@@AndreasSpiess Short and precisely to the point. You are focused and provide good material without all the ridiculous flashy screens and horrible music that a lot of other tubers do! Thank you for keeping your videos interesting and informational. If I want "entertainment", I can watch a movie. ;)
Thanks Andreas, every time I watch one of these, I stand on the edge of diving in to this radio stuff, as I feel well informed by your videos.... thanks ....
@@AndreasSpiess Desperately trying to prove, at the tender age of 64, that I'm still 'douwn ther wiv the yoof'. Not sure even Google Translate can deal with this :)
@@AndreasSpiess I'm not sure that 'down there with the youth' - correcting the spelling is that helpful. At the risk of going further down this rabbit hole ...... it's 'street cred' (Social recognition with/by young people who spend time congregating on the streets). It's a self mocking attitude based on the impossibility of ever achieving this status. a.k.a. 'bollocks' :)
Love your videos. Impressed that Al welding rods can be solderable 5:33, and 6:30 thru 6:45. I had "stuck" thinking because Al is normally not solderable, but of course the rods are alloyed!
The 0.95 velocity factor varies with wire diameter as a proportion of wavelength. In addition the effective length of a wire is also increased by the ‘end effect’ - it behaves as if the wire end has a capacitor on it - also proportional to frequency. This is why we always start long and snip down to resonance / minimum SWR.
Great video as always Andreas! I got into radiosonde tracking with your last video and now have my own station. My nanoVNA is arriving tomorrow and I already designed and 3D printed a ground plane antenna hub for easy mounting. I will be also getting my radio amateur certification very soon! Thanks for the inspiration!
Loved the video. You spoke of Teflon. I thought I'd share info about how it was discovered in 1938. "Plunkett’s first assignment at DuPont was researching new chlorofluorocarbon refrigerants-then seen as great advances over earlier refrigerants like sulfur dioxide and ammonia, which regularly poisoned food-industry workers and people in their homes. Plunkett had produced a hundred pounds of tetrafluoroethylene gas (TFE) and stored it in small cylinders at dry-ice temperatures before chlorinating it. When he and his helper prepared a cylinder for use, none of the gas came out-yet the cylinder weighed the same as before. They opened it and found a white powder, which Plunkett had the presence of mind to characterize for properties other than refrigeration potential. He found the substance to be heat resistant and chemically inert, and to have very low surface friction so that most other substances would not adhere to it. Plunkett realized that against the predictions of polymer science of the day, TFE had polymerized to produce this substance-later named Teflon-with such potentially useful characteristics." From ScienceHistory.org
If you have a lightning rod use that. Else make one. A good ground rod is at least 50cm deep in the ground, you can also put some coal into the hole for better connection.
@@AndreasSpiess 'something else' should be conducting and capable of withstanding large currents, not say clouds or birds ;ø) - caveat is that antennas should not be mounted near conductors or other metals... Catch-22
Andreas, 4:30 minutes into your video you raised the subject of "Velocity Factor = 0.95" being the reason that in practice antennas are 5% shorter. Throughout my 35 years of experience, I believed an antenna was 5% shorter, due to what is known as the "end effect", while "velocity factor" was the propagation speed through a medium (such as a coaxial cable). From memory, RG58/RG8/RG213 has a velocity factor of 0.66, while a balanced transmission line such as 300 ohm ribbon around 0.95, while obviously, the "velocity factor" of an electromagnetic signal through space is 1.0. . So I was curious as to was I wrong for all those years to believe it to be the "end effect" and not "velocity factor" which required an antenna to be 5% shorter? www.electronics-notes.com/articles/antennas-propagation/dipole-antenna/length-calculations-equation-formula.php
Yes I believe you have been correct for 35 years. I think the author of the web page has taken a bit of liberty with the term velocity factor. To get a lower phase velocity you need some capacitance to ground. Yes that does exist in this monopole antenna (radiator to ground plane) but that’s not a function of the wire but rather the antenna configuration.
Thanks for the overview. Some details are missing about actually joining the material and specific parts used. So for some clarity: The flanged SMA connector used as a base for the antenna has holes of roughly 2.6mm I.D. This would pair well with M2.5 screws and nuts. The flange plate of the SMA connector is about 1.6mm thick, so a threaded length on the screws of about 4mm should allow for space to lock the terminal with a nut. It is also unclear what size knurled copper insert is used to connect the vertical radiating element. As a guess I would say they are M3*5*4. It's ambiguous how this is joined to the coaxial cable tip of the SMA flange connector. Another guess: it is sat on top the teflon shield and solder is pooled into the insert with a gas torch. Here's a video specifically about soldering an element to an SMA connector: ua-cam.com/video/34Ii-C8kYRI/v-deo.html More detailed assembly info would be appreciated!
Your assumptions concerning the dimensions are correct. My SMA connectors are different to the ones used by Andrew. I needed a "pipe" in-between. If you find the ones Andrew used it is easier.
Nice simple DIY solution. Just an observation, I noticed your velocity factor was still set to 0.95, which is generic for copper, using aluminium velocity factor, the result would have been a lot closer to the actual length.
You are right. My measurements indicate a slightly lower VF. I did not investigate into the VF of my rods. They seem to be a mixture of several metals...
And a bare copper wire will corrode outdoors.. Does surface corrosion matter, or is that only a problem for connectors? (I recall someone saying even cheap 8266 chips have gold-plating for the onboard meandering-F aerial because the copper corrodes)
@@dave_dennis Measuring is simply the reverse of stipulating it in the first place once the wire is cut to the required length using the calculations the velocity factor is derived from the new measurement. I use to do this a lot as a lab supervisor. Obviously the measurements have a certain amount of precision based on the measuring standard used, but it is close. Many calculator do not provide a reverse measurement so it has to be done but hand. Fortunately is is simple algebra.
Soldering aluminium welding rod is not that easy for most makers. I mostly use standard steel welding rods. For my LoRa gateway I selected the M0UKD J-Pole. With the J-Pole in a piece of plastic tube, the gateway does not attract any attention and is more resistant to birds trying to land on it. As a tip for anyone building one: Bend 3 or 4 wires, leaving the ends too long as soon as you start building. As soon as you place the antenna in the plastic tube, you will see a change in the frequency due to the fact that waves travel slower through the plastic than through the air. Either calculate the difference in length by hand or change the velocity factor in the J-Pole calculator and then cut the second antenna to the calculated length, add a few mm so you can cut/grind/file the antenna to the correct length during the tuning process.
1. How do these welding rods behave outdoors? Do they rust? 2. I built a J-pole for 868. But I found the position of the cable is not easy determine without a VNA for such small antennas.
@@AndreasSpiess I did not yet see any rust on welding rods I used - they are a blend of metals with a coating that seems to prevent rust. An yes - as you also mentioned in the video, you do need a VNA for the J-Pole. It takes a few tries to get the correct feed point but not an impossible task to do. I made multiple GP, J-Pole and coaxial antennas. A GP is surely the easiest and with correct measurements you can get around without a VNA. The coaxial antenna is a nightmare: at 868 MHz, 0.5mm measurement error results in a 5 MHz offset.
@@AndreasSpiess If they're the rods I'm thinking of (for gas and tig welding low carbon steel) they're just copper washed low-medium carbon steel. Look for bronze "brazing rods" for corossion resistance.
