For Gil. I watched your video on operation of your mag loop with the toroid feed configuration. i noticed the problem you had with matching.

i wanted to pass to you, that i use a coupling coil one fifth the diameter of the large coil
and have not had a matching problem on my operating freqs.

my present loop has a 5ft diameter made from 19 ft 3/8 od, flexable copper tubing.
so using pi, we figure
19x3.14=59.69 inches(diameter)

59.69 x .2 (1/5th) = 11.93 inch diameter (coupling loop diameter)

11.63 x 3.14 = 37.50 (length of tubing, coax needed for coupling loop)

in a nut shell, you can figure the diameter of loop to use in space you have, then you can divide your diameter by 3.14 and get length of material needed to complete loop.

my config: using two 3.5 KV air variables. both in the 40-400pfds. i have them in parallel
which allows me to use 75m to 40m bands. i run 100watts to the loop. but the efficiency is 2%
on 75-80m band, about 25% on 40m. as freqs increase, efficiency can reach 90% on 20 meters.

this info from loop design software.
i am still evaulating the loop to verticals and dipoles. off the top, i am leaning toward those antennas, then the propagation favors me, and i am suprised at my sig reports.
on a 3ft loop on 40 meters, got a report of 20db over 9! wow.

software i am using is
small magnetic loop antenna calculator ver 1.22a
by steve yates  AA5TB
aa5tb@yahoo.com