#188

Everything goes wireless these days. This is why we have a close look at the “black magic” of antennas, how they work, what is essential, and how to test them.
Based on this knowledge we will build a cheap antenna tester for LoRa antennas. A similar device can be built to test Wi-Fi antennas.
It uses an ESP32 TTGO board on one side and a Wemos D1 mini with a Hope RFM95 module on the other side.
Links:
Sketches: github.com/Sen...
Stuart's Page: www.loratracker...
and his results: github.com/LoR...
Watts to dBm converter: www.rapidtable... / www.g4urh.co.uk...
Radio link budget calculator: en.jirous.com/c...
Coax cable loss calculator: www.qsl.net/co8...
Ground plane Calculator: www.csgnetwork....
LoRaWAN Balloon experiment: bit.ly/2DgSBUB
Moxon Antenna: www.moxonantenn...
Moxon antenna 3D: www.thingivers...
VSWR to dB table: bit.ly/2IgrWuI
50$ satelite: www.50dollarsat...
Supporting Material and Blog Page: www.sensorsiot.org
Github: www.github.com...
My Patreon Page: / andreasspiess
If you want to support the channel, please use the links below to start your shopping. No additional charges for you, but I get a commission (of your purchases the next 24 hours) to buy new stuff for the channel
For Banggood bit.ly/2jAQEf4
For AliExpress: bit.ly/2B0yTLL
For ebay.com: ebay.to/2DuYXBp
www.facebook.c...
/ spiessa
www.instructab...
Please do not try to Email me or invite me on LinkedIn. These communication channels are reserved for my primary job
Equipment in my lab: www.sensorsiot....

[@3aboosh123]

nice to see my entire bachelor degree summed up in one video, great content !

[@AndreasSpiess]

Thank you!

[@doggo7567]

I can't thank this guy who Andreas chooses to take his own time to share his huge knowledge with us, making video after video. It's people like you that make the world great.

[@anilvadgama9803]

L)0pl0pplpll

[@arigetas]

This video contains the most crucial points on how the antenna and transceiver worked and felt light to digest. Thanks a lot.

[@AndreasSpiess]

Glad it was helpful!

[@Willam_J]

Excellent video, Andreas. I fly model aircraft at a flying field which is about 1.25miles (2Km) from my home. I have have a weather station at my home, which other club members can access, to check flying conditions before traveling to the field. A few of the members expressed concern about the accuracy of the weather data, even though the whole area is farmland, my home is at the same elevation as the flying field and I have no obstructions around my weather station. To appease these members, I placed a second weather station on an existing tower at the field and linked it to my home network, through a secure gateway, with an ESP3266 based link. Even though the readings were the same, they still preferred to have wind speed and direction readings right at the field. I made it a permanent installation using a solar panel, charge controller and a LiPo battery pack enclosed in a weather-proof enclosure. Using yagi antennas between my tower and the tower at the field, I am able to maintain a very stable link on 915MHz with only 25mw of RF power. You’re very correct about using good quality, short lengths of coax cable. Just like a piece of chain, an antenna system is only as good as its weakest link. As always, I’m looking forward to your next video! Take care! :-)

[@gte24v]

Nice project. Using a directional antenna at the transmitter end might be a little dubious with respect to keeping within the defined Equivalent Isotropically Radiated Power (EIRP) but what always excites me is that receive gain is indeed free and sometimes we can make more gains by simply removing the length of coax between transmitter and antenna, same for receiver and antenna. The radios now are *so* small and low power that it is entirely feasible to site them at the mast head and completely do away with these losses. Sounds to me like you already have. :-)

[@AndreasSpiess]

Sounds like a useful application of our technology.

[@IDoNotLikeHandlesOnYT]

"ESP3266" Does that mean one end has an ESP32 and the other end has an ESP8266? But how did you get them to use 915 MHz?

[@zazugee]

@@IDoNotLikeHandlesOnYT i think it's a typo

[@rollbeats7342]

Never seen any RF tut as detailed as this. Even from time I was at Uni. This had me getting communication electronic...BRAVO

[@AndreasSpiess]

Glad you liked it!

[@Conservator.]

Hi everybody, lets try to improve Andreas’ like/view ratio! 15.4% is not bad at all but I think we can do even better ;-). He surely deserves it!

[@AndreasSpiess]

:-) Thanks!

[@maicod]

yes people tend to forget to press the like button. I hope this helps for the likes on this great video and hope people will remember it next time.

