019 Inverted-F PCB Antenna: How to tune PCB circuits using a NanoVNA
Переглядів 37,748
2 роки томуPCB antennas are pretty common because they are small and cheap. Can we use them for our projects? How do they work? And: How can we test and tune them? Let’s look at an antenna for the 868-915MHz ISM bands. As a side-effect, you will learn how to measure impedances directly on a PCB.
Links:
LiteVNA (Currently best "NanoVNA"): s.click.aliexpress.com/e/_ALJ8bh or amzn.to/3IE8cza
IFA explanation video: • Antenna-Theory.com Pre...
The links above usually are affiliate links that support the channel (no additional cost for you).
Github: www.github.com/sensorsiot
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 in the next 24 hours)
My Amazon.com shop: www.amazon.com/shop/andreassp...
For Banggood bit.ly/2jAQEf4
For AliExpress: bit.ly/2B0yTLL For Amazon.de: amzn.to/2r0ZCYI
For Amazon UK: amzn.to/2mxBaJf For ebay.com: ebay.to/2DuYXBp
/ spiessa
As an Amazon Associate, I earn from qualifying purchases
@greg4367 2 роки тому
Hi Andreas, In the future video you mention perhaps you could show how you measured the time delay in the coax pigtail. Thank you for another fun Sunday morning and regards from San Francisco.
@HB9BLA 2 роки тому
The coax had the 700psec I mentioned. In Video 001I showed how to measure it.
@andreavergani7414 2 роки тому
Both of your channels are pure gold. Great job and support
@HB9BLA 2 роки тому
Glad you like them! Thank you.
@jmr 2 роки тому
Great video. You confirmed some of my thoughts from a discussion I had about a similar device. I wish I had this video to point to back then.
@HB9BLA 2 роки тому
Next time you will have it ;-)
@LarryKapp1 2 роки тому
I always wondered how those pcb antennas worked - thanks for the info .
@HB9BLA 2 роки тому
Me too. This is why I took the opportunity…
@victorchorques4893 2 роки тому
Wow! Right to the point. I have a little experience on this and you summed up 6 months of learning in 10 minutes. Awesome video
@HB9BLA 2 роки тому
It took me also some time to learn ;-) Thank you!
@johnwest7993 Рік тому
Same here. A lot of RF knowledge has been boiled down into this short video and will save others a lot of time. As for me, I've always learned things the hard way. I'm good at that.
@johnwest7993 Рік тому
Excellent information Andres. Thank you. It may have been helpful to mention how to determine the new reference plane. That can of course be learned elsewhere, but this may have been a good place to mention it.
@HB9BLA Рік тому
I made a whole video on how to use the VNAs where this topic is covered.
@PortableRadio 2 роки тому
Thanks Andreas for another interesting video! 73 Stephan
@HB9BLA 2 роки тому
You are welcome!
@johnkelly7264 24 дні тому
This channel looks really interesting. Subbed here.
@ingmarm8858 2 роки тому
Nice video Andreas. I'm glad you specifically mentioned the need to perform matching in the final installation. Many people fluff about trying to create a nominally perfect antenna and matching network without considering or realising all their work is largely wasted in the real world due to external influences :-)
@HB9BLA 2 роки тому
This becomes quite obvious when you leave the ivory tower ;-)
@newsogn5148 Рік тому
Is this why we were not so concerned about the 50ohm transmission line? Because it was tuned end to end?
@PhG1961 2 роки тому
Waw, very interesting video and excellent explained !
@HB9BLA 2 роки тому
Glad you liked it!
@str8upkickyaindanuts289 2 роки тому
Thanks for the black magic lesson! It's starting to become understood as a technology rather than magical, I'll pick up a liteVNA for S-parameter measurements. I wasn't sure how to take these measurements and was relying on functional testing after trying my best to follow the barely understood rules. Thought I needed a $4k VNA to do these measurements, that's outstanding the liteVNA is so affordable. You help me so much it's ridiculous, thank you Sir!
@HB9BLA 2 роки тому
You are welcome. Video #001 is also interesting for VNA usage.
@ehvway Рік тому
No (Swiss) distortion in the signal sir! Received the message loud and clear! I love to learn from my (Swiss) teacher! School would have been a lot of fun if I had you as teacher!
