[Elecraft] OT: SGC Coupler / Small Wire Loops

[Stuart Rohre]

Martin,
A Google.com search on "Loop Transmitting Antennas" and "Small Loop
Antennas" will bring you a number of sites for Loop info.

As some have said, one turn loops are the most efficient solution for
transmitting.  Large diameter conductor, and low loss joints are
essential.

Multi turn loops then, will have in contrast, higher I squared R losses
due to length of several turns of wire.  The efficiency of an antenna is
measured by the amount of Resistance in the overall Radiation Resistance.
Thus, you need to maximize the current flow for efficient transmission,
and multi turns of ordinary wire defeat that objective.

The single large turn, makes high current flow more easily introduced
into the antenna.  (If the joints are low loss)

The SGC antenna is more of a "gimmick" to demonstrate their coupler
will match most anything as a radiator.  They HAD to have multi turns
most likely to get the coupler to adequately load the thing.  Wonder
if anyone has tried the SGC on a single turn copper pipe loop?

Most of those, that work efficiently, like the MFJ model, have a small
coupling loop to the coax, and inductively couple to the large trans-
mitting loop.  The motor driven capacitor opposite the feedpoint
takes care of tuning the loop to various bands, and within a band.

Hope that helps, and you will get more detail in the web sites.
72,
Stuart K5KVH