Getting Started with Meshtastic [BONUS] - NanoVNA

what's up everyone and welcome back to the coms channel in today's video for the getting started with mesh tastic series we're going to cover the bonus video I mentioned in the previous video on antennas the reason I'm calling this a bonus video is because it isn't really needed to get up and running with mesh tastic and this is just for those of you who would like to learn how to test your own antennas it's a simple process and in this video we're going to go through a brief overview of the Nano VNA why I picked the model I chose the calibration of the Nano DNA and then we'll go and test out some antennas to see if they're suitable for our mesh Network I hope that you'll join me as we dig into it I'll be back we approaching a restricted area restricted area is one mile West before we get into it I just want to give a quick shout out to the Channel's recent supporters your support is very much appreciated and if you're finding these videos useful and would like to support the channel as well you can do so by using the coffee Link in the video description or by using the thanks button below the video thank you for your support and helping with the Channel's continued production as I mentioned in the previous video the antenna is an important part of any radio system and it's good to run your own test on them to do these tests I'm using this device called a nano VNA which is a vector Network analyzer these used to be expensive measurement equipment used by RF Engineers that costs thousands of dollar but now with some open- Source software and microcontrollers the Nano VNA was born and we're able to do these things with a much cheaper device the Nano VNA isn't as advanced of course but it does just fine for normal home users there's quite a few different versions out there and I'll explain why I got this one when looking at these you'll notice different frequency ranges for them on the cheaper end you'll see a frequency range from 10 khz to 1 5 GHz which is 1,500 MHz so if you just want to test antennas for your lower device that you're using for mesh tastic one of these cheaper models would be fine the model I got however is 10 khz to 3 GHz and the reason I got this one is cuz I'm also testing antennas for Bluetooth which is on 2.4 GHz so I needed one that covered this range and the reason for this is I mostly use whiz blocks which have an antenna Jack for Bluetooth but if you're not worried about Bluetooth one of the cheaper models that only goes to 1.5 GHz will be fine and I'll include affiliate links to mine and other options to these in the video description all right so let's get into testing antennas with the Nano VNA the first thing we're going to need to do is calibrate it for the frequency range that we're going to be testing on to do that they include these three SMA connectors that use during the three parts of the calibration the first one will be the open SMA connector this one will just have a hole in the middle as you can see here and then the next one will be the short SMA connector and this one will be completely solid inside with a center pin finally we have the load SMA connector and this one should be silver in color with a center pin with an insulator around it as you can see here now before we calibrate let's get a few things set up if you look at the screen here you'll notice all these crazy lines and measurements this is called A Smith chart and we're not going to need it for our antenna tests you can do a lot with the Nano VNA and I may cover that in a different video but for this one we're only worried about checking the SWR of our antennas we want to use for mesh tastic so let's clear all of the extra stuff off the screen by just uh tap on the screen to bring up the menus then select display then select Trace then and here you'll see a list of enabled traces in their colors just tap on each one until you only have one left you'll sometimes have to double tap on them if you don't tap in order once you only have one Trace enabled hit back now select format and then select SWR since that's what we're going to be measuring now that we have it set to SWR we need to select the frequency range we want to measure for the lower radios here in the US we're using for meas tastic that range is going to be 902 to 928 MHz to set that we're going to hit back until we get back to the main menu here then go ahead and select stimulus then select start and we're going to enter in the start range of 902 megahertz so we'll hit 9 02 and then hit M for megahertz then tap the screen to bring the menu back now select stop and we'll do the same for the end of the range so 9 28 and then M for megahertz now we're ready for the calibration to do this tap on the screen to bring the menu and hit back to get to the main menu if needed and from the main menu select Cal to bring up the calibration menu then select reset to reset the previous calibration then go and select calibrate then here you'll see the three calibration settings for each of the three SMA connectors we just went over so first we'll grab our open SMA connector with nothing in the middle and screw that onto the SMA Jack now mine here is labeled ch0 or Channel Zero but most of them will be labeled Port one so go ahead and screw that on and once you have that screwed on tap open and wait a moment and you'll see it highlight the word open when it's done uh once you see that we can go and unscrew the open SMA connector and we'll move on to the short SMA connector which is the one that's completely solid with a center pin inside so go ahead and screw that on on to the same port and once that's on we can tap short and then wait for it to highlight now we can unscrew that and now we can do the last one which will be the load SMA connector and that that'll be the silver one so go and screw that one on and then tap on load so once that's highlighted we're done you'll notice there's an option for through that's not needed for SWR testing so we'll skip that and go ah and tap on done now we can save the calibration with one of the save slots here I'll select save zero and then we're done with the calibration so each time you test a different frequency range you'll need to run through this calibration so just remember the save slot for each frequency range and you can quickly return to all of your settings that you have here so for example the next time I need to test a lower antenna I'll just open up the menu tap recall and then recall zero to bring up the settings I saved in slot zero so now we're ready to test an antenna so we can go and unscrew that load SMA connector if it's still there and then go ahead and screw on the antenna that will be testing so looking at this antenna here it looks to be good across the whole range and we can see the specific sbrr by frequency by moving the marker left or right using the buttons on the top of the Nano VNA uh mine has buttons but most of them seem to have a jog wheel of sorts for this purpose now the number on the top right is the current frequency and then the number on the top left that changes is going to be the current SWR and as you can see here it's good across the entire range now one thing that's good to check with these antennas that bend is to check the SWR on them with them bent if you're planning on using the antenna in this configuration and as you can see here as we bend the antenna the SWR changes a little bit and this is actually pretty rare for the SWR to only change a little with most of these folding antennas the SWR is going to go way up so definitely take that into consideration if you plan on using an one of these antennas in a bent configuration now I have a different model antenna here here that I'll demonstrate this with so here we have the antenna straight and the SR is fine now after I bend it you'll see that the SWR goes way up past the acceptable SWR level of two so you'll definitely want to check your bending antennas to see if they'll still perform well when folded like I mentioned earlier it's rare that you'll find one that works well both straight and folded but this one does work well bent and the model number on this one is tx915 djk d-20 I'll include a link to this one in the video description but the the downside is that I've only seen these shipped from China so if you do get one you'll have to wait a few weeks for it to arrive if if you don't mind the weight they're a great antenna and I'll include a link to this in the video description as well I've gotten a few comments W me to cover building antennas and I think that is is a good idea I won't cover in this getting started with mesh tastic series but I do plan on doing another series with some more advanced usage of mesh tastic once this one's completed and I'll likely cover that there that'll do it for this video covering the Nano VNA and how to test your own antennas and the next video will be going over my favorite the rack wirless whiz block we'll go over assembling it installing sensors in other modules and how to flash the mesh tastic firmware on it hopefully you're finding these videos informative and useful if so please be sure to hit the Thumbs Up And subscribe if you haven't already done so thank you all and have a good one

Channel: The Comms Channel

Views: 12,466

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Id: k5hBr6ada-I

Length: 10min 55sec (655 seconds)

Published: Wed Nov 22 2023