video starts: "I know some people prefer to watch short videos" video ends: almost two hours later xD Robert, I prefer to watch short videos, but most of your videos got amazing content that I wish the content was 10 hours!
The topic of a single antenna transmitting and receiving simultaneously at the same frequency is quite an interesting one and can give some insights about how VNA measurements actually work. The "impedance" of an antenna is actually measured and shown (on smith) as the amount of the reflection off of the feedpoint of an antenna. That signal can be reflected either by the antenna itself, but it can also be transmitted from the antenna, reflected off of a nearby structure, and then received again, which then shows as a slight shift in the measured impedance. So yes, receiving a signal same like the transmitted one is manifested as a change in impedance. And changes in impedance cause circuits to change behavior. There is a circuit called "regenerative receiver" which is basically a weak transmitter which drastically changes its power consumption (and frequency) depending on the antenna impedance. Hook it up in series with some headphones and it's an AM receiver. But in fact, it's a CW transmitter and can be picked up by an SDR. Two of those in the same room can even lock their frequencies to each other. But it's impractical to transmit and receive at the same time and band, especially when modulating both signals, since the transmitted noise would drastically desensitize the receiver. (Just my two cents :D)
@Robert Feranec: THX for that video, it is an eye opener even to me. But either there are some misconceptions in the explaination John gave of the Inverted-F Antenna or at least I got it wrong: The BOARD itself exceeds the place where the Antenna itself goes to. The Dielectric material FR4 itself exceeds where the Antenna is. What you can see on that simulation is not where the PCB is cut down, it shows where the electrical layers go. The picture only shows that the ground plane is recessed a little from the board's outer edges for maybe 30 mm or 40 mm. And instead of the ground plane on both sides of the FR-4 material the downside copper is removed completely and the upper side copper is edged to the form of the inverted-F Antenna. It does not mean the manufacturer has to cut out the FR4 material to the form of the inverted-F Antenna. The antenna length has to be calculated to the shortening-factor of the specific material the antenna is made from. So, for FR-4 this is round about a factor of I think 0.8. Taking that into consideration this shortens the antenna to the shown round about 2.5 cm length. The radiating length is all of the outside track. You can think of it being a Tap connecting the radiating "track" to adapt the impedance. It works kind of like a tap in a transformer, moving the tap to the end of the radiator more would increase the impedance, moving it more to the ground section would make impedance going to your transmitter smaller value. And John did already explain the section being in shape of a big "C" character being kind of inductor whilest the "=" looking shaped part is a pair of capacitance plates. So they're forming some resonant L-C circuit as part of the impedance matching and adaptor part. Me as an radio amateur sometimes got the impression that John was a little bit of unsure as well when he was explaining some details of the antenna specific stuff, but at least most of it was kind of correct. Sorry, John! But changing an asymmetric driven inverted-F antenna into a symmetric Lambda-half antenna takes a little bit more than just changing the shape of the antenna. You need matching parts, kind of "transformator" for adapting your single ended power output of the transmitter into the 2 anti-cyclic driven parts of the antenna (while part 1 of it gets positiv voltage output at a time the other one needs to get the negative one and vice versa.... ;)
Robert thank you for all the amazing content you are putting out. I am especially loving these collaborations you're doing w/ knowledgeable industry pros, they're explaining concepts so simply without sparing the technical details.
Man, i have no words for those videos. I've learned so much from you!!! I'm not even an EE, I'm a software developer but this kind of videos are so full of contend and from leaders of the field. For me RF is absolutely pitch black magic. This was a really good introduction!
@@RobertFeranec Would be nice to see a video on Multi-Phase buck converters. I have played with those at high currents, and even after years of experience (mostly with Intersil chips, such as ISL6307), often times the first prototype fails the smoke test (especially if you're going for more than 300 Amps using six phases). I think a comprehensive research addressing all the concepts in play (especially with High-Side MOSFETs) would make an interesting tutorial.
This is all fine as long as you want to use your antenna without any enclosure, and you don't care about the interactions of the rest of the PCB with the antenna. XFDTD by Remcom will pull in your entire PCB design, each layer and dielectric etc, plus the plastics and everything surrounding the antenna. Then the edges of the PIFA can be "parameterized" so that you can change the position of those edges during each sim. Over multiple runs, you then tune the length for resonance, and the impedance matching, and the whole thing converges. The resulting antenna is then adjusted in Altium, then simulated one more time to verify the changes. I've done a lot of antennas this way. My first try tripled the operating range of the device. (Given the inverse square law, that's impressive). Having your antenna impedance too far away from nominal can result in a lot of harmonics and cause you to fail compliance testing. RF current flows over your whole PCB, which interacts with the antenna and changes both the impedance and the pattern of radiation. This is not bad, and in some cases it will be enough, but even a simple ABS enclosure will affect the tuning of the antenna. Designing as if none of the enclosure and most of the PCB is missing is not a path to dependable success.
I had to design the same inverted f antenna as a project 2 months ago in my university. We've done it in ADS Momentum and the funny thing is that we find that if you have just a straight lower portion of copper, it gives a better S11. We didn't managed to get something better than -10 dB with the original design, so we started looking for a resize. So by making the low part straight and by adjusting the horizontal length of the antenna we obtained -25 dB for S11 at 2.45 GHz. In the same source, a Meandred Inverted F Antenna design was proposed, that we also had to simulate. And guess what? We didn't even nearly came to the -25 dB from the article. The best we obtained was -12 dB. As a conclusion there's no antenna design that will be the same as the one offered in the guidelines. Even using the same exact values, sizes, pcb thickness, vias, it's not guaranteed that the antenna will perform the same way as on the guidelines. And that's only on simulation, I'm not even talking about real pcb where a ton of additional other factors could appear.
Awesome, this is really good for those of us that have never designed an intentional pcb antenna. Perhaps in the future I would like to see as interview with someone that knows about EMI/EMC.
You might want to check the port of excitation (the signal line and ground plane), it is very likely where most of your mismatches come from because regions of it are no longer a coplanar waveguide.
