Peter, wot's a 'mode'. Don't bother to answer. ;o)

All I know is that there are a great number of them. I became aware of their
existence when in 1944 I first twiddled the 3 slugs in the matching section
of rectangular waveguide (the tuner) between Randall and Boot's 50 KW
magnetron and a renewed radar dish. This was a tedious, aggravating process
because when tightening the locking nuts the slugs never failed rotate with
the nuts so returning the process to square one.

I have always been under the impression Modes were invented by academics
just to explain by using pictures in their published papers the
peculiarities of waves when confined to waveguides. As I have never come
across another waveguide since 1946, and my favourite band has always been
160 meters, what microscopic amount of knowledge of modes I may have gleaned
from tightening nuts while lying on my belly inside an aircraft fuselage has
long ago evaporated.

On the other hand, 1875 telegraphists' equations have always provided good
enough answers when used to analyse behaviour of single wire lines including
antennas. If it looks by eye like a line it will behave like one. After all,
the very first telegraph lines were just single wires strung up on poles.
All have uniformly distributed R,L,C & G except at their ends. And end
effects, which are related to wire diameter, are calculable and can (if
necessary for precision) be accounted for.

The only problem, and it's not a serious one in practice, using classical
transmission line analysis is due to uncertainty in the antenna's
environment such as height above ground, ground conductivity, or dogs' hind
legs. or trees. Attempts to use some sort of mode analysis to relieve
environmental uncertainty would be just as likely to fail.

The modelling and number-crunching methods of EZNEC-type programs, which are
neither classical nor modal, will eventually remove the guesswork by fully
including the environment in the model. But the time and effort taken to
enter the data and to ensure absence of errors may prove overwhelming to
professionals and amateurs alike.

I would think trying to find a use for modes would be as fruitless as
considering what happens to the so-called power which is supposed to be
reflected back into transmitters.
----
Reg.