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Why can Yagi antennas focus signals and dramatically improve wireless communications?
In the modern technology of the 21st century, wireless communications are developing faster than ever before. In this process, various antenna technologies have emerged one after another, among which the Yagi antenna is undoubtedly one of the most influential. Since this antenna was first proposed in 1926, it has been widely used in various wireless communication systems, including radio broadcasting, television reception and wireless data transmission. This article will take a closer look at how the Yagi antenna works and why it can focus signals to improve wireless communications.
Basic structure of Yagi antenna
Yagi antennas are typically made up of many parallel metal elements, including a driven element and other reflectors and directors called "parasitic elements." The driving element is connected to a radio transmitter or receiver and transmits the signal through the transmission line. Parasitic elements, on the other hand, have no electrical connection and are primarily used to receive and re-radiate signals to change the radiation pattern.
Due to its unique design, the Yagi antenna can effectively focus the signal, thereby enhancing the signal in a specific direction.
Principles of Focusing Signals
The core of the Yagi antenna lies in the setting of its parasitic elements. The reflector is usually located behind the drive element and is slightly longer than the drive element, while the director is located in front and is slightly shorter than the drive element. Adjusting the relative length and position of these elements can change the phase relationship of the signal, thereby causing signal enhancement or destructive effects.
Interaction of electromagnetic waves
When the driving element emits electromagnetic waves, the parasitic element can receive the signal from the driving element and re-radiate it. Depending on their size and relative position, the signal from the parasitic element can interact with the signal from the driven element at different phases. This design enhances the signal strength directly in front of the camera, while suppressing the signal radiating backward.
This design enables the Yagi antenna to achieve up to 20 dBi gain in a specific direction while suppressing the radiation of reverse signals.
Wide Application of Yagi Antenna
In practical applications, Yagi antennas are often used in fixed wireless communication links, radar systems, and long-distance shortwave communications because of their high directivity and diffusion ratio. The most well-known use is as a rooftop terrestrial television antenna. Due to its relatively simple structure and low construction cost, the Yagi antenna is very suitable for home users.
Creative design and performance optimization
In addition to the basic Yagi design, RF engineers have used many innovative methods to improve the performance of the Yagi antenna. For example, triangular reflectors and larger diameter conductors are used to expand its bandwidth, making it suitable for signal transmission in different frequency bands. In addition, some advanced Yagi antennas use trap technology to achieve multi-frequency operation to meet the needs of different users.
The flexibility of these designs makes Yagi antennas not only meet professional needs, but also can be used in amateur radio operations.
Future challenges and opportunities
Although Yagi antennas have played an important role in wireless communications, they still face challenges with the emergence of new technologies, such as the development of MIMO (multiple-input, multiple-output) antenna technology. Future research will likely focus on improving its bandwidth and efficiency, and incorporating the latest materials technology to further enhance its performance.
In this era of ever-changing technology, we can't help but wonder how the development space and possible future applications of Yagi antennas will evolve?