[@Conservator.]

Now 16.4% :-)

[@Conservator.]

Now down to 12.3%. I guess subscribers and fans are the early viewers. Still I think Andreas can be very proud to get 1300 likes.

[@Conservator.]

Warning ⚠️ Phishing scam👆

[@cabe_bedlam]

Thank you for also spending some time on the legal use of the RF. So few people appreciate that the aiwaves are shared.

[@AndreasSpiess]

You are welcome!

[@ArztvomDienst]

Content like you are producing is the real value of youtube.

[@AndreasSpiess]

Thank you!

[@Lew114]

Thank you for taking some of the mystery out of antennas. I always assumed that understanding them was simply over my head. Now I’m interested in trying to learn more. I look forward to future videos on this subject.

[@AndreasSpiess]

Understanding them is over my head. But using them is ok ;-)

[@mojoxide]

This needs to be a required video for anyone getting into this. Explains everything relevant, in one nice neat package.

[@AndreasSpiess]

If you enjoyed this video, you might also be interested in the one about how to use a VNA...

[@gte24v]

Great stuff - I do this for a living and still enjoyed it. Well done. :-)

[@AndreasSpiess]

This is a big compliment. Thank you!

[@neppub320]

I'm not studying any engineering but always was thinking of how this work. Exactly the content needed. Thank you so much sir for giving us your precious time

[@AndreasSpiess]

Happy to help!

[@SteveWrightNZ]

Excellent!! This is a very good absolute-beginner introduction, and it is technically exactly correct, thank you Andreas. Regarding the legality of adding antenna gain, yes you must lower the transmit power to stay inside the EIRP power limits, BUT remember that the gain antenna ALSO works on receive so you get your "lost power" back again at the receive end! The cheap N1201SA analyser will show cable loss. Antennas are like fittings for your garden hose - you use a shower fitting for wider coverage and less range, or a squirty nozzle for longer range and less coverage.

[@AndreasSpiess]

Thank you for your additions!

[@magadogian]

Hi Andreas, I really enjoyed watching this, although it has passed years since you put it down here, I have been searching for long trying to find a good explanation, here I am, Thanks a lot for your time and wonderful knowledge you have.

[@AndreasSpiess]

You find more (and newer) videos about the topic on this channel.

[@rodericksibelius8472]

I took a 9 month course in Microwaves taught by a retired Stanford Electrical engineer and had a school and had hired practicing electrical engineers from the microwave companies here in Silicon Valley, we learned the history of microwaves, the practical physics and the mathematics, the use of the Smith Chart, vector network analyzers, spectrum analyzers and how stripline microwave amplifiers were currently designed, this was way back in the mid' 80s. It's is great that we have THESE SMALL high tech test instruments now like this one - I know microwaves is 'black magic' to technicians and rf engineers.

[@AndreasSpiess]

Indeed these devices are very helpful!

[@MikeKranidis]

Dear Mr. Spiess I think this is one of your fascinating research. Let me congratulate you.

[@AndreasSpiess]

Thank you!

[@fjs1111]

You have the best RF engineering tutorials anywhere.

[@AndreasSpiess]

Thank you!

[@Anonymous-b3m]

I'm so new to LoRa...or antenna's...but I've learned a lot in this video! Thank you!

[@AndreasSpiess]

You are welcome. Maybe you watch also the other antenna videos on this channel...

[@TheFlyingZephyr]

Excellent video. I wish I had your videos when I was in engineering school!

[@AndreasSpiess]

Thank you!

[@victoryfirst2878]

This has to be the best video on the subject matter I have seen on KZbin. I can make a killer antenna from your information Andreas. Thanks a bunch too. vf

[@AndreasSpiess]

Glad you liked the video!

[@victoryfirst2878]

@@AndreasSpiess Look forward to more videos Sir.

[@victoryfirst2878]

@@AndreasSpiess Sir, I remember an TV antenna that had about 16 squares in a square. I am wondering if this is something you are familiar with for TV reception.

[@AndreasSpiess]

@@victoryfirst2878 I have no knowledge of TV antennas :-(

[@victoryfirst2878]

@@AndreasSpiess VHF and UHF TV Frequencies used in US. The VHF television band occupies frequencies between 54 and 216 MHz and the UHF band between 470 and 608 MHz. I was thinking that since signals are close you would know. Thanks for setting me straight Andreas. Good day too.

[@RubenLensvelt]

Your new microphone is great. It adds a lot to the production value of your videos. You sound professional. Very nice!