@HB9BLA Рік тому
Thank you for your kind words!
@acestudioscouk-Ace-G0ACE 2 роки тому
This is a really well explained video, thanks. It revised some things I know and taught me some new facts too. I need to check your work on VNAs as there are so many versions available now and from good and dubious suppliers. I'll check to see if you have covered this topic, if not, one of your clear thinking videos on the subject of VNAs would be good.
@HB9BLA 2 роки тому
The LiteVNA currently is the best version. You should find a link in the video description. #001 should give you a good overview on a VNA.
@acestudioscouk-Ace-G0ACE 2 роки тому
@@HB9BLA Thanks Andreas, I'll check the first video and take it from there.
@GOODINET 8 місяців тому
Дякую. Це те що мені треба)
@HB9BLA 7 місяців тому
будь ласка
@MPYadav-cp6sy 4 місяці тому
Great sir
@HB9BLA 4 місяці тому
Thank you!
@SteveWrightNZ 2 роки тому
Strongly recommend Petes' Antenna Theory youtube vids - you can learn a huge amount by warping your brain around Petes' descriptions.
@HB9BLA 2 роки тому
Yes. The link to the IFA is for one of his videos.
@SteveWrightNZ 2 роки тому
@@HB9BLA Yes, I was agreeing with you ;)
@mickgibson370 2 роки тому
It is like the j-pole that I did over 30 years ago! I measure the coax with dummy load. Got it down to 1:1. Then resonator, got it down to 1:1. Then the pole, got it down to 1:1. At 147.18 MHz I was talking to other Hams that were 200 miles directly at 5 watts! The j-pole mounted would talk 146.60 - 147.35 MHz at 1:1 and all across the band it 1:1.5! The coax, resonator, and pole were linked.
@HB9BLA 2 роки тому
They are similar. Both have a resonator and a matching circuit. The j-pole, however, is lambda-half and not only a quarter as this one. So the matching is also different.
@Vanolli21 25 днів тому
Hi! It seems that you tested it without the RF source component. This way you tested the RF path and anthenna with the matching components. My question is: how to test it with the RF component populated? Because we don't know the its pin's impedance, so we need to match the impedance with the component populated. Thanks!
@NOW-IS 2 роки тому
Thanks for this informative video it is just what I was searching for! Is there a way to calibrate it directly to end of the coax-cable without using the E-Delay parameter? Isn't this the better approach? Or did i get something wrong?
@HB9BLA 2 роки тому
You need a calibration set for calibration. The sets I know have SMA connectors (or other connectors). If you want to attach a connector just for calibration you can do it.
@JonBlackmon 23 дні тому
Very good presentation! 73 de K5VA
@Ritzz45 7 місяців тому
In this example the antenna is matched and hence the pi network is left unpopulated. In an example where impedance matching is needed would you recommend measuring at the output of the transceiver including the transmission line up to the point of the pi network? Also, if using a balun (in the case of differential load impedance) would you measure after the balun and before the pi network? Many thanks
@HB9BLA 7 місяців тому
You have to measure where your interest is starting with the chip (usually you should get its impedance in the datasheet. The goal is, that, at this point, the impedance of the antenna plus network (including balun) should match the chip impedance.
@OxOOCOFFEE Рік тому
Great video!!! The only question I have is about E-Delay. Do you have a video about how to calculate/estimate delay value for any given cable? I like to do a few tests with IoT PCB antennas as you did.
@LaboussoleNano Рік тому
ukposts.info/have/v-deo/mnWBiZuHsJWT1oE.html You can find it here
@HB9BLA Рік тому
You have to try it out. I do not think it makes sense to calculate it because the distances are small
@harisan5135 Рік тому
@@HB9BLA What do you mean by try it out? What are you looking at while adjusting the delay? How do you confirm, the delay you added is the correct one?
@HB9BLA Рік тому
@@harisan5135 I showed the procedure in my VNA tutorial video.
@harisan5135 Рік тому
@@HB9BLA Thank you for your prompt response and for your great videos! I have already watched this video (if we are talking for the same video 001 @18:34) but to tell you the truth I didn't got it on the first pass. What you actually do is you add e-delay until the point on the Smith Chart, for open leads goes to zero. Is this enough? I'm new to the field so I'm looking to learn out of this. Would it be wrong to calibrate it with the pigtail flying leads open, then short them and calibrate it for short and finally solder a 50 ohm resistor on the ends and calibrate it for load?