Hey Robert, super nice video! I just want to give a comment on the biggest radiator in the F antenna or at least the way I like to see it. I think it is actually the vertical part that connects to ground (what has been called inductor). That one is effectively a monopole that is vertical to the ground plane (you need to see the groundplane as in the pcb cross section, which is more like a ground knife). For image theory it will duplicate the size and that is why it is called monopole. then there is the 90 degree turn and then the line is parallel to the ground. This still radiates, but less. You can visualize this using the polarization, as it follows the direction of the current. The feeding point is at a distance from the ground connection in order to have a matching. When resonating, the ground has the lower impedance (0) and the open part the highest. In the middle you find a point that, by adding that capacitance in parallel, you can match it to the desired impedance. The reason why it radiates most from the vertical line, is because the current is maximum near the ground connection and the voltage is maximum near the open end. This is due to the resonance. As you might imagine, the radiation come from the oscillating electric current. These antennas radiates from the magnetic field, unlike a patch antenna that radiates using electric fringing fields. Keep un the good work and thanks again for the videos!
Although it is possible to use a single antenna for transmission and receiption at the same time, it is rarely used and more common in radar applications. Nevertheless, (at least modern) automotive radars do have different antennas for receiving and transmitting. It is much cheaper than to implement a circulator/directional coupler. Additionally, you get a higher angular resolution using MIMO/beamforming techniques if you have seperate tx/rx antennas. And yes, modern automotive radars have like three transmit and four receive antennas or even more, each with an individual tarnsmitter/receiver and the signals get combined digitally afterwards (see beamforming/MIMO). Nice video anyways :)
Would be also nice to know about real pcb antennas matching practices using vector analyzers. And also there was shown, but not discussed, about inverted F meander antennas - what the difference to plain F? I use it in my device, got the shape from Texas datasheet, but have no theory behind it…)
The meander does two things. The far field radiation from an antenna can be directly related back to the currents on the antenna; i.e. the currents cause the radiation. The highest current density is on the low impedance section of the antennas, specifically the back-short and feed section, or the first 40% of the electrical length. The remaining 60% you can meander to increase the electrical length without affecting the radiation pattern too much. This allows you to compact the antenna into a smaller area. Meandering also helps with the impedance match. The IFA is really just an offset fed monopole, and an electrically short monopole has a large capacitive reactance (and low radiation resistance). Meandering the feed introduces some inductive reactance to compensate, and is better than a lumped element inductor as the currents contribute to the radiation. As I commented in another thread, this walks through the evolution of the IFA from a monople, discusses the tradeoffs of bandwidth and efficiency, and shows meandering. Tuning on the VNA is shown, and GPS C/N0 measurement. ruclips.net/video/q6f6m2j1nYs/видео.html ruclips.net/video/br4-9p_6GOA/видео.html ruclips.net/video/8gVFonUfoao/видео.html There really is no free lunch, but there are methods to maximize the tradeoff of efficiency vs bandwidth. Look up the "Chu Harrington limit", which is akin to Shannon capacity limit for antennas.
on last antena mismatch is because of gap, and lack of opening to transition to correct impedance. it is CPWG with Ground and it is VERY sensitive to the GAP even 0.5 mil makes huge difference in impedance thats why I would choose antena which is feed with MICROSTRIP, like previous example. MICROSTRIP is much easier to manufacture and even JLCPCB without impedance control can make it more or less reliale. I would avoid CPWG nd CPWGG completely if I go for RF.
That is a really interesting topic and truely a whole nother world of electronics! I would be looking forward to another video about the RF circuits John talked about!
Hello Robert. You make excellent videos about PCB design. I really enjoy and learn a lot from your videos. I think two things that are missing from your videos are High Voltage(>1kV) and/or high current (>100A) PCB designs. Keep up the good work.
This video is very informative ,please make few more videos on PCB antennas ,if possible topics related to meander line antenna, guidelines in designing small, compact RF module , ROT.
@@RobertFeranec Hi Robert, thanks for the quick reply! To answer your question, I'm definitely interested in going more in depth, perhaps with some numbers and calculations for the geometry of an inverted F antenna. Additionally, I'd love to see his analysis on the meandering trace antenna. Finally, he mentioned in this video phased arrays of antennas, which I'd love to see a video about. I know it's a big ask, especially for 1 video, but that's my 2cents!
Thank you for making this video and sharing it with all of us. Can you please explain the issue at 51 minutes 46 seconds, that graph does not show the frequency centered at 2.4 GHz. In fact it shows the antenna length looks to be a little long and tuned for around 2.3 GHz. That return loss graph is not centered at 2.4 GHz. Throughout the video, 2.4 GHz was mentioned but the graph does not indicate proper tuning for that frequency. Can you please review and explain?
The return loss S11 plot he shows is not centered at 2.4GHZ because the length of the stub need to shortened a bit. In other words, the design he used was not fully optimized. Additionally, there are dielectric losses he needs to account for in his simulation to tune to exactly 2.4GHz. The er he might use is not exactly what TI might have used. also when you fab it there will be some skew as vendoe dielectric is going to slightly different than the one used in the simulator. the bottom line is the design he showed was not optimized for exactly 2.4 GHz. He just used the artwork as is.
I absolutely love this format, but please check your audio before recording and touch it up before uploading. Sometimes the speech is very loud and clear, and sometimes it is very quiet and hard to hear.
I wish you had a video on using a ceramic omni directional antenna and it effect on antenna design. They are becoming a alternative to a pad copper plus filter set up. I believe phones use them and they are made for bluetooth , etc . They are small package simple design and talk of higher db over range.
OOooookay! This is very new to me! I am not even interested in this topic and I am not a designer! But simply drawing lines, those lines can be either capacitor or inductor or both. By "simply" I do not mean simply simply, if you know what I mean. Most of the time capacitance and inductance are determined by huge discrete devices (physical capacitors and wire-wound) or integrated in an insanely small blob by the power of science and technology.
I'd love to see you interview Alan Wolke (W2AEW). He's got a ton of great RF videos on RUclips (EG his video #297 on the basics of Smith charts), but you tend to ask good and interesting questions.
