Resonance and RFI...

[74IN]

are they related?

I put up a 20M dipole and screwed up on my measurements.

It was coming through computer speakers, on or off.

I corrected my mistake and the RFI is almost nil.

BTW, the antenna was too short and one end is almost over the speakers.

 

[W5LZ]

No, they are not related. You can have either without the other.
- 'Doc

 

[74IN]

Thanks.

 

[C2]

Think that if you messed up on your measurements, that the antenna would still be resonant at some other frequency. No? So noise would not care about which frequency you wanted to use.

 

[freecell]

"BTW, the antenna was too short and one end is almost over the speakers."

that being the case, the proximity of the speakers to the end of the dipole represents aperture interference and so effects the operation of the dipole, to say nothing of the magnetic field (E) inducing voltages into the speakers themselves.

voltage (E) is at maximum & current (I) is minimal at the ends of a dipole. if when the antenna was too short one end of the dipole was located over the speakers and whatever change you made moved the end of the dipole away from the speaker location this could explain it, resonance would have little-to-nothing to do with it. the amount of energy transference between two AC circuits is directly proportional to their proximity to one another.

 

[dudmuck]

This is a horizontal dipole?
If so, it should be at least 1/2 wavelength above ground to get a useable radiation angle.
you can get the details here Dipole Height