In any kind of wireless access point, the wireless antenna is always among the most important of its components. The underlying reason behind this is that the antenna is the one lone element that is taking charge of determining how the radio signals will be propagated, the right amount of gain that it will need to produce, as well as the type of radiation that it will create for it.
As for the radiation pattern, it could be isotropic. This only means to say that the antenna is radiating its signal in all 4 cardinal directions, equally. We refer to this kind of antenna as omni-direction, Omni meaning encompassing “all”.
With respect to how the antenna is seated, it may necessitate from us a radiation pattern that is not at all isotropic, however, still radiating in a pattern where the radio signal is still maximized in a particular direction only.
Before we try to delve deeper into the different kinds of wifi antennas available today in the market, the amount of gain they can create, and even the type of radiation they usually provide, we need to emphasize that when it is our first time to deploy a wireless LAN, we must conduct first a wireless site survey.
This will help us determine the right site for the access points. In addition to that, it will also highlight to us the presence of any problem areas in which case will necessitate the help and technical assistance of a wireless antenna specialist.
It is normal for the design of any wireless antenna to work with the greatest efficiency over a band of narrow frequencies. The greater range of frequencies that you make an antenna to operate over, the more “broadband” it becomes.
WiFi antennas will run either in a 5GHz band or 2.4GHz band. Hence, it is crucial to see to it that the antenna is structured to work within those ranges of specific frequencies.
Here is a quick look at some of the types of antennas we have today, and a peek to give you an idea of how they work.
Like how we described this type of antenna above, it is known to produce an isotropic radiation pattern. Industry insiders would fondly refer to this as resembling a “doughnut” shape. One needs to be reminded that a true, authentic isotropic antenna has a natural tendency to become purely theoretical.
They have based this type of omnidirectional antenna on a dipole design. The dipole antenna’s radiation pattern here in a horizontal plane is typically 360 degrees. As for the vertical plane, it tends to vary depending on whether the dipole is vertical or not.
If a dipole antenna is vertically oriented, it is likely to come with a radiation pattern of 75 degrees. On average, it is kind of normal for dipole antennas to have an average gain of a little over 2Db.
As the name itself suggests, this type of omnidirectional antenna is intended to be mounted on the ceiling. But you can also choose to install it on walls or above false ceilings. Since they offer us a less obstructed view, it’s not unusual that they come with a higher gain, around 3Db.
Radiating and reflecting elements can be integrated into the standard dipole design. By this measure, the signal energy can be concentrated in just one specific direction. Directional antennas enjoy a reputation of being able to give out a gain that is beyond what the standard isotropic antenna can deliver between 3dB to as much as 20Db.
This type of antenna is known in the industry as a high gain antenna. They usually come with multiple reflectors and its radiating elements are known to produce gain within the range of 12 and 20dB. They are often installed outside homes as outdoor wifi antennas with horizontal beamwidth of 30 degrees and a vertical beamwidth of 15-25 degrees.
When it comes to dish wireless antennas, the parabolic dish is believed to be the most common type for this. It makes use of a curved parabolic dish which is extremely helpful in directing the wireless radio signal to a narrow beamwidth. Besides the fact that they are highly directive, they also come with an extremely high gain — around 40 to 50dB.
Most of the time the dish would come larger compared to the design radio frequency wavelength. You would often find dish antennas being used in point to point wireless communication links. Of course, what we have here is not to be considered as exhaustive since our only intention is just to educate the layman on the basic types of WiFi antennas we have today.