What would be a typical WIFI range for ESP32-C3 Mini Dev Board?
Hey there, @Rod321444,
With any WiFi project, the limiting factor is going to be the antenna that youâre using. The ESP32-C3 Mini Dev Board 's donât have a particularly large antenna, but a small ceramic one directly attached to the PCB. The Datasheets donât even include any specifics about the hardware. My rough estimate is that itâs going to be on the lower side of tens of meters, maybe fifteen at most.
If WiFi range is important for your project, I would go with something like the Seeed Studio XIAO ESP32-C3 | Buy in Australia | SS113991054 | Core Electronics. The Xiao Range are my personal favourite ESP32s at the moment and that sentiment is pretty much the same throughout the CS and TS offices. Pair it with a 2.4GHz Rod Antenna for XIAO ESP32C3 (SKU: SS103990623) and youâll be good as golden.
Tks for the info
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Im not really a fan of the âhow farâ can something go with radio.
there are many factors and antenna quality is just one of them.
What is between the two points will have a big impact as well.
Even if you can connect, can it connect at the speed you need ?
e.g. as you get further away from the AP, your speