Folded Dipole Calculator
The impedance of this antenna is around 300 Ω,
so you may want to use a transformer or a λ/4 long piece of 120 Ω coaxial cable
to match this impedance to 50 Ω. Geometriy is not that critical. If you want to
put this thing outdoors, do not use brass, as it gets brittle.
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