Very good declared. I remember the hours of learning military radio things and later the amateur radio. Hours of fun while experimenting and the guys who teached us all these things had a more funny way to teach this.
I will say for that frequency, a Dipole antenna construction will be more easier. You don't need to buy anything at all.. Take a piece of RG58 separate the bread and core in different direction by stripping the outer insulation. Your dipole should be ready. And more interestingly the VNA is definitely a good tool here, but for general audience a simple Impedance bridge or a reflection loss bridge will also work fabulously. But this video really helps those kids putting the same rubber ducky antenna on NRF24, LORA, Zigbee, FM Tx, Toy cars, RC remotes and expecting a better range. The idea of resonance is what matters and that's beautifully said in the video.
A dipole for sure also works. But it has a higher impedance. Because I wanted to show a perfect match, a ground plane was a better choice for me. It is also quite easy to build for those high frequencies.
@@joelong9260 For HAM operators, 10 turns of coaxial on a 4-inch PVC pipe works, for non-licensed ISM band the Tx power is damn low, it may not matter. But to make it 50 Ohms, a little bit inverted vee configuration can be done to accommodate impedance. And the perfect isotropic radiation pattern may not be possible with a dipole as we know in general. In that case, a vertical 1/4 wave is good enough.
Thank you for an excellent video! I learned more from your 14min Antenna video than I have from reading the ARRL antenna book! I am a beginner who just got my General amateur license and your explanations are simple and understandable! BTW, I have a lifelong friend in Zurich so I enjoy listening to you!
Glad it was helpful! The handbook is probably not made for a beginner and this channel is not made for HAM operators. So I have to explain also the basics...
Funny, after seeing your videos on the weather balloons, I thought I would need a video on building a suitable antenna for the rtlsdr stick. But I managed to do it by myself. I used the nano vna for tuning as well. What came out is the exact same antenna you built! It's working for a coupler of weeks now.
@@AndreasSpiess in the video I can hardly see the gain. Do I see right, that it's over 30!? That's a lot and would explain the 200km. I have around 20dB and 80km. How did you do that?
Most viewers are not HAM operators and therefor not legally allowed to use directional antennas. So you have to go to another channel for this info :-(
Another great presentation, thank you. I hope to get into building my own antennas this year with the help from your videos. And another thanks for finding that VNA meter for us.
The J-pole performs very well on 868 MHz if you add a sleeve Balun /Bazooka balun (1:1) around the feed line to make its input balanced. Forget Ferrite chokes and coax loops, they are too lossy at 868 MHz. I simply soldered a 1/4 wave O.D. 4mm brass tube to the cable end of a SMA connector, so the coax emerges at the other end by a few mm past the end of the tube at the feed point. It has to be a coax with an outer insulator, not a naked semi rigid coax like you use. The bottom of the J, with the feedpoint, together with the end of the brass tube, can then be encased in a cylinder of Epoxy to make sleek straight vertical antenna assembly 3/4+1/4 = 1 Lambda long only. It is sturdy enough to be free standing, or will fit inside an only 10mm I.D. tube.
I think one thing that would be useful is a proper tutorial on using your minivna to properly add an antenna to cheap RF modules. I've seen lots of projects were people have used a premade module that doesn't have an antenna and thought that just sticking a trace with the right length on their board is enough. Now the tools to do it properly are within makers reach we should really be trying to do it properly.
I made a video on how to use a VNA. For the topic you proposed, my video would be very short: Do not do it because most people have no idea what they do. It needs to re-engineer the design to find out which impedance is where you cut and then to match a newly build antenna. I go with boards with a connector where I can assume it is around 50 ohms. But still, I have to hope they copied the reference design of the manufacturer...
Who are you, Mr. Spiess, so wise in the ways of science?! You are putting my generation in an invaluable position to recieve information. The hobby still lives, and we intend to continue to contribute to its beauty. Now I wonder if an amateur radio license will impress the ladies or not...🤓🤔
Taught how to get straight wire from a roll 40 years ago - just wrap one end around something strong and grab the other with pliers and pull - the wire stretches slightly but you get a beautifully straight section of wire - just cut off ends Did use tinned copper wire for interconnects on electronics so not sure how it will work on larger diameter
Thank you Andreas. I was going to spend $$$ on a formal RAK antenna for a Lora Gateway at our hacker-space. Now I can use the money to purchase a VNA analyzer and build my own!
Very well done. I am waiting for my 3 GHz nanoVNA on the slow boat from China. I have the 900 MHz version, but LoRa here is over 900 MHz and I do lots of home automation with wifi and zwave so this video and the 3 GHz nanoVNA will be very useful (new sites for M0UKD and MMANA-GAL appreciated!). Thanks, glad I am a patron. Doug, N8VY 73
I had similar results to your ugly antenna using tests for Aircraft tracking. The signal plot graph was so good. i just pulled the core out of coax cable and used it as elements.
Nice. Technical and Insightful video! I remember once trying to build an aluminium foil antennae for boosting WiFi signal and ended up with nothing. Inspiration was some prank DIY video :/
Andreas, I like all your videos a lot, thank you much for creating good content! One remark: @12:28 you say "it [the gain] multiplies the power output of your device by a factor of 3". I guess you should re-state that :) Otherwise, one may have an impression they would get 3W from a 1W emitted from their TX device.
@@AndreasSpiess OK, agreed - with the important note: the RF level in a small spatial angle that is the same as if from an isotropic antenna fed with 3 watts of RF power. Obviously, in other directions, it is way less than the RF level obtained from such an isotropic antenna (for example, as you pointed out in your video, for the vertical direction - i.e. straight up from the antenna).
Very good vid Andreas! Something to try, when putting heat shrink or something else over the radiator element, even if an insulator, it affects the s-parameters of the antenna. So adding conformal coating likely will change the tune of the antenna. If I remember correctly adding heat shrink to the antenna radiator moves the 50 ohm point down in freq. And when tuning the antenna on a VNA with a coax I would highly recommend a ferrite beaded coax to prevent the coax from becoming a radiator. I was working on an antenna that I had tuned nicely and one of my engineers noted the lack of a beaded coax and I installed one and it made a huge difference in my antenna design. It was a small 750 MHz ground plane very similar to what you have designed there for weather balloon frequencies.
You are right: Adding plastic changes the response of the antenna. I would not do conformal coating on the radiator. I used Aluminum because of that. I only would cover the connector. Most people suggest using ferrites for (stronger) transmitters to protect the equipment. The cable should not radiate too much if the antenna is 50 ohms. But maybe I have to try it with a LoRa ground plane...
@@AndreasSpiess I was on a Agilent N5230A PNA and was spot on 50 ohms and adding the ferrite beaded coax really changed it away from 50 ohms for the desired frequency, my PhD RF Engineer showed me how much the coax was radiating. Really surprised me. I didn't have any idea. But touching the coax almost anywhere on it had a noticeable effect on the VNA. Try having it on the VNA, and handle the coax and see how much it changes. A comment one of my engineers made is a 50 ohm resistor is perfectly matched, it just doesn't radiate, but on the VNA is looks perfectly matched. We did a LOT of antenna testing on our Satimo Starlab. I did test this antenna (very similar to yours, just smaller for 750 MHz) and it was a beautiful radiation pattern. Those ground planes are very nice omnidirectional antennas.