Your videos are one of those things that give me knowledge and motivation to hold me on to my current job. You are impressive 🤯 -Love and thanks from India ❤️
Thank you Robert for creating the video, but it's a bit complicated for non-RF engineers. Would you please make a tutorial on designing the PCB antenna alongside the matching network using Altium designer? it would be much more helpful to understand it.
Unfortunately RF/MW are fields that are studied separately. Antennas are their own field and to understand it, I recommend you read Constantine A. Balanis. all of the video content is covered in the book. Then use Sonnet EM, HFSS or CST to start modeling the antennae. Without 3d EM field solver you can't really design them. I have been doing this for several year and I use ADS, HFSS or sonnet EM for simulations. good luck as this is not a lightweight topic.
It would had been good if you'd had shown how to make the pcb instructing in altium or easyeda, man I couldn't do my board! that antenas are really hard!
Robert, Thank you very much for this video , There is a lot of interesting information about RF , Please keep doing this kind of videos. Regarding what John said that you have to play and play with the printed antenna shape to get the ideal performance then basically you can draw any random pattern and maybe you could get a very good antenna ? , Obviously taking into account the theory of lumped or distributed circuits, I mean , it doesnt have to be like an "inverted F " shape or an special shape ?
That was amazing video! Thanks a lot Robert!!! Well, it opened my mind, but brought more questions: If I use a Flex- Rigid PCB where the flex part is the antenna, should I use 30.6mm length for 2.4 Ghz? How reliable Smith Chart is to tune my antenna? Is there an example how to match the antenna with Smith chart? So, when I start a design it's really important to know where my product will be pointed out, once the antenna might be facing a metal plate and kill my antenna.
If the antenna is flexible, this basically means its geometry will be variable. This throws all your fine tuning out the window! You can simulate the antenna for the shape you expect it to have inside your casing. If it will just be flopping around, there's not much you can do at all. In practice you don't just simulate your antenna, but then also make prototypes and measure their real-life behavior using a VNA. It will never fully agree with your simulation anyway, so what you do is add a few SMD footprints for matching components (tiny inductors and capacitors) and then populate those with different values until you get the best possible reading.
At one hour, 19 minutes, 40, the inverted F PCB antenna is simulated. However there is a difference: On the original drawing from the Cyprus company, the transmission line opens up; wider spacing between ground and the center conductor as it reaches the antenna. That is likely to make the feed balanced, which an inverted F antenna needs. However in the simulation, you narrow to shielding to keep the unbalanced 50 Ohm all the way to the feed point? You do mention the spacing later in the video, but are more concerned about the via placement. Am I missing the obvious here?
time: 46:48 minute... is the Reference Antenna Design can we use RF AND Bluetooth (Combine with 1 Chip) like (ESP-32) IC.. ? I know many IC Company they recommended us there own Design Antenna.. but in this case if the wifi Frequency are same (2.4Ghz) .. then can we use other model PCB Antenna ? is it work same...?
Would it be possible for you to get guest speakers to record their audio at their end, so you can merge it with your local audio for better quality? I found it very hard to understand what John was saying as the volume of his voice trailed off towards the end of sentences. This looks like great content, but unfortunately I had to give up on watching this one because I couldn't follow along.
We actually discussed audio quality at the beginning of our call - and it was ok. I only noticed the problem when I started working on the recorded file - so I am not sure why it is recorded as it is. I am creating a new setup at home for these recordings, I hope that will help a little.
I wonder if the first stage RF amplifier has 50 Ohm input and output impedence, can you connect it to a buffer stage with a high input impedence (so that the buffer stage receives the output of the rf amplifier)? We can limit to modest frequency of FM radio at 100 mhz. Thanks kindly for the interesting video and for the effort in making it..
Yes, provided the electrical length between the amp output and buffer input is short. It’s done a lot in RFIC. There are other issues such and load line and stability to consider, even with short electrical length.
@@rfengr00 Thanks Louis that really helps to know that. As otherwise, if at every stage you have to maintain 50 Ohms, it'd be difficult to do much with the signal. My hope for the FM radio is to take a whip antenna (a monopole telescopic antenna), connect it to a RF amplifier, possibly buffer the RF amplifier's output and then pass the result to a Gilbert mixer to reduce it to about 0.5 mhz (from about 100 mhz). I'm Ok with the notion that the RF amp of the first stage has to be impedance matched with the antenna, but if this had to hold for every stage, such that you couldn't escape from 50 ohm input and output impedances, the design would be an order of magnitude more complicated. I'm glad we have people who understand this, as lots of the high frequency stuff and monopole antennas that don't even connect to the ground of your circuit (they have a single connection, unlike a voltage source which has two wires - one to ground and one as output) seems like black magic to me.
@@danielfromca Have a look at Razavi's RF Microelectronics book, as he discusses the philosophy of RF design with matched impedance vs RFIC where you are more in the voltage domain; I took the UCLA RFIC course last semester where we went through a lot of this book. That said, you don't need matched impedances in RF, as it really depends on how much ripple you can tolerate over the passband. Many amplifiers have poor output impedance (i.e. S22) and it's of no concern unless you are driving a poorly matched load through a large electrical delay, or worried about signals getting back in from the antenna to generate distortion. You could take an ideal common-gate cascode amplifier with perfect 50 Ohm input impedance, and it would have infinite output impedance, and can hook it up to a 50 Ohm cable with a 50 Ohm load. It's only when the load and cable are mismatched is when you have a problem. But as I replied earlier, there are a ton of other factors to consider too.
Though it connected to ground, I guess the idea it produces such energy burst that the electrons fly of the copper trace into the air , and as it's 2.4MHz on/off and not DC, there is not many electrons actually making its way all to the end and into the ground.
I have used a wire which i added to a existing antenna which i believe is not well designed the signal is limited and why i came here . Adding this wire doubled my range and kept my signal solid as i moved. No bluetooth has a great range most are lucky to have 30 cm line of sight distance and are further limited by walls or door ways which mess with the flow of electrons to the receiver/transmitter. This wire idea works but it requires external mounting not internal mounting which is my preference.
