My First QSO on the 80m band

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It was with a domestic station about 400 km or 250 miles north of Tokyo.

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My dipole antenna is for the 40m band with the length of about 10 m for each side, and it does not work well on the 80m band as it is.

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Its radiation impedance is ZL=11.8 – 1061 [ohm] and the VSWR value is 1913 at 3.550MHz.

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MMANA-GAL is an antenna-analyzing tool, but it can also tell you the network you need in such cases.

If you prefer to solve the problem with a Smith Chart, the following figures may help.

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Since your antenna is short for the band and thus highly capacitive, you first need to add some inductor in series. But its inductance, XL=1082 [ohm], is slightly larger than to exactly compensate the imaginary part of ZL=11.8 – 1061 [ohm] to have XL+ZL not on the Im{Z}=0 line, which is the only straight line on the chart, but on the upper half of the yellow circle.

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And then with C2=1613pF in parallel, you will have Zin=50.0 + j0.0 [ohm].

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