I've purchased the parts to build an outdoor 1/4 wave antenna for LoRa per your video and even figured out how to mount it on my tile roof which has a great view of my city (I live higher up in the foothills). However, at minute 12:18. your video suggests maximum gain near the ground plane. How does this antenna perform looking down into the valley from my roof for covering remote nodes in the city? Will it cover the valley, or is coverage limited to the ground plane and above? I've learned so much watching your videos - thanks Andreas!!!
@@AndreasSpiess BTW, have you heard of a sleeved monopole antenna? I was reminded of it last night while I had a UHF magnet mount antenna connected to the NanoVNA. The SWR was about 1.5 but if I carefully wrapped my hand around the driven element without touching it, I could get the SWR down to REALLY low and it was broad and flat which is ideal for GMRS. Here is a video about using it for WiFi. I am trying to send WiFi through about a meter or two of dirt from inside our buried polyethylene cistern so we can monitor the water level (using an ESP8266) from inside the house. ua-cam.com/video/78ECVt7OHl8/v-deo.html
I may try one of these to improve the range and reliability of my garage door opener. I think it is in the 433 MHz range. The opener just uses about a 6 inch (15 cm) piece of wire. However, the main door is steel and I think that reduces the signal strength. If I build an external antenna, I can mount is where the door will not block the signal.
I encourage you to seek out other channels to find more about antenna designs. There are many good channels that will help. Be warned... Pure antenna design is *very* mathematical in nature! I would need advanced training in calculus to understand it. Instead, I use ideas from others and use the tools available to me, such as MMANA-GAL. And, of course, experimentation. I made one antenna from copper foil tape and laminated it with plastic. It works quite well!
@@judhi In this case for the calculator that Andreas used it was for the antenna material. Coaxial cables also have a velocity factor to consider , like RG58 is around 65% i think if remember correctly. For the test with VNA Andreas connected directly to the SMA connector on the VNA, that was his reference plane. You can however calibrate the VNA reference plane to the end of a coax if you need to. There are a few videos on the subject on UA-cam.
I am just starting with 'telecom stuff' and trying different antenna designs for LoRa. I got some "Autogen-Schweissdraht CFH verkupfert Ø 1,5x333 mm 15er Pack" which seems to work quite well: it is very stiff copper plated steel rods and can be bent into shape (you can find that stuff at Hornbach for example) and solders quite well. As I don't have a Harley that looked like a good option to get stiff wires 😃
Straightening copper wires: Put one side of the wire in a bench wise, the other side in a (cordless)drill. Twist the wire with the drill while pulling slightly. If you pull to hard or twist too much, you will end up sitting on the floor ;)
I have built and bought many antennas for 868MHz LoRa. But my best performing one by far is a hastily built simple wire antenna. I have tried to replicate it with no luck and I have no idea why it performs so well. It is wrapped up with glue lined heatshrink, so I can't/don't want to dissect it so I could figure out its magic!
Andreas, this was a thoughtful and well-produced explanation. But you didn't address two issues with the J-pole at the end: (1) very high SWR, and (2) it is outperformed at low elevation by the ground plane, despite having similar theoretical gain. Many people believe a J-pole will outperform a ground plane for land-mobile use. It is rarely true!
1. The SWR can be tuned with the position of the coax. Mine was 1:1.05 2. I thought I showed the two patterns and mentioned this fact. But after the summary. Only for the ones who stick till the end ;-)
Eine Frage : Oft wäre es besser, wenn Antennen ein kurzes Anschlusskabel (z.B. 1 Meter) hätten, damit man sie nicht direkt am Gerät anschliessen muss und besser positionieren kann.. Ein starres Koaxialkabel ist dafür ja weniger geeignet, das Kabel sollte flexibel sein. Welchen Kabeltyp würdest Du dafür empfehlen ? Danke und viele Grüsse aus der Nachbarschaft, hier kommt aus Richtung Schweiz gerade wieder der blaue Himmel.
Hallo Andreas, vielen Dank für die schnelle Antwort ! Ich werde ich bei Aliexpress nachsehen. Was für ein Kabel würdest Du nehmen, wenn man es mit SMA-Konnektoren selbst bauen will ? P.S.: Respekt, du weisst sogar, dass Kabel mit male/Female-Steckern die Nummer RG316 haben ! Wieder was dazugelernt. Die Bestellung bei Aliexpress ist schon raus.
At 11:10 we get a glimpse of the sma connectors. Is it okay to let them sit in the rain, or do you take countermeasures against water, other than sealing the connector to the case?
Great video! A couple of questions for later videos perhaps? 1) Can you explain the effect of different thickness of material on the antenna? I believe a thinner diameter generally has a narrower bandwidth, meaning it can help "focus" on a signal and reflect interference, but I've seen conflicting info. 2) Any hints as to better antenna designs for receive only antennas? Does it make sense to use a different design if radiating is less needed? 3) Copper versus Aluminium, does it really make much difference for our typical usages?
This is not an antenna channel. I only covered the basics which is interesting for many viewers who build LoRa or other devices. But you find a lot of channels dealing with antennas and antenna design. The antenna for receiving usually is the same as for transmitting. It is less critical because a bad antenna cannot hurt your device. Thicker wires usually lead to a broader bandwidth Aluminum is very similar to copper. The (electrical) difference is small
just what I was looking for! Next video: how to make the antennas smaller, and embeddable? What is the mystery of 3D antennas? How much worse are circuit printed antennas compared to the ipex type (e.g. in esp32 versions)? Will consider Patreon, great content!
The size of an antenna is important for its performance. So make it smaller does only make sense if you have no space because its performance will not be good.
Best way to straighten 12 to 16 gauge wire, one a vise, and small drill. Clamp wire with vise, and clamp other end with drill chuck. Slowly spin drill while pulling wire, it doesn't take much. Perfectly straight wire.
@@AndreasSpiess no harley necessary lol. Found your video looking for "folded dipole" antennas on the 440 mhz, there not much out there. Going to try building an array of 4.
very informative episode! now we want to see a comparison of your DIY-WiFi antenna vs. the standard delivered with a WiFi router vs. a PCB based YAGI as presented e.g. in IMSAI guy channel 😊
I would have liked to see in more detail how you attached the driven element to the center conductor of the SMA. I did not follow how the threaded pieces from 3D print helps. I thought maybe you were going to cut threads into the driven element.
If I remember you see it in one of the shots. It stands on the isolation and has the inner conductor and the vertical element inside. Ans solder to keep everything together. The threads are not used.
Another excellent video How are you soldering the Aluminium rod? i.e. what solder + flux combination? I personally prefer a J-Pole over the ground plane, but currently use a Flower-pot antenna for 2 & .7m which I guess is a bit more like the ground plane in its operation
Welding aluminum seems to be a problem. I did not know, I just did it with standard solder and a lot of heat. Maybe it worked because the rods are not pure aluminum. The j-Pole for 868 was not easy to build without a VNA because of the small dimensions. It is probably ok for lower frequencies.
