Measuring Antenna SWR with a NanoVNA

This video is a quick primer on how to look at and interpret SWR on a NanoVNA.

[@thehunter3386]

Thanks for you informative video. It answered my questions. Keep up the good work!

[@amham48]

Thanks for the very straight forward refresher on the NanoNNA-F. I purchased several yeas ago and just pulled it out again. The device is amazingly accurate. Also thanks for the calibration info.

[@miked9104]

Awesome video! I’m a Tech, getting ready for General test, and starting to plus up my test gear. I’m waiting on a VNA in the mail. Excited 😃😃

[@brentjohnson6654]

Thanks for the video. I needed a refresher as I am trying to tune shark ham sticks on my truck. The sun is washing out the nano-vna and I need to place an umbrella under it. I do love having a network analyzer that fits in my pocket - never thought that would be possible remembering the big units they used to use at work. All the best, 73 de KI5HXM

[@maxgarascia]

You are a great teacher keep up the amazing work it is appreciated

[@permanentlypatriotic]

This was great 👍. Got my NanoVNA working just the way I needed it too!

[@MountainMan7.62x39]

This is going to work as a good quickstart guide for me. Thanks.

[@fotografm]

Thanks for this great series !

[@malchaschwatrz5706]

Well done straight forward explanation. Thank you.

[@transmittinguntilrobotsrep1045]

You are very welcome. I'm glad that it was helpful. Thanks for writing! 73 - AC3DS

[@geirha75]

Excellent explanation

[@lukeoid153]

Great vid my friend.

[@Andrew-dg7qm]

Very helpful, thank you

[@genestanley553]

Nice video!

[@lyerger8232]

Just bought one. Really like it. Don't know how I ever lived the past 48 years in am Radio without it. lol

[@transmittinguntilrobotsrep1045]

Glad to hear you are enjoying your new purchase. If you've been in this for 48 years, my guess is that you've had some other excellent equipment along the way.

[@g-whiz286]

Could you be any closer to those power lines?

[@transmittinguntilrobotsrep1045]

I think the closest that I came was about 25' to them. With a taller antenna, I would have moved farther away. It is a good reminder though to always be cognizant of the power lines. Thanks!

[@jcjc4jesus]

Great video, thank you

[@N9IWJ]

Thanks so much excellent, learning my nano what a cool toy

[@dang25272549]

Thanks so much 👍

[@jerry-suhrstedt]

Dude's got a lavalier microphone. Niiiiiice. (your audio is on point)

[@bradleyruhberg8626]

Assuming you calibrated the original freq. range, when you changed to 7.0-7.3 is it safe for us to understand that no recalibration is needed as it was within the original range? Thanks for the video.

[@Bassist1953]

Very usefull! 😊 TNX!

[@transmittinguntilrobotsrep1045]

Glad it was helpful! 73, AC3DS

[@John_Henry83]

Kudos to you for even mentioning that you need and adapter. I have watch half a dozen videos on the NanoVNA and how to use it for ham radio and NONE of them show an adapter or even mention. Its like the device just magically connects to the feed line.,

[@transmittinguntilrobotsrep1045]

Thanks John. Sometimes it is the little things (an adapter in this case) that can make or break a day of testing and being on the air. Happy radioing!

[@williambob111]

@@transmittinguntilrobotsrep1045 do you have to calibrate with the adapter as the load?

[@usernamemykel]

So, if you're looking at 40M, and you want 7.123 to be at the lowest SWR, but the swr is higher at that frequency than you want it, do you decrease or increase the antenna length (and then check the SWR again)? Thank You!

[@RC-Heli835]

I like to use a 6 inch flexible lead on my Nano to keep stiff cables from being hooked directly to the circuit board of the Nano. Have you tried calibrating to the end of the feed line? I did a 6 ft jumper yesterday and it worked fine. 6 ft is not nearly long enough for most antenna's though. It might be for a 70cm & 2M dual band possibly just to tinker with on the desk.

[@transmittinguntilrobotsrep1045]

You bring up a good point about calibrating to the end of the feedline, and yes, I have done it that way up to about 30' and it always seemed to work fine. I suppose I don't think about it too much though because most of my calibrations of antennas are "close enough" calibrations such that I can work out the details in the practical use. It probably isn't an efficient method, but I don't mind it. Thanks for bringing up this topic - definitely something worth considering in the future. 73.

[@RC-Heli835]

@@transmittinguntilrobotsrep1045 The reason I ask is that Rig Expert instructions say to calibrate to the end of the feed line essentially moving the antenna analyser to the antenna hiding the coax and at the same time keeping your body away from the antenna. According to Bells cb to know the true SwR of an untuned antenna you have to have calculated half wavelength coax. Coax repeats exactly what's at the other end every half wavelength. He says after the antenna is tuned that coax length no longer matters. I helped tune a new big rig antenna the other day on a 6ft coax with my NanoVna h4 not calibrated to the end until ch 20 was 1.36:1 while 1 and 40 were 1.56 :1. Then we hooked the radio back up to the antenna with his 18 foot coax and the 6 ft jumper with an analog SWR Meter. The the SWR was 3.5:1. On ch 40. We had to cut another inch off the antenna to get the SWR back perfect.

