Something else you should be aware of when talking about wireless networks is the type of antenna in use. If you are working with consumer-grade access points, this typically is not a big concern as the antenna is built in or provided with these products. However, when working with enterprise and commercial-grade access points you may very well need to select an antenna to suit your environment or for a specific purpose. In this section we’ll look at each of the available types and what makes them unique and why you would choose one over another.
The first type of antenna we’ll discuss is the Yagi antenna (Figure .1), which is designed to be a unidirectional (more commonly known as directional) antenna. As a unidirectional antenna, it works well transmitting and receiving signals in some directions but not in others. Typically this type of antenna is used in applications where the transmission of signals is needed from site to site instead of covering a wider area. From a security standpoint, this type of antenna enhances security by limiting signals to smaller areas.
F I G U R E 1 – A Yagi antenna
he next antenna type is one of the more common ones and is known as an omnidirectional antenna. This type of antenna emanates radio energy in all directions, but typically in some directions better than others. In many cases, these types of antennas can transmit data in two dimensions well, but not in three dimensions.
A parabolic grid antenna (Figure-2) is another popular type of design and is commonly seen in various applications. This type of antenna takes the form of a dish and is a directional antenna because it sends and receives data over one axis; in fact, it can be said that this type of antenna is unidirectional, working well only over a single axis and in one direction. One big advantage of this type of antenna is that its dish catches parallel signals and focuses them to a single receiving point, so it gets better signal quality and over longer ranges. In many cases, this type of antenna can receive Wi-Fi signals over a distance of 10 miles.
F I G U R E 2-A parabolic antenna