"Owen" wrote in message
...

I have been working on the BPL Interference issue.

One of my projects has been exploring ways by which ordinary (well,
competent anyway,) amateurs can make reasonably reliable measurements of
noise / interference using existing amateur station equipment or equipment
that is easy for amateurs to construct.

This has led me to search for a portable antenna of reasonably predictable
gain that can be used with a known HF SSB receiver.

I have had a hack at predicting the gain and antenna factor of a small
square untuned loop driving a 50 ohm load. The model is in a Mathcad
worksheet, but I have copied it to a gif file which you can view on my
website at http://www.vk1od.net/bpl/loop.mcd.gif . (The worksheet is
entirely in metric units.)

I would appreciate any comments / review on the model and calcs.

Owen


Looks pretty decent, until the very end. Antenna Factor (AF) is the ratio of
the field strength voltage to the output VOLTAGE, not power, although you
did get the numbers right.

So practically, since the average ham has a receiver with a sensitivity in
the order of a microvolt, then your antenna limits your minimum discernable
signal level to around 65 uV/m. Maybe 100 uV/m to be on the safe side.
That's likely quite adequate for detecting BPL noise, but the real problem
is having the average ham get an anywhere near reasonably accurate
measurement of 100 uV. Your S meter just isn't good enough, so now you're
moving beyond the "average" ham's capability. Accurizing your receiver into
an RF microvoltmeter is a tough task, so maybe the best route is to use a
signal generator as a comparison standard. Old boatanchor signal generators
in the 7 MHz region are reasonably available, and their attenuators are a
lot better than their frequency stability and portability. g

I applaud your goals, but getting data accurate enough to toss into an
intelligent argument about BPL is a tough task. Good luck.

--
Ed
WB6WSN
El Cajon, CA USA