What is the correct resistance (10 Ohm) with respect to the size of the square holding the
Antenna wires. Is 20'' the square diagonal, side-length, or total length?
If you are a long distance away from your transmitter, say in Europe,
then you should definitely build the large antenna.
The antenna resistance will be between 4 and 12 ohms -- it really doesn't
matter to be exactly a certain resistance, just as long as it's not a short
circuit or the wire is broken.
The size is about 3' to 5' per arm (1~1.5 meters).
The measurements are made at the arms of the antenna frame... or to say
it another way -- the "diameter" is two arms so that makes it between
6 and 10 feet. The wire side of the antenna is calculated by the hypotenuse
of the triangle.