I use my NanoVNA from 0.4 to 150 MHz. I wonder of installing a 10uF coupling capacitor with the 1uF would help the low frequency response. Can anyone recommend a SMD part from Mouser or Digikey?
Thanks,
Mike N2MS
toggle quoted message
Show quoted text
On 03/05/2023 8:22 AM Brian Beezley <k6sti@...> wrote:
I've been looking into the S21 and Y21 methods of calculating an unknown impedance connected between the two VNA ports. The port impedances play a role. I used Micro-Cap to model the NanoVNA-H4 rev 4.3 port networks and calculate their input impedance. I used data sheet values for the semiconductor impedances. Port 1 is on the left in the schematic. Blue/red curves are for port 1 and green/brown are for port 2. Even though the AC-coupling filter corners are only a kHz or two, the phase shift they cause extends much higher. I have seen the effect on measurements at a few hundred kHz.
Brian
