Hello,

How accurate would measurement of large impedances (say > 1 k ohm) at RF frequencies would be, when one uses a VNA to do it? And how susceptible it is to the stray capacitance coupling of the measurement cables with the device under test?

thanks

How accurate would measurement of large impedances (say > 1 k ohm) at RF frequencies would be, when one uses a VNA to do it? And how susceptible it is to the stray capacitance coupling of the measurement cables with the device under test?

thanks

> Hello,

>

> How accurate would measurement of large impedances (say > 1 k ohm) at RF frequencies would be, when one uses a VNA to do it? And how susceptible it is to the stray capacitance coupling of the measurement cables with the device under test?

>

> thanks

It comes down to reflection tracking accuracy and the short answer is "not very accurate". But do the math:

1kohm is 0.904 reflection (0.9 dB return loss). If the source match and directivity are each -40 dB (0.01 reflection) then the rss error would be 0.014, and measure would be 0.918, or an impedance of 1171.

But then, you could have figured that out for yourself, if you had read my book ;-)