[@AndreasSpiess]

Thank you!

[@joshportelli]

Wow, this guy can teach! Great examples, sketches, equations, and experiments to make it clear and interactive. Also great narration.

[@AndreasSpiess]

Glad you enjoyed it! And thank you for your nice words!

[@zachhoy]

at 2:50 before the content appears, the cryptic screenshot is "The Power of the Sender depends on: Andreas Spiess". For me, this is 100% accurate.

[@AndreasSpiess]

:-))

[@acestudioscouk-Ace-G0ACE]

I love the clarity of explanation in your videos. For me there were some good revision points and some new facts to take on board. Thank-you.

[@AndreasSpiess]

If you are interested in RF and antennas, maybe you like also my second chanel...

[@acestudioscouk-Ace-G0ACE]

@@AndreasSpiess I was one of the first to subscribe, it is excellent as well!

[@mattgrooms8479]

Excellent video, as always. Thank you so much for providing crystal clear information about all aspects of LoRa. You have a real gift for presenting things clearly, efficiently, without noise. Please provide the details of your test setup and sketches as soon as you can, so we can test our antennas in the same manner. Matt G. K5MWG

[@AndreasSpiess]

Thank you! You should find the link to the sketches in the description.

[@mecommenting]

En suivant tes videos il y a un an, j'ai pris goût aux technologies radio, tout en apprenant beaucoup Grand merci !!

[@AndreasSpiess]

De rien!

[@xDR1TeK]

Normally, when I speak of RF, I would mention the many math equations to compliment the analogies. However, I like how it was compiled here. If one wants more information, then they can look it up later. Quite an efficient layout of information. Andeas, you gave useful information about debugging something invisible and get meaningful data out of it as well. This is such a good way, good work man!!

[@AndreasSpiess]

Thank you for your nice words.

[@chrisw1462]

FCC rules for Amateur Radio (and most other RF licenses) currently use 'ERP' as the power limit specification, which stands for Effective Radiated Power. This means your antenna gain is included in the limitation. If you have a 3 dB gain antenna connected to a 50 watt transmitter (and everything is properly tuned), your ERP is 100 watts. Directional antennas have more gain in one direction, obviously, and that is the gain figure you have to use to figure ERP. (But you also get to subtract and dB loss in your antenna feed line.) This doesn't mean directional antennas don't help, though, and in fact they can lower the cost of the system. Let's say you're limited to 100 mW ERP. With an 'omnidirectional' antenna, that power goes in every direction, which may be what you want. But if there's only one receiver, a directional antenna is a much better idea. A 13 dB gain antenna would give you 2000 mW (or 2 watts) ERP, way above the legal limit. But that 13 dB gain would allow you to re-design your transmitter's output power to only 5 mW !!! That is a substantial power savings, and may save on RF component costs, too.

[@AndreasSpiess]

I agree with all your statements. In my tests, I also was able to prove that power was not a big issue. I got 200km reach with a very short omnidirectional antenna.

[@chrisw1462]

@@AndreasSpiess Of course, the FCC rules don't apply to you, but from what I've read, the international agreements for amateur radio make other countries rules similar.

[@phineasIV]

Lieber Herr Spiess, ich sende Ihnen meinen Dank und Anerkennung für Ihren herausragenden Bildungskanal. Saludos desde Chiapas / Mexico OE7EDT

[@AndreasSpiess]

Gern geschehen. Und vielen Dank für Ihre netten Worte!

[@dmurphydrtc]

Excellent work. Learning so much here. Happy Sunday.

[@AndreasSpiess]

Happy Sunday, too.

[@amydadogisabum]

Great video Andreas! Thanks for making this. I believe your videos on LoRa are among the best I've seen on youTube.

[@AndreasSpiess]

Thank you!

[@distancelab2010]

Yey another awesome video. Just what I need at the moment as I am working on a ZigBee based data logger system for work at the moment and antennas performance is a black art. Thanks for explaining this so well. Looking forward to the next antenna video. Thank you.

[@AndreasSpiess]

Good luck with your project!

[@TheDanyschannel]

Came here for the IoT, stayed for the Swiss accent and the cat. Great content as always!

[@AndreasSpiess]

Thank you!

