Jim Lux 2024/08/27 11:12
Normally, you’d put it on Port 2, to boost the signal coming from the probe.
If you amplify the Port 1 signal, you don’t get the S11 of the AUT (if probe
is Port 2 and AUT is Port 1).
I’ll note that sometimes you want S11 of the probe, because then you can
calibrate out the cable effects as it bends and moves. You look for the
impedance discontinuity in a sweep, and use that to back out the cable
contribution. There’s a bunch of papers from places like Nearfield Systems
Inc (and before that Scientific Atlanta) that describe how it’s done.
Important if you’re doing near field because you’re sensitive to the phase of
the measurement when it goes into the FFT processing to turn near field into
far field patterns.
Yes, they are cascadable, and Minicircuits has dozens of similar amplifiers
with different gain and 1dB compression points. Considering that the NanoVNA
isn’t sinusoidal and depends on using harmonics, compressing the amplifier may
not be an issue, the extra harmonics are fine, and maybe even desirable.
You’ll calibrate with the amplifier in the system, of course.
> On Aug 27, 2024, at 8:59 AM, Dave <david.matthew.daniel@gmail.com> wrote:
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> This should bring the output power of the test port on the VNA 6000b from
-10 dBm to around 0 or +2 dBm, good. Maybe two of these could be cascaded to
increase the gain, have you tried that with these types of amplifiers?
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