I was not aware of problems, it just worked ;-) These rods are not only Al. This might help. And, as described in the paper, a lot of heat which was produced by the gas heater.
That is very interesting for me, thanks for the video Andreas. With such a knowledge and equipment in your hand, i would like to see a comparison video between on the shelf wifi antennas vs ground plane. May be a Yagi antenna also. Anyway thanks for the great video.
Soldering was hard and with lots of heat. In the meantime, I changed to different rods. They have a yellowish color and are easy solderable. I added a link in the description
When we look at how the antenna radiates using the four radials for a ground plane, I assume this is for transmitting only and would have no effect on reception? Lowering the SWR gets the antenna to the right length (or the other way around). Does the length of the antenna help to eliminate other signals during reception?
Schönes Video Andreas. Ich hatte meine GP auch etwas durch den Winkel der Radiale getuned. Man muss das wirklich am besten am Aufstellort machen, wenn man Perfektionist ist. Gut dass du so viel Balkongeländer für Antennen hast. Sicher ziehen deine Nachbarn schon Aluhüte auf 🤡. Übrigens sollte man PTFE nicht zu lange zu heiss machen, da sonst giftige Gase entstehen. Gibt für Pfannen wie auch für Isolatoren. En schöne....
Indeed interesting. I'm looking forward to see more antenna related videos. What about an array of antenna's. I remember the days of the 27MHz antenna's quite well... what an interesting time it was...
I missed/skipped a few videos, is that pipe containing a RPI for tracking balloons? If so, brilliant idea, was about to order a weatherproof case to mount mine in it, to pvrevent huge cable loss.
Perfect as usual.
This guy gives better explanations in fifteen minutes than others in one hour!
Thank you. That is my ambition. I need more time to create the video, but you save it while watching...
Every time you post a video like this I think “There’s no way he can do that topic justice in less than an hour. And then you do it! This was great!
Thank you. You are right, it is not easy to create short videos...
@@AndreasSpiess Short and precisely to the point. You are focused and provide good material without all the ridiculous flashy screens and horrible music that a lot of other tubers do! Thank you for keeping your videos interesting and informational. If I want "entertainment", I can watch a movie. ;)
Thanks Andreas, every time I watch one of these, I stand on the edge of diving in to this radio stuff, as I feel well informed by your videos.... thanks ....
It is well worth to dive into this topic (says an addicted ;-)
Awesome as usual, amazing that you manage to find so many good topics and present them so well.
Thank you! I just present what is interesting for me, too...
Love ALL YOUR WORK badass swiss oldman! thanks for the video!
I believe that this may be accepted as a generally favourable review :)
@Michael: Thank you!
@Richard: Thank you for your translation. It is really slang for me ;-)
@@AndreasSpiess Desperately trying to prove, at the tender age of 64, that I'm still 'douwn ther wiv the yoof'. Not sure even Google Translate can deal with this :)
@Richard: This one was not easy. But I think I understood: www.macmillandictionary.com/buzzword/entries/youth-speak.html
@@AndreasSpiess I'm not sure that 'down there with the youth' - correcting the spelling is that helpful.
At the risk of going further down this rabbit hole ...... it's 'street cred' (Social recognition with/by young people who spend time congregating on the streets).
It's a self mocking attitude based on the impossibility of ever achieving this status. a.k.a. 'bollocks' :)
Love your videos. Impressed that Al welding rods can be solderable 5:33, and 6:30 thru 6:45. I had "stuck" thinking because Al is normally not solderable, but of course the rods are alloyed!
You are right. It probably helped that the rods are not completely Al. It needed a lot of heat, thou.
The 0.95 velocity factor varies with wire diameter as a proportion of wavelength. In addition the effective length of a wire is also increased by the ‘end effect’ - it behaves as if the wire end has a capacitor on it - also proportional to frequency. This is why we always start long and snip down to resonance / minimum SWR.
You are right. For me the VF is just an indicator for somebody without an instrument.
Great video as always Andreas! I got into radiosonde tracking with your last video and now have my own station. My nanoVNA is arriving tomorrow and I already designed and 3D printed a ground plane antenna hub for easy mounting.
I will be also getting my radio amateur certification very soon!
Thanks for the inspiration!
Great to read that you get you call sign :-)
Loved the video. You spoke of Teflon. I thought I'd share info about how it was discovered in 1938. "Plunkett’s first assignment at DuPont was researching new chlorofluorocarbon refrigerants-then seen as great advances over earlier refrigerants like sulfur dioxide and ammonia, which regularly poisoned food-industry workers and people in their homes. Plunkett had produced a hundred pounds of tetrafluoroethylene gas (TFE) and stored it in small cylinders at dry-ice temperatures before chlorinating it. When he and his helper prepared a cylinder for use, none of the gas came out-yet the cylinder weighed the same as before. They opened it and found a white powder, which Plunkett had the presence of mind to characterize for properties other than refrigeration potential. He found the substance to be heat resistant and chemically inert, and to have very low surface friction so that most other substances would not adhere to it. Plunkett realized that against the predictions of polymer science of the day, TFE had polymerized to produce this substance-later named Teflon-with such potentially useful characteristics." From ScienceHistory.org
Thank you for the historical update. We see, also our fathers played with technology...
A video about how to "ground" all these outdoor devices, to be safe of lightings, would interesting.
I just pay attention that something else is higher up ;-)
If you have a lightning rod use that. Else make one. A good ground rod is at least 50cm deep in the ground, you can also put some coal into the hole for better connection.
@@AndreasSpiess 'something else' should be conducting and capable of withstanding large currents, not say clouds or birds ;ø)
- caveat is that antennas should not be mounted near conductors or other metals... Catch-22
From my earlier days as an electrician, I can say that standing antenna pipes on the roof in Germany have to be grounded with 16 mm² copper wire.
You can ground antenna with calculated aircoil on antenna.
Excellent presentation for Beginners and old timers.❤
Thank you!
Excellent video introducing simple antenna construction.
It's a long way from long-wire for HF, thrown over a tree branch.
With the arrival of the nanoVNA I discover more and more videos about wire antennas. End fed, for example...
Andreas, 4:30 minutes into your video you raised the subject of "Velocity Factor = 0.95" being the reason that in practice antennas are 5% shorter.
Throughout my 35 years of experience, I believed an antenna was 5% shorter, due to what is known as the "end effect", while "velocity factor" was the propagation speed through a medium (such as a coaxial cable). From memory, RG58/RG8/RG213 has a velocity factor of 0.66, while a balanced transmission line such as 300 ohm ribbon around 0.95, while obviously, the "velocity factor" of an electromagnetic signal through space is 1.0.
.
So I was curious as to was I wrong for all those years to believe it to be the "end effect" and not "velocity factor" which required an antenna to be 5% shorter?
www.electronics-notes.com/articles/antennas-propagation/dipole-antenna/length-calculations-equation-formula.php
I never heard the term "end effect". But you find the velocity factor everywhere, not only in cables. Cables are much slower, though.
Yes I believe you have been correct for 35 years. I think the author of the web page has taken a bit of liberty with the term velocity factor. To get a lower phase velocity you need some capacitance to ground. Yes that does exist in this monopole antenna (radiator to ground plane) but that’s not a function of the wire but rather the antenna configuration.