Hi, I am doing a project in which I would do communication between the antennas (PCB),but I am not sure of the module which can send raw data without any encoding Anyone has any suggestions?
You should defenitely including it in your simulation. So yes, it can influence the matching of the antenna. Espeically for higher frequencies. And once you plug something into that connector it will have a significant influence.
Have the same question) If I put the connector in my design to perform matching and then remove from the prod device (keeping the pads for connector on the board). How significant will be the impedance change?
@@MrBorsoft good question. As I understand, if the designer don't develop a impedance change in terms of decreasing resistance by changing track width, it's acceptably "ok". But problem is whether this will act as a stub. At the end of the day, everything you do will detune the antenna, but the question is how much? (everyone please feel free to enlighten me!)
The standard answer of "it depends". Generalized to the design shown in the video, when you tack on the coax, you are extending the counterpoise (notice I did not say ground) and generating common mode currents on the exterior of the coax, both of which will change the radiation pattern, and to some extent the impedance. There are a couple of things you can do. Use the tin-dipped, hand formable coax and solder that to the ground plane. That will short-circuit the common mode current. Since the test connection will still go off-board, you then use a ferrite beads (right where it comes off the PCB) to form a high impedance on the coax exterior. This is compact but with the disadvantage of lower antenna efficiency, and giving you a (fake) improved return loss due to the absorption in the ferrite. Alternately you can wind the coax into a tight coil to form an inductive choke. This will have low loss, but is larger and lower bandwidth. I have a series of videos here on IFA theory design (in Microwave Office), manufacture, tuning, and test: ruclips.net/video/q6f6m2j1nYs/видео.html ruclips.net/video/br4-9p_6GOA/видео.html ruclips.net/video/8gVFonUfoao/видео.html This also shows the issues with common mode radiation and the fix: ruclips.net/video/Hcc3FO2BmOQ/видео.html
@@MrBorsoft Like Louis said, it depends. However, there are connectors exactly for this use-case, like the MS-162A by Hirose. You put them into your feed line (like you break the line and the connector has two pads for input/output). It behaves as a "perfect" through connection, but once you plug in a cable, it will break the connection to the antenna and route the signal from the amplifier to your cable (or vice versa for receiving).
There is a lot of good information for beginners here. But I've got to say that the complexity of antenna design is not covered here. Some of the explanations about the simulation and the graphs that it produces are simplistic at best.
I like your videos, but it is very annoying when the guest speaks into his microphone such that the audio ranges form barely audible to screaming laud many times per sentence. Please watch for this in future videos.
I did not notice that when we were recording. I only noticed that when I was playing the recorded file. I am working on a new setup, let;s see if that will help. Yeah, I am sorry for that
Cadence/AWR Microwave Office: Only $990(USD)/month! Hmm... Do I get that new Tesla or this nifty software instead? Multitudes, multitudes in the valley of decision: for the day of the LORD is near in the valley of decision. (Joel 3:14) Lol. Where's RMS when you need him?
1:27:00 Presenter disparages Cypress' inverted F antenna because it didn't have good results in his software, then admits he's not certain he has the dimensions correct. Meanwhile, if the viewer looks at the image from Cypress and the image that the presenter used as an example, it is easy to see they are not the same. It's no wonder he didn't get good results 🤣
He explained more than once that his result with the Cypress antenna is an example of why you need to follow the manufacturer's instructions carefully with these types of antenna design guidelines. Did you watch the video to the end?
After finishing this video I had to check orientation of my WiFi router antennas :D
video starts: "I know some people prefer to watch short videos"
video ends: almost two hours later
xD
Robert, I prefer to watch short videos, but most of your videos got amazing content that I wish the content was 10 hours!
:D
Coupled with such slow talking ... All these are best played at 2x speed.
As of this writing this is the only 1.5hr+ video I have ever watched on RUclips. Worth it.
Thank you very much Brad. I am very happy you liked the video.
The topic of a single antenna transmitting and receiving simultaneously at the same frequency is quite an interesting one and can give some insights about how VNA measurements actually work.
The "impedance" of an antenna is actually measured and shown (on smith) as the amount of the reflection off of the feedpoint of an antenna.
That signal can be reflected either by the antenna itself, but it can also be transmitted from the antenna, reflected off of a nearby structure, and then received again, which then shows as a slight shift in the measured impedance.
So yes, receiving a signal same like the transmitted one is manifested as a change in impedance.
And changes in impedance cause circuits to change behavior.
There is a circuit called "regenerative receiver" which is basically a weak transmitter which drastically changes its power consumption (and frequency) depending on the antenna impedance.
Hook it up in series with some headphones and it's an AM receiver. But in fact, it's a CW transmitter and can be picked up by an SDR.
Two of those in the same room can even lock their frequencies to each other.
But it's impractical to transmit and receive at the same time and band, especially when modulating both signals, since the transmitted noise would drastically desensitize the receiver.
(Just my two cents :D)
I have been looking for that topic for a while. You are the KING!
Thank you Kemal
I second that!
this guy always asks the right questions, I love it
Wow. What an amazing lecture it was. Thanks to the professor and you robert.
@Robert Feranec: THX for that video, it is an eye opener even to me. But either there are some misconceptions in the explaination John gave of the Inverted-F Antenna or at least I got it wrong: The BOARD itself exceeds the place where the Antenna itself goes to. The Dielectric material FR4 itself exceeds where the Antenna is. What you can see on that simulation is not where the PCB is cut down, it shows where the electrical layers go. The picture only shows that the ground plane is recessed a little from the board's outer edges for maybe 30 mm or 40 mm. And instead of the ground plane on both sides of the FR-4 material the downside copper is removed completely and the upper side copper is edged to the form of the inverted-F Antenna. It does not mean the manufacturer has to cut out the FR4 material to the form of the inverted-F Antenna. The antenna length has to be calculated to the shortening-factor of the specific material the antenna is made from. So, for FR-4 this is round about a factor of I think 0.8. Taking that into consideration this shortens the antenna to the shown round about 2.5 cm length. The radiating length is all of the outside track. You can think of it being a Tap connecting the radiating "track" to adapt the impedance. It works kind of like a tap in a transformer, moving the tap to the end of the radiator more would increase the impedance, moving it more to the ground section would make impedance going to your transmitter smaller value. And John did already explain the section being in shape of a big "C" character being kind of inductor whilest the "=" looking shaped part is a pair of capacitance plates. So they're forming some resonant L-C circuit as part of the impedance matching and adaptor part.
