Review, Experiments and Teardown of a NanoVNA-F V2 Vector Network Analyzer

hi in this video let's take a look at this nano vna made by sysjoint i requested this one from banggood for a review as usual i will leave a product link in the video description below for those who are interested in getting one after watching this video most viewers following my channel most likely already know what a vna is and probably already have a version of many of the nano dnas available on the market but in case you don't i will explain very briefly what a vna is so that you have some context as to what we're looking at here a vna is a vector network analyzer and it is also known as a gain phase meter as a vna can do both amplitude and phase measurements this is in contrast to a spectral analyzer which only provides amplitude measurement spectral analyzer along with a tracking generator is sometimes referred to as a sna or scalar network analyzer prior to the advent of nano vna very few hobbyists had access to a vector network analyzer due to its extreme high cost even with used equipment like the hp 8753 which covers 30 kilohertz to 3 gigahertz or 6 gigahertz depends on the model can easily set you back over a thousand dollars on ebay nowadays as for a nano vna depends on the model and frequency range you can get one for about between 50 and 150 one of the challenges in getting one these days is that there seems to be at least a dozen different models some are fully open source some are proprietary choosing one can be a bit overwhelming these different models vary mainly by their hardware capabilities for instance 2.8 inch lcd versus 4.3 inch lcd 1.5 gigahertz frequency range versus 3 gigahertz and 4 gigahertz frequency range so on and so forth the good news is that the software most of these nano dnas operate on is very similar across all different models so if you know how to use one you will have no problem adapting to a different model now the model we're looking at here is a nano vna-fv2 and it can operate between 50 kilohertz to 3 gigahertz this frequency range should be able to satisfy most of the hobbyists use and price-wise it is currently on sale at banggood for just above one hundred dollars so you may wonder why nano vnas are so cheap compared to professional grade ones well like any other nano vnas out there on the market at this low price point a few compromises had to be made one area of compromise is the dynamic range from the spec you will see that the dynamic range for the s21 is at 70 decibels at 1.5 gigahertz and it drops to 60 decibels at the maximum three gigahertz for the s11 measurement the dynamic range is 10 decibels lower than the s21 at the same frequency for a commercial vna like the hp 8753 the dynamic range is at 100 decibels and for modern dnas this figure can easily be better than 120 decibels another area is limited frequency resolution you can achieve with these nano vnas depending on the firmware you use you only have between 100 and 400 points captured per sweep and the sweep speed is relatively slow as well so if you are sweeping the entire three gigahertz range each point on the screen would only represent about 15 megahertz which could potentially omit a lot of important details of course you can always sweep a narrower band and get better resolutions that way again these compromises are well thought out design choices and for hobbyists they are perfectly acceptable now to be very honest i'm very impressed by the build quality of this nano vna dash fv2 as you can see it is nicely enclosed in this beautiful aluminum case with the ports clearly marked the metal case here is not just for aesthetics and protection it definitely adds extra shielding and reduces the noise introduced from the environments and the silk screen here are clearly marked reminds you what each port is used for for instance s11 is used for input return loss measurement and s21 is used for insertion loss and if you flip over the case you will see an even more elaborate diagram of what each of the s-parameters means in a two-port network in case you are a little bit rusty on your rf knowledge besides the nano vna itself you also get a calibration kit which consists of a open short and 50 ohm load and you also have a couple of these semi-rigid high quality coax cables i believe these are rg 405 cables and you also have a few connectors which definitely come in handy of course you also get a couple of silences depends on your style you can use either one of these for the touch screen and there is of course also a supplied usb cable for charging the unit and connect to the computer everything packs in in this nice plastic box so you don't end up misplacing any of the components although it is slightly more expensive than other nano vnas of similar performance you actually get a lot for the price you pay with all these high quality accessories this is actually one of the main reasons i wanted to look at this particular nano vna at the first place so if everything works as expected i think this is certainly a good investment for your money by the way the built-in battery is a 5m power lipo battery which according to spec should give you 7 hours of continuous use it also has an usb charging port right here and you can use it as a battery bank if you want to i think this is definitely a very nice touch especially given that the hardware for enabling this feature is minimal now let's part it on and do a few measurements and afterwards i will open it up and take a look inside by the way this video is by no means a thorough tutorial on how to use a nano vna i'm sure i'll be making videos using the nano vna on more specific topics in the future and by the way the manual system of this nano vna is very similar to other nano vnas if you have used one before and there are a few variations and minor differences but overall is largely the same but if you are not familiar you can definitely print out this start guide and quickly you can go through how to get to a specific settings and i had played around for a little while so you will see that actually currently the screen is no longer the factory default when it