Roy Lewallen, W7EL wrote:
"Can you please explain that a little more? (Radiation is a function of
loop area.)"

Not being a typist, I`ll refer you to "TV And Other Receiving Antennas"
by Arnold Bailey. On pages 407 and 408 Bailey gives two formulas for
computing the antenna resistance for a loop antenna.

On page 408, Bailey has Fig. 8-14 which plots radiation resistance (the
stuff we build antennas for) versus the loop perimeter in wavelengths.
For a square closed loop of one wavelength perimeter, the graph
indicates about 50 ohms.

Bill Orr, W6SAI in "All About Cubical Quad Antennas" gives the full-wave
vertical loop antenna an impedance of 125 ohms on page 15.

On page 14, Orr writes:
"For purposes of illustration, the two wire folded dipole may be "pulled
open" to a diamond-shaped loop fed at the bottom point. If this
distortion of the loop is continued the antenna will become a shorted
transmission line."

A perfect circle is the geometric shape enclosing the most area for a
given perimeter. The more corners a closed figure has, the more closely
it usually approximates a circle. That is why I commented on an octagon
versus a square.

Best regards, Richard Harrison, KB5WZI