Airspy SDR as a Network Analyzer using for Antenna Characterization

[@faditech6793]

You have all my respect & appreciation for this extensive and professional test. I wish you can give us a test using "RTL-SDR" rather than the AirSpy

[@milekokotov1964]

Adam, 9A4QV have been already did it for RTL-SDR. Here is the link: kzbin.info/www/bejne/iXKkd2V8q7tsnZY

[@travelcanon847]

Very clear and informative video thx!

[@barabucho]

14:45:Не пойму,как Вы расчитываете КСВ? 14:45:I can't understand...so,how you calculate SWR?

[@milekokotov1964]

Dear Бармалей Дуримаров, Look at the table on 0:15 and Table on 0:45 on this video. It is Return Loss in dB / SWR

[@WheezyE]

Excellent presentation! New ham here: Are the signals generated by this setup transmitted into the "real world?" Or are they mostly dissipated into some kind of dummy load in the SWR bridge?

[@milekokotov1964]

The RF noise generated by RF noise generator has very low level. RF signals (rf-noise) are transmitted trough antenna (device under test) but it is only at very close distance around the antenna.

[@WheezyE]

Thank you! And 73 from KI7POL in Washington State

[@hunterantonov5105]

50 ohm cable is too long? It recommended to improve the signal to the dongle RTL2832U R820T2

[@mikeburch2998]

Thank you so much for the effort in send this up for us. I learned a lot. Greetings from Arizona.

[@milekokotov1964]

Thanks Mike. It was my pleasure. We all learn from each other

[@davidharper4289]

Thank you so much. I have a Tektronix spectrum analyzer but will order the SD one anyway. Looks like fun. You have helped me more than I can say. Thank you again, David Harper (Australia)

[@milekokotov1964]

Thanks for nice words David Harper. We all learning from one another! Best wishes !

[@Ztbmrc1]

Interesting! What has come to my mind is that there is probably a different between (dualband) antennas for the european market and e.g. the us market. Since the us ham bands are wider. So they might center their best swr on 146 MHz. Where as we here in Europe have 2m from 144.00 MHz to 146 MHz, you would like to center the best swr on 145 MHz. And I think the two last antennas in your test use the mass of the portable housing as counterpoll. So measuring them off the portable trx will result in incorrect swr. This could be tested with a tin box with antenna connector to srew the antenna on.

[@milekokotov1964]

When You choosing which Directional coupler to buy for antenna analyzer, have to look for better directivity Coupler. Directivity must be as high as possible. The Directivity limits the range of the Return loss or SWR analyzer. If the Directivity of the directional coupler is 20 dB on some frequency, it means that highest Return loss the analyzer can achieve on that frequency is 20 dB, or minimum SWR can be measured is 1:1,22 If the Directivity of the directional coupler is 30 dB on some frequency, it means that highest Return loss the analyzer can achieve on that frequency is 30 dB, or minimum SWR can be measured is 1:1,065 and so on... The second important thing when you choosing Directional Coupler is Coupling loss. The more coupling loss - the more power from noise generator needs to compensate coupling loss... And, of coarse, very important thing is frequency range in which Directional coupler has those characteristics. At the end, The Return loss directional coupler has on his ports has to be as high as possible.

[@peterkooistra4824]

Hello Mile,interesting tutorial, i would like to test my feeds for L-band (1500-1800 mhz), what swrbridge and noice generator do you recommend ?

[@milekokotov1964]

The Noise source I am using is by BG7TBL design. It is good up to 3 GHz. You can find in ebay. Here is link: www.ebay.com/itm/DC12V-SMA-noise-source-Simple-spectrum-external-tracking-source-no-power-adapter-/142105288275?hash=item2116229e53:g:d0EAAOSwOdpXyQfW Unfortunately, I have not tested any directional coupler or SWR bridge for frequency you are interested for. I suggest some of the "Mini Circuits" directional couplers or others on e-bay. Read my guidance above... 73

[@peterkooistra4824]

Hello Mile,thank's for your advice,Regards,Peter.

[@milekokotov1964]

But SWR-Bridge from BG7TBL is not suitable for 1500 - 1800 MHz. You can try some Directional coupler from Mini-circuits in that frequency range for example...

[@barabucho]

How to find resonance?

