ESP32 + PCB Antenna Hardware Design Tutorial - Phil's Lab #90

How to design custom hardware using ESP32 MCUs (ESP32-C3, NOT pre-made modules!) and PCB antennas (inverted F, in this case). PCBs by PCBWay www.pcbway.com
Showing examples and real, working hardware (WiFi scan test), a full schematic walkthrough, and a PCB design walkthrough. Final test using Arduino IDE & ESP32 expansion.
Many more ESP32 firmware & hardware tutorial videos to come!
[SUPPORT]
Free trial of Altium Designer: www.altium.com/yt/philslab
PCBs manufactured and assembled by PCBWay: www.pcbway.com
Patreon: / phils94
Mixed-signal hardware design course: phils-lab-shop.fedevel.education
Advanced Hardware Design Course Survey
forms.gle/X4jwvtZeJ1jTXh7r9
[GIT]
github.com/pms67/ESP32-USB-Do...
[LINKS]
Instagram: / philslabyt
ESP32 Hardware Design Guidelines: www.espressif.com/sites/defau...
ESP32-C3 Datasheet: www.espressif.com/sites/defau...
TI PCB Antenna Application Note: www.ti.com/lit/an/swra117d/sw...
[TIMESTAMPS]
00:00 Introduction
00:29 Altium Designer Free Trial
00:49 PCBWay
01:19 ESP32-C3 and Hardware Overview
04:28 ESP32 Hardware Design Guidelines
06:14 Schematic - ESP32-C3 Power Pins
07:26 Schematic - Crystal
08:50 Schematic - Chip Enabled (Reset)
09:16 Schematic - SPI FLASH
10:21 Schematic - USB and Power
12:29 Schematic - UART, Sensor
13:26 Schematic - Bootmode Select
14:10 Schematic - PCB Antenna
17:43 Schematic - RF Matching Network
22:15 PCB - Overview & Stack-Up
23:47 PCB - Controlled Impedance
24:10 PCB - General Guidelines, Decoupling
25:54 PCB - Antenna and Matching Network
29:22 WiFi Test (Arduino IDE)
33:37 Outro

[@PhilsLab]

New ESP32 hardware design tutorial coming soon! Some comments: 1) I'd strongly recommend using off-the-shelf, pre-certified modules unless you have a very good reason not to. This video is more of a 'fun demonstration', rather than something that should be used practically. 2) Although I haven't had issues so far, the chip-enable cap (C19) value should be increased for reliability (as otherwise the default bootmode and chip enable come up at the same time on power on). 3) The antenna matching network and antenna itself will need to be tuned on the real PCB. These are just ballpark values. 4) There is a variant of the C3 (C3FN4) which contains built-in 4MB flash. Meaning you don't need external flash - however, these SPI pins on the C3FN4 cannot be used. Additionally, I believe the C3FN4 is NRND.

[@hxtec32]

Thanks so much for putting this video back up Phil. Me and the rest of the beginner ESP32 designer guys really appreciate it. Why'd you put it back up btw? Also, for any of you guys reading this, you can just use the ESP32-C3FH4X, ESP8685H4, or upcoming ESP8686 for your new designs as they are either active or about to be released.

[@thedrunknmunky6571]

Once again, Phil has come to the rescue by making a video of exactly what I need, as if by telepathy. This is the 2nd time this has happened and that’s strange.

[@PhilsLab]

Glad to hear it's helpful! Hopefully just by coincidence rather than telepathy :D

[@mbarras_ing]

Next video is Phil's Lab 'Cerebro'...

[@lasmurf4175]

Ya. Happened to me as well. He's a weird German....in a positive way @Phil....great job

[@ArtamisBot]

If I had a nickel for every time that's happened then I'd have two nickels... Which isn't a lot of nickels, but it's weird that it happened twice.

[@shauss5448]

Dude same wtf

I've learned more electronic design from you than the entire five years of my master's of EE university studies.

[@PhilsLab]

Glad to hear the videos are helpful - it's a sorry state of affairs when it's this way round though :(

@@PhilsLab The course was very theory-heavy. We never got to actually design a PCB, build it and bring it up. Thanks to your videos, I'm more confident now designing my own PCBs.

