Principle, production and adjustment for FM broadcasts receiving eight wood antennas ----- YAGI Antenna

Keywords: J-type communication antenna production J-type communication antenna production Remember the ZEPP ANT in front? If we apply it to the frequency of VHF or more, then its size is smaller, we will easily change it into vertical framework. It turns into a vertical half-wave antenna. The shape is as if "J", as shown in Figure 7 (a). The characteristics of vertical half wave are very low and very suitable for DX communications. If you have a way to set up a 28m Hz J Ant, you will find it quite fierce, no less than 3-ELE YAGI. In order to increase the antenna in a limited space, J-Ant can be deformed into SLIM-J Ant, which is to fold the long Wire Ant from the middle, so that the two-semi-wave antenna of the original phase is changed by 180 degrees. Together, there is 3 dB gain, as shown in Figure 7 (B). Similarly, the same trick can also be applied to horizontal ZEPP Ant. Another method of increasing gain is shown in Figure 8, and the half-wave antenna in the middle of the antenna originally 3/2 λ is 1/4 λ Stub, It became a 2-stage half-wave antenna in the same direction. Thus, we can always stack the half-wave antenna to get gain (2 paragraphs 3dB, 4 paragraphs 6dB), this technique is quite practical at 144 MHz and 430MHz. The antenna used by the author is J-ANT, as long as the propagation status is open, 100MW can be connected to Japan, 3W is more than enough, and it is sufficient to see its low elevation characteristics.

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