Yagi Uda Antennas

Wireless technology in industrial environments is becoming more and more common, whether it is utilizing Wi-Fi or proprietary systems for long-distance communication. In order for wireless technology to be successful, the signal must be transferred between a transmitter and receiver, converting the RF electrical signal from the transmitter into an electromagnetic wave in free space, and then converting that wave back again at the receiver. The device that makes this possible is the antenna. 

In industrial environments, there may be elements that interfere with the reception of a signal at the receiver and the right type of antenna can provide the transmission path to suit the application’s needs. Antennas come in many shapes and sizes and each has its own specific design characteristics that determine the range and radiation pattern of the radio signal. The radiation pattern or shape of the radio signal is what is referred to as antenna gain. Antenna gain is measured in decibels. The higher the gain of the antenna, the more focused the signal. The transmitting radiation pattern is the same as the sensitivity pattern for receiving. Which means that the direction in which the antenna transmits the strongest signal is also the direction in which it is most sensitive for receiving signals.

Yagi antennas are the most commonly used directional antennas for communication applications. They are also known as beam antennas and are used in amateur radio operations, cellular phone applications and as a bridge antenna to connect a site to a Wi-Fi access point. Yagi antennas focus all of their signal strength in one direction, resulting in increased gain over an antenna that is dispersing energy in a 360 degree circle, such as an omnidirectional antenna. Yagi antennas have two to three straight antenna elements which are set at a length of approximately half of the electrical wavelength they are designed to support. The signal output of the antenna comes from the front of the antenna and can range from 20 to 90 degrees in width. The directional design of Yagi antennas makes them ideal for receiving lower signal strengths, while filtering out almost all signal noise coming from the opposite direction. They are suitable for long-range communications, however, there must be a clear line of sight between the antennas. Any obstructions, including buildings, trees and terrain, will interfere with the radio signal transmission.