[@JxH]

This video is very good. Accuracy of the information is simply excellent!! Well done. The word 'Transmitter' is more common in the context of antennas. I've seen the word 'Sender' being used to denote the gadget that is sending data (but perhaps also receiving acknowledgement packets back), so actually an RF Transceiver. The distinction is between the Physical Layer (RF) and the higher Layers (Data) [ref 7 Layer Model]. Antennas are at the Physical Layer, so Transmitter and Receiver (actually they're Transceivers at both ends). @13m43s, it would be better if the antenna was not so closely paralleled with the USB power cable. It's best if they're installed free and clear of other conductors. Especially to maintain consistency for measurements. (I know you know; I'm just commenting on what's shown in the video.) This point was touched on later. Thank you for your excellent videos. 73

[@AndreasSpiess]

As you know I am no native speaker. So I do not know the language well. Concerning the USB cable: You are right, but the board I used did not allow a different setup. Maybe in the future, I will power also the receiver with a battery to avoid this situation.

[@Optimuseq]

Good quality of video, sound, no annoying music in background, everything detailed. This tutorials we want to see!

[@AndreasSpiess]

Glad you liked it!

[@klassichd10]

Thanks a lot, looking forward to the next lesson including the test gear and the results of your testing.

[@AndreasSpiess]

You have to wait a few weeks. Currently, the schedule is quite full with the "wish list".

[@PhG1961]

Awesome content. Indeed, the impact of the antenna cable is under estimated. I found out the hard way many years ago...

[@AndreasSpiess]

And it becomes part of the antenna if you do not pay attention...

[@tonybell1597]

Thanks Andreas, you managed to pack more info into this video than hours of trawling the net for this info, many thanks, learnt a great deal....

[@AndreasSpiess]

Thank you!

[@skeptical_bystander]

Great video, Andreas. Suggestion for a rule #8: Do not use more power then you need to. You will save battery and, which is more important, create less interference for others

[@AndreasSpiess]

You are right!

[@mr_beg_exe]

THANKS MAN...... IT HELPED ME ALOT... LOVE FROM SILCHAR, ASSAM(INDIA)

[@AndreasSpiess]

You are welcome!

[@npc9352]

Your channel is a gold!

[@AndreasSpiess]

Thank you!

[@karllaun2427]

Good timing on this video. Taking my FCC exam next week.

[@AndreasSpiess]

Hope you will pass!

[@karllaun2427]

Passed Technician and General.

[@rmhayes1954]

Good topic. It might be worth mentioning that RSSI drops with distance squared. (87km/123km)=0.707. Squared = 0.5, same as -3dB. So the change in distance in air corresponding to -3dB will be the original distance * sqrt(2).

[@AndreasSpiess]

Thank you for your explanations. I briefly mentioned it, but not as thorough as you.

[@paziipa]

Good job man, keep the quality up. You deserve way more followers!

[@AndreasSpiess]

Thank you!

[@michaels3003]

ruuhkis , I agree. Subscribed today...

[@planker]

I enjoyed this video, Like. The concept of Buget clicks. Cool, I was tought electron flow is Neg to Pos. The thinking and staying in concept just feels correct. Thanks

[@AndreasSpiess]

You are welcome!

[@piero957]

The rssi can be roughly evaluated also using a 10$ sdr and rtl_power or other tools, without decoding the signal. Another indicator could be the digital RX quality, it's the percentage of lost beacons, a wifi example is with airodump on a fixed channel.

[@piero957]

The RX quality could be something like the bert (bit error rate) so precious in the good old days. All that stuff can be implemented using cheap MCUs ;)

[@AndreasSpiess]

You are right. But these signals are quite short and not so easy to detect. And you have to take your Laptop with you! Concerning RX quality: This setup is not focussed on link quality, it is purely made to check out antennas. Link quality is probably more important if you want to check out how big the range of your devices is.

[@outtony]

if you put antena directly to arduino, you can surelly send AM signal in KHz and listen it using am radio. I used it with 386 (33mhz) and LPT port back then.

[@AndreasSpiess]

I agree. There is even a program for the Raspberry Pi to create different modulations...

[@AzatSharafetdin]

Thanks a lot for explaining such a hard topic in easy words

[@AndreasSpiess]

You are welcome!

[@paulhamilton3993]

Andreas, thanks for sharing your knowledge!

[@AndreasSpiess]

You are welcome!

[@KunalGautam]

Thank you. Understood many things about antenna.

[@AndreasSpiess]

You are welcome!

[@TonyLehto]

Excellent video! So eagerly waiting for the antenna tuning video!