[@rallymax2]

Me too. 6 yrs of grad and 20yrs of work and I never picked up this much.

[@visualcocaine4623]

​@ simple question, do you designed pcb with this complexity at school or it was more soft ?

[@nichonaugle]

Literally the exact video I needed. Don’t forget the strapping pins when developing the board. I forgot to pull in of them high when I was designing the board and it caused it to fail when programming. Once I added a trace to 3v3 it all worked again

[@Naster001]

More ESP32 plz. Great video!

[@lucdrouin2625]

Phil, congratulations for making such exquisitely detailed videos. You expound every detail, offer practical advice and support for your growing community of subscribers.

[@PhilsLab]

Thank you very much for your kind words, Luc!

[@l01]

This was really what I needed! Created a similar board a few months ago, and this video has really answered a lot of questions I had.

[@PhilsLab]

Very glad to hear that, thanks!

[@kampi89]

You can use the C3FN4 variant of the ESP32-C3 which has a built-in 4 MB flash memory instead of a dedicated memory.

[@MsSebaastian]

Nice catch

[@KPruthviRaaj]

So, in the C3FN4 variant do you just leave one of the SPI pins as Not Connected or can they be used as normal SPI pins?

[@lels3618]

@@KPruthviRaajas far as i know, other pins need to be strapped - read the doc!

[@harrybmortoniii263]

I have just discovered your channel today and have been watching several of your videos on KiCad and I have picked up a wealth of information, I happen to be in my mid-seventies, a retired electronics design engineer, very much into RF design, and this old dog is still learning new tricks. Well done, Mate! Looking forward to watching more of your Great instructional videos .

[@PhilsLab]

Thanks a lot, Harry - glad to have you here! :)

[@ameliabuns4058]

Aww. As someone who’s 25, I always worried that I won’t be able to do as much or learn as much when I’m older because I’m already so much slower than I was since I was a teenager, glad to know that you can still do cool stuff when you age !

[@yacineyaker7485]

i need to say that you are the best embedded systems channel on youtube by far. watching your videos motivate me to learn more and more and tbh comparing myself to last year i've improved a lot in pcb designs and it's thanks to your videos and robert feranec's. hope you continue this quality containt and thanks for the efforts.

[@PhilsLab]

Thank you very much, Yacine! I'm glad to hear that - hopefully I can keep up with interesting videos!

[@abdultairu]

As a rookie PCB designer, I am always in awe of what you do taking us to the design considerations used to produce boards that we buy off the shelf. I have no intention of reproducing this particular design (obviously above my paygrade) but I enjoyed watching the detail description of this author. Thank you very much professor Phil.

[@geluidsbox9195]

Wow I've been working on a bare ESP32 project and have been stuck on the antenna part for a while. This video just comes 2 weeks after, amazing thank you so much!

[@PhilsLab]

Glad to hear the timing's right :)

[@3DKreateFPV]

I just want to thank you for your free videos that you release on these topics. It has led me to discover what I want to study in college end goninto as a career. Thanks Phil

[@PhilsLab]

That's awesome, thanks!

[@lolsypussy]

Thank you very much, Phil. We've been producing boards using the ESP32 modules because we haven't found yet an in-depth tutorial on customization such as this and also the concern about FCC compliance.

[@PhilsLab]

Thanks for watching! Yeah, FCC compliance of course can be quite a hurdle when going the custom route...

[@velho6298]

Amazing project! I'll hope you'll continue with it!

[@PhilsLab]

Thanks! Firmware videos coming next :)

[@HardDiskSpeaker]

Awesome, I've never saw those unique ESP32 design! Thank you for great video.

[@PhilsLab]

Thanks for watching!

[@rick_er2481]

Truly amazing content, a lot of different subjects, HW, SW, indepth practical design. Thank you so much

[@PhilsLab]

Thank you for watching, Rick!

[@rick_er2481]

@@PhilsLab are you maybe planning on a similar board with some LoRa IC + PCB antenna?

[@Sebo419]

Cheers, Phil. Amazing content.

[@WinterCircuits]

Awesome video Phil, an absolute joy to watch and learn. Was looking into antennas in general and wanting to learn. This would be a great start! Thanks again!

