Frank wrote:

In the BPL report at
http://www.ofcom.org.uk/research/tec...line/ascom.pdf
I noticed the system noise floor at about 10 dBuV/m (in 9 kHz). For the
tests they used an active bi-conical antenna. (By my calculations 10 dBuV/m
is about 9 uV(2.5 kHz BW) from a 40 m dipole at 7 MHz.) In the previously

Yes, Fig 8 shows about 10dBuV/m in 9KHz which interpolates to 5dBuV/m in
3KHz, and their measurements used a peak detector. On white noise, the
QP value would probably be 2 to 3dB lower.

I have made a large number of measurements at my home QTH (in a
residential neighbourhoos) using a half wave dipole and assuming an
average gain of -1.2dBi or an AF of -11.6dB/m and I regularly get
ambient noise readings down to around 0 to 3dBuV/m QP in 3KHz or
extrapolated to 9KHz BW, 5 to 8dBuV/m QP. Ambient noise is probably
lower than indicated by ITU P372-8!

mentioned report most of the BPL signals -- even at 1 meter from the
source -- is 60 dBuV/m. It seems your system with the loop will be much
less sensitive at about 100 uV/m (+40 dBuV/m).


See my response to Reg re the noise floor for the setup, I make it
around 8dbuV/m or 2.5uV/m. I don't pretend it can measure ambient noise,
but it can and has measured BPL interference at 40dBuV/m to 70dBuV/m.

Incidentally, when I attempted to save your web page of math, it was saved
as an ".mcd" document. Obviously I was not able to open it with Mathcad,
but will have to type it in by hand.

No you won't, I have posted a later version of the mathcad file to
http://www.vk1od.net/bpl/loop02.mcd .

The file you downloaded is an image (.gif) called loop.mcd.gif, and it
looks like your download process dropped the extension, or you hide the
extension on your machine. (Some software thinks that the first dot
begins the file extension, whereas it is the last dot that does so.)


Might be interesting to replicate your results with NEC2.

I have modeled the loop in EZNEC and get very similar inductance and
resistances.

Thanks Fred, appreciate the review.

Owen