Thanks for the overview. Some details are missing about actually joining the material and specific parts used.
So for some clarity:
The flanged SMA connector used as a base for the antenna has holes of roughly 2.6mm I.D. This would pair well with M2.5 screws and nuts.
The flange plate of the SMA connector is about 1.6mm thick, so a threaded length on the screws of about 4mm should allow for space to lock the terminal with a nut.
It is also unclear what size knurled copper insert is used to connect the vertical radiating element.
As a guess I would say they are M3*5*4. It's ambiguous how this is joined to the coaxial cable tip of the SMA flange connector. Another guess: it is sat on top the teflon shield and solder is pooled into the insert with a gas torch. Here's a video specifically about soldering an element to an SMA connector: ua-cam.com/video/34Ii-C8kYRI/v-deo.html
More detailed assembly info would be appreciated!
Your assumptions concerning the dimensions are correct. My SMA connectors are different to the ones used by Andrew. I needed a "pipe" in-between. If you find the ones Andrew used it is easier.
Nice simple DIY solution. Just an observation, I noticed your velocity factor was still set to 0.95, which is generic for copper, using aluminium velocity factor, the result would have been a lot closer to the actual length.
You are right. My measurements indicate a slightly lower VF. I did not investigate into the VF of my rods. They seem to be a mixture of several metals...
Makes sense but I never thought of a bare wire having a velocity factor. Is there a way to measure this? Or is it more accurate just to Google this?
And a bare copper wire will corrode outdoors.. Does surface corrosion matter, or is that only a problem for connectors? (I recall someone saying even cheap 8266 chips have gold-plating for the onboard meandering-F aerial because the copper corrodes)
@@dave_dennis Measuring is simply the reverse of stipulating it in the first place once the wire is cut to the required length using the calculations the velocity factor is derived from the new measurement. I use to do this a lot as a lab supervisor. Obviously the measurements have a certain amount of precision based on the measuring standard used, but it is close. Many calculator do not provide a reverse measurement so it has to be done but hand. Fortunately is is simple algebra.
Hi Andreas, thanks so much for your reply. I hope to complete my new antenna soon. All the best....
Soldering aluminium welding rod is not that easy for most makers. I mostly use standard steel welding rods.
For my LoRa gateway I selected the M0UKD J-Pole. With the J-Pole in a piece of plastic tube, the gateway does not attract any attention and is more resistant to birds trying to land on it.
As a tip for anyone building one: Bend 3 or 4 wires, leaving the ends too long as soon as you start building. As soon as you place the antenna in the plastic tube, you will see a change in the frequency due to the fact that waves travel slower through the plastic than through the air. Either calculate the difference in length by hand or change the velocity factor in the J-Pole calculator and then cut the second antenna to the calculated length, add a few mm so you can cut/grind/file the antenna to the correct length during the tuning process.
1. How do these welding rods behave outdoors? Do they rust?
2. I built a J-pole for 868. But I found the position of the cable is not easy determine without a VNA for such small antennas.
@@AndreasSpiess I did not yet see any rust on welding rods I used - they are a blend of metals with a coating that seems to prevent rust.
An yes - as you also mentioned in the video, you do need a VNA for the J-Pole. It takes a few tries to get the correct feed point but not an impossible task to do.
I made multiple GP, J-Pole and coaxial antennas. A GP is surely the easiest and with correct measurements you can get around without a VNA. The coaxial antenna is a nightmare: at 868 MHz, 0.5mm measurement error results in a 5 MHz offset.
@@AndreasSpiess If they're the rods I'm thinking of (for gas and tig welding low carbon steel) they're just copper washed low-medium carbon steel. Look for bronze "brazing rods" for corossion resistance.
Thank you for the info. I will look if I get such material.
Very good declared. I remember the hours of learning military radio things and later the amateur radio. Hours of fun while experimenting and the guys who teached us all these things had a more funny way to teach this.
I also think building antennas is rewarding...
I will say for that frequency, a Dipole antenna construction will be more easier. You don't need to buy anything at all.. Take a piece of RG58 separate the bread and core in different direction by stripping the outer insulation. Your dipole should be ready.
And more interestingly the VNA is definitely a good tool here, but for general audience a simple Impedance bridge or a reflection loss bridge will also work fabulously.
But this video really helps those kids putting the same rubber ducky antenna on NRF24, LORA, Zigbee, FM Tx, Toy cars, RC remotes and expecting a better range.
The idea of resonance is what matters and that's beautifully said in the video.
A dipole for sure also works. But it has a higher impedance. Because I wanted to show a perfect match, a ground plane was a better choice for me. It is also quite easy to build for those high frequencies.
This type of dipole will work but you need a choke on the outer shield if you are running any appreciable power or want a decent radiation pattern.
@@joelong9260 For HAM operators, 10 turns of coaxial on a 4-inch PVC pipe works, for non-licensed ISM band the Tx power is damn low, it may not matter. But to make it 50 Ohms, a little bit inverted vee configuration can be done to accommodate impedance. And the perfect isotropic radiation pattern may not be possible with a dipole as we know in general. In that case, a vertical 1/4 wave is good enough.
I was doing my wireless communication lab classes today and your video helped me understand a lot about these VNAs
Glad the video was helpful!
@@AndreasSpiess I also watched that other video about vna. UA-cam algorithm sure knows what you want to see nowadays
Hello Andreas great video as always! I've built the same antenna and tunned it according to your previous videos it worked very well!
Thank you for sharing your experience.
Perfect. I just got a Flight Aware dongle to track aircraft, but I wanted to build my own antenna. This is just what I needed. Thanks.
Enjoy!
Thank you for an excellent video! I learned more from your 14min Antenna video than I have from reading the ARRL antenna book! I am a beginner who just got my General amateur license and your explanations are simple and understandable! BTW, I have a lifelong friend in Zurich so I enjoy listening to you!
Glad it was helpful! The handbook is probably not made for a beginner and this channel is not made for HAM operators. So I have to explain also the basics...
Funny, after seeing your videos on the weather balloons, I thought I would need a video on building a suitable antenna for the rtlsdr stick. But I managed to do it by myself. I used the nano vna for tuning as well. What came out is the exact same antenna you built! It's working for a coupler of weeks now.
It is the most basic design. This is why I chose it (and you probably too)
@@AndreasSpiess in the video I can hardly see the gain. Do I see right, that it's over 30!? That's a lot and would explain the 200km. I have around 20dB and 80km. How did you do that?
I used a SO239 plug as a base. Didn't know the 100mhz limit. I used messing pipes. And I included the cable in the measurements.
ua-cam.com/video/dNHS_3Qjo4c/v-deo.html
It is probably not a limit. Did you watch ma VNA video about reference planes? Might be interesting.
This channel is precious! Wonderful! I'm in love with it... Mr. Spiess, you have my AXE!!!
Thank you!
I would love to see videos like this for other antenna designs, especially directional ones.
Most viewers are not HAM operators and therefor not legally allowed to use directional antennas. So you have to go to another channel for this info :-(
Nice content. It explains a lot about practical implementation.
Thanks✌🎇
Cheers ✨
You are welcome!
I love your presentations. Thanks!
You are welcome!
I used to make 2m and 70cm YAGI antennas for HAM radio contesting. I never thought of using a ground plane antenna for wifi I will give it a go. 73.
