New answers tagged dipole
2
Zero reactance means voltage and current are in phase.
For example, consider a voltage source connected to a nonreactive load. This means the peaks of the applied voltage should coincide with the peaks of the resulting current.
It's equally valid to consider a current source connected to a nonreactive load. In this case the peaks of the applied current ...
4
And why is an antenna resonant, because the voltage and current are in phase or because the reactances cancel out, or both ?
Reactance ($X$), resistance ($R$), and the phase difference between voltage and current ($\theta$) are related by:
$$ \tan \theta = { X \over R } $$
So if reactance is zero then $X/R$ is zero, so $\theta$ must be zero, meaning voltage ...
3
The original question was, "Why do ham radio operators insist that a half wave dipole is resonant when the inductive and capacitive reactances cancel out?" That question seems to be about psychology, and I will answer accordingly. I don't know that my answer will be very useful to others, but I'll proceed anyway.
People who are hams come from all ...
0
To add to what Hotpaw stated ...
There's the theoretical half-wave dipole, which is 492/f.
However, a practical resonant dipole is shorter. When making one, we must account for the end effect, by cutting its length to 468/f.
The end effect results from the fact that the antenna is normally operating surrounded by air, and the signal is travelling in a ...
4
What you miss is that a resonant dipole doesn't need to be a half wave length long. You can add series inductors near the center or part way out from the middle, and/or capacitors (hats) near the tip ends, with L's and C's varying in value from small to large, to vary the dipole length from a just tiny bit shorter to significantly smaller (e.g. HT rubber ...
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