Home |
Search |
Today's Posts |
#15
![]() |
|||
|
|||
![]()
Roy Lewallen wrote in message ...
It's not clear to me what's meant by the voltage (presumably relative to ground) at the tip of a dipole. Suppose it's a quarter wavelength above ground. How would you measure it? Or, how would you measure the voltage at the top of a quarter wavelength vertical? Roy Lewallen, W7EL Indeed... Or putting it another way, the potential between two points does not have a unique value in the presence of a time-varying magnetic field, which certainly is the case for a radiating dipole. If you measure the voltage drop along the wire, it's essentially zero, so along the wire the voltage between the end points of the dipole is essentially the same as the voltage across the feedpoint. The only difference between the ends and the feedpoint is due to I*R drop in the wire. The voltage at the top of Roy's vertical, made out of fairly large diameter aluminum tubing, is essentially the same as the voltage at the bottom of that tube, if you measure along the tube. It would be better to talk about electric field strengths in the vicinity of the dipole. You could find the potential along a path from the field if you wished. (I'm recalling that Roy turned on a lightbulb in my head quite a few years ago about this. And I'm sad that Kevin, W9CF, doesn't jump in on things like this very often these days, though I can understand why.) Cheers, Tom |
Thread Tools | Search this Thread |
Display Modes | |
|
|
![]() |
||||
Thread | Forum | |||
Pls comment on this dipole | Antenna | |||
shortened dipole loaded | Antenna | |||
10m dipole and tuner | Antenna | |||
Comet VA30 (base loaded tri-band dipole 40/15/10) | Antenna | |||
Dipole connected to grounded receiver? | Antenna |