[@AndreasSpiess]

:-)

[@stanrock01]

This is fantastic information. I should of watched this video before I learned the hard way :-)

[@AndreasSpiess]

Thank you! There are a few other videos about antennas on this channel ;-)

[@zahlex]

Amazing Video! I'd really like to see more on this topic from you! Didn't knew you are an Amateurfunker 🙂

[@AndreasSpiess]

I am a ham operator for 40 years. And if you watch my first videos you see, that I even can do the Morse...

[@pe2kmv]

Oh so true! I've experienced a wire cut to the correct length being a better performer than an off the shelf 868 antenna (also considering connector losses).

[@AndreasSpiess]

Only a wire is probably not the best solution as you saw with my Ground Plane antenna

[@pe2kmv]

Andreas Spiess That's exactly The message.... A wire outperforming a factory made antenna, tells a lot about the latter. Probably it's more a waterproof dummy load than an antenna. Unfortunately my antenna analyser only covers HF and VHF, so I'm looking forward to some instructions regarding a 868 reference antenna. Keep it up! Your videos are great!

[@AlbertEspinRodriguez]

A master antenna class. Thank you soo much. 73 de EA3HSP !

[@AndreasSpiess]

73, too

[@lmamakos]

This was very nicely presented. Antennas are somewhat of a black art, and since my background is computer science, not electrical engineering, my knowledge is more empirical from 30 years of amateur radio and the occasional RF burn. I think it would be useful if you could incorporate some testing and present the effect of other conductors/cables in proximity to the antenna and how the gain is impacted. This is something that has always concerned me, and in some scenarios, could degrade the performance in a surprising way. Taping a wire antenna to wood "works", but maybe when it rains and the wood becomes soaked with some water.. not so well? Or having just having other cabling in the near-field of the antenna.. Thanks for making this video and sharing it with us.

[@AndreasSpiess]

Thanks for your feedback. We will see what I can do. This channel has many different topics and I cannot stick too long on antennas only. There are some others focussing on Ham radio. But at least one will come which will cover parts of what you wrote.

[@illperipherals]

Once again, great coverage of a difficult subject. I have been recently working with a noise-gen/rf-bridge/SDR to get a rough idea of what I am doing out here ;)

[@AndreasSpiess]

That is a good start. SDR is great stuff.

[@shazam6274]

I think it would be very beneficial to show the amount of signal loss by having a human and other objects (tree, building, etc.) near the antennas. It is amazingly large! Even at 27 MHz (old "CB" Radio) it was huge with a handheld "walkie-talkie" I measured in the '60s. One of the major misunderstandings about T-R link is the need for a ground plane at both ends. With hand held devices, you are the ground plane. Lastly, what is discussed for line of sight at high frequencies is correct, but low frequency LW & MW (AM) radio receivers use magnetic coupling ("H"wave"). This is increases reception range and is a way to get around the "line of sight" issue. Look inside an old radio for a loop of wire for the antenna. In handheld radios, the loop is on a ferrite core, which was often referred to as a "loop stick" antenna.

[@AndreasSpiess]

You are of course right. But this is no "ham" channel and the topic was big enough for one video...

[@shazam6274]

Yes. Thank you for this video. I only raised these specific issues, which could be a basis for a future video summary, because of the large impact to your topic: Radio Range. I can tell you of many instances of unknowing guys complaining of bad or no reception when they had a wire antenna wrapped around the receiver and clasped in their hand, or a transmitter (and antenna) taped to the side of a refrigerator or stuck in a pine tree.

[@florianoberacker6500]

About your question about the gain and the law Restriction: Most of the given restrictions (I know for sure in Europe) are based on the ERP which calculates from sent Power an the gain: ERP=P_tx*G_tx (for linear values) = P_tx + G_tx (in dB). P_tx is the Power which goes into the antenna. So if youre allowed to send 1000W and you have an antenna with an gain e.g. 13dBd, the maximum Power which is allowed to go in the antenna P_tx is 50W (transceiver power - Cable loss).

[@florianoberacker6500]

This is the same also for Lora, Wifi, Bluetooth,...

[@AndreasSpiess]

This is what I thought.

