Hello
I appeal to your wisdom. It's on the sidelines of nanoVNA but some participants in this forum seem to me to know a lot of things, which is not the case everywhere
With a circuit as attached 2F-01.png, I adapt to 50 ? an antenna on two separate frequencies. In the example the same antenna shows
Frequency = 7.1 MHz Impedance = 50.01 - J 0 ohms
Frequency = 3.65 MHz Impedance = 121.1 + J 41.1 ohms
In the case of a real and not simulated construction, it is my nanaoVNA which indicates the values of Z to me. This is how I set up my 80-40-20m antenna with 4 traps
To calculate the circuit, I separately calculate
1/ a 3.650 MHz high pass
2/ a 7.100 MHz low pass
I cascade the two adapters. The best combination shows:
Frequency = 3.65 MHz Impedance = 50.03 + J 0 ohms
Frequency = 7.1 MHz Impedance = 48.38 - J 24.62 ohms
It's obviously not perfect; there is still reactive on 7.1 MHz
Putting the complete circuit into an equation and calculating the roots is not simple at all. There are various calculators on the Net for 'T' or 'pi' adapters but I don't see my double 'L' circuit
Have a way to calculate, in one go, the L and C components so as to obtain a result of 50 +j0 on two frequencies.
To illustrate I put the EZnec file corresponding to my example and the .s1p r¨¦sult calculated
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F1AMM
Fran?ois
