering RF signal propagation, getting into how we actually get the signal from point a to point b. A little bit of a deeper dive there. But for now, that's the end of this video. I'll see you guys in the next one.