They are quite neat compared with one for 2m...
Another great presentation, thank you. I hope to get into building my own antennas this year with the help from your videos. And another thanks for finding that VNA meter for us.
You are welcome! And have fun with building antennas.
The J-pole performs very well on 868 MHz if you add a sleeve Balun /Bazooka balun (1:1) around the feed line to make its input balanced. Forget Ferrite chokes and coax loops, they are too lossy at 868 MHz. I simply soldered a 1/4 wave O.D. 4mm brass tube to the cable end of a SMA connector, so the coax emerges at the other end by a few mm past the end of the tube at the feed point. It has to be a coax with an outer insulator, not a naked semi rigid coax like you use. The bottom of the J, with the feedpoint, together with the end of the brass tube, can then be encased in a cylinder of Epoxy to make sleek straight vertical antenna assembly 3/4+1/4 = 1 Lambda long only. It is sturdy enough to be free standing, or will fit inside an only 10mm I.D. tube.
Thank you for the precise description!
@@AndreasSpiess What I intended to be a simple tip, turned into a technical build guide! It often happens when trying to be accurate.
I think one thing that would be useful is a proper tutorial on using your minivna to properly add an antenna to cheap RF modules. I've seen lots of projects were people have used a premade module that doesn't have an antenna and thought that just sticking a trace with the right length on their board is enough. Now the tools to do it properly are within makers reach we should really be trying to do it properly.
I made a video on how to use a VNA. For the topic you proposed, my video would be very short: Do not do it because most people have no idea what they do. It needs to re-engineer the design to find out which impedance is where you cut and then to match a newly build antenna. I go with boards with a connector where I can assume it is around 50 ohms. But still, I have to hope they copied the reference design of the manufacturer...
Who are you, Mr. Spiess, so wise in the ways of science?! You are putting my generation in an invaluable position to recieve information. The hobby still lives, and we intend to continue to contribute to its beauty. Now I wonder if an amateur radio license will impress the ladies or not...🤓🤔
It will for sure not impress ladies ;-) But I am married to a wonderful woman. So there is hope.
Thank you Andreas. Your videos are very informative and very practical. Actual measurements and builds not just theory.
Thank you for your nice words!
Taught how to get straight wire from a roll 40 years ago - just wrap one end around something strong and grab the other with pliers and pull - the wire stretches slightly but you get a beautifully straight section of wire - just cut off ends
Did use tinned copper wire for interconnects on electronics so not sure how it will work on larger diameter
It worked when we used my Harley instead of pliers ;-)
Your videos are always fantastic and informative. this is EXACTLYWHY I FOLLOW YOU!!!! this is perfect for my current project
Thank you!
Thank you Andreas. I was going to spend $$$ on a formal RAK antenna for a Lora Gateway at our hacker-space. Now I can use the money to purchase a VNA analyzer and build my own!
The RAK antenna is also ok... But the NanoVNA can be used for many other antennas...
Very well done. I am waiting for my 3 GHz nanoVNA on the slow boat from China. I have the 900 MHz version, but LoRa here is over 900 MHz and I do lots of home automation with wifi and zwave so this video and the 3 GHz nanoVNA will be very useful (new sites for M0UKD and MMANA-GAL appreciated!). Thanks, glad I am a patron. Doug, N8VY 73
You are welcome. These nanoVNAs are really color the money. And with simulation we are well equipped for antenna building...
I had similar results to your ugly antenna using tests for Aircraft tracking. The signal plot graph was so good. i just pulled the core out of coax cable and used it as elements.
Cool!
Jesus! It just saved my time! Thankyou sir!
You are welcome! That is the goal of this channel ;-)
Excellent channel. full details explained !
Glad you found the explanations useful!
Nice. Technical and Insightful video!
I remember once trying to build an aluminium foil antennae for boosting WiFi signal and ended up with nothing. Inspiration was some prank DIY video :/
Cantenna? We used to scout for public hotspots with a diy antenna and a windoes program called netstumbler.
@@gbowne1 Yep, crazy! That's supercool.
Cantennas are cool for WiFi, but probably too big for 433MHz...
You are cristal clear for such a complicated topic! Thx so much. As you seem to make everything easy, i probably experiment with Lora sms backup mesh.
Thank you. All things are easy if you know how ;-)
Andreas, I like all your videos a lot, thank you much for creating good content! One remark: @12:28 you say "it [the gain] multiplies the power output of your device by a factor of 3". I guess you should re-state that :) Otherwise, one may have an impression they would get 3W from a 1W emitted from their TX device.
You are welcome. They get the equivalent of 3 W emitted to the air. I hope this was clear for most. At least nobody asked so far ;-)
@@AndreasSpiess OK, agreed - with the important note: the RF level in a small spatial angle that is the same as if from an isotropic antenna fed with 3 watts of RF power. Obviously, in other directions, it is way less than the RF level obtained from such an isotropic antenna (for example, as you pointed out in your video, for the vertical direction - i.e. straight up from the antenna).
Very good vid Andreas!
Something to try, when putting heat shrink or something else over the radiator element, even if an insulator, it affects the s-parameters of the antenna. So adding conformal coating likely will change the tune of the antenna. If I remember correctly adding heat shrink to the antenna radiator moves the 50 ohm point down in freq. And when tuning the antenna on a VNA with a coax I would highly recommend a ferrite beaded coax to prevent the coax from becoming a radiator. I was working on an antenna that I had tuned nicely and one of my engineers noted the lack of a beaded coax and I installed one and it made a huge difference in my antenna design. It was a small 750 MHz ground plane very similar to what you have designed there for weather balloon frequencies.
You are right: Adding plastic changes the response of the antenna. I would not do conformal coating on the radiator. I used Aluminum because of that. I only would cover the connector.
Most people suggest using ferrites for (stronger) transmitters to protect the equipment. The cable should not radiate too much if the antenna is 50 ohms. But maybe I have to try it with a LoRa ground plane...
@@AndreasSpiess I was on a Agilent N5230A PNA and was spot on 50 ohms and adding the ferrite beaded coax really changed it away from 50 ohms for the desired frequency, my PhD RF Engineer showed me how much the coax was radiating. Really surprised me. I didn't have any idea. But touching the coax almost anywhere on it had a noticeable effect on the VNA.
Try having it on the VNA, and handle the coax and see how much it changes.
A comment one of my engineers made is a 50 ohm resistor is perfectly matched, it just doesn't radiate, but on the VNA is looks perfectly matched.
We did a LOT of antenna testing on our Satimo Starlab. I did test this antenna (very similar to yours, just smaller for 750 MHz) and it was a beautiful radiation pattern. Those ground planes are very nice omnidirectional antennas.
I've purchased the parts to build an outdoor 1/4 wave antenna for LoRa per your video and even figured out how to mount it on my tile roof which has a great view of my city (I live higher up in the foothills). However, at minute 12:18. your video suggests maximum gain near the ground plane. How does this antenna perform looking down into the valley from my roof for covering remote nodes in the city? Will it cover the valley, or is coverage limited to the ground plane and above?
I've learned so much watching your videos - thanks Andreas!!!