powered on but you can pretty much use this just like any nano vnas you can see that we have the manual systems here you can type display you can turn on all the traces you want to see and of course right now we turn off these traces and we just want to see the has one one for now so the first thing i wanted to do is to measure a couple of antennas what i have here are a couple of whip antennas now if you know the rough working frequency you should set your frequency range accordingly as we mentioned earlier that the number points is limited so the narrower the band the better the resolution but let's pretend we don't know anything about these antennas and we want to find out what their resonant frequencies are for that let's calibrate the entire 3k expanse and the first time i'm going to do that on camera so you get a rough idea what the calibration procedures are later on i'm going to calibrate off camera so that you don't have to see me doing the same thing again and again and i just want to remind you the rule of thumb of using nano vna is whenever your change of frequency range you almost always have to recalibrate so let's first define our frequency range before we do the calibration as we said earlier we wanted to do the entire frequency range between 50 kilohertz to 3 gigahertz so for that i'm going to choose my stimulus to start with 50 kilohertz and also i'm going to choose the stop frequency to be 3 gigahertz so that covers the entire frequency band that this nano vna supports now of course you see that the curve here showing is a little bit of odd that's because i haven't done calibration yet so now let's uh proceed to do the calibration and for the calibration let's come here again we will come back to do cal let's reset the calibration and start a fresh one so the first one we're going to do open and this is open slug so we plug it in just finger tight will be good open it takes a few seconds to do the calibration and it's relatively quick the next one is short so you want to make sure that you're using the correct adapter here again finger tight would be sufficient short and the last one is load so for that we're going to put on the 50 ohm terminator here that's the 50 ohm and we do load so now this actually we're done with the s11 measurement and if you're doing s21 measurement you will have to do the through calibration as well but for now we are just measuring the antenna using s11 so we're okay with just the open short load calibration here and you notice once you are done here you do see this osl at the bottom of the screen that tells you that you have done these three calibrations so for that we're done and i'm going to save it to slot 0. so let me remove it you should see a perfect line again and that tells you that it's calibrated and in case you want to further verify that the calibration has done successfully you also can enable the smith chart so you can do display trace yeah two so you will see that right now we're kind of open but we don't have a selection so that dot should be all the way to the right and if you do short that dot should be all the way to the left so this is another way to verify you have done the calibration correctly and when you put in a 50 ohm you will see that the dot should be smack in the middle so which means that we have done our calibration correctly here for the antenna measurement let's switch off the smith chart so it will be cleaner we only need the s11 measurement here and let me screw in the first antenna this is the antenna we're using so i'm going to put it on here and you'll see that we get a div here and that tells you the operating frequency and there are a couple ways to measure that the first one is you can use this stylus to drag it to the location so it is around 840 megahertz of course you can always use the menu item to automatically place the cursor here so for that let's try and we're going to go back we go to marker we go to search in this case we're going to select a minimum so let's try it yup so it already found the minimum is 840 megahertz so again you can see that for this antenna the resonant frequency is at 840 megahertz and of course right now we're showing the return loss chart for hem radio operators it is more natural to use swr measurement of course these are related but nevertheless we can change the view to swr so for that let's see the display and we will see the format and let's change it to swr now you can see that for this antenna the operating range is clearly around the 840 megahertz area as here is where the swr is close to 1.0 so let me switch this back to the log mag display and you can see that this is the log mag display for the return loss so that's our first antenna now let's try the second antenna we'll unscrew this one and the second antenna looks very similar to the first one but let's screw it on and see what we got and you can see that this antenna is slightly different than the one we used before instead of a one dip we have two dips clearly this is a multiband antenna and the first frequency is still at 840 roughly the same frequency as the antenna before but we also have another dip right here so let's take a look at what that is so for that i'm going to drag it over now sometimes it's a little bit hard to drag these yeah sometimes it's very difficult so for that i'm just going to use the arrow key here actually let me see if i can drag it now yeah now i can drag it so the second one you can see is roughly at 1.77 gigahertz clearly this antenna supports both 840 and 1.77 gigahertz frequencies so it's a dual frequency antenna and let's change it back to swr and take a look at what we see there so for that we're going back to display and format let's change to swr so clearly you can see that if you recall the first antenna we saw we only have one dip here and the curve goes all the way back to pretty high swr's but here we stayed relatively low between 840 and 1.77 next i will do a couple of measurements of a capacitor and the inductor with the smith chart the calibration has been done between 1 megahertz and the 200 megahertz and if you look carefully you'll notice that i added