ANTENTOP- 01- 2020 # 024

Antenna with Rotating Directional Pattern for the 80, 40, 20, 14 and 10 meter Band

Let's show this with practical example. I have a length of coaxial cable in 9 meter long. Therefore, if the velocity factor of the coaxial cable is equal to 1 then this coaxial cable should have lambda/2 wavelength at 18 meters, or at the frequency of 16.65- MHz. It is theoretically. This length of the cable was loaded to 100- Ohm resistor and connected to the MFJ- 259B.

Figure 3 shows the practical test. MFJ- 259B found the 100- Ohm impedance at the 14.023- MHz. So the velocity factor of the coaxial cable is: 14.023/16.65= 0.84. Such velocity factor has coaxial cable with foam polyethylene dielectric that it is right for the tested coaxial cable.

Each coaxial cable going from the sloper antenna is connected to the special Antenna Tuning Unit. Figure 4 shows schematic of the ATU. Base of the ATU is home brew variable capacitor four section of 12-700-pF. The capacitor was made from a military butterfly capacitor. Stator of the capacitor was divided to four sections, as it shown on the Figure 5. Figure 5A shows stator before rework, Figure 5B shows stator after rework. Rotor of the capacitor was remade to one section, as it is shown on the Figure 6. Figure 6A shows rotor before rework, Figure 6B shows rotor after rework.

Figure 3 Practical Test of the Coaxial Cable

MFJ-259B Shows the Frequency of the Lambda/2 Length

Curious Cat and 100- Ohm Resistor (2x 50- Ohm) at the End of the Coaxial Cable

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