[@PhilsLab]

Thank you very much! Hope this proves to be helpful for your designs :)

[@david_owen]

Once again, a great video and very informative. Looking forward to the further firmware videos with this board.

[@PhilsLab]

Thanks, David - firmware video coming out this month!

[@m.e.5018]

Thank you Phil for another awesome pcb project video!

[@PhilsLab]

Thank you very much for watching!

[@DeeBash]

I was looking for antenna design for esp all over the internet, but all of them were difficult and I lost hope. Now I got your notification, let's see.

[@PhilsLab]

Hope it's helpful!

[@sergioibarramunoz3511]

Thanks for your content! It is amazingly useful for learning. I'm considering to use the ESP32-C3 for my next project 😁

[@PhilsLab]

Thanks for watching, Sergio!

[@pietrogagliano4484]

Very cool video! I design hardware with the ESP32 Wroom modules for work so it's super cool to see a design with the ESP32 C3 chip itself

[@TheVideoVolcano]

What does your company make? Seems weird as we are not allowed to use esp32 as it's not 'a real mcu'. We use pic24, FPGAs, etc

[@AmanpreetSingh-ff7ng]

I am learning enormous things from your tutorials ....Really thanks

[@PhilsLab]

Thanks for watching :)

[@dmitrynuzhdin]

Thank you! I thought to make custom esp32 board with pcb antenna and after research came up with similar guidelines. But did not make it yet ... :) Now I will have more confidence that this thing will work, can't wait for your next videos!

[@PhilsLab]

Thank you, Dmitriy - good luck with your design!

[@alexlovett1991]

Great video Phil! Certainly a project I’m planning on doing at some point. Love the Wi-Fi name!

[@PhilsLab]

Haha thanks, Alex!

[@LeLaboDeHarry]

I was waiting for a video like this for so long!!! Thanks you Phils

[@PhilsLab]

Thanks for waiting! :)

[@RazorRadios]

Awesome video!

[@ameliabuns4058]

100x better than any college course and free. I hope you realize that you’re helping a lot of people!

[@atta1798]

Nice work 👍👍👍

[@emielv7677]

This is amazing. I learned so much. I made a pcb a couple of weeks ago and I thought I did quite well but I now know there are so many small mistakes in it after seeing this video haha. It might be fun to do a video about my pcb and point good/bad things out along the way.

[@PhilsLab]

Thanks, Emiel! I do design reviews on the channel, if you'd like - send it in via phils-lab.net/contact :)

[@emielv7677]

@@PhilsLab hi thank you for your reply. I have sent my design in via the link you gave me. If there are any questions please let me know. I hope my design is not too bad 😬

[@BlueyMcPhluey]

wow, this is exactly what I have been looking for, the KZbin algorithm nailed me with this one. Just throwing it out there, but I'd also be really interested in a guide for how to use ceramic antennas in designs

[@PhilsLab]

Thanks, Josh - glad to have you here! Great suggestion as well!

[@quarteratom]

Really good video, explains the design process even to those, who don't know all this.

[@PhilsLab]

Thanks you!

[@M4XD4B0ZZ]

Super impressive and relevant

[@ricardomarques1769]

Ironically as it may sound, I was trying to design a depth measure system using the same MCU and a ToF but I found myself with difficulties specially designing the antenna part. So thank you once again Phil, for the wonderful surprises, and help you've been giving me. Waiting for your new course.

[@PhilsLab]

Very glad to hear that! Thank you for your support, Ricardo :)

[@GremDR]

Very detailed video about the whole steps that is essential to create an excellent PCB! But I have one suggestion for improvement that you can comment on: It's necessary for PCB antennas to open solder mask above them. Solder mask dielectric constant can dramatically change the characteristics of the created antenna, because it is located in the path of radio waves propagation.

[@RSP13]

Question: without soder mask, the antenna will then be affected by the finish (ENIG or HAS). Wouldn't that affect also be an unknown variable?