[@florianoberacker6500]

But now I see, I made a mistake and forgot to mention something. The ERP is calculated with the gain in dBd and the EIRP with the gain in dBi. The differnce is just the reference Antenne and the relation is: gain in dBi=gain in dBd + 2,15dB. This is equivalent for the Relation of ERP and EIRP. This is also something you have to pay attention to, when reading the regulations. Sometimes it´s ERP, sometimes EIRP and when reading Datasheets. The antennas are mostly given in dBi, but the regulations for low frequency stuff are often in ERP (mostly

[@majidnasr3329]

Hi Andreas Thank you so much for such a nice video. Antenna has never been this much user-friendly like this video!! As it was predictable, everyone asking for creating another nice video about antenna. Probably the main reason is antenna measurement devices are so expensive. So, I think, If you can focus on presenting DIY antenna, should be awesome!!!. Please consider on 915Mhz as well if possible because this is the legal amateur band here or at least, how to modify for another frequencies.

[@AndreasSpiess]

The frequency is not so important for Antenna theory. So the new video will also cover 915, even if we are not allowed to use it here.

[@garychap8384]

When it comes to wire antennas, longer is definitely better... In fact, I've found that the optimum wire length is one which reaches from the transmitter to the receiver ; )

[@AndreasSpiess]

This is definitely not true, even if it sounds strange. Use a simple example: A transmitter in Europe with 100 watts and a coax cable towards New Zealand. Calculate how far the signal would travel and you will find a few 100 miles with a good coax. I often get connections to New Zealand trough the air. This is one of the things which keep me in amateur radio…

[@garychap8384]

@@AndreasSpiess Ahhhh... I think you may have missed the _"humour wink"_ at the end of my post : ) Yes, of course it's not true! You are, of course, absolutely and unamusingly correct! I've always been very familiar with the losses in coax and ladder-line as it comes into all my ERP calculations. But ... a joke is a joke... and I'll never let 'the obvious' or the 'factual' stop me from saying something completely silly for my own amusement ; ) Of course, there's also the expense. A cable across Europe to New Zealand would costs a lot of money.... but that's nothing compared to how much you'd have to spend on signs saying : [ *CAUTION* - *TRIP HAZARD* ] ; ) Sorry. I may be 50 years old in November, but I'm still just a big kid XD 73s

[@AndreasSpiess]

@@garychap8384 i was not sure because a lot of people are not aware that „air“ can be much better than copper… Anyway, no problem ;-)

[@garychap8384]

@@AndreasSpiess No problem Andreas. And, thanks for the content... you're one of the most charming creators on youtube and I always look forward to spending some time seeing what you're up to : ) The work you put into your videos is truly appreciated OM. Much love to you and your family, from the UK!

[@murrayzhong3968]

I like your tutorial. Please make more.

[@AndreasSpiess]

Thank you. There are many more videos on this topic on the channel.

[@JuergenBoehringer]

Brilliant Video, Thanks for that! Best greatings from Germany.

[@AndreasSpiess]

You are welcome!

[@jon_raymond]

I never expected to see a Casey Neistat hoodie in one of your videos :). Great video as always. Thank you for sharing this information!

[@AndreasSpiess]

I am a big fan of Casey. He is also a hard worker ;-)

[@captainboing]

Excellent vid. Thanks

[@AndreasSpiess]

You are welcome!

[@mikehudson3620]

I love antennas. Your Moxon was presumably to get some gain. I looked it up on Wikipedia and it looks like a form of folded yagi. Somewhere back in history, I was a great fan of the quad (in HF use). The quad is quite effective as a directional antenna (Wikipedia has a brief description ) and may give better performance. Theoretically it should behave more predictably at the short wavelengths you are using than at HF and be quite compact. Your lovely vector analyser would allow it to be perfectly matched too! Just a thought...

[@AndreasSpiess]

A quad is on my list, too...

[@thisusernameismine10]

Not sure if you are aware of Windsurfer Antenna additions to add direction to the normal stubby antennas, I tried this with some NRF24L01 radios and it worked. I thought of it when I noticed in the video the piece of what looked like duct tape on the wooden pole behind the tx end, a piece of kitchen foil would probably also skew your results to the better too. I submit this in the interest of achieving cheap improvements for those of us on a budget, for whom you seem to champion. Bravo.

[@AndreasSpiess]

Antenna design has to do with dimensions. Unfortunately, 868 antennas become much bigger than 2.4G antennas. I am not sure of the feasibility of such a design. Maybe you try it once?

[@thisusernameismine10]

No, have not yet tried with 868 (still waiting for my TTN Backer kit to arrive). From my very simple experiment with NRF24s, even a plastic box in my case, or probably that piece of wood and duct tape will possibly have added some directional bias to your experiment - for zero cost. Be nice to prove it, but don't let me divert you! I will let you know if I get chance to try it.