Me as an radio amateur sometimes got the impression that John was a little bit of unsure as well when he was explaining some details of the antenna specific stuff, but at least most of it was kind of correct. Sorry, John! But changing an asymmetric driven inverted-F antenna into a symmetric Lambda-half antenna takes a little bit more than just changing the shape of the antenna. You need matching parts, kind of "transformator" for adapting your single ended power output of the transmitter into the 2 anti-cyclic driven parts of the antenna (while part 1 of it gets positiv voltage output at a time the other one needs to get the negative one and vice versa.... ;)
Robert thank you for all the amazing content you are putting out. I am especially loving these collaborations you're doing w/ knowledgeable industry pros, they're explaining concepts so simply without sparing the technical details.
Thank you very much Liam for leaving your feedback. I am very happy you like these videos.
Man, i have no words for those videos. I've learned so much from you!!!
I'm not even an EE, I'm a software developer but this kind of videos are so full of contend and from leaders of the field.
For me RF is absolutely pitch black magic. This was a really good introduction!
Thank you very much TuttoCrafting
Just get a hard copy of Smith Chart. It actually has Black magic design written on it. 😁
We want more long videos ...your work is highly appreciated
Excellent video Robert. It's sad to see so few subscribers for a channel producing such informative content. Keep up the good work...
Thank you very much Nasser for nice words
@@RobertFeranec Would be nice to see a video on Multi-Phase buck converters. I have played with those at high currents, and even after years of experience (mostly with Intersil chips, such as ISL6307), often times the first prototype fails the smoke test (especially if you're going for more than 300 Amps using six phases). I think a comprehensive research addressing all the concepts in play (especially with High-Side MOSFETs) would make an interesting tutorial.
This is all fine as long as you want to use your antenna without any enclosure, and you don't care about the interactions of the rest of the PCB with the antenna. XFDTD by Remcom will pull in your entire PCB design, each layer and dielectric etc, plus the plastics and everything surrounding the antenna. Then the edges of the PIFA can be "parameterized" so that you can change the position of those edges during each sim. Over multiple runs, you then tune the length for resonance, and the impedance matching, and the whole thing converges. The resulting antenna is then adjusted in Altium, then simulated one more time to verify the changes. I've done a lot of antennas this way. My first try tripled the operating range of the device. (Given the inverse square law, that's impressive). Having your antenna impedance too far away from nominal can result in a lot of harmonics and cause you to fail compliance testing. RF current flows over your whole PCB, which interacts with the antenna and changes both the impedance and the pattern of radiation.
This is not bad, and in some cases it will be enough, but even a simple ABS enclosure will affect the tuning of the antenna. Designing as if none of the enclosure and most of the PCB is missing is not a path to dependable success.
I had to design the same inverted f antenna as a project 2 months ago in my university. We've done it in ADS Momentum and the funny thing is that we find that if you have just a straight lower portion of copper, it gives a better S11. We didn't managed to get something better than -10 dB with the original design, so we started looking for a resize. So by making the low part straight and by adjusting the horizontal length of the antenna we obtained -25 dB for S11 at 2.45 GHz. In the same source, a Meandred Inverted F Antenna design was proposed, that we also had to simulate. And guess what? We didn't even nearly came to the -25 dB from the article. The best we obtained was -12 dB.
As a conclusion there's no antenna design that will be the same as the one offered in the guidelines. Even using the same exact values, sizes, pcb thickness, vias, it's not guaranteed that the antenna will perform the same way as on the guidelines. And that's only on simulation, I'm not even talking about real pcb where a ton of additional other factors could appear.
This is very interesting Victor
Thank you Robert for this video, waiting for this topic for a long time.
I have been waiting for this topic too :D
Awesome, this is really good for those of us that have never designed an intentional pcb antenna.
Perhaps in the future I would like to see as interview with someone that knows about EMI/EMC.
Thank you. PS: I am working on the EMC videos
I have taken a masters EE course in antennas, and I still learned some things more efficiently from John than that class.
I watched this trying to make sense of circuit board antennas, learned a ton of stuff, thanks.
You might want to check the port of excitation (the signal line and ground plane), it is very likely where most of your mismatches come from because regions of it are no longer a coplanar waveguide.
Hey Robert, super nice video!
I just want to give a comment on the biggest radiator in the F antenna or at least the way I like to see it.
I think it is actually the vertical part that connects to ground (what has been called inductor).
That one is effectively a monopole that is vertical to the ground plane (you need to see the groundplane as in the pcb cross section, which is more like a ground knife).
For image theory it will duplicate the size and that is why it is called monopole.
then there is the 90 degree turn and then the line is parallel to the ground.
This still radiates, but less.
You can visualize this using the polarization, as it follows the direction of the current.
The feeding point is at a distance from the ground connection in order to have a matching.
When resonating, the ground has the lower impedance (0) and the open part the highest.
In the middle you find a point that, by adding that capacitance in parallel, you can match it to the desired impedance.
The reason why it radiates most from the vertical line, is because the current is maximum near the ground connection and the voltage is maximum near the open end. This is due to the resonance.
As you might imagine, the radiation come from the oscillating electric current.
These antennas radiates from the magnetic field, unlike a patch antenna that radiates using electric fringing fields.
Keep un the good work and thanks again for the videos!
Thank you so much Alex
Great video! Less questions/interruptions would be better. Love to see more from John Dunn!
This John guy is amazing, great explanation
Would you mind making a video to show how to design a matching circuit and PCB layout for Chip antenna ?