[@TD-er]

Great video! I've been working with ESP boards for years now (developing ESPEasy) and I alway wondered what made one board work great with WiFi and why it worked so bad on others. I really would like to know how the WiFi quality is of this board, compared to other boards when running the same kind of scan at the same location in your house. Maybe also nice to check running some AP on various channels to see whether you hit the perfect center frequency and what the actual bandwidth/range is of your PCB antenna. Perhaps let some ESP board run a few meters away, starting AP mode on the next channel every minute and let your board (and others) scan and compare the RSSI values. Still this will of course also include some offsets caused by the "bad" antenna of the other ESP board acting as an AP. So maybe you could also test using a real access point and test on channels 1, 6 and 11 to cover the entire 2.4 GHz spectrum. Also really nice to see those ESP32-C3 are so easy to wire and program due to their internal USB interface. Meaning I really should start supporting the C3 also in ESPEasy :)

[@drumbum7999]

your videos are soooo invaluable. thank you

[@PhilsLab]

Thank you!

[@shadielshazly5877]

Thank you very much for putting time and effort into this great work. I had a question, you interfaced the USB_P and USB_N of the esp-32 with the USB port, thought the USB gives 5 volts which the esp-32 pins can't handle, does this means that the USB ESD Protection will take the 5volts down to a 3.3v, or that the esp-32 USB pins are 5v tolerant.

[@jackk2860]

great video, always blown away

[@PhilsLab]

Thank you, Jack!

[@Avriox]

Oh yes exactely what I was waiting for!!! Thanks!

[@PhilsLab]

Glad to hear that - thanks for watching!

[@Avriox]

@@PhilsLab Could the ESP32 c3 also be used to negotiate other USB-PD voltages or would I always need a separate IC for that?

[@PhilsLab]

I guess you could try and control the CC lines through the ESP32 directly, but it's far easier to use a dedicated USB C PD IC, which interfaces to ESP32 via I2C, for example.

[@Avriox]

@@PhilsLab Okay so if it's a size-constrained application it might be possible but if I have the space is probably not worth the hustle. Thanks!

[@PhilsLab]

You'll have to add in control circuitry + FETs as well in any/most cases, so I'd definitely just go with a dedicated controller that has the right gate drivers, etc. as well.

[@newsogn5148]

I was looking for something like this too…. Phils lab is theee best!

[@PhilsLab]

Awesome, glad to hear that!

[@michajoko7534]

Wow, really cool. First of all, your video with the ESC FOC controller helped me, because I was experimenting with BLDCs at that time and now this year I wanted to start a project with an esp32. Thanks for that. Will there be another video about the ESC and the FOC? Many greetings Michael. The content on your channel is great and so helpful.

[@PhilsLab]

Thanks, Micha. Glad to hear the videos have been helpful. Yes, I'd like to make a follow up vid to the ESC design, however, I have many projects ongoing at once, so it can take a bit of time I''m afraid.

[@ingmarm8858]

Hi Phil, Nice video overall. It was refreshing to hear you admit that there were going to be many external factors that will impact the overall tuning of the onboard antenna. A very realistic approach since the end user can put the board into a completely unknown environment with various other nearby metalic elements which will all impact upon the tuning and performance of the antenna. It was amusing to then see you worry about the PI matching network to match the 35j10 to the 50 ohms (nominal) IFA impedance. If by some chance your antenna ends up at 50 ohms (unlikely in the real world) without any actual verification / trimming then the power loss from the resulting mismatch is still pretty much negligible. All made more novel by the "close enough" values of the PI elements ;-) I realise the whole point is to demonstrate a complete RF path from the chip to the antenna and you did that well. Some people go to extraordinary lengths to try and get the match of some onboard antenna and matching network perfect whilst ignoring the reality that it will only ever be "right" at that moment in time on their bench lol. Just one more thing, in your layout you had the PI matching network inductor close and parallel to (I think) one of the RF power rail inductors. Personally I'd seperate those or put them at right angles to reduce any possible coupling but it again may make no practical difference! I'm not going to touch the whole solder mask or not issue in the RF path. All the best.

[@KeanM]

Funny to see you here. I cannot imagine who you may be referring to above... 🫠

[@sfnembedded]

Great tutorial! Thank you

[@PhilsLab]

Thank you!

[@bill6943]

Great video again Phil, love it. I downloaded STM32CubeMX and have been working through the tutorials. The software sounds awesome. I usually use Studio code composer, I might be switching to CudeMX for a while.