@alexanderwagner9524 8 місяців тому
I use a NanoVNA for adjusting antenna length and at high frequencies like 868MHz I saw that holding the VNA in my hand makes a difference. Even touching it on different positions with just one finger, moves curves. If i touch the top side near to the SMA connector, its diffferent, to touching it on the far right side. This behavior makes it hard to trust measurements. I guess I should measure only when not holding it.
@HB9BLA 7 місяців тому
The measurement is always right. But you see, that handheld devices are less than optimal. I try to simulate a typical setup for my measurements and hope, it will be the optimum when I use the device.
@sofyanhardiyono9152 Рік тому
thank you for the video you shared, sorry I'm still learning, I'm confused by the impedance and vswr measurement method you are doing, in my understanding the antenna impedance is already parallel to the rf source impedance, because the process of measuring the antenna impedance match, can only be done in series with an rf source, where the position of the vswr meter is in the middle between the source and the antenna, please correct me if I'm wrong.
@sofyanhardiyono9152 Рік тому
Sorry, maybe I paid attention wrongly, after I looked at your video again, at 7:20, it turned out that the antenna was not connected to the rf source. Thank you, I'm still looking into what if the antenna and source mismatch is caused by the rf source that doesn't have a 50ohm impedance. and how to measure source impedance.
@HB9BLA Рік тому
Maybe you watch my video(s) on VNA and antenna tuning on this and my primary channel.
@sofyanhardiyono9152 Рік тому
@@HB9BLA thank you , will check your play list..
@mahudson3547 2 роки тому
Very interesting. VNA calibration must be vital. Question: Can you calibrate by applying 50 ohms, open and short at the end of the co-ax stub? What happens to the SWR if you connect the ground plane to the actual planet? Or is it too many wavelengths away to be significant...
@HB9BLA 2 роки тому
1, You could calibrate it also with a 50 ohms resistor. (open and short are anyway used to determine the delay). In video #001 I used the test PCB for that reason (which had U-FL connectors) 2. I would hope that the ground plane ( I assume "planet" is a typo and means plane) is already well connected to the reference plane.
@mahudson3547 2 роки тому
@@HB9BLA Planet was not a typo. I was an HF engineer and the planet was an essential part of the antenna.
@HB9BLA 2 роки тому
Aha. I have never heard of it :-( The inverted F is designed like that to get the 50 ohms matching. The plane is connected to the feed point of the strip line. He also placed quite a few vias from the top to the bottom ground plane. So I think this is what we can expect from this small part (the antenna has about the same dimension as the ground plane).
@matheokoning4456 Рік тому
As always a very good video and explanation. I do notice that I still have a lot to learn :-) Maybe you can answer this strange situation. I am playing a bit with one of those cheap fs1000a 433mhz transmitter. I wanted to improve the range a bit and soldered a 17.3cm antenna to it. But instead of a better range, I had no range at all. If I hold the antenna at the end until about the middle, the transmitter works agian. If I hold the antenna from the beginning to the middle the transmitter sends nothing again. I saw another person on the internet with the same problem but the question remained unanswered. Do you have any idea how this is possible?
@HB9BLA Рік тому
All antennas need counterpoises. Search for "Ground Plane Antenna"
@matheokoning4456 Рік тому
@@HB9BLA yes I've been looking for ground plane and 50 ohm impedance but I don't understand much of that yet. In this case it is a simple fs1000a module where there is already a hole to solder the antenna to. you would expect it to just work then.
@chuxxsss 2 роки тому
Are you calibrating it before soldering to the board first? Or measuring the distance of the wire?
@HB9BLA 2 роки тому
I calibrate without coax. Then I add the coax and determine the delay. Then I solder it to the PCB (it has to be shortened to dermine the delay)
@leonardoprates8224 Рік тому
Is correct to move the reference plane to the end of the cable as you did at video or do I have to consider the microstrip too? Because it's away from the feed point. And matching network is near to feed point. Could you explain the reason to not use the reference plane at this location?
@HB9BLA Рік тому
The output impedance of the chip has 50 ohms. This is why I wanted to know if from there, the "antenna" also offers 50 ohms
@kamilbro6106 2 роки тому
Hahaha I was just looking at a couple on aliexpress!
