[Fwd: LF: DJ1ZB's antenna measurements]
Tue, 07 Apr 1998 07:10:23 -0400
Peter Martinez wrote:
> >From Peter Martinez G3PLX Kendal Cumbria
> I found the antenna measurements from DJ1ZB very interesting, as
> they confirm my own, reported here a few weeks ago. In particular
> that strapping the house ground to the antenna ground made the
> antenna series-equivalent (loss) resistance rise rather than fall. I
> also ended up separating the house ground from the antenna
> ground, and that also dropped the man-made noise level on receive.
> I used a similar resistive bridge to make my measurements and a
> similar audio chip to drive it.
> Joachim's measurement of the coil losses and ground losses also
> confirm my suspicion that the ground losses are rather larger than
> the coil losses, and therefore imply that we don't need to try too
> hard to make better coils, at least not unless we have far better
> ground systems. The ground loss resistance figure that Joachim
> quoted includes the losses incurred by the current flowing thrugh
> the lossy stray capacitance to ground from the antenna, which are
> real losses which won't show up on any measurements which are
> aimed at measuring the resistance (at DC or RF) of ground
> electrodes alone.
> Has anyone else done similar measurements of coil and antenna
> Peter Martinez G3PLX