[@PhilsLab]

Thank you very much, Bill. If you haven't already, I'd highly suggest given the newer STM32CubeIDE a try!

[@bill6943]

@@PhilsLab I already downloaded it. I got my hands on a STM32 nucleo. I also enjoy using MSP430 series as well.

[@nicoladellino8124]

Very nice video, TNX Phil.

[@PhilsLab]

Thanks, Nicola!

[@rajjolal23]

Phil i ove your videos. so clear, clean, ogranized and amazing in general. so informative. please do one with standalon bluetooth audio SOC. I will forever be grateful.

[@PhilsLab]

Thank you very much, Srijan!

[@PCrazy4]

For my semester project i literally have to implement an ESP32-C3. It is as if god sent you Phil.

[@PhilsLab]

Awesome, good luck with your project!

[@kylejosephjr]

Very nice! Thanks for the video - I enjoyed it as usual. By the way, you should change your wifi access point off of channel 6. According to your new scanner that band looks quite congested :)

[@bishoydaniel6107]

Thank you so much , very helpful.

[@PhilsLab]

Thanks for watching!

[@samuie2]

Your video is great and saved me from making a critical error. I read the docs and didn't see anything about the LNA_IN output impedance (35 + j10) so assumed it was 50 ohm since that's the "standard". Turns out its not listed in the datasheets but is mentioned on the hardware forum.

[@PhilsLab]

Thanks, glad to hear that it helped!

[@montvydasklumbys7584]

Thanks for the video, it is really informative and I am glad that the content is of such a high quality! I had a couple of questions though. First of all, could you have just connected the antenna ground pin to the GND plane on the top layer. Of course adding a via to GND is also a neccessity there, but it seems against any logic not directly grounding that pin to the top layer of the ground. I checked some designs online and I see this being grounded to the top (if the top pour is GND that is). So potentially did you manage to find some information that was against doing this? Another questions is that I see people adding a picket-fence around the antenna feed line and the antenna itself, which should reduce stray signals from antenna entering the PCB and the opposite. I thought it is quite essential, but you seem to have managed to make it work without adding one. I wonder how would that affect the SNR overall.

[@jumadhaheri]

This is fantastic, thanks

[@PhilsLab]

Thanks, Juma!

[@vladoportos]

Very nice, I was designing esp32 data logger some time ago, and I remember including "reset" circuit connected to the external IC USB to UART and that had Data Terminal Ready and Ready to Send control output connected through two transistors to the EN and BOOT pin on ESP32, that helped with the reset after sketch upload. I wonder if this can be implemented in the SOC when the UART chip is "build in"

[@MikeHarris1984]

THANK YOU FOR THIS!!!!!!!!!!!!!!!!!!!! I am designing my own ESP32 based board and didnt want to do what everyone else does and just solder on a single ESP32 pre-built board (the one with the wifi antenea and such, not the full dev board, tho i've seen that too).... I am wanting to use the SOC direct and then design my own firmware and setup for it... and the ESP32-S3 is STUPID cheap and so simple!!! I just am getting hung up on the design of the memory and flash and such... I think i'll do an SD card for the flash part... but playing around with options... I am doing an external antenea plug in on the board since it will be in a case and wanted to have the full range available. But this helps out so much! i've been looking at recommendations from other sites and reading all the SOC documentation inside and out and printed it all out and marking my notes... This is by far the biggest custom PCB project i've taken on for my own little things... I normally would do the ESP32 and solder the wifi pre-made package board on it. But I wanted something more "professional". Learning to design and build PCB's self taught can be pretty steep learning curve. Only my Electrical Engineering classes in highschool from the late 90's is what I have education wise and all self taught componant diagnosis and repair and small self designed PCBs. But NO ONE has an SOC totorial for me to go through and verify my design and deployment based off the technical and design documentation from espressif direct.

[@MikeHarris1984]

New sub from me! Love this walk thru! Simplified some of my questions I was dealing with trying to figure out via documentations.

[@eslamshahin0]

Amazing video again 😍 Hope yo do same video for a GPS module Because i have to put components on the pcb with its antenna but i didn't find much resources

[@perceptron9834]

Great video, thank you.

