QT Py ESP32 onboard wifi antenna signal quality

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movsesk
 
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QT Py ESP32 onboard wifi antenna signal quality

Post by movsesk »

Hello everyone!

Can anyone share any practical experience with wifi signal quality with the onboard wifi antennas on the QT Py ESP32 modules? Expected range?

I'm testing out the Pico, S3 and C3 modules and they seem fairly reliable at about 20 feet and 1 plasterboard wall in between. I get about -70 dBm at this distance. At times, likely due to interference, it may take a few retries to connect, but otherwise ok.

Thank you!

Regards,
-Moses

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adafruit_support_mike
 
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Re: QT Py ESP32 onboard wifi antenna signal quality

Post by adafruit_support_mike »

Wifi is sensitive enough to local conditions.. both physical materials in the signal path and ambient radio interference.. that general estimates are meaningless.

The empirical tests you're doing are the best option (without several thousand dollars of radio test equipment), but be sure to check the device at the other end of the connection too. See what limits there are on its ability to pick up other devices too.

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movsesk
 
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Re: QT Py ESP32 onboard wifi antenna signal quality

Post by movsesk »

Hi Mike!

No budget for expensive radio equipment right now.. but here is a good comparison. dBm display of various ESP32 modules at about 20 feet.

Upper, left=QT PY S3 (on board chip antenna), right=Xiao C3 (stock off board 'external' pcb antenna)
Lower left and right, ESP32-DevKitC-VE with pcb 'printed' antenna

The Xiao 'external' antenna and the DevkitC boards are about the same, although the Xiao seems to edge a couple of dBm higher at times. The QT Py chip antenna is usually about 8-10 dBm away.

And of course YMMV!

Regards,
-Moses
IV-9-6D-RR-rssi-comparison-of-diffrent-ESP32-boards.jpg
IV-9-6D-RR-rssi-comparison-of-diffrent-ESP32-boards.jpg (319.82 KiB) Viewed 483 times

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adafruit_support_mike
 
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Re: QT Py ESP32 onboard wifi antenna signal quality

Post by adafruit_support_mike »

Those are gorgeous nixie displays. Of course, if they're anywhere near the Wifi devices we have a strong guess about where to find possible interference. ;-)

It does look like the QT Py is a few db down from the other devices, but it's hard to attribute that to any cause. Real-world radio is full of influences we can't see.

One possible option would be the orientation of the QT Py's antenna. Try it in multiple orientations and see if there's any change. IIRC it uses a dipole antenna, so the signal should be strongest in a torus around the antenna.

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movsesk
 
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Re: QT Py ESP32 onboard wifi antenna signal quality

Post by movsesk »

Thank you! Most of the visible ones are numitrons (incandescent 7 segments), which are also very cool!
You can see two tubes of an actual nixie clock on the right edge.

This is my prototype clock shelf of what is usually under current development. I have been designing and selling clock for a while now. I would make them out of atmega chips, now I like these ESP32 modules with wifi connectivity. NTP is great, never have to set them!

The nixie clocks do have switching DC-DC converters, but these are pretty well designed with minimum RFI. It doesn't bother their on board ESP modules. The numitron clocks, where I am testing the QT Py actually have no switching power supplies on board, and really no other noisy parts, so they are really quiet electrically. About the only noise I can see would be from the serial lines to the shift registers, and this has not been an issue.

Good point on the dipole. I just checked my test setup in the picture and the QT Py dipole is broadside to the wifi source. A turn towards the null brings me another 5-8 dBm down.

Yes, of course there are many causes for the a signal to not be as strong, I'm not complaining, it all appears to working as designed. There was an engineering compromise made in the antenna to actually fit it onto such a small board, which is what attracted me to it in the first place! But it is obvious that a 3.5mm chip antenna is almost always going to perform worse then a 15mm PCB antenna. I just wanted to know what others were experiencing with it.

Regards,
-Moses

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Re: QT Py ESP32 onboard wifi antenna signal quality

Post by adafruit_support_mike »

Sorry I couldn't give you any quantified comparison data, but being a few db down from a larger antenna sounds reasonable.

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