The problem is quite significant. Here's my understanding:
1. "Antenna" and "feedline" are generally used as synonyms. Impedance matching problems typically occur between an antenna, a feedline, and a radio. Once the antenna is fixed, its efficiency is essentially fixed. The term "VSWR" (Voltage Standing Wave Ratio) actually refers to impedance matching issues. This requires personal understanding and practice.
2. In principle, a Yagi antenna (or other complex antenna) can be seen as a combination of multiple simple antennas. It primarily utilizes spacing and height to create phase differences, thereby enhancing certain effects, such as overall gain and front-to-back ratio, over a wide bandwidth. This concept is similar to the way a flute produces sound.
3. In terms of performance, they are all relative. There is no need to prioritize one over the other; instead, different parameters result in different characteristics. For example, a simple antenna has an impedance of around 75 ohms, while a vertical dipole can have an impedance of 50 ohms. However, their performance differs. A Yagi-Uda antenna with two feed lines on each side has an impedance of several thousand ohms.
4. The principles and design specifications for a Yagi antenna (Yagi-Uda antenna) can be referenced. However, it is important to note that this is not the only option. The best choice depends on your specific needs and practical experience. For example, a low-angle Yagi antenna is suitable for DX communication, while a high-angle Yagi antenna is better suited for emergency communications. https://www.antenna-theory.com/cn/antennas/travelling/yagi3.php
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