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-------- Original message --------From: Peter Gottlieb <hpnpilot@...> Date: 07/08/2019 17:29 (GMT+01:00) To: [email protected] Subject: Re: [nanovna-users] Some basic load measurements Is the basic OSL calibration sufficient?? Or do I need to do something special?Peter> On Aug 7, 2019, at 11:18 AM, tuckvk3cca <tuckvk3cca@...> wrote:> > I don't understand you Peter, the 8753 is a network analyzer, which will> give you S11 the reflection coefficient.? The log of its magnitude will be> the return loss.? It should be able to convert your readings into complex> impedance R+jX too. I have the equivalent of the minivNA which only> calibrates with one point, an open load. I still get 38 to 40 dB return loss> at HF for some of my better 50ohm loads.? I use the j-VNA software which> converts all magnitudes and phase measurements to S parameters of R+jX etc.> Most of the time I just live with this simple calibration procedure. On> transmission just a through pass for baseline calibration works for most> applications.? For a full S parameter set measurement one does need to work> much harder in terms of calibration.?? > > -----Original Message-----> From: [email protected] <[email protected]> On Behalf Of Peter> Gottlieb> Sent: Wednesday, August 7, 2019 4:29 PM> To: [email protected]> Subject: Re: [nanovna-users] Some basic load measurements> > If you can tell me a simple way to set up to measure return loss I can do> that for the various loads. I can do the smith chart but it is very hard to> see in a photo as the loads are all just tiny dots near the center on the> horizontal line. Perhaps easier to see if I change display colors or save> onto the floppy instead. What I call the cheap BNC is an old mil spec> terminator probably designed for HF and it gives a nice little spiral around> the center. > > > Peter> >> On Aug 7, 2019, at 5:48 AM, tuckvk3cca <tuckvk3cca@...> wrote:>> >> That is expected Peter. Have you got the imaginary parts or phases? Best> to plot on a Smith chart too and see how your samples rotate from low to> high frequency.? 1.02 swr corresponds to about 40dB return loss which is> very respectable at 900MHz.Sent from my Samsung Galaxy smartphone.>> -------- Original message --------From: Peter Gottlieb> <hpnpilot@...> Date: 07/08/2019? 04:43? (GMT+01:00) To:> [email protected] Subject: [nanovna-users] Some basic load> measurements Resending from website as it didn't seem to go through as a> message.? Also my pasted table from Excel lost formatting so I tried to fix> it to be more readable.I just did some very simple resistance and SWR> measurements using a HP 8753ES with 85046A, resistance was measured using a> calibrated Agilent 34401A in 4 wire mode.I did a very basic one port 3 point> cal using a Anritsu OSL which is specified to over 3 GHz.I took measurements> at 900 MHz.Load????????????????????? R ohms????? SWR????????? SWR notesOSL> 50.052?????? 1.001???????? FlatCheap BNC??????????? 51.104?????? 1.908> Sloping up with freqNano load?????????????? 49.044?????? 1.019> FlatNarda 12.4 GHz????? 49.536?????? 1.018????????? FlatTiny SMA> 50.787????? 1.009????????? FlatI am guessing there is some significant> reactive component in the BNC terminator.? All three of the SMA loads showed> a flat SWR with frequency so I'm thinking they all have a minimal reactive> component.The difference in resistances while keeping SWR low was a bit of a> surprise to me.? The load that came with the Nano is over an ohm off of the> load I used to calibrate yet the SWR remains at a low 1.019. Why is this?? I> did the math and surprisingly this is indeed correct, per calculation the> SWR should be 1.021 vs my measured 1.019.? I'd say this is darn close seeing> one measurement is DC resistance and the other is at 900 MHz.So my> conclusion is that SWR is not a sensitive number to see resistance> differences.Once I read some of the references cited I can do some more> advanced measurements.Peter>> >> > > > > > > >