@HB9BLA 2 роки тому
:-)
@David_11111 2 роки тому
yay how did you find the delay of edelay 700 Pico seconds ?
@HB9BLA 2 роки тому
I showed it in video #001. Not simple to explain.
@Zhaymoor Місяць тому
How did you calculate or measure the cable delay ?
@HB9BLA Місяць тому
I did not calculate it, I showed in video 001 how to find it with an experiment.
@anlpereira 4 місяці тому
Hi Andreas, great video. Can you make this video for an ESP32-S3 board with MIFA? I’m saw in the Design Guidelines that the output impedance of this IC is 35ohm+0j. So, how to calculate the CLC matching circuit if the output impedance of the ESP32 is 35Ohm and the NanoVna has a 50Ohm impedance? I have seen a few online calculators. I want to design a small esp32-s3 board with a pcb antenna and another with a chip antenna. Another question is, is it possible to design a 35ohm PCB Antenna and don't use any macthing component? Thank you very much.
@andersonlima4068 2 місяці тому
I think if you add a 110 Ohm shunt resistor in the output of the NanoVna you can change its output impedance to approximately 35 Ohm. But I think you need to recalibrate the NanoVna and you need to have a 35 Ohm load instead of the 50 Ohm that comes with it. At this time you see a 35ohm impedance in the Smith Chart. After that you can measure the Return Loss or VSWR of your 50Ohm antenna with the Pi Matching circuit.
@HB9BLA Місяць тому
Most people use a match to 50 ohms beteween the chip and the antenna (it usually is a low-pass filter in addition). Often, you get the design from the manufacturer. You can calibrate a VNA to any reference by using the respective load (35 ohms in your case).
@anlpereira Місяць тому
@@HB9BLA I didn’t understand. How to calibrate it?
@HB9BLA Місяць тому
@@anlpereira Just as normal. Then apply the delay.
@anlpereira Місяць тому
@@HB9BLA thank you very much. I will try this approach. A 35 Ohm resistor soldered in a pcb.
@sanjikaneki6226 2 роки тому
I have a few questions : Why use a o ohm resistor and not simply use a piece or wire or a solder ball? What Lora module was used? Would i need a HAM license in order to use Lora ( assuming i stay under 14dbw , it i remember well ) ? Also if yes does this apply for hardware i make? ( l was considering making a Lora board and u bot the timing more or less right )
@HB9BLA 2 роки тому
1. 0 Ohms resistors can be places with machines. Solder bridges not 2. The RFM95 3. If you use these boards on ISM frequencies, you do not need a HAM license (and it would not help you because these frequencies are not HAM frequencies 4. You have absolutely no right to change or build hardware without HAM license, you only can buy and use certified products. Most IOT builders do not know that or do not respect this law.
@sanjikaneki6226 2 роки тому
@@HB9BLA THX wow 4 was unexpected So if interpret it well then using that module and building a PCB for it is technically illegal for a non HAM ? And i guess the same goes for any WIFI/BT IC that comes without an antenna ( like esp32 s) .
@mickgibson370 2 роки тому
@@sanjikaneki6226 When I had a phone 3 license in the USA, anything under 100 milliwatts was OK. You could not build a circuit did exceed100 milliwatts. I build an FM transmitter that had1 transistor that had 65 milliwatts!
@mickgibson370 2 роки тому
I used to transmit to Australia using 100 milliwatts from the state of Washington in the 60's.
@sanjikaneki6226 2 роки тому
@@mickgibson370 wow that it not that much power but something tells me it was a low frequency as 2 side note i am from the EU so not sure how the law it also what is a phone license 3 ?
@desertshadowqe Рік тому
Have a quick question. Might be very silly! Why is the rfm95 not attached during testing. Will it affect the readings??
@HB9BLA Рік тому
Yes, it would affect the reading. This is why we standardize on 50 ohms. Then you can divide systems for measuring.
@yannkitson116 2 місяці тому
I have just bought myself a LiteVNA 64 and the first problem is how to test an antenna that only has an ipex connector. It is the small antenna that comes with a Heltec V3. Any ideas?
@HB9BLA Місяць тому
I use an IPEX SMA adapter for that purpose.
