An end firing array consisting of an excited unit, a reflecting unit and one or more guiding units. Note: In fact, a reflection unit may consist of a number of units or a reflecting surface.
AdvantageYagi antennas really work. It has good directivity and higher gain than dipole antenna. It is especially good for direction finding and long-distance communication. If it is equipped with elevation and azimuth rotation control devices, it can also communicate with radio stations in all directions, including space vehicles, at will, which is not possible from the upright antenna.
TransmitOur communication machine output is designed according to 50Ω, with 50Ω cable as a feeder. How can Yagi antenna and feeder achieve impedance matching? Obviously, this question cannot be ignored. So there are all kinds of matching methods. The "hairpin" matching commonly used by Yagi in short-wave band is to connect a U-shaped conductor at the feed, which acts as an inductor and forms a parallel resonance with the capacitance of the antenna itself to improve the antenna impedance; There are also classic "gamma" matching, the famous HB9CV antenna and more. The simplest way to do this is to wrap the feeder near the antenna feed into a coil of about six or seven circles with a diameter of about 15 centimeters and hang it there, I think this should be the same principle as the hairpin match.There is another problem to note: Yagi antenna is "balanced output", its two feed points show the same characteristics to the "ground", but the usual transceiver antenna port is "unbalanced", the core wire is the hot end, the outer conductor is grounded. Although we can also ignore the feeder core wire randomly connected to one of the two feeding points of the antenna, the other point is connected to the outer conductor layer of the feeder, but this will destroy the original directional characteristics of the antenna, and will also produce unnecessary emission on the feeder line. A good Yagi pair should have a "balanced - unbalanced" transition.
Application of Yagi antenna
Yagi antennas are widely used in many applications, especially in satellite communications, radar and television broadcasting. In satellite communications, Yagi antennas are used to receive signals from satellites in order to convert them into useful information. In radar, Yagi antennas are used
To send and receive radar signals in order to detect and track objects. In television broadcasting, Yagi antennas are used to send and receive television signals in order to display images on receivers on the ground. In short, Yagi antennas have a wide range of applications and are an integral part of modern communications, navigation and broadcasting.
Yagi antenna is a very special antenna structure with excellent directional performance. It works by using a horseshoe-shaped reflector and horseshoe-shaped elements to focus, enhance and direct radio signals. Because of its excellent performance and wide application, Yagi antenna has been widely used in modern communication, navigation and broadcasting fields.