[@giannismarkidis9546]

You are the best.!! Thanks for your perfect video

[@AndreasSpiess]

You're welcome! Maybe you watch also my newer videos about antennas and the Smith chart?

[@ufohunter3688]

Awesome video. Just awesome.

[@AndreasSpiess]

Thank you!

[@Perspectologist]

This is great! I’m currently working toward my first amateur radio license. I’ve been thinking a lot about what kinds of antennas I want to buy/build. John Park, on the Adafruit KZbin channel, recently did a video on an making an Morse code AM transmitter. He used an analog output pin and a long enameled wire for an antenna. It was very low power and had a very short range but seems like a really interesting concept to play with.

[@AndreasSpiess]

To build a CW transmitter is simple: Just switch an oscillator on and off ;-) But to understand what was sent is a little more complicated.

[@Perspectologist]

Andreas Spiess yes. CW isn’t required for my license, but I’m interested in learning it.

[@zaferaltun]

Very good, thanks for the video!

[@AndreasSpiess]

Glad you liked it!

[@michelmullernh]

Antes de mais nada, sua informações passada pelo seu canal são muito enriquecedoras, parabéns! As informações sobre as antenas foram muito importantes para tirar algumas dúvidas, e lhe agradeço por isto. Antes que me esqueça, sou do Brasil e moro na região sul do País (Cidade: Novo Hamburgo.. Estado: Rio Grande do Sul... País: Brasil).

[@AndreasSpiess]

I do not speak Portuguese, but Google Translate helped. Thank you for your nice words!

[@sethalump]

I've been an antenna / RF nerd for decades. This is the best explanation of all the important factors I've ever seen. (Also a nice review for the old timers) Good work!!!!!

[@AndreasSpiess]

Thank you! I am pretty sure you will like the next video ;-)

[@unstopp]

Hi @sethalump, do you do any freelancing work? I would like to extend an esp32-s3 ble transmitting range (to a smartphone)

[@sethalump]

@@unstopp look into LoRA, that's the wireless tech you want if you want to go far

[@unstopp]

@@sethalump thank you, do they have standalone bluetooth modules? I’m a bit lost searching for something on the web. Can you recommend any?

[@sethalump]

@@unstopp Sure there's lots. But maybe we should start with what you are trying to accomplish?

[@bassome3000ify]

You have created content good for use in all universities

[@AndreasSpiess]

Hopefully it will be used ;-)

[@jangAckman]

You're such a great teacher.. thank you so much... thumbs up!

[@AndreasSpiess]

You are welcome!

[@ErnestGWilsonII]

Excellent video as always sir! Thumbs up! 73s W3TCP

[@AndreasSpiess]

Thank you!

[@raymondbruns3291]

Nice video! I Noticed that you took measurements with the sender and receiver on different elevation levels. Seen in that licht, it doesn't surprise me that longer antenna's prefom worse than the shorter ones. The shorter antenna's radiate more or less in a round spherical pattern, while the longer ones have a flatter one. If this flatter sphere isn't properly alligned with the receiving antanna you get big losses. You can run simulations of this effect in Eznec.

[@AndreasSpiess]

You are right. In reality, the longer antenna was not properly adjusted to 868. Because I found many of these antennas with my friends I wanted to make this point.

[@freesaxon6835]

Excellent video

[@AndreasSpiess]

:-)

[@naidadad9311]

A great video! Thank you very much!

[@AndreasSpiess]

You are welcome!

[@aarunpm]

Very interesting and awesome as always

[@AndreasSpiess]

Thank you!

[@chriscauwelier]

So that means that your 3D-printed antenna did extremely well? 5.2dB gain is huge! I'm an amateur audio technician, waves are waves. :)

[@AndreasSpiess]

I think so. But it was directional...

[@demoosaad8579]

This dude is elite

[@AndreasSpiess]

:-)

[@DonzLockz]

Great videos! lots of information and tips. :)

[@AndreasSpiess]

Thank you for your feedback!

[@billyg.7032]

Great resource! Thanks, Gracias!

[@AndreasSpiess]

De nada!

[@kissingfrogs]

To reinforce the "keep coax cables short" .. 3G over 50kms air gap + 21m coax = 0 bars. 3G over 50kms air gap + 0.2m coax = 4.5 bars. I was surprised to discover the amount of loss in the cable compared with FSL.

[@AndreasSpiess]

Thanks for your example.