[@PhilsLab]

Thanks!

[@tonygiguere2495]

Golly! great video!!!!!!!!!

[@PhilsLab]

Thanks, Tony!

[@gsuberland]

I enjoy your AP name being "Cheeky WiFi 'n That"

[@PhilsLab]

Haha I've been listening to too much Karl Pilkington...

[@gsuberland]

@@PhilsLab "not getting on a camel" is a frequent reference in my household

[@giovannitroncosobordoni461]

Thanks you Phil for all the videos you´re making, i´ve learn a lot on pcb design thanks to you!!. Great content and very professional. Since you make the antenna design topic, if you can, could you make something on the "gnss" topic?, based on a module or an IC. Once again thanks!!!

[@PhilsLab]

Thanks, Giovanni! Is there anything specifically to a system with GNSS you'd like to see? Usually there isn't much to incoporating those modules in designs.

[@giovannitroncosobordoni461]

@@PhilsLab You are right!, i want to implement a ublox module (NEO-M8N) and i saw that the most relevant component it´s an inductor on the antena line for active antennas. But my insecurities appear hahahaha.

[@TechnopolisDotTV]

I love it! only thing missing, is a CAN bus IC (SN65HVD230DR). 😅

[@ianmosquera3741]

As always, a quality content from you Phillip. Thank you for this. Can you also explore STM32WB55 mcu for BLE, We are currently had a designed custom board from this but having some RF issues.

[@PhilsLab]

Thank you, Ian! The STM32WB* series is definitely something I'd like to feature in upcoming videos.

[@hichammhm7741]

thank you

[@TrickyNekro]

Video is gold, I´ve seen extremely few people going over so much detail and the correct reason behind it over the years. And yes, technically you are being a bit naughty with the USB. As per IF-standard you should not draw more than 100mA continuously before enumeration, that being said, you would probably still be fine, if the first thing that you try to do when the device connects is to try to enumerate before activating the RF section. I do not know the C3 specifications, but I would guess, if you really wanted to turn this into a product with the USB-IF approved logo on the outside, it should not be a problem. But rumor has it, they turn a blind eye with a lot of products anyhow.

[@AmanpreetSingh-ff7ng]

You are Awesome

[@alphaprot2518]

After this being the somewhat twenty-x-ish video of Phil I watched, I realised I have not yet subscrided to this channel, which I "fixed" immediately. I would love to hear and see even more about design considerations for EMI/SI ,because at least to me it appears that most people (including me) have still a lot to learn in this field.

[@PhilsLab]

Glad to hear that you subscribed! Definitely will be making more videos on SI/EMC techniques.

[@sanjikaneki6226]

Great video again! Why did you go for the C line and not the S line? Is it because it is RISK V ? Also in the future when you will cover more firmware will you use Arduino or the ESP-IDF?

[@blogactivities5462]

Thanks

[@dimitarzhekov9550]

If you want to have a receiver and transmitting antenna (one with high gain) one with low gain, can we use the LNA pin since it's I/O?

[@autumngreen86]

This content is worth a lot, I struggle to find books and Udemy courses that will teach me more about embedded systems on this level. Please consider turning some of your work into Udemy courses in future.Thank you.

[@behzadabf]

you awesome bro..thanks

[@PhilsLab]

Thanks!

[@zhaojia511]

Finally, this topic😂

[@drdistorzion]

Just for anyone watching, there is a version of C3 with built in flash as well (C3FN4, C3FH4, 4MB flash). I've used it on my own board and I thought that meant the SPI pins could be used for other things then but appears that the internal flash is connected to the same pins as they would for external. (yes I know it's stated in the datasheet that these pins are not recommended for other use, but I thought that was fi external flash was used). So good to know so you don't do the same mistake as me. :).

[@yanbiaozhu4093]

Thank you so much for making this video. It gives me alot of insight of making pcb board with MCU, i am wondering you like to add CLC pi filter to the power supply and analog supply, any tips for this kind of filter? For eg how to select the right value of the components. Thank you!

[@mihaidumbrava5498]

Thank you for sharing your knowledge with us! Great video, as usual, but I would like something similar made with KICAD if possible.

