ANTENTOP- 01- 2020 # 024

End Fed 6- meter Zepp Antenna with Resonance at 2- meter Band

Two wire line and wire in plastic insulation both has the own velocity factor (or shortening factor). It means that physical length of the quarter wave transformer and the half wave antenna should be less the shown in the Figure 1. I do not know the velocity factor not for wire neither for two wire line it should be find in my experiment with the antenna.

So I made antenna according the Figure 1. The antenna was hanged up to the ceiling of the room in my house. Antenna feed through 50- Ohm coaxial cable in 3 meter length. I begin tune the antenna to 50.1- MHz (because I work CW on the 6 meter band) by shortening antenna wire and quarter- wave transformer. For tuning the antenna I used MFJ- 259. Figure 2 shows final variant of the antenna with 1.0:1.0 SWR at 50.1- MHz.

Photo 2 RF- Choke

Figure 2 Final Variant of the Antenna with 1.0:1.0 SWR at 50.1- MHz

Practical found velocity factor for the 450-Ohm MFJ Two Wire Line is 0.765 and practical found velocity factor for the electrical green wire is 0.89. It is quite close to the supposed theoretical value. Figure 3 shows real design of the 6- meter Zepp antenna. I used two porcelain dog bone ribbed insulators at the ends of the quarter wave line. A porcelain egg insulator was installed at the end of the half-wave antenna.

Photo 3 shows the antenna wire connection to the two wire line. Photo 4 shows the coaxial cable connection to the two wire line. This antenna was again hanged up to ceiling and antenna parameters were measured with the help of MFJ- 259. The antenna requires some small tuning. To achieve the resonance at 50.1 MHz and a resistance of 50 ohms at this frequency, the antenna wire was shortened by 2 cm, and three small ferrite clips were installed on the two wire line (see Photo 3).

Photo 3 Antenna Wire Connection to the Two Wire Line

Figure 3 Real Design of the 6- meter Zepp Antenna

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