[@SelectLOL]

@ 1:18 Not important but if you want to say, that somthing sends out data or maybe light you could use the word "E/Trans-mitter" like in Tx/Rx = Transmitter and reciever. Because the word sender is german and not well used in english.

[@AndreasSpiess]

Thank you for your tip!

[@RTPTechTips]

An excellent video. 🙂

[@AndreasSpiess]

Thank you. Have you seen the newer videos about the topic?

[@cfedundrum1]

excellent video on RF theory

[@AndreasSpiess]

Thank you!

[@richsonner1930]

​@@AndreasSpiess😮ppppppppppp0

[@DavidMishchenko]

I'm a simple man. I see cat; I upvote.

[@AndreasSpiess]

She says „Thank you“!

[@anthon5504]

8:30 no that is not allowed (In Germany) the max power out put on the Antenna is defined as 100mW EIRP (equivalent isotropically radiated power). You can use 100mW whit a 0db antenna ore 50mW on a 3db antenna. In some cases you're not even allowed to change the Antenna at all.

[@AndreasSpiess]

You are right. There were quite a few comments aroound this topic.

[@CircuitCreator]

GREAT JOB

[@AndreasSpiess]

Thank you!

[@Kuba_kubowy]

Great! Waiting for continuation :)

[@AndreasSpiess]

:-)

[@v.gedace1519]

EXCELLENT! And thank you very much! Can you please make a separate and detailed video about your ESP(32) test device incl. the sketches? Because I face currently the issue that I do have a very low WiFi signal in our basement where some ESP32´s trying to send low resolution video streams to the upper floor. And wiring them up is currently not possible. Thanks in advance!

[@AndreasSpiess]

I have no such plans. The only thing you can do is to use a proper external Wi-Fi antenna and move it around to at least find the best spot. Sometimes, a few cm make a bi difference (2.4GHz is a very short wavelength).

[@v.gedace1519]

@@AndreasSpiess Schade! Hatte die Hoffnung Tips, wenn nicht gar Details zu bekommen, so dass ich mir Ihr "RSSI - Messgerät" nachbauen kann. Das Ding ist Gold wert!!! Aber kein Ding, ich finde das schon heraus. Zumal es ja "nur" ein JSON formatiertes Datenpaket ist was hin und her geschickt wird. Für mich liegt das Problem eher darin, wie auf der Receiver-Seite der RSSI Wert ermittelt wird. (BTW: Dieser muss ja nicht absolut (richtig) sein. Das Delta zwischen zwei Messung sagt ja bereits aus, ob die eine oder andere Antenne (für die akt. zu testende Situation) besser geeignet ist oder nicht - so halt wie von Ihnen im Video gezeigt.) Diesen (RSSI-) Wert dann per JSON formatierten string zurückzusenden ist nun wirklich nicht das Problem. Trotzdem Danke! EDIT: Found it: After WiFi connection is established: ... Serial.println(WiFi.RSSI()); ... lol.

[@AndreasSpiess]

Genau. So einfach ist das mit dem RSSI ;-)

[@ME-en9ud]

Thanks for the interesting video. Best regards from Germany!

[@AndreasSpiess]

You are welcome!

[@emadjabbour]

Sir you are great and very generous Thanks

[@AndreasSpiess]

You are welcome!

[@adtwomey]

good work keep up the work

[@AndreasSpiess]

:-)

[@magnusskarklins5662]

Very informative, thanks!

[@AndreasSpiess]

You are welcome!

[@Francois_Dupont]

i think as you showed us, if you can isolate variables and get consistant results then you can successfully test anything without even talking into consideration the units of measurement. for example even if you measured only in imaginary numbers like 300 for good antenna and 200 for bad antenna, you could have still looked at the results and scientifically compare the measurements.

[@AndreasSpiess]

I do not understand :-(

[@Francois_Dupont]

@@AndreasSpiess sorry my message wasnt clear. i am only saying that with a good scientific method it is possible to get good result. i love your videos!

[@shubhamadtp]

Nice i was expecting some discussio. In wavelenth and lenth of antena Liked

[@AndreasSpiess]

Thanks!

[@richardstott4159]

I'm fairly certain that antenna lenght is crucial to match frequency for the TX but on the RX end it isn't relevant so perhaps for RX longer is better. However, separate TX/RX antennas is an additional complication for simle links!

[@AndreasSpiess]

You are right with the length and the frequency. Basic physical principles, however, are valid for the receiving and the transmitting side.