[@UTube4075]

Yeah mate. Need more videos in KiCad as I'm a beginner.

[@theGamer-kt9pf]

Could you please make a video on GPS module/ system design

[@RafaGmod]

I'm currently working on a SAE Hydrogen powered formula and we need a solution for a boost converter. We found some off the shelf solutions but you are slowly making me get the job of developing it! hahahhaha So cool to make the PCB and also the simulation and control are related to my masters dissertation. Oh god i will have to much to do this year

[@PhilsLab]

Haha glad to hear this is making you do design work! :D

[@TimPerfetto]

Thank you

[@PhilsLab]

Thanks for watching, Tim!

[@PavloD9]

Thanks for the informative video. Is there any guidance on these ground planes on the top layer? Why some designs have them, but others don’t? When holes are required? Why there are some uncovered blanks spots?

[@andrew2004sydney]

Thank you so much for making this great, educational video. With the implementation of the PCB antenna and matching network, how do you know if the design achieved a low SWR? Is there any practical way of measuring it?

[@avinadadmendez4019]

NanoVNA

[@47lokeshkumar74]

Nice bro

[@PhilsLab]

Thanks!

[@kirkhamandy]

I have found SimSmith (free JAVA-based software) excellent for designing various matching networks. Of course, a basic understanding of Smith Charts is needed but the program will choose "standard" values for the various network types you want to implement and give you a pretty good Smith Chart representation of how it should react (also Bode plots).

[@PhilsLab]

Yes, I use SimSmith myself sometimes as well - really neat tool.

[@avinadadmendez4019]

I manufactured an ESP32-S2 board and the impedance I got on the RF input was very different from the one on the datasheet ( 11 + 1j vs 31 + 1j ). This means the impedance matching network I designed actually reflected 95% of the signal at the 2.4Ghz carrier frequency, it actually worsened the problem instead of improving it, as removing the network and using a 0 Ohm resistor only reflected 50% of the signal. I have to say my stackup was completely different too from the one recommended in the datasheet. It might be worth to mention to ALWAYS leave an u.FL connector on the board to hook up a vector analyzer in case it doesn't work properly (and it will not if you make even a slight change on the stackup)

[@avinadadmendez4019]

I might mention, the change I did to the stackup was using 0.8mm thick 2 layer board instead of 1.6mm thick 4 layer board. It also changed the impedance of the PCB antenna from 50 + 0j Ohms to 30 + 0j Ohms. Luckily I left an u.FL connector in place to know this information, and also pads to solder a Pi Network on the antenna end

[@RSP13]

Sir, could you tell me in what position did you place the U.FL connector? Was it between the ESP pin and the matching network or between the matching network and the PCB antenna? Thanks.

[@jagadishk4513]

I used Ti's ISM PCB antenna app note for Lora pcb design, fortunately they had shared gerber so creating footprint was a breeze

[@originuk]

@ Very informative! I always feel a bit smarter after watching your vids. Thank you for covering the ESP 32 and custom PCB antenna design,.plus touching on capacitance,.inductance and impedance tuning of tracks... Plus way more! I'm need clarity about why you have the ground layers in the middle of the PCB. I've seen gnd, signal and pwr planes on the outside... Not sure what effect the order of planes make in PCBs.... With the exception of grounding ic pins with a via, why not use 2 layers for your design? Is it personal choice, best practice, convenient or something else?

[@montvydasklumbys7584]