this electrical delay of 120 pico seconds or 25.18 millimeters that's because i will be using this through to connect my device under test and this nano vna and when i calibrated this nano vna i did not have this through on the unit here my test capacitor is mounted on this sma connector here so i'm going to screw it in so there are a couple of things you may find interesting on this curve the first thing is obviously that for the majority of time the curve stays at the bottom half of the smith chart which indicates that this is indeed a capacitive load if you look at the measured capacitance it's a roughly 470 picofarad which is roughly in line with what the capacitor is and as you increase the frequency at some point you will see that the capacitance increased dramatically and at some point it crosses the middle line and became a inductive load so this tells you that when you are dealing with the high frequency rfs you have to be very careful of your layout and the component you use as sometimes they may not appear to be what you think they are next we'll take a look at a hand wand inductor here as an inductor the curve naturally stays on the upper half of the smith chart and you can see that the measured inductance is roughly at nano henries across the frequency range what we have done so far are just s11 measurements and for completeness i do want to show you an s21 measurement for that i have set up the nano vna to sweep between 300 macros and 500 macros and if you look carefully you'll notice that the calibration status right now has a t and the t stands for through the through calibration is required only for s21 measurement the circuit we're trying to measure is a pretty standard lc filter as you can see here with this two long coax so let me hook that up and we'll see what the measured response is and now you'll see that we have two curves showing here and one is s11 and the cyan one is s21 and you can see we do have a notch at around 340 meters which is the filter frequency of this specific filter and throughout the range the s11 stays relatively flat now i have hooked up the s11 port of the nano vna to a spectral analyzer the 8566eb in the background and let's take a look at the characteristics of the sweep that this nano dna generates the hp 8566b is currently set to sweep between 0 to 2.5 gigahertz band and the nano dna is sweeping between 50 kilohertz and 3 gigahertz let's uh set the 8566b to maximum hold so that we will let the [Music] smash will accumulate for a while and we will take a look at what it looks like in a little bit now we have left the trace accumulating for a while you can clearly see that we have this maximum envelope that is showing that represents the maximum output power from the nano dna then as you can see that the curve is not entirely flat but is actually reasonably good so at highest output power we get roughly 0 dbm which is uh what is expect now as frequency increases you can see that output power started to drop and to about minus 5 dbm at the higher end of the scan here is at 2.5 gigahertz so this is well within the range of between 0 and -10 according to the specification so while still hooked up to the hp 8566 while it's scanning i just want to show you what's going on on the nano dna currently we have two traces set up one is for s11 the magnitude the other one is the smith chart for the return loss you can see that the s11 is relatively flat and on the smith chart you can see all the dots are congregated around the center which is the 50 ohms this tells you that the impedance matching between the nano vna and spectral analyzer is very good across the entire frequency range between 50 kilohertz and 3 gigahertz the nano vna can also be used as a signal generator while we're still hooked up to the spectral analyzer let's take a look at the spectrum it generates so for that i'm going to change it to the signal generator and by default it's outputting 1 gigahertz let's change the frequency down a little bit to 100 megahertz let's enable the rf output and now with the output enabled let's briefly switch to the special analyzer we can see the output so clearly you can see that we have a lot of harmonics so clearly this is not a sinusoidal output and i'm going to zoom it in and just to do a quick measure so we can see what is going on there [Music] so let's find the peak the peak is at 95 megahertz which is close enough and let's take a look at the next speed so it's at almost 300 megahertz so that tells you that's a third harmonics which means the output is a square wave so we can take a look at that later on an oscilloscope as well and you'll notice that at 100 megahertz output the output attenuation is disabled i did some experiment and it appears that once you start exceeding 135 macros is becoming able that means that the internal synthesizer was not able to level the signal below 135 megahertz just to show you that let's set the frequency to 130 megahertz you can see that it's still disabled as soon as i set to 135 meters you can see the output is enabled so now let's set the frequency to say 500 megahertz and let's take a look at the signal output again you can see that the output currently is at measured 495 members and let's just call it 500 macros and it's sitting at -10 dbm which is actually 0 dbm because of the attenuation of the input for the special analyzer so that's very good and indeed on the display here we're selecting a 0 dbm you can see that the output signal is 0 db so let's reduce it to minus three db and you can see we have changed this to minus three db and indeed on the screen we were shown minus 13 dbm so that's actually very good so let's do minus six so try to magic c here and it's difficult but i'm going to select minus six and on the screen you see the minus six as well so so far so good and minus nine and actually that works out very well so just for completeness let's change the frequency to two gigahertz and you can see that add two gigahertz but again try to search the peak [Music] so the amplitude actually drops significantly now let's change to 0 dbm and you can see that even at 0 dbm we have about -5 dbm down