[@davidinston8231]

Well I did the trials on my existing antenna which is a copy of a Diamond antenna by Moonraker. I found that the use of the attenuator board was not necessary. The results for the 2m and 70cm bands were perfectly acceptable. And, as you suggested Mile, the results were meaningless on the 23cm band using this swr bridge. This not a problem for me though as there is no one near me who I can receive on a vertical antenna. And I don't have a transceiver for this band. Now to make some home made antennas for HF...

[@milekokotov1964]

Well done David. Enjoy in your new RF tool! 73

[@SeAfasia]

Μile thnks for share,a question: only airspy can we use for this characterization or other sdr usb dongle? Dinos..73's

[@milekokotov1964]

Hello Dinos, You can use RTL-SDR or SDRplay RSP, but then you have to do it with other software. I want to suggest you a new NanoVNA, which is very cheap (about 50 euro, but it is really good Vector Network Analyser from 50 khz up to 900 MHz. Just type "NanoVNA" in Google and you can find many information for this little VNA!

[@SeAfasia]

@@milekokotov1964 Thanks for your quick reply Mile,order nanoVNA really nice device...almost 39 euro...on e-bay market place..73's

[@davidinston8231]

Hello Mile. I have now received all the parts to duplicate the tests in your video. The swr bridge is the same one you have used from BG7TBL. The noise source I have is also from BG7TBL but it doesn't look exactly the same as the one you have used, it uses entirely smd parts, there is no large capacitors. An additional item I got is a 3 way attenuator board giving 0, -6 or 40db attenuation. I'm hesitating to start the experiment as I have no test equipment yet to measure the output of the noise source and I don't want to damage the input of my Airspy. Would you suggest I add some attenuation to the noise bridge to be safe?

[@milekokotov1964]

Hi David, I am glad that you can try this setup as a network analyzer now. Noise source power is not significant to make any damage to Airspy SDR, but you could use those attenuators (0 dB, 6 dB and 40 dB) for the first try. Starting from 40 dB, than 6 dB and at the end, you can connect the noise source directly to the Airspy. It could be good experience to learn how is the signal from noise generator... You can try to connect many different RF stuff between the noise source and Airspy and see their amplitude-frequency characteristic (filters, low signal amplifiers, attenuators, baluns, pieces of coaxial cables as a notch filters and so on...), Adding the SWR bridge to the setup, you can measure antenna characteristics as in above video... Let us know what is your results with this setup. Shear your experience with us please. 73

[@peterkooistra4824]

hello Mile,the noise generator seems to work well, as coupler i bought the mini circuits ZNDC-23-G (for 800 - 2000 mhz), for i want to fine tune my patch antenna for 1700 mhz, i cannot find the resonant point in spectrumspy, maybe the mini circuits device is not the right choice?(not much happening in the spectrum), regards, peter.

[@milekokotov1964]

Hello Peter Kooistra, send me a picture of your setup connection please...

[@peterkooistra4824]

Hello Mile,i do not have your email adress..how can i send pictures?

[@milekokotov1964]

You can find my e-mail address on my web page: www.qsl.net/z33t/

[@davidaguirre4544]

Peter Kooistra, You managed to make the correct settings for your patch antenna at 1700MHZ?

[@-vermin-]

It would be nice to see SpectrumSpy updated with an average, max and min hold trace mode. The ability to normalise a noise source too.

[@milekokotov1964]

Yes. I agree 100%. I am sure that developers will do that.

[@hunterantonov5105]

118-136 omni antenna and cable that brings RadarBox ComStation connected to a dongle RTL2832U R820T2 the reception is poor what am I doing wrong ?

[@SimonShaws]

What voltage are you supplying to the noise generator? I heard 12Volts it runs very hot. Some say it works better at 9 volts? Thoughts?

[@milekokotov1964]

I am using 12V for the noise generator. Yes it becomes hot after some time, but you can put a smal fan for cooling...

[@davidharper4289]

Hi again Mile, Where can I get the program you use for the return loss calculations? My Noise PCB has arrived from ebay (same as yours) but strange dB specs on his little sheet for its power out. He is saying that at 0.1g/60db output ? 1000W (I don't think so.) at 0.5G/ 55db? Any way I will test this as I also have variable attenuators etc. He does not sell the bridge on his site anymore so I have purchased (2) to test.After the bridges arrive I will hook all this up to my HP spectrum analyzer before I buy the Airspy. I will keep you informed. Thank you, David

[@milekokotov1964]

