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problem started when i attempted to upgrade, screen went black, foolishly did not save the old version.. now i can read the vna with stm32, it even appears to write the new firmware but still a black screen, how do i know if i am using the correct firmware for my vna? what are the correct steps to read and program with stm32? i must be missing something, any help would be appreciated. thanks for any advice Bob VA4BG

Hi, Currently trying to design and tune a 1/2 end fed antenna (RF is applied on one end), I am looking for the correct method to measure its impedance. As this one is very high I don't know the right méthode ! The result of this measurement should allow me to create a Stub with SimNEC to tune it. Thanks in advance for your help -- 73 s Christian F8GHE

Since most filters are a series of resonators of some kind or another, terminating them in a resistance other than the design resistance will probably change the filter characteristics. Consider a filter that effectively has an input that is a RLC circuit, where the R is the terminating impedance of the source. If you change R from, say, 300 ohms to 50 ohms, then the Q will be different. That will certainly change the skirts, and will also probably change the overall passband (since most filters are stacked up responses of multiple resonances).

Folks, Using the NanoVNA as a signal source for Ground Penetrating Radar (GPR) was discussed a couple of years ago. Today on Hacker News, there is an article about a home-built Synthetic Aperture Radar (SAR) unit using a freq around 6GHz. https://hforsten.com/homemade-polarimetric-synthetic-aperture-radar-drone.html The article discusses theory and the problem of finding a suitable Rcv A/D. The LiteVNA has the freq range, is capable of resolving nS time (to a certain amount), can measure phase and is programmable. The big issue is probably the switching time of the generator/reflection ICs in the front-end of the LiteVNA. As for the A/D spec, would the heterodyne method and DSP used be a limiting factor? So - might it be feasible to make use of the LiteVNA in a simplified radar setup using an external controller and appropriate antennas? Could the TDR routines be adapted? Could the LiteVNA be used with a TinSA-Ultra and a controller for something? Just thinking out of the box here. In my 60+ years of Tech, I have always looked at repurposing stuff. So, instead of "not possible" answers, I would rather hear what might need to be changed (electronics /software) to achieve a minimal proof of concept. Thinking caps on.... ... Larry

I am a new NanoVNA user. Mine is an H v3.6. No firmware updates have been done. I have been using it only for a few days. Sometimes, on sliding the switch on, the screen is blank, but the blue LED is lit. After a few on/off cycles, the screen becomes functional and I can use it. Does any of you have a similar problem? Jon, VU2JO

A very useful PC application for the NanoVNA was developed by One Of Eleven as an alternative to NanoVNA Saver and other earlier programs. It was originally done for personal use but was kindly offered to the community. After development was stopped by the author the source code was released so that improvements could be done by others. The program is easy to use and has many nice features... - Multiple graphing options and flexible scaling options. - Calibration works reliably and includes averaging and smoothing options - Built in firmware uploading tool that is easy to use - Continuous run mode which is useful for tuning filters and antennas - Four memories that can be used to compare results in the graphs - Export and Import of Touchstone files (s1p and s2p) - Multiple marker capability with various display options. DiSlord and Owen Duffy have made several recent improvements and bug fixes. The updated program can be downloaded here >> https://github.com/owenduffy/NanoVNA-App/releases The program is mouse driven and by right clicking on any graph you can change the tiling options (# of graphs on screen) and the type of graph (SWR, RL, Reactance, Smith etc.). Please post any questions about how to use the program in this topic. Roger

NanoVNA has a port renormalization function (called Port Z, see DISPLAY->PORT Z: 50) that allows you to see the measured S parameters at other port impedances. But since NanoVNA is only available for measuring S11 and S21 parameters, the following assumptions are made for renormalization: S22 = S11 and S12 = S21, i.e. the DUT is symmetrical. To simplify the calculations, a non-complex impedance value is used and the new impedance of both ports is the same. And now the question is to what extent it is necessary to make calculations for different values ??of port impedance, because then the DUT is not symmetrical?? and the assumption that the S22 = S11 and S12 = S21 are equal is not true. Or this can be useful?