开云体育

This would be known as "dispersion" and would cause problems with either the pulsed (time domain) or swept frequency (synthetic time domain) approach. A fast pulse (as used in TDR) has all frequencies

Coax is, of course, not identical to paired cable, but using a low end of 50 kHz makes me wonder whether the velocity might be lower than the published high frequency value sufficiently to skew the

All of them together. It will show the SWR of the combined elements, it has no way to distinguish one from another. 73, Don N2VGU

I take a known length of the coax of the same physical batch and do a TDR and see what the measurement is and physically measure the sample coax and then can change the velocity factor to equal the

There are many models. The smallest, cheapest is about $60. And any (nanovna) model will also need connector adapters. The models with larger screens than the small 2.8 inch $60 model are easier to

That depends on your "sweep width" setting - the START and STOP frequencies. -- Doug, K8RFT

If you are sweeping across all bands the antenna is designed for as the NanoVNA sweeps across each resonant point it will indicate the SWR for each band. If you had a fan for 40, 20, and 15 meters

my friend....dont listen to what people say when they tell you nano vna isnt as good as a REAL antenna analyzer because that exactly what a nano vna is. only is generally has more features than others

All of them together. It is showing the swr of the system of antennas. If one of the elements is for 20M, the swr at 14MHz is primarily affected by the 20M element - but the other nearby elements

Hello The nanoVNA sees all antennas as a localized dipole. The word DUT is used during measurements. The NanoVNA measures, for you, the impedance shown by this dipole as a *function of the frequency*.

When using a NanoVNA to measure SWR on a multi-element antenna, with different length elements but all fed from the same feedpoint, which element’s swr is the Nanvna displaying data for?

Kindly allow me to restate my objective Find out if the unknown length of coaxial cable is in multiples of 1/4 wavelength of selected frequency. My tool of choice is nanoVNASaver and its TDR option. I

At 50 kHz for paired telephone cable, the the velocity of propagation is somewhat lower than at higher frequencies. For 22 gauge plastic insulated pairs, AIEE Paper 59-778, "Transmission

Thank you everyone for your input. I will give the nanoVNA a shot. I also came across this little book which explained much that concerned me. – "A guide to the NanoVNA" by Christoph Schw?rzler,

...which totally depends upon the correct velocity factor; any error in that will have a proportionate effect on your (physical) length measurements. 73, Don N2VGU

Stan, I have to disagree with you on this one. The method uses the 1/4 wavelength measurement method but it is prone to more error that the TDR method. Here are some actual measurements to illustrate

A far easier and more accurate way to measure cable length is by using the "Measure -> Cable" function in the nanovna firmware (if you have a firmware with this function). Just connect to an

Follow up to my previous post... You can also use the Transform option in the NanoVNA menu to do TDR measurements without connecting to a PC. From the Display menu you select a trace and set it to S11

The NanoVNA does not calculate the physical cable length using traditional Time Domain Reflectometry (with pulses on the cable). It calculates using frequency domain S11 data and then performs an

I have added to this /g/nanovna-users/photo/286949/3628295?p=Created%2C%2C%2C20%2C2%2C0%2C0 to show the difference between "solo TDR" display and main nanoVNASaver display with "TDR"