It will work, no worry. I do not know why they do not include the lower part in the drawing.
now I feel that I should taste in the adventurous world of antenna crafting and check some weather balloon signal...:) thanks for the video!
Have fun!
MMANA-GAL falling from the sky! I’ve used that program in undergrad rf classes, it is quite an amazing freeware program!
True!
Great explanation, as always (and nice Harley)
Thank you. Now we just need a little summer...
Excellent presentation and and I finally understood the difference between PL-259 and SO-239 !!
It is still not obvious why they used different numbers...
@@AndreasSpiess I played with CB radios in the late 80s and remembered PL-259 but SO-239 always threw me, LOL!
@@AndreasSpiess BTW, have you heard of a sleeved monopole antenna? I was reminded of it last night while I had a UHF magnet mount antenna connected to the NanoVNA. The SWR was about 1.5 but if I carefully wrapped my hand around the driven element without touching it, I could get the SWR down to REALLY low and it was broad and flat which is ideal for GMRS. Here is a video about using it for WiFi. I am trying to send WiFi through about a meter or two of dirt from inside our buried polyethylene cistern so we can monitor the water level (using an ESP8266) from inside the house.
ua-cam.com/video/78ECVt7OHl8/v-deo.html
Thanks for the link. I never tried one. But maybe I have to build one...
I may try one of these to improve the range and reliability of my garage door opener. I think it is in the 433 MHz range. The opener just uses about a 6 inch (15 cm) piece of wire. However, the main door is steel and I think that reduces the signal strength. If I build an external antenna, I can mount is where the door will not block the signal.
The frequency usually is marked on the devices. If not, maybe you watch my videos about 433MHz hacking
Really nice tutorial on building a ground plane antenna. Thanks Andreas - VK3TWC / Trevor
You are welcome! 73 de HB9BLA
One of the best channels on youtube.
Thank you!
Wow. This was super interesting for an amateur Maker. I'd love to see you do similar videos about different Antenna designs.
Thank you. This channel is more about electronics with some extensions to RF and antennas. So do not expect too much in this topic :-(
I encourage you to seek out other channels to find more about antenna designs. There are many good channels that will help. Be warned... Pure antenna design is *very* mathematical in nature! I would need advanced training in calculus to understand it. Instead, I use ideas from others and use the tools available to me, such as MMANA-GAL. And, of course, experimentation. I made one antenna from copper foil tape and laminated it with plastic. It works quite well!
You know exactly what I am looking for , this is very helpful , thanks a lot
Glad it was helpful!
Very practical and useful video. To me, RF always looks like a black magic and your video definitely defies such thinking.
RF for sure is not the easiest topic. This is why it is on this channel ;-)
Ausgezeichnet! Grüße aus Australien.
Subscribed. 👍
Welcome aboard the channel! Und vielen Dank.
Andreas - you'll retire in ~15 years, but engineering students will keep learning from your videos.
Thank you! I will "officially" retire next year ;-)
Your videos are amazing! I'm working on a radar sensor for motorcycle's detection and your work is going to be very useful
@Peter Mortensen I don't know :( because I just joined the project, besides being very excited about it, I don't know many details
@Peter Mortensen 76 to 81 GHz =)
Thank you so much for this video! You are, as usual, so clear!
You are so welcome!
Wow, this makes me remember my years at University. Cool project!
Thank you!
Very good video! Appreciate the quality of the info.
Glad it was helpful!
Great video as always! I think the calculator included the cable velocity factor (
I am not sure. The reference plane of an antenna should be its connector.
The velocity factor in the calculator is for the bare wire or rod in free space used to make the antenna. 95% is reasonable for most wire antennas.
So the velocity factor is not for the cable but for the antenna material itself?
@@judhi In this case for the calculator that Andreas used it was for the antenna material. Coaxial cables also have a velocity factor to consider , like RG58 is around 65% i think if remember correctly. For the test with VNA Andreas connected directly to the SMA connector on the VNA, that was his reference plane. You can however calibrate the VNA reference plane to the end of a coax if you need to. There are a few videos on the subject on UA-cam.
I am just starting with 'telecom stuff' and trying different antenna designs for LoRa.
I got some "Autogen-Schweissdraht CFH verkupfert Ø 1,5x333 mm 15er Pack" which seems to work quite well: it is very stiff copper plated steel rods and can be bent into shape (you can find that stuff at Hornbach for example) and solders quite well. As I don't have a Harley that looked like a good option to get stiff wires 😃
I also use these "Autogen-Schweissdrähte". They are perfect for short antennas.
Thank you for this! I have been wanting to do this so badly
So you can start right now...
Thank you for the straight forward and informative video on antennas!
You are welcome!
Straightening copper wires:
Put one side of the wire in a bench wise, the other side in a (cordless)drill. Twist the wire with the drill while pulling slightly. If you pull to hard or twist too much, you will end up sitting on the floor ;)
I never tried but was under the impression one merely needs to pull hard enough to make the copper yield (permanently stretch) slightly.
You are right. Twisting and stretching work.
Excellent work Andreas 🏴👍 completely relevant to my work 😇
Thank you. And a happy 2021 to you and your family
I have built and bought many antennas for 868MHz LoRa. But my best performing one by far is a hastily built simple wire antenna. I have tried to replicate it with no luck and I have no idea why it performs so well. It is wrapped up with glue lined heatshrink, so I can't/don't want to dissect it so I could figure out its magic!
Maybe it was full moon when you built it ;-)
Andreas, this was a thoughtful and well-produced explanation. But you didn't address two issues with the J-pole at the end: (1) very high SWR, and (2) it is outperformed at low elevation by the ground plane, despite having similar theoretical gain. Many people believe a J-pole will outperform a ground plane for land-mobile use. It is rarely true!
1. The SWR can be tuned with the position of the coax. Mine was 1:1.05
2. I thought I showed the two patterns and mentioned this fact. But after the summary. Only for the ones who stick till the end ;-)
Interesting, short and practical ... Thank you !
You are welcome!
As always meine Herr, usefull and interesting video's with the cool swiss accent 😎
Thank you!
Well, adding any coating to the antenna will change the resonant frequency. Mainly capacitive.
You are right. I would not coat the rods. This is why I chose aluminum.
Eine Frage : Oft wäre es besser, wenn Antennen ein kurzes Anschlusskabel (z.B. 1 Meter) hätten, damit man sie nicht direkt am Gerät anschliessen muss und besser positionieren kann..
Ein starres Koaxialkabel ist dafür ja weniger geeignet, das Kabel sollte flexibel sein.
Welchen Kabeltyp würdest Du dafür empfehlen ?
Danke und viele Grüsse aus der Nachbarschaft, hier kommt aus Richtung Schweiz gerade wieder der blaue Himmel.
Du kannst ein Pigtail mit RG316 nehmen. Die kriegst du bei AliExpress vorkonfiguriert. Nicht zu lang. Die Frequenz ist hoch ;-)
Hallo Andreas, vielen Dank für die schnelle Antwort !
Ich werde ich bei Aliexpress nachsehen.
Was für ein Kabel würdest Du nehmen, wenn man es mit SMA-Konnektoren selbst bauen will ?
P.S.: Respekt, du weisst sogar, dass Kabel mit male/Female-Steckern die Nummer RG316 haben ! Wieder was dazugelernt.
