Yes of course, the ohmic, or DC resistance itself in the context of the antenna impedance measurement?is a far less significant contributor than the reactance's; capacitive, and inductive. But, in terms of the device?calibration the DC components are all we use. So, I was wondering that how flawed (or not) any subsequent?analysis might be as a result of using a 50 ohm calibrator that was somewhat less or greater than 50 ohms.?I suspect not much at all.
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On Friday, August 5, 2022 at 12:00:35 AM EDT, Dragan Milivojevic <d.milivojevic@...> wrote:
You are thinking in DC, switch to AC + calibration plane, fringing
capacitance etc.
On Fri, 5 Aug 2022 at 05:08, Chris Gardner via groups.io <seaman98=
[email protected]> wrote:
? Pondering a simple question relating to SMA calibration devices as in
those that are generally supplied with a newly purchased Nano VNA as an
example. Open is Open, that is obvious. The connector simply shields
the the female connector from any outside interference during calibration.
The short is obvious as well, 0 (Zero Ohms) resistive load. But, more to
the point, my biggest concern is with the supposedly 50 Ohm resistive
calibration load. I have 3 such devices from various sources, and none are
precisely 50 Ohms. My most recent purchase has a calibration sticker
enclosed in the kit indicating the 50 ohm load is 48.9 ohms. I confirmed
that value with my DVM. Would that be considered adequate, or good enough.
How significant does that difference in the ohmic resistance become in the
final sweep product. Of course assuming I am calibrating the VNA at the end
of the feed line just before the actual antenna.
? ? On Thursday, August 4, 2022 at 09:36:02 PM EDT, Donald S Brant Jr <
dsbrantjr@...> wrote:
? I got my cal kit from Dr. David Kirkby kirkbymicrowave.co.uk.? It
includes not only extensive characterization data but also optionally
verification standards which will allow you to check the quality of your
calibrations.
73, Don N2VGU