[@ernestb.2377]

Hi. Nanovna (display) shows S11 swr 500m/ ... (in the top left corner). That should be 1: .... I have seen that on my nanoVNA as well, but then I changed the scale (I believe) and then it changed to 1:. I am a newbe user and still learning, but I think that is something to look at.

[@Index-o1234]

How do you know reliably what a good SWR is for whichever antenna you choose to use?

[@ltlt6117]

Hello! It's my question that how we can test an antenna for a bipolar monopulse uwb signal for example if that signal has a 5ns width and 100khz repetition..What is the frequency that I have to use as start and stop on nanovna to measure my antenna parameters?????

[@PeterJavea]

Hi. Interesting. As a newbie, I have a question. Because we are not transmitting when we use the Nano VNA. Couldn't you leave it on and go shorten or lengthen the whip while watching "live" the changes to the SWR...? Peter Hume ON3VCF

[@Radiogenes]

Hello! When you travel across the swr curve with the left and right keys… is it to adjust the steps? For instance, i find that mine goes from 7050 to 7150 or so… Thank you

[@transmittinguntilrobotsrep1045]

Hello Diogenes. If you are asking if it is possible to adjust the incremental steps, it is. The NanoVNA always pulls about 100 reading points, so in order to adjust the width of the steps between movements with the left/right keys, you change the start and stop frequencies. By decreasing the amount of spectrum that the VNA is observing, you are able to get more refined steps between the start and stop frequencies. If I've misinterpreted your question, I apologize. 73. AC3DS

[@o2bnov0307]

On my screen the top left corner says S21 SWR 5/1.000. My scale is set 7.0 - 14.2 MHz. I see nothing. Any help you can share would be nice.

[@vinces.2862]

Terrific video. Thanks. KI4AWJ

[@thork0tjt515]

Do you need to recalibrate the VNA each time you change the band you want to measure? Or just calibrate the VNA once at start-up? Thanks and 73

[@transmittinguntilrobotsrep1045]

I’ve heard and read that you are supposed to calibrate it each time you use it, however I have actively tested (days and weeks later, outside to inside, etc...)to see if there is a measurable difference and haven’t found any difference. I believe that you should recalibrate when the frequency range goes beyond the bounds of the most recent calibration, or the calibration used to save into one of the recall slots. For my NanoVNA, there was no appreciable calibration change difference until I got over 500MHz, so it has been one calibration that worked for me.

[@thork0tjt515]

@@transmittinguntilrobotsrep1045 thank you

[@MrBanzoid]

At HF it doesn't really matter. It matters once you start going into VHF and UHF frequencies. Also technically you should calibrate at the end of your feedline, but again at HF it doesn't really matter. You're only looking for a dip. You might get better results using S11 logmag instead of SWR.

[@DavidBamford]

If you change stimulus ranges, you have to recalibrate each time.

[@transmittinguntilrobotsrep1045]

Hi David, thanks for commenting. There seems to be differing understandings about this in the community, and I don't claim to be fully sure that I'm correct. I could certainly be wrong about this, but through experimental testing, I have not been able to validate any significant effect of not calibrating each time when the most recent calibration was for within the same broad range of the spectrum (HF, VHF, UHF)... The difference between broad ranges is also very minimal such that I don't always recalibrate between them if the original calibration included the new stimulus range. I would be curious to see what the actual numeric offset (calibration amount) is between the bands. 73

[@DavidBamford]

@@transmittinguntilrobotsrep1045 I agree that some don't, I guess I'm a stickler! ha, ha. I've had fun with mine. 73 OM

[@rodericksibelius8472]

You plugged that nanoVNA on the feed cable, aren't you going to FRY that VNA how much power can that VNA handle before it SMOKES?

[@transmittinguntilrobotsrep1045]

Fry the VNA by attaching it to the feedline? No smoke from the VNA yet, but "the day ain't over yet."

[@SergeantExtreme]

@@transmittinguntilrobotsrep1045 No, he's right. You should probably have some sort of protection in place, as is shown here: kzbin.info/www/bejne/qqDXqKhqfseUrKc

[@UDX4570PalmSprings-yh1mv]

I have a NaNo vna and cant figure it out to save my ass!

[@SergeantExtreme]

You're not going to include ANY advice as to including circuit protection between the NanoVNA and the antenna? The problem is that it's fairly common for newbies to fry their NanoVNAs, so in a video like this, you should at least include a link to a video that shows them how to do this.

[@Incindio13]

If you want to include that in your own video then go for it, go make your own video. Lol at you telling him what he needs to include in his video.

[@RickRollington]

Bruh you really needed to explain what an adapter is? Ffs... Get on with it 😂

[@transmittinguntilrobotsrep1045]

Yeah, the unit doesn't come with adapters, so I felt like it was necessary to say, but I get it. Being comprehensive is sometimes at the expense of brevity. 73

[@RickRollington]

@@transmittinguntilrobotsrep1045 Based on solely what a vna is, I feel like there is a certain level of competency needed to be able to properly digest these videos, and understand the content correctly. So going into depths on what an adapter is, in my book paints a bad picture for the rest of the video.