from these supposedly the 0 dbm as you can see currently we're set at the 0 dbm so that's it consistent with what we observed before as the output signal started dropping rolling off as the frequency increases so that's just the nature of the synthesizer used without output leveling okay so now it's time for us to open it up and take a look at what is inside i really like the design as everything comes out as one piece and you can see that this is just the entire case and the whole assembly sits sliding right into the case itself on this side of the board we don't have too much going on besides this lcd now on the side we do see two ports this one is presumably a jtag port and the other one by the marking designation it appears to be a i square c port now let me flip it over so the main circuitry by the look of it it all resides on this side of the board and if you take a closer look it uses this kind of sandwiched board design to have the battery the there's another riser board and the main board at the bottom and because we're curious we can't just stop here we have to remove the battery and the top board so give me a second [Music] and right now we can already see quite a few chips here i do want to take these metal shielding cans off if i can later on to show you guys what is underneath but right now if you look at here we have this ip530 that is your charging controller that also drives the boost converter to go to your battery bank for the five volts and here by the look of it we have a buzzer and not entirely sure what that chip is but it's probably just something to drive the buzzer as the marking i think has been send it off here one thing interesting is that if you look at here by the look of it we have a connector here but it is gunked off so i'm not entirely sure what the connector is here for and because we have a touch screen we also have this xpt 2046 which is a touch screen controller here and to the left of here we have a eeprom that is a giga device 25q16e which is a 16 megabit eeprom that is used to store your firmware and calibration data towards the middle here we have this large chip that's the brain of this nano vna that is a gd32f103 which is an stm32f compatible 32-bit microcontroller chip and then further to the left in the middle we have two chips here this one is marked as a cs 8722 and this one has a marking of 8641 i'm not entirely sure what these two chips are but according to some literatures these are base band amplifiers and further to the left here we have another chip here that is an ms-5351m which is a programmable clock generator i'm glad that the shooting cans are not soldered directly onto the board but rather they're clipped on i carefully removed all of them so that we can take a closer look by the way i will upload all the high resolution pictures to my website and you can check them out there as well the hardware implementation of this nano vna dash fv2 is unfortunately proprietary nevertheless we do have a high level architecture diagram from sysjoint and we can get a rough idea of how it works according to this diagram you can see we have two of these adf 4350 137.5 megahertz to 4.4 gigahertz wideband synthesizer chips with integrated vco here and we can also see that lo is generated by this si 5351 clock generator and the signals are being mixed by this 8083 42 which is an active mixer although i couldn't figure out on the board which chip is the ad8342 perhaps they used a compatible chip from a different manufacturer with a slightly different smd packaging than the original 80 83 42. anyway the mix signal goes through this baseband amplifier which is the gs 8722 we saw earlier and that is a real two-rail op-amp and the resulting signal is processed by the gd32f103 microcontroller and now let's take a closer look on the board to see if we can match up with the architecture diagram we saw earlier towards the upper left this is the s11 port and the signal comes in there are three of these tiny chips these are 8641 they are the rf switches there is another chip here that is marked as a q01 i am not entirely sure what that chip is and for each of the channel we have one of these adf 4350 and again as we mentioned earlier these are two of the wideband synthesizer with integrated vcos and here at the s21 port you can see we have again quite a few of these 86 41 rf switches and towards the s21 port we also can see two of these rf transformers now they could be an implementation of a directional coupler and again just to remind you towards the middle here that's the 5351 which is where the lo is generated also we have another one of these 86 41 rf switches and towards the middle that's the gs 8722 that's a rail-to-rail amplifier for the baseband signal amplification before going into the microcontroller here and of course here we have another one of these 8641 rf switch as mentioned earlier i'm not sure where the 80 83 42 the mixer is located but just by looking around perhaps i'm just guessing here it probably is this little chip here and that's probably the most reasonable place for that as everything else we have already accounted for but if you know for sure where that mixer chip is located please leave a comment below so i really like the design and build quality of this nano vna dash f v2 and it certainly works pretty much as expected if you are in the market for one you certainly can't go wrong with this nano vna-fv2 by sysjoint although it is slightly more expensive than some other units out there the case the accessories and the larger lcd screen makes it well worth the extra cost in my opinion again the product link is in the video description below be sure to check it out if you are interested i hope you enjoyed the video please remember to subscribe share and don't forget to give it a big thumbs up i will catch up with you next time

Channel: Kerry Wong

Views: 48,118

Keywords: VNA, SNA, Vector Network Analyzer, Scalar Network Analyzer, NanoVNA, NanoVNA-F V2, S Parameter, Scattering Matrix, IP5306, XPT2046, GD32F103, ADF4350, GS8722, 8641, MS5351M, HP8566B

Id: dOnhdWGvz7k

Length: 31min 46sec (1906 seconds)

Published: Fri Jan 07 2022