That isn't a lossy transmission line model! Model it with a lossy transmission line using real coax cable parameters and you'll see I'm right and your simulation is wrong. The 'regular' transmission line model is an over simplification. In the pspice I use I don't even get the 'dip' if I put 22pf in parallel with the 50 Ohm resistor.
Of course it isn't a lossy transmission line model; it is only 2m of RG174 or similar!
Resistive divider Z0 probes use standard 50ohm coax, not the lossy lines used in 10Mohm probes.
If you try to make a Z0 probe with lossy cable, you are misunderstanding the theory and will get suboptimal results!
You are misunderstanding. A lossy transmission line model has nothing to do with lossy coax! A lossy transmission line is a Spice simulation model with a better approximation of real coax so you will also get more realistic results. And you'll also need to model the probe head itself more accurately (including parasitic capacitances). You'll see that the latter will introduce a dip.
Your second sentence directly contradicts your third sentence.
No it doesn't; your statement only shows a lack of understanding Spice models for transmission lines. You seem to get stuck at the word 'lossy' but it is used in an entirely different context which has nothing to do with coax. The lossy transmission line model can be used to model any kind of transmission line which does not have to be coax at all.
Explain the measurements I have shown.
All your measurements show is that your probe shows seemingly correct behaviour. However, your probe is a 1:10 model with a 450 Ohm series resistor instead of a 1:20 model with a 950 Ohm series resistor. Crafting the attenuator cartridges for low-Z probes is an art in itself. Maybe HP is better at that than Tektronix but a simple 1k resistor in series with a piece of coax is not going to cut it. Try that first!
If you really think that the issue is related to 1:10 vs 1:20 then there is little point in continuing this conversation.
Please explain why Z0 probes use standard coax, not the very resistive coax used in 10Mohm probes.
Please provide your simulations that justify your conjectures. If you choose not to, please starts why not!
Come on; it took me 15minutes.I sure it won't take you much longer than that!