What is a Wireless Antenna and what are the uses

 

A Wireless Antenna is a system that enables radio waves to be transmitted and received over a spectrum of radio frequencies. The more broadband the antenna is said to be in its service, the greater the range of frequencies over which the antenna operates. An Aerial is another common term for an Antenna.

Over a variety of frequency bands, Wi-Fi signals run, with the 2.4Ghz and 5Ghz ranges being the most common. The 2.4 GHz ISM (Industrial, Science and Medical) the band is used by IEEE 802.11b and 802.11g, and the 5 GHz band is used by IEEE 802.11a. For a given amount of power, radio signals in the 2.4 GHz band move faster and are less absorbed by barriers such as walls than 5 GHz band signals, although the effective range of 5 GHz signals is slightly smaller.

Omni-Directional and Directional Wireless Antennas fall into 2 general groups.

Omni-Directional Antennas - These antennas spread the signal continuously over 360 degrees, making it suitable in every direction to reach computing devices. For example, a home broadband wireless router, which acts as an omnidirectional antenna, would usually be seen with a small stick style aerial attached. To obtain the best performance, it is usually flexible so that it can be rotated from the vertical plane to the horizontal plane. These days, the antenna would be embedded and not visible externally in modern notebooks.

Directional antennas - This type of aerial is designed to focus the intensity of the radio signal in a single direction, and the narrower the antenna beam diameter, generally speaking, the greater the gain. High-Gain aerials with a narrow beam diameter appear to be present. Yagi, Dish, Horn and Patch are examples of directional antennas.

The range of a wireless antenna depends on a variety of factors, including the power output, the characteristics of the devices transmitting the signal, and the composition of any obstacles, such as the wireless access point and the receiving device. The amount of power that a wireless system can radiate is regulated, at least since we work in the frequency range of microwaves and too much power may be harmful. Secondly, many different devices use these frequency bands and interference may be a major problem.

Choosing the most fitting antenna will depend on the setting in which you intend to work. The omnidirectional, ceiling-mounted antennas will be used primarily in most home and office environments to ensure the greatest all-around coverage. Multiple wireless access points may be used in wide areas, and some type of directional antennas may be necessary in some areas of the building, depending on the physical layout of the building.

Now we are going to provide a short overview of some famous directional antennas:

Yagi

The Yagi antenna was named after a major Japanese inventor, but Yagi-Uda is the full name of the antenna. Basically, it is a dipole antenna with extra elements known as parasitic elements. Only the main dipole part is guided and only the signal is re-radiated by the parasitic components, helping to focus the signal power in one direction.

Dish

These antennas can be highly directional and can have small beam widths and can be very efficient high-gain devices. They are very good for point-to-point instead of point-to-multipoint connections. It is important to align the two dishes to ensure that they propagate the radio signal to each other. A slight physical motion of one antenna or another may have a drastic impact, or none at all, on the signal intensity received.

Patch

In small to medium-sized office settings, patch antennas are commonly used and are usually placed on the wall or ceiling. Coverage is usually about 50-100 degrees from where the unit has been mounted, but if necessary, it can be configured to radiate over 180 degrees. Microstrip or flat panel are other names for this type of antenna due to the fact that they are typically made of a pair of metallic plates that are the elements of the antenna.

The environment in which the wireless signals are needed and over what range they are required will determine the choice of wireless antenna. In order to achieve maximum coverage, large buildings needing coverage throughout will primarily use Omni-directional, but may be forced to use the patch or some other type of sector or directional antenna.

A good Wireless Site Survey that should indicate the problem areas, where specialist antennas might be needed, is not replaced.