So, I've got a couple of piezos to test.
- Small (~7MHz)
- Medium (~5MHz)
- Small (~3MHz) and I want to test electrical impedance matching. I've done some tests in the past, but hopefully we can go a bit more into the details.
The piezo related data are stored in this folder for reference. I'll focus on the 3MHz one for this experiment.
So, I started with checking its Smith chart profile (also as a s1p file):
And, playing with Ls, I've added one to ground, something I've seen in a couple of probes.
Cool! We're going from a -4dB loss at 4MHz to something less cute but around -10 to -16dB between 2 to 5MHz. That's a 3MHz bandwidth for a central freq at 3.5MHz... better (possibly, depends on the piezo datasheet) !
Crappy setup, noisy, but ... fast.
Distance piezo - reflector == 92mm (119/120us -- which we should see below)
The results are consistent with the smith chart we've seen for the adapted system. Echo is larger, saturates more. Looses a bit of frequency, but linked to a larger bandwidth.
