Alan Peake wrote:

However, if
the CW can be thought of as a series of pulses, then does that not mean
that real reflections occur and that the sum of the reflections for each
pulse looks like they have come from a virtual discontinuity?

Hi Alan -

The point of using pulses is that their width is short, and the time
between pulses is long compared to the delay times in the system. In
the case of of CW there will be standing waves all throughout the
system obscuring any possible measurement of transient response.
These pulses only reflect from physical discontinuities in the surge
impedance of the transmission line. Otherwise, TDR would be a
complete wild goose chase; a real cluster _blank_, in the vernacular
of the trade.

If not, how would one go about proving or disproving the idea of
reflections from virtual discontinuities?
Alan

Disproving the idea of reflections from virtual discontinuities would
be done, for instance, and has been suggested, by measuring the
presence of fields beyond the virtual short in a 1/4 wave stub.
Finding waves reflecting instead from the open end sure would not lend
support to the notion. The fact that the idea is inconsistent with
Maxwell's equations doesn't help either.

I don't think there is a way to prove the idea of reflections from
virtual discontinuities. But with certain specific exceptions, a
system could in other ways appear to behave as though reflections are
originating at virtual impedance discontinuities (+/- n half wavelengths).

73, Jim AC6XG