From previous threads, e.g.
https://www.eevblog.com/forum/testgear/50-ohm-terminators/Here's an example of bandwidth and terminator use.
My terminators seem to be pretty awful: not sure if it's the effect of the tee, or the terminators themselves (who would use a wirewound resistor in a terminator..??!), but see for yourself.
Setup:
Avalanche pulse generator, with 20ns pulse line
10ns cable from generator to scope
At scope: tee + terminator
First, Tektronix 475, 200MHz bandwidth. Looks a little lumpy, doesn't it? The risetime is mostly there, though.
100MHz bandwidth. Still a little lumpy, so, whatever's causing those bumps, isn't really great for general purpose (Tek 465 and many other entry-level scopes are around this 100MHz baseline -- take note).
20MHz bandwidth. Not lumpy, but you can't even tell it's a pulse anymore, it's just a... pile. Note the bandwidth reduction is 2.5 times greater than the step between the first two, so this is a pretty drastic change, rather than a progression.
Tektronix TDS460, 400MHz bandwidth. You can see the wave does indeed look lumpy like that, plus some finer bumps that weren't visible before. Likely, this signal source doesn't have much energy beyond 400MHz, so that a scope of 1GHz wouldn't see much different, and would finally be observing the true risetime of this source.
External terminator disconnected (tee remains), internal terminator switched on. The change is pretty dramatic!
Tim