Die Bestellung bei Aliexpress ist schon raus.
RG316 ist der Kabeltyp
At 11:10 we get a glimpse of the sma connectors.
Is it okay to let them sit in the rain, or do you take countermeasures against water, other than sealing the connector to the case?
So far I had no problems with them. They are also not too expensive if they have to be replaced after a few years.
Wow! Respect. When you know your sh**, you make it sound simple!
I agree, it is not always simple. But you can learn it ;-)
Great video! A couple of questions for later videos perhaps?
1) Can you explain the effect of different thickness of material on the antenna? I believe a thinner diameter generally has a narrower bandwidth, meaning it can help "focus" on a signal and reflect interference, but I've seen conflicting info.
2) Any hints as to better antenna designs for receive only antennas? Does it make sense to use a different design if radiating is less needed?
3) Copper versus Aluminium, does it really make much difference for our typical usages?
This is not an antenna channel. I only covered the basics which is interesting for many viewers who build LoRa or other devices. But you find a lot of channels dealing with antennas and antenna design.
The antenna for receiving usually is the same as for transmitting. It is less critical because a bad antenna cannot hurt your device.
Thicker wires usually lead to a broader bandwidth
Aluminum is very similar to copper. The (electrical) difference is small
Not a RF expert, but thicker wires can slightly alter your impedance (higher capacitance/lower inductance), so keep that in mind
Learned so much from this video. thank you (subbed)
Welcome aboard the channel!
just what I was looking for! Next video: how to make the antennas smaller, and embeddable? What is the mystery of 3D antennas? How much worse are circuit printed antennas compared to the ipex type (e.g. in esp32 versions)? Will consider Patreon, great content!
The size of an antenna is important for its performance. So make it smaller does only make sense if you have no space because its performance will not be good.
@@AndreasSpiess yes, that's the reality of embedded devices, IoT and wearables, I thought that's what the channel is all about :)
Best way to straighten 12 to 16 gauge wire, one a vise, and small drill. Clamp wire with vise, and clamp other end with drill chuck. Slowly spin drill while pulling wire, it doesn't take much. Perfectly straight wire.
Thank you for your tip! So you do not have to buy a Harley ;-)
@@AndreasSpiess no harley necessary lol. Found your video looking for "folded dipole" antennas on the 440 mhz, there not much out there. Going to try building an array of 4.
Very well done and supremely interesting.🇨🇮👍
Thank you!
very informative episode! now we want to see a comparison of your DIY-WiFi antenna vs. the standard delivered with a WiFi router vs. a PCB based YAGI as presented e.g. in IMSAI guy channel 😊
This is not an antenna channel. Maybe somebody else does it?
Great info. Cheers from Austin!
Thanks for watching!
"in my youth" ... the CB antenna is still mounted on my sheds rooth. But there is not so much ongoing in the air. 25 years ago we had more guys "on".
Same on 2m and 70cm...
SDR killed the hobby.
@@piconano If anything, they gave it a new breath of life.
I would have liked to see in more detail how you attached the driven element to the center conductor of the SMA. I did not follow how the threaded pieces from 3D print helps.
I thought maybe you were going to cut threads into the driven element.
If I remember you see it in one of the shots. It stands on the isolation and has the inner conductor and the vertical element inside. Ans solder to keep everything together. The threads are not used.
Another excellent video
How are you soldering the Aluminium rod? i.e. what solder + flux combination?
I personally prefer a J-Pole over the ground plane, but currently use a Flower-pot antenna for 2 & .7m which I guess is a bit more like the ground plane in its operation
Welding aluminum seems to be a problem. I did not know, I just did it with standard solder and a lot of heat. Maybe it worked because the rods are not pure aluminum.
The j-Pole for 868 was not easy to build without a VNA because of the small dimensions. It is probably ok for lower frequencies.
ah the trivial soldering of aluminum to tinned connectors
Definitely not as easy as it looks, I really struggled, in the end I used oil as a form of flux, which helped, but it was not easy!
@@JohnBaxendale , haha, yes I'm surprised Andreas did not dedicated some explanation to it. ;-)
for those who care: superiorflux.com/papers/TWJ.May.2018.Tech.Solder.Al.pdf
I was not aware of problems, it just worked ;-) These rods are not only Al. This might help. And, as described in the paper, a lot of heat which was produced by the gas heater.
Thanks for great content again ... all best from Croatia
You are welcome!
Great video, very informative. Thank you 🙏
Glad it was helpful!
That is very interesting for me, thanks for the video Andreas. With such a knowledge and equipment in your hand, i would like to see a comparison video between on the shelf wifi antennas vs ground plane. May be a Yagi antenna also. Anyway thanks for the great video.
I did some tests with directional antennas... Nothing planned in the near future.
Greetings: It is not all about VSWR as presented here. Antenna manufacture is about ERP with VSWR as compatibility. Thx 4 the share.
I agree. However, a proper match is maybe cheaper than a lot of ERP ;-)
@AndreasSpiess Greetings: Indeed, as I noted.
Great video, thank you! How Dow you solder to the aluminum radials? I don’t know what type of solder connects and conducts with aluminum.
Soldering was hard and with lots of heat. In the meantime, I changed to different rods. They have a yellowish color and are easy solderable. I added a link in the description
When we look at how the antenna radiates using the four radials for a ground plane, I assume this is for transmitting only and would have no effect on reception? Lowering the SWR gets the antenna to the right length (or the other way around). Does the length of the antenna help to eliminate other signals during reception?
The patterns apply for reception, too. Amid an antenna behaves like a mild filter.
Schönes Video Andreas. Ich hatte meine GP auch etwas durch den Winkel der Radiale getuned. Man muss das wirklich am besten am Aufstellort machen, wenn man Perfektionist ist. Gut dass du so viel Balkongeländer für Antennen hast. Sicher ziehen deine Nachbarn schon Aluhüte auf 🤡. Übrigens sollte man PTFE nicht zu lange zu heiss machen, da sonst giftige Gase entstehen. Gibt für Pfannen wie auch für Isolatoren. En schöne....
Mit viel Hitze ging es relativ schnell... und vom Nachbar habe ich (bis jetzt) noch nichts gehört. Hoffentlich bleibts dabei...
Great video! Would either design benefit from a Balun?
Excellent information 👍
Glad you think so!
Indeed interesting. I'm looking forward to see more antenna related videos. What about an array of antenna's. I remember the days of the 27MHz antenna's quite well... what an interesting time it was...
This is not a antenna channel. So I only cover the basics :-(
@@AndreasSpiess for the basics you're doing quite well ;-)
Thanks for sharing this knowledge. 🍻
You are welcome!
Oh, you see this guy, this Swiss guy! Number 1 teacher guy!
Thank you!
5:04 Hahaha Andreas you're just so cool, I'll have to check video 212 :-)
Hope you did it already ;-)
@@AndreasSpiess Yes, and it was great hahaha! RF and Harley-Davidson in the same video, what more could I ask for hahahah!
I missed/skipped a few videos, is that pipe containing a RPI for tracking balloons? If so, brilliant idea, was about to order a weatherproof case to mount mine in it, to pvrevent huge cable loss.
One contains the LoRa gateway and one the balloon tracker.