Length calculation of shorted (TRX) feeder wire
Dear hamoperator, for the generally consideration of reaktance for a shorted feeder wire is following formula generally applicable:
Zr = Zo * tan(360 * l/Lambda) for degrease or Zr = Zo * tan(2*pi * l/Lambda) for radianten calculation
Wether degrease or radiant calculation you must switch it on your pocket calculator. Zr is the reactance from the load, Zo the input impedance of the wire, l the length or wire an lambda the wave length (300/frequency in mc)
Now a special case - resonance length:
For lambda/4 and uneven more of that takes effect: Zo² = Za * Ze ====> parallel resonance circuit
Zo is the wire impedance, Za the output load (also Zr reactance matching) and Ze the impedance of input load.
For Lambda/2 and even more takes effect: Ze = Za ====> serial resonance circuit
Wire length Frequency Cable impedanc
Here you can view the charts for the most cable impedances an frequencies!
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