Hi David, There are many online calculators for return loss to SWR calulations. Here is one link: cgi.www.telestrian.co.uk/cgi-bin/www.telestrian.co.uk/vswr.pl Forget what some chinese sellers have written on their web pages as information about Noise source specs :-) Just get BG7TBL one and you will be satisfied. Let as know about your results Regards

[@davidharper4289]

Hi Mile, Thanks for the site. Perfect. All the best, David. P.S. Are you into HF? I have just started. So although I have my Marine HF/Satellite License I have to sit HAM accreditation, I will do it soon. That is what the equipment I am building is to help me with. I have purchased a lot of Icom Gear. So I have VHF/UHF (in commercial frequencies - Simoco mainly but some Motorola) otherwise I have both the time and funds (luckily) to pursue it as a full time hobby . I will keep you up with my antics. Just found a 8Mtr, Sat dish to try to do some moon bouncing. If you have a call sign send it to me and I will have a go at contacting you. Love the learning curve. Keeps me sane in a pretty crazy world. All the best, David

[@mdblack98]

The only flaw I can see in what you did was the non-mag antennas can't be tested out-of-circuit with the radio. Holding it in your hand, connecting to the HT, how you hold the HT all affect the SWR.

[@milekokotov1964]

I Was aware about that for non-magnet antennas (they also needs some kind of counterpoise) They use handheld transceiver body and hand capacity as a counterpoise. But for this test I was simply hold those two antennas in my hand moving around during the test to obtain the best SWR/Return Loss results. The same conditions were for both antennas and one of them, as we can see in the video, shows better results (the original Quangsheng TG-UV2 antenna)...

[@bodd72]

Hi Mile i have the swr bridge and noise generator you rekommended connected to my airspy mini , but i have very diffrent levels in db , it seems sensitive to the gain slider ... Trying to get the 50 ohm db correct before mesuaring antenna ... Do you have any tip ? It seems as they have uppdated the software as well ... //kindly Kristian

[@milekokotov1964]

Kristian Jönsson, What is "very different levels in dB"? Can you post here a link to some screenshots you get? What you mean when you write "Trying to get 50 ohm db correct"? Be more specific please? I am trying to help but I need more information on what you did and what you get...

[@bodd72]

Hi again .. I meant the RF-gain slider . I have connected a 79 mhz antenna and took some before after pictures . please se them here .. With and without dummy it seems wrong? the 79 mhz antenna is on 80-81 mhz ... drive.google.com/drive/folders/0B8YToHy1FPZNUUtVWHIxRHJDRVk?usp=sharing

[@milekokotov1964]

Hi Kristian Jönsson, I saw all of your pictures carefully. The setup looks that is OK. Except SWR bridge seem to has less directivity, but, anyway, directivity is more than 20 or 25 dB, so you can analyze the antennas SWR down to 1:1.2 or 1:1.1 minimum. (return loss 20 to 25 dB). Airspy frequency is very accurate, so, according to your pictures, is obvious that the antenna you tested is resonant on 81 MHz, and in that frequency you could expect SWR around 1:1.8 or something (about 10 dB return loss) for 50 ohm load. Can you post link or picture of your antenna? Which model is it? Where is it located? I hope that antenna is not in your room... Regards, Mile Kokotov

[@Veso266]

Hi do you think I can damage my airspy if I connect 75ohm antena to it?

[@milekokotov1964]

No, You can not damage Airspy SDR if you connect 75 antenna to it.

[@davidinston8231]

Thanks Mile, First of all I will test the diamond tri-band antenna for 2m, 70 and 23cm that is on my roof and verify its performance. After that I'm making simple wire dipoles for 30, 17 and 20 metre bands and this time also use the spyverter. I will of course share my results. 73

[@milekokotov1964]

Pay attention that SWR Bridge is not designed for such high frequency as 23 cm band. But anyway it will be interesting to see the results :-)

[@davidinston8231]

I have also found the Airspy very useful to recalibrate an RF signal generator I purchased at low cost from Ebay.

[@milekokotov1964]

Sure it is!

[@ionogramjuliusruh4178]

Great Demo. Do you think this setup will also work with SDRPlay instead of AirSpy ?

[@milekokotov1964]

I am not sure if there is a software like SpectrumSpy for SDRplay. But it will be good if SDRplay, SDRuno or other developers thinks about such features for RSP1.

[@ionogramjuliusruh4178]

Ok, it seems SpectrumSpy is only working with AirSpy. Do you think the same can be done with SDRUno ?

[@milekokotov1964]

SDRuno has 10 MHz maximum bandwidth (frequency span on the spectrum window). It is enough for HF antenna analysis, up to some 30, 40 or maximum 50 MHz.