The reason why he does that is due to the way how PCBs are constructed. Internally a 4-layer PCB looks like this: 1. copper -prepreg (thin)- 2. copper -core (thick)- 3. copper -prepreg (thin)- 4. copper So the first two copper layers (1 and 2) are very close together, since they're separated by a prepreg, then there is core, which is thick, then the following two layers (3 and 4) are close to each other. The idea here is that you want your signals to have a good reference, which usually is ground. The closer the ground plane is to your signals, the better the reference. This btw has nothing to do with DC, DC will be fine on wires.. But this has something to do with what happens when the signals change e.g. digital signals go from low to high to low... Each change introduces thousands of different frequencies (fourier series), which all need to have a good reference, otherwise they will radiate energy into space until it finds that reference it's looking for. For RF circuits you do not want stray signals flying about, since you care about getting the best SNR from your antenna and stray signals are basically noise, especially when the antenna is passive (PCB antenna, chip antenna) as opposed to active antenna. Plus EMF radiation is increased if you do not have good references, due to which you might fail consumer tests, which will cost tens of thousands to re-test. Anyway, getting back to the subject, why didn't he just use a 2-layer PCB? 2-layer PCB has the following structure: 1. copper -core (thick)- 2. copper It doesn't use prepreg to separate the layers, so unless your PCB thickness is like 0.3mm, you won't have a good ground reference, thus EMF radiation. On top of that, you will have a worse ground return path, since there will be wiring on your ground layer. If you reduce the thickness of such PCB, you will get other problems, since you need both layers to route your signals, singals from the top layer will interact with the signals on the bottom layer, since they are then in close proximity to each other. So again, noise issues, EMF issues, basically at this point you start regretting not going 4-layer board here :) P.s. if you want my recommendation, when you go 4-layer, use 1 and 3 copper layers as GND planes, while the 1 and 2 copper layers will be your signals with power pours in between those signals. The design here requires you to put a GND via next to each signal via to ensure that your return path is good, otherwise again EMF problem! And power pours will ensure good power delivery, since the energy lives not on the copper, but in between the two copper plates. So you want to build a powerful capacitor, which can deliver as much power as needed :)

[@th3magist3r]

Awesome video! Please add firmware videos!

[@PhilsLab]

Thanks, Alexandros - firmware vids are coming!

[@persupersulast2506]

Can you make a video discussing high current or high power switching devices like relays?

[@dekideky2881]

is rf antenna integrable with any kind of mcu? i'm asking because i bought sygonix minicam and i want to integrate antenna and connect it with wifi to make it remote.

[@romancharak3675]

Wowee, so interesting!

[@PhilsLab]

Thanks, Roman!

[@na-uu4nw]

Wonderful presentation with exquisite explanations! I did have one question though. I attempted to create a similar board with a ESP32C3 SoC. The WiFi didn't work (no reception or transmission). As I reviewed my design, it was nearly identical to yours but I had a 2 layer board vs a 4 layer board that you used. Does having the build use a 4 layer board make that much of a difference? Funny thing is that everything else worked swimmingly.

[@PhilsLab]

Thank you! There's a few things that can go wrong - hard to tell without seeing the design. For example, antenna sizing/tuning/placement, matching network, incorrect trace impedance, and so on. Most RF boards are actually 2 layers, so that won't be a problem - but will typically mean wider traces for a given impedance (compared to a board with thinner dielectrics).

[@losaminos59]

Nice video, very very useful. Just wanted to ask why did you put a pull-up resistor on pin 6 (GPIO2) and pin 14 (GPIO8)? Is it because of the strapping modes from page 15 of the datasheet? Of all the GPIOs, that two pins are the only ones with a pull-up resistor.

[@Graham1904]

Phil. Great videos. Leant much. Why did you terminate the GND of the antenna at the GND pour directly instead going have a gap around that leg?

[@ernestoflores495]

Amazing! Thank you so much for sharing. Did someone send this to PCBway for manufacturing and assembly? I would like to know how expensive it is.

[@rustyutb]

Do you have a ground reference beneth your LNA trace? its clear that there is no ground beneath the antenna itself, but what about the LNA trace?

[@gorkemsay]

Thanks for the video. It is very informative. I got a question. Is there any minimum or maximum feed line length after the PI filter? and what is the minimum gap length between feed line and ground?

[@twin1q]

Great videos. It would be great to see the performance of the atenna and the matching network. The USB VNA from Amazon should be a good cheap way of measuring the 50ohm matching. I think they are

[@PhilsLab]

Thanks! Yes, I really need to get my hands on one of those.

[@jorgeneiva6671]

Nice guide, The antenna impedance (35+10J)R for ESP32-S3 can be the same of ESP32-C3?

[@nabeast1980]

While like you said, it may not be a concern here for the capacitor/inductor pads being slightly thicker than the straight trace through it, would it be slightly beneficial to have a tapered transition to reduce the "blip" effect?