On Mon, 16 Sep 2019 at 02:27, alan victor <avictor73@...> wrote:
Hi Tom,
Very good.
The paper published by Copper Mountain applications was irrespective of
frequency.
The paper did however assume all parameters of the VNA are independent too:
Directivity 50 dB
Source match 46 dB
etc. Those parameters are *very* good, and most unlikely to be achieved
with the NanoVNA, but will *not* be independent of frequency. One can
expect the performance of the load used in the calibration to be poorer at
higher frequencies. One can expect the directivity of the bridge to be be
poorer at high frequencies. So the fact Tom¡¯s results deteriorate at high
frequencies is not surprising to me.
Whilst it is possible to purchase very close tolerance resistors, the same
is not going to be true of inductors or capacitors. I use some 0.005%
resistors to check my HP 4284A LCR meter. They are readably available.
They are 10 times better than the basic accuracy of the LCR meter (0.05%).
But it¡¯s impossible to buy capacitors of that tolerance, and for inductors
the situation is even worse
Alan
Dave
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