@AlexejSvirid 3 місяці тому
You use a cable without a common mode choke. This may elongate the antenna.
@HB9BLA Місяць тому
I do not sknow what you mean :-(
@mcconkeyb 2 роки тому
Is it possible to measure forward and reverse power with your NanoVNA? If you could do that it would be easy to get the efficiency of the antenna. :-)
@HB9BLA 2 роки тому
That is the main purpose of the VNA. This measure is called return loss. Efficiency is what is radiated into the air compared with what is inserted into the antenna.
@mcconkeyb 2 роки тому
@@HB9BLA OK, then you know the power going into the antenna, you know the power coming back from the antenna. Measure the temperature of the antenna, to know the resistive losses of the antenna. and you then calculate the efficiency by [power in / (power in - [power return + resistive power loss]) *100. :-)
@HB9BLA 2 роки тому
@@mcconkeyb I read that these antennas also lose some power to the PCB. But, as I said, it is not a lot.
@mcconkeyb 2 роки тому
@@HB9BLA Any power loss in the PCB material should be accounted for in the temperature measurement. There might be some error as the heat capacity of the conductors will be different than the insulation. But if you allow the temperature to stabilize it should work out to less than a few percent error. If you want more accuracy then put the antenna into a calorimeter, thus the heat loss can be measured very accurately.
@nerdwerx2292 2 роки тому
"At 50 Ohms,if done right"...I see what you did there! 😏 Various soldering abilities WILL yield various results..🤔🙀😒
@HB9BLA 2 роки тому
It Is less about soldering. It is about the size of the trace and the stack-up of the PCB.
@matheokoning4456 11 місяців тому
I am still working on recreating an fs1000a module to incorporate into my own pcb. I have no intention of amplifying the module or anything. I'm using the exact same components as on the module and still I can't manage to get this working (properly). Unfortunately, there is still very little information on this subject. At least not about 433mhz like the fs1000a module specifically. I still do not understand exactly where the feedpoint of this module starts. Is that at L2 or is that from the capacitor. And should I make a 50ohm strip line from the feedpoint to the connection of the antenna? And could such a LiteVNA help me with this? I know I have asked this question before in the past and I apologize for that. I am getting crazy with myself that I do not understand this and I do not feel I can find the information anywhere to develop myself in this. Apologies again if I am spamming you!
@HB9BLA 9 місяців тому
No problem! I probably would include pinheaders for a purchased module on my PCB to avoid all the RF stuff ;-)
@remy- Рік тому
2:39 maybe it’s a really stupid question.. but the zero ohm resistor, why not an 50 ohm?
@remy- Рік тому
Edit: I think I know. Because 50=0+j50
@adbas6201 Рік тому
Lite vna is same as arinst ?
@HB9BLA Рік тому
No
@adbas6201 Рік тому
I need to be more precise. To compare 5.8 ghz fpv antenna, can i use litevna64 from accuracy point of view ?
@HB9BLA Рік тому
@@adbas6201 It depends on what you want to know. Just to check SWR it should work. If you need a lot of sensitivity, it will not work (check specifications of sensitivity in this frequency range.
@user-lo8gq3pr6e 5 місяців тому
I think it is incorrect to just apply the delay in the cable to set the measurement plane. The problem with that is that it does not take into the account the connector to coaxial connection imperfections and imperfections of the cable itself. Even the calculation of the delay is also questionable at these frequencies, as it assumes the cable speed factor from datasheet, and does not take connector into account. I think the better approach is to calibrate the measurement plane at the end of the cable. It is possible and being practiced, as explained in TI application note SWRA726.
@HB9BLA 4 місяці тому
You are right. If you have a u.fl calibration set. I do not own one an can live with a bit of imperfection.
@HE9JSD Рік тому
73 from a radio enthusiastic
@HB9BLA Рік тому
73 to you, too!
@technoman9000 2 роки тому
Yet another way that military research (missile telemetry) has unintended benefits!
@HB9BLA 2 роки тому
True.
HB9BLA Wireless
Переглядів 9 тис.
Andreas Spiess
Переглядів 210 тис.
Жекич Дубровский
Переглядів 2,5 млн
Andreas Spiess
Переглядів 312 тис.
joe smith
Переглядів 17 тис.