A wireless network is only as good as its antennas. In this video, you’ll learn about wireless power levels, antenna placement, and omnidirectional and directional antennas.
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On many more advanced access points, you have control over the power that will be used over the wireless networks. This is something that you generally want to set as low as you can so that everybody in your area can use the wireless network. But you want to prevent those wireless signals from going outside of your immediate area.
How low is that? Well, this may take some work. You may need to grab some wireless devices, go and look at the perimeter of your particular office area or your particular building, and try to determine what is the proper amount of power for your wireless network.
This can really involve a lot of different variables. You have to think about the type of antennas that are in use. High-gain antennas are going to hear better than others might. You also have to consider what’s in the area and what frequencies are in use. Some types of devices will absorb wireless frequencies while others will reflect the wireless frequencies.
So this is not something that you would generally find a number and set it to be that number across all of your different access points. You’re generally going to find a very specific power level for a very specific access point. And each access point is going to be a little bit different.
Another challenge you have is where do you put the access points themselves? You, of course, have to think about where you need these particular signals. And you also have to think about the frequencies that might be in use.
If you’re using 802.11b or 11g frequencies, then you might want to choose channels that are non-overlapping. And depending on the size of the area, you may have to use many, many different access points. And in that case, you can have a large number of access points as long as you remember not to have frequencies that are going to conflict with each other. So you might want to use channel one, channel six, and channel 11 here in the United States and create a layered set of frequencies that will not create any conflicts between any of them.
There’s many different kinds of antennas that you can connect to your access points. One of the most common is the omnidirectional antenna. This is an antenna that’s going to give you the same amount of sending and receiving control across all sides of the antenna. It’s omnidirectional. The signal is not distributed more on one side than it would be for another.
If you’re in a generic environment, you want to cover an entire floor of a building, this is probably the type of antenna that you would use because you are getting that very even coverage on all sides of the access point. This particular antenna doesn’t really give you a way to focus the signal. And if you’re trying to create a signal in a corner of a building or down a particular hallway, you’re not really going to be able to get the proper coverage with an omnidirectional antenna.
In those cases, we may want to use a directional antenna. With a directional antenna we can really focus exactly where the signal’s going. And with a focused signal, you’re also getting a stronger signal. This is one where you are both sending and listening in a single type of direction. So you’re going to need an antenna that is created, in shape, specifically for that area.
We would determine what type of antenna to get based on how much signal we can send or receive. And we generally measure this in decibels. This is a logarithmic scale. So every time you double the signal, the decibels will increase by three decibels. And if your signal strength is cut in half, you’re going to lose three decibels from that particular signal.
To be able to take advantage of this directionality, you’ll need antennas that are specifically designed for direction. One is the Yagi antenna. The Yagi is a very directional antenna. And it’s going to give you a very high gain because you’re really pinpointing the signal to one particular area.
Another type of antenna that we can use for directional use is the parabolic antenna. The parabolic antenna also focuses to a single point. You can see it has a little bit more rounded or curved area. And the signals will bounce off of that curve to a single feed horn. This gives us a lot more control in where the signal is going and really allows us to focus on one particular area.
Category: CompTIA Network+ N10-006