Owen Duffy wrote:
Are the principles that apply to this example inconsistent with the
general case (eg dc, ac, transient, steady state etc)?

Of course, pure DC principles are not adequate to cover
general case distributed network problems. Else, there
would have been no need to develop the distributed network
model. How would your transmission line calculator work
if you only used DC principles?

For instance, the conditions at the source are opposite
between the RF frequency where the feedline length is 1/4WL
and the RF frequency where the same feedline length is 1/2WL.

Conditions are also opposite depending upon whether a
Thevenin equivalent or a Norton equivalent is chosen.

Ramo and Whinnery, of "Fields and Waves ..." fame, warn
us not to attach any significance to the dissipation
within those two equivalent circuits. They are still
equivalent even though one is dissipating zero watts
and the other is dissipating 200 watts.

Even when the impedance is the same between the DC problem
and the 1/2WL RF problem, the DC current in the middle of
the feedline is zero while the RF current in the middle
of the 1/2WL section is at a maximum.
--
73, Cecil, w5dxp.com