Single turn loops work well for transmitting. Multiple turn
transmitting loops have a nasty habit of disappointing the user.
--
73, Cecil http://www.qsl.net/w5dxp

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The reason a multi-turn maggloop of the same diameter would be
disappointing is because of increased loss in the loop conductor.

The ability to collect or radiate signals is a function only of the
diameter, ie., the longest linear dimension. Alternatively stated, a
function of the area enclosed.

With a single turn loop, conductor loss is due simply to skin effect.

With a multi-turn loop and the same amount of copper, proximity effect
comes into play and loss resistance increases faster than radiation
resistance.

Also, with a transmitting magloop, for the same power input, the
voltage across the tuning capacitor increases proportional to the
number of turns. Ridiculously high voltages appear. Although, the
value of the capacitor in pF is very much smaller, the physical size
of the capacitor remains the same.
----
Reg.