Cecil, W5DXP wrote:
"What caused the voltage to go to zero?"

Equal and opposite voltages. Reaction to connecting wires together
generates an opposite voltage which adds to zero with the incident
voltage. Current doubles at the short.

1/4-wave back from the short, a virtual open circuit appears. Cecil
claims this open circuit does not impede current.

1/4-wave short-circuit stubs are used as metallic insulators. They have
the characteristics of resonant circuits constructed of a
parallel-connected capacitor and coil, a very high impedance at
resonance.

From King, Mimno, and Wing, "Transmission Lines, Antennas, and Wave
Guides" page 29:

"A short-circuited line, one-quarter wavelength long at the desired
output frequency may be connected across the output terminals of a
transmitter or across the antenna feeder at any point without placing
much load on the transmitter at this fundamental or desired output
frequency, since at this frequency such a section has an impedance
ideally infinite, actually about 400,000 ohms."

Since I = E/Z, how much current do you think will flow into 400,000
ohms?

King, Mimno, and Wing`s impedance might scale down to only 33,333 ohms
on a 50-ohm line, still high, as they may have been considering a
600-ohm line.

All my radar texts say resonant transmission line sections have the same
characteristics as resonant lumped circuits and I trust them because the
radar circuits using tuned transmission lines to route the signal, work.

Best regards, Richard Harrison, KB5WZI