Many thanks
Although it is possible to use a single antenna for transmission and receiption at the same time, it is rarely used and more common in radar applications. Nevertheless, (at least modern) automotive radars do have different antennas for receiving and transmitting. It is much cheaper than to implement a circulator/directional coupler. Additionally, you get a higher angular resolution using MIMO/beamforming techniques if you have seperate tx/rx antennas. And yes, modern automotive radars have like three transmit and four receive antennas or even more, each with an individual tarnsmitter/receiver and the signals get combined digitally afterwards (see beamforming/MIMO).
Nice video anyways :)
Thank you very much FabianS
we appreciate the work you do on this channel, good content. keep on going
Thank you very much Btima
Would be also nice to know about real pcb antennas matching practices using vector analyzers. And also there was shown, but not discussed, about inverted F meander antennas - what the difference to plain F? I use it in my device, got the shape from Texas datasheet, but have no theory behind it…)
The meander does two things. The far field radiation from an antenna can be directly related back to the currents on the antenna; i.e. the currents cause the radiation. The highest current density is on the low impedance section of the antennas, specifically the back-short and feed section, or the first 40% of the electrical length. The remaining 60% you can meander to increase the electrical length without affecting the radiation pattern too much. This allows you to compact the antenna into a smaller area.
Meandering also helps with the impedance match. The IFA is really just an offset fed monopole, and an electrically short monopole has a large capacitive reactance (and low radiation resistance). Meandering the feed introduces some inductive reactance to compensate, and is better than a lumped element inductor as the currents contribute to the radiation.
As I commented in another thread, this walks through the evolution of the IFA from a monople, discusses the tradeoffs of bandwidth and efficiency, and shows meandering. Tuning on the VNA is shown, and GPS C/N0 measurement.
ruclips.net/video/q6f6m2j1nYs/видео.html
ruclips.net/video/br4-9p_6GOA/видео.html
ruclips.net/video/8gVFonUfoao/видео.html
There really is no free lunch, but there are methods to maximize the tradeoff of efficiency vs bandwidth. Look up the "Chu Harrington limit", which is akin to Shannon capacity limit for antennas.
on last antena mismatch is because of gap, and lack of opening to transition to correct impedance. it is CPWG with Ground and it is VERY sensitive to the GAP even 0.5 mil makes huge difference in impedance thats why I would choose antena which is feed with MICROSTRIP, like previous example. MICROSTRIP is much easier to manufacture and even JLCPCB without impedance control can make it more or less reliale. I would avoid CPWG nd CPWGG completely if I go for RF.
That is a really interesting topic and truely a whole nother world of electronics! I would be looking forward to another video about the RF circuits John talked about!
Thank you very much Nils
Ready to learn something, and appreciate all this sharing
Thank you John and thank you Robert!
Hello Robert. You make excellent videos about PCB design. I really enjoy and learn a lot from your videos. I think two things that are missing from your videos are High Voltage(>1kV) and/or high current (>100A) PCB designs. Keep up the good work.
Thank you Moien PS: These are on my todo list
Wow.. loved it. I would love to have the complete 3 hour video please. Also, waiting for 2nd part. Do have one more call with John Dunn Sir...
This video is very informative ,please make few more videos on PCB antennas ,if possible topics related to meander line antenna, guidelines in designing small, compact RF module , ROT.
Thank you very much Shruthi
Incredible video!!! I was always looking for a video like this! I always wonder how a pcb antenna works.
Congrats! excellente video
Eagerly looking forward to the next video you do with John!
Thank you Brian. Any ideas for specific topics you would like to learn more about?
@@RobertFeranec Hi Robert, thanks for the quick reply! To answer your question, I'm definitely interested in going more in depth, perhaps with some numbers and calculations for the geometry of an inverted F antenna. Additionally, I'd love to see his analysis on the meandering trace antenna. Finally, he mentioned in this video phased arrays of antennas, which I'd love to see a video about. I know it's a big ask, especially for 1 video, but that's my 2cents!
w2aew has a nice video on directional couplers with explanation. It's video 196. Should be easy to find.
And some good videos about antenna matching as well (although more into CB frequencies, the theory is the same).
What a great video! Thank you MrEN0046 for pointing that out.
@@RobertFeranec thank you for your videos. They have helped me out and are interesting.
Thank you Robert for uploading such great content. This video was extremely helpful and look forward to more of your videos!
Thank you for making this video and sharing it with all of us.
Can you please explain the issue at 51 minutes 46 seconds, that graph does not show the frequency centered at 2.4 GHz.
In fact it shows the antenna length looks to be a little long and tuned for around 2.3 GHz.
That return loss graph is not centered at 2.4 GHz. Throughout the video, 2.4 GHz was mentioned but the graph does not indicate proper tuning for that frequency. Can you please review and explain?
The return loss S11 plot he shows is not centered at 2.4GHZ because the length of the stub need to shortened a bit. In other words, the design he used was not fully optimized. Additionally, there are dielectric losses he needs to account for in his simulation to tune to exactly 2.4GHz. The er he might use is not exactly what TI might have used. also when you fab it there will be some skew as vendoe dielectric is going to slightly different than the one used in the simulator. the bottom line is the design he showed was not optimized for exactly 2.4 GHz. He just used the artwork as is.
I absolutely love this format, but please check your audio before recording and touch it up before uploading. Sometimes the speech is very loud and clear, and sometimes it is very quiet and hard to hear.
I wish you had a video on using a ceramic omni directional antenna and it effect on antenna design. They are becoming a alternative to a pad copper plus filter set up. I believe phones use them and they are made for bluetooth , etc . They are small package simple design and talk of higher db over range.
Robert, tôi thích xem các video ngắn hơn, nhưng hầu hết các video của bạn đều có nội dung tuyệt vời mà tôi ước nội dung đó dài 10 giờ
OOooookay! This is very new to me! I am not even interested in this topic and I am not a designer! But simply drawing lines, those lines can be either capacitor or inductor or both. By "simply" I do not mean simply simply, if you know what I mean.
Most of the time capacitance and inductance are determined by huge discrete devices (physical capacitors and wire-wound) or integrated in an insanely small blob by the power of science and technology.
I'd love to see you interview Alan Wolke (W2AEW). He's got a ton of great RF videos on RUclips (EG his video #297 on the basics of Smith charts), but you tend to ask good and interesting questions.
