Spam Collector wrote in
:

....
What are the performance differences between the
three configurations, and is there a upper frequency
limit for practical use of them? For example, would it
work on say 2m or 70cm, where the antenna would be
hundreds of wavelengths long?

Frank, as you will have noted from others' responses, the answer to this
is not simple.

Longer or larger antennas are not necessarily better. You would benefit
from examining the changes in pattern and feedpoint impedance of a loop
as it grows from 1/10 of a wavelength to 10 wavelengths per side, and
compare a very large loop with a rhombic.

You can only evaluate different antennas in your own context if you list
the relevant factors and rank their importance, factors like size,
height, frequency agility, transmission lines, matching arrangements,
automated operation etc.

Efficient and effective multi-band antennas don't happen by accident,
they are a significant challenge, and an efficient and effective 160m to
70cm is an extreme challenge. On the other hand, you will see proof that
"loading up the fencewire works", but it goes to the meaning of 'works',
which is less specific than 'effective and efficient'.

Owen