Thanks you for posting a screenshot of your scope readings, however to convince me of what you are saying you will need to do more than this.Sorry about that, anyway here is a pic.
Top trace is input signal.
I want to make a casual observation of your experiment:
You state that if "a signal is applied to a circuit that is non-capacitive and non-inductive", but as thingmaker3 correctly pointed out above: "How do we achieve zero capacitance and zero inductance in the real world?" Whether we consider your experimental set-up or think of this purely as a TM line thought exercise, your set up will have (parasitic) inductance and capacitance therefore cannot satisfy your one criterion above. Quoting appropriate sources:
For parasitic capacitance: Voltage applied between two conductors creates an electric field between those conductors. Your frame has the main TM line interleaved with the return path, therefore some form of parasitic capacitance will be present in the set-up.
For parasitic inductance: Current through any conductor develops a magnetic field of proportional magnitude. Energy is stored in this magnetic field, and this storage of energy results in an opposition to change in current. For your TM line the wire develops a magnetic field as it carries charging current for the parasitic capacitance between the wires.
Therefore, you are suggesting that your model is an ideal model with zero inductance and capacitance, I say this is impossible due to the very nature of physics. So to back up your claim can you prove that your set-up exhibited zero inductance and zero capacitance?
Dave