This is a TI reference design, inverted F...I used it in my products 2 years before.
:)
Your videos are one of those things that give me knowledge and motivation to hold me on to my current job.
You are impressive 🤯
-Love and thanks from India ❤️
Thank you very much Mohan for very nice words.
Thank you Robert for creating the video, but it's a bit complicated for non-RF engineers.
Would you please make a tutorial on designing the PCB antenna alongside the matching network using Altium designer? it would be much more helpful to understand it.
Unfortunately RF/MW are fields that are studied separately. Antennas are their own field and to understand it, I recommend you read Constantine A. Balanis. all of the video content is covered in the book. Then use Sonnet EM, HFSS or CST to start modeling the antennae. Without 3d EM field solver you can't really design them. I have been doing this for several year and I use ADS, HFSS or sonnet EM for simulations. good luck as this is not a lightweight topic.
It would had been good if you'd had shown how to make the pcb instructing in altium or easyeda, man I couldn't do my board! that antenas are really hard!
true will be much helpful
Great. Thank you.
There's a lot of good RF info in the YT channel "The Signal Path". VERY recommended.
Loved this video!
Thank you, Robert for this video. Can make video about reflections?
Thank you very much for this video
Thank you. Very good info
Robert, Thank you very much for this video , There is a lot of interesting information about RF , Please keep doing this kind of videos.
Regarding what John said that you have to play and play with the printed antenna shape to get the ideal performance then basically you can draw any random pattern and maybe you could get a very good antenna ? , Obviously taking into account the theory of lumped or distributed circuits, I mean , it doesnt have to be like an "inverted F " shape or an special shape ?
That was amazing video! Thanks a lot Robert!!!
Well, it opened my mind, but brought more questions:
If I use a Flex- Rigid PCB where the flex part is the antenna, should I use 30.6mm length for 2.4 Ghz?
How reliable Smith Chart is to tune my antenna? Is there an example how to match the antenna with Smith chart?
So, when I start a design it's really important to know where my product will be pointed out, once the antenna might be facing a metal plate and kill my antenna.
If the antenna is flexible, this basically means its geometry will be variable. This throws all your fine tuning out the window! You can simulate the antenna for the shape you expect it to have inside your casing. If it will just be flopping around, there's not much you can do at all.
In practice you don't just simulate your antenna, but then also make prototypes and measure their real-life behavior using a VNA. It will never fully agree with your simulation anyway, so what you do is add a few SMD footprints for matching components (tiny inductors and capacitors) and then populate those with different values until you get the best possible reading.
At one hour, 19 minutes, 40, the inverted F PCB antenna is simulated. However there is a difference: On the original drawing from the Cyprus company, the transmission line opens up; wider spacing between ground and the center conductor as it reaches the antenna. That is likely to make the feed balanced, which an inverted F antenna needs. However in the simulation, you narrow to shielding to keep the unbalanced 50 Ohm all the way to the feed point? You do mention the spacing later in the video, but are more concerned about the via placement. Am I missing the obvious here?
I have a similar series of videos here that walks thru the design, fab and test:
ruclips.net/video/q6f6m2j1nYs/видео.html
Great video!
Thank you Jean-Christophe
Like this video. Please do next version of it
Thank you Sajin
Great stuff Robert!
Thank you very much Hemal
No! Power does not come OUT of GND, the return current does. Power flows into the feed point.
i prefer LONG videos. more long videos please. thank you.
time: 46:48 minute...
is the Reference Antenna Design can we use RF AND Bluetooth (Combine with 1 Chip) like (ESP-32) IC.. ?
I know many IC Company they recommended us there own Design Antenna..
but in this case if the wifi Frequency are same (2.4Ghz) ..
then can we use other model PCB Antenna ?
is it work same...?
Love your videos!!!
A magnetic loop is also shorted to ground, but I suppose the inductance saves the day?
Would it be possible for you to get guest speakers to record their audio at their end, so you can merge it with your local audio for better quality? I found it very hard to understand what John was saying as the volume of his voice trailed off towards the end of sentences. This looks like great content, but unfortunately I had to give up on watching this one because I couldn't follow along.
We actually discussed audio quality at the beginning of our call - and it was ok. I only noticed the problem when I started working on the recorded file - so I am not sure why it is recorded as it is. I am creating a new setup at home for these recordings, I hope that will help a little.
Thanks a lot! Very useful video👍🏼
Thank you Dmitriy
I wonder if the first stage RF amplifier has 50 Ohm input and output impedence, can you connect it to a buffer stage with a high input impedence (so that the buffer stage receives the output of the rf amplifier)?
We can limit to modest frequency of FM radio at 100 mhz. Thanks kindly for the interesting video and for the effort in making it..
Thank you danielfromca. PS: I do not know the answer, but maybe someone else can help?
@@RobertFeranec Thanks Robert & I appreciate all the educational work you do in this great channel.
Yes, provided the electrical length between the amp output and buffer input is short. It’s done a lot in RFIC. There are other issues such and load line and stability to consider, even with short electrical length.
@@rfengr00 Thanks Louis that really helps to know that. As otherwise, if at every stage you have to maintain 50 Ohms, it'd be difficult to do much with the signal. My hope for the FM radio is to take a whip antenna (a monopole telescopic antenna), connect it to a RF amplifier, possibly buffer the RF amplifier's output and then pass the result to a Gilbert mixer to reduce it to about 0.5 mhz (from about 100 mhz). I'm Ok with the notion that the RF amp of the first stage has to be impedance matched with the antenna, but if this had to hold for every stage, such that you couldn't escape from 50 ohm input and output impedances, the design would be an order of magnitude more complicated. I'm glad we have people who understand this, as lots of the high frequency stuff and monopole antennas that don't even connect to the ground of your circuit (they have a single connection, unlike a voltage source which has two wires - one to ground and one as output) seems like black magic to me.