[@ionogramjuliusruh4178]

That's great ! I am not very familiar with SDRUno yet. Would you midn to make a video showing the Return Loss and VSWR measurement with SDRUno ? That would be awesome , TNX !

[@milekokotov1964]

Joy Rider, Here is my video for HF filters characterizing with SDRplay+SDRuno. The antenna analyzer is very similar to this, but with addition of SWR Bridge or Directional coupler...

[@jolebole-yt]

Белиот coax кабел на видеото е 75 или 50 Оми? Ми изгледа како обичен 75. Имав некаде прочитано дека за SDR не е битна импедансата на кабелот пошто само примаме сигнел. Точно е тоа? Поздрав!

[@milekokotov1964]

Здраво горан, Белиот кабел е RG-6 (75 оми) 75 омски кабел може да се употребува без некои поголеми проблеми. Во некои случаи е подобар од 50 омски кабел. Поопширно за коаксијалните кабли, можеш да прочиташ на мојата веб страница: www.qsl.net/z33t/koaksijalen_kabel_mkd.html Таму има и примери кога е подобро да се користи 75 омски кабел и за прием и за емитување ! 73

[@sergey7dvd]

Thank you for video! It's good idea!

[@hobbycornermk5415]

Барем за прием на комерцијални ФМ радија е супер :D ☺

[@StuttgartHD]

this should also be possible with rtlsdr.

[@milekokotov1964]

Yes, it is possible with RTL-SDR also (with Touchstone software, or RTL-SDR Scanner software for example), but "Spectrum Spy" software for Airspy is Very fast, with better RBW, and Airspy has better Dynamic range for better measurements

[@StuttgartHD]

for fun, can you make a test with rtlsdr an rtl-sdr scanner? no video need, only a screenshot would be ok.

[@black2999ro]

many thanks ! 73 de YO8SCT !

[@killrb13]

Wery nice wideo!

[@milekokotov1964]

Thanks Bryan!

[@jolebole-yt]

Great demonstration video. I need this so I can test some antennas. Can you share BG7TBK's eBay page? I found several sellers on eBay selling the same generator and SWR Bridge. Thanks!!! 73 KD9HBU.

[@milekokotov1964]

Здраво Горан, Те слушав пред некој ден на локалниот репетитор во Скопје (R0). Ти се јавуваше преку ехо линк од Чикаго. И јас сум исто така од Штип. :-) Јас не знам дали BG7TBL има своја eBay-страница. Мојот генератор на шум го купив од eBay на следниов линк: www.ebay.com/itm/DC12V-SMA-noise-source-Simple-spectrum-external-tracking-source-no-power-adapter-/142105288275?hash=item2116229e53:g:d0EAAOSwOdpXyQfW Подетално за овој одличен Анализатор на антени можеш да прочиташ на мојата веб страница: drive.google.com/file/d/0B7Bk3JifFLbSRjlEYms4bnV5clU/view или на англиски: drive.google.com/file/d/0B7Bk3JifFLbSbTVNUWduLU9lR2s/view Ако нешто не ти е јасно слободно пиши. Мојата е-mail адреса ја има на мојата веб страница. 73 Миле Кокотов, Z33T

[@jolebole-yt]

Здраво Миле! Фала за одговорот. Ти пратив email :)

[@milekokotov1964]

Here is the link of KZbin video posted by Roland, HB9VQQ. He has made great setup for HF antenna analyzer with SDRplay and SDRuno software according to my suggestions, and tested his Diamond CP-6R Antenna: kzbin.info/www/bejne/nIK8pamGbbeZhM0 Nice and clear resonance but not very wideband as the antenna was claimed :-) Here is what he has written: Tnx Mile, your video inspired me to try to setup a similar test with SDRPlay. I am a bit disappointed with my new Antenna the Diamond CP-6R. At least I can now prove and characterize any Antenna in order to judge whether it is good or not :-) And yes I am using the same Noise Generator and SWR Bridge from BG7TBK (ebay) as in your video ! 73 de HB9VQQ

[@gss15004372]

thanks 73

[@LitAlexV]

Спасибо!

[@milekokotov1964]

You can find more about this and other similar articles on my web page: www.qsl.net/z33t

[@hobbycornermk5415]

Одлично видео. Значи NA-771 е стварно лоша.. :/

[@antunes7831]

PY9BG BRAZIL