@@danielfromca Have a look at Razavi's RF Microelectronics book, as he discusses the philosophy of RF design with matched impedance vs RFIC where you are more in the voltage domain; I took the UCLA RFIC course last semester where we went through a lot of this book. That said, you don't need matched impedances in RF, as it really depends on how much ripple you can tolerate over the passband. Many amplifiers have poor output impedance (i.e. S22) and it's of no concern unless you are driving a poorly matched load through a large electrical delay, or worried about signals getting back in from the antenna to generate distortion. You could take an ideal common-gate cascode amplifier with perfect 50 Ohm input impedance, and it would have infinite output impedance, and can hook it up to a 50 Ohm cable with a 50 Ohm load. It's only when the load and cable are mismatched is when you have a problem. But as I replied earlier, there are a ton of other factors to consider too.
It would have been better to draw the equivalent LC matching circuit of the inverted F antenna while discussing
Cool info, is it possible making a PCB trace for GPS ? thanks
When i make antennas to and jeah, this is how it goes. :)
No such thing as "short circuit" in antennas
Though it connected to ground, I guess the idea it produces such energy burst that the electrons fly of the copper trace into the air
, and as it's 2.4MHz on/off and not DC, there is not many electrons actually making its way all to the end and into the ground.
Nice... excellent video..!! thanks Robert and John. (PD: Was anyone hungry..?? 1:08:00 jajaja)
Thank you Diego PS: That would be me :D I always have the calls in the evening and sometimes I have no time to eat :D
@@RobertFeranec stay healthy... we need you..!! jajaja!! Again, thanks.!
You always make very nice videos :-) Robert
I have used a wire which i added to a existing antenna which i believe is not well designed the signal is limited and why i came here . Adding this wire doubled my range and kept my signal solid as i moved. No bluetooth has a great range most are lucky to have 30 cm line of sight distance and are further limited by walls or door ways which mess with the flow of electrons to the receiver/transmitter. This wire idea works but it requires external mounting not internal mounting which is my preference.
Hi, I am doing a project in which I would do communication between the antennas (PCB),but I am not sure of the module which can send raw data without any encoding
Anyone has any suggestions?
amazing
Thank you
Thank you saeed
TI support said me that copper thickness does not matter for this antenna due to skin effect.
What about placing a ipex connector in parallel to a pcb antenna, is it that bad at all? Actually it could act like a stub and detune the antena?
You should defenitely including it in your simulation. So yes, it can influence the matching of the antenna. Espeically for higher frequencies. And once you plug something into that connector it will have a significant influence.
Have the same question) If I put the connector in my design to perform matching and then remove from the prod device (keeping the pads for connector on the board). How significant will be the impedance change?
@@MrBorsoft good question. As I understand, if the designer don't develop a impedance change in terms of decreasing resistance by changing track width, it's acceptably "ok". But problem is whether this will act as a stub. At the end of the day, everything you do will detune the antenna, but the question is how much? (everyone please feel free to enlighten me!)
The standard answer of "it depends". Generalized to the design shown in the video, when you tack on the coax, you are extending the counterpoise (notice I did not say ground) and generating common mode currents on the exterior of the coax, both of which will change the radiation pattern, and to some extent the impedance. There are a couple of things you can do. Use the tin-dipped, hand formable coax and solder that to the ground plane. That will short-circuit the common mode current. Since the test connection will still go off-board, you then use a ferrite beads (right where it comes off the PCB) to form a high impedance on the coax exterior. This is compact but with the disadvantage of lower antenna efficiency, and giving you a (fake) improved return loss due to the absorption in the ferrite. Alternately you can wind the coax into a tight coil to form an inductive choke. This will have low loss, but is larger and lower bandwidth.
I have a series of videos here on IFA theory design (in Microwave Office), manufacture, tuning, and test:
ruclips.net/video/q6f6m2j1nYs/видео.html
ruclips.net/video/br4-9p_6GOA/видео.html
ruclips.net/video/8gVFonUfoao/видео.html
This also shows the issues with common mode radiation and the fix:
ruclips.net/video/Hcc3FO2BmOQ/видео.html
@@MrBorsoft Like Louis said, it depends. However, there are connectors exactly for this use-case, like the MS-162A by Hirose. You put them into your feed line (like you break the line and the connector has two pads for input/output). It behaves as a "perfect" through connection, but once you plug in a cable, it will break the connection to the antenna and route the signal from the amplifier to your cable (or vice versa for receiving).
There is a lot of good information for beginners here. But I've got to say that the complexity of antenna design is not covered here. Some of the explanations about the simulation and the graphs that it produces are simplistic at best.
Thank you Brian. If this video does well, we may do other videos.
this is good shid 👍
Does anyone know a good video of how to match printed IFA antennas with afordable equipment?
Search two things: NaniVNA and a video on this channel interviewing a Nordic engineer about antennas.
Cool! Realty f cool!
I use taoglas antenna
мне понравилось
subsrcribed :)
I design antenna for IoT and wireless products daily 😂😂
I like your videos, but it is very annoying when the guest speaks into his microphone such that the audio ranges form barely audible to screaming laud many times per sentence. Please watch for this in future videos.
Try to add some sort of compression and limiting on the audio signal to avoid this.
I did not notice that when we were recording. I only noticed that when I was playing the recorded file. I am working on a new setup, let;s see if that will help. Yeah, I am sorry for that
I need source file for cypress models, please
Cadence/AWR Microwave Office:
Only $990(USD)/month!
Hmm... Do I get that new Tesla or this nifty software instead?
Multitudes, multitudes in the valley of decision: for the day of the LORD is near in the valley of decision.
(Joel 3:14)
Lol. Where's RMS when you need him?
1:27:00 Presenter disparages Cypress' inverted F antenna because it didn't have good results in his software, then admits he's not certain he has the dimensions correct. Meanwhile, if the viewer looks at the image from Cypress and the image that the presenter used as an example, it is easy to see they are not the same. It's no wonder he didn't get good results 🤣
He explained more than once that his result with the Cypress antenna is an example of why you need to follow the manufacturer's instructions carefully with these types of antenna design guidelines. Did you watch the video to the end?
Ah, criticism based on fallacious argument from an anonymous account.
Pity John is always mumbling the 2nd half of sentence, inaudible!
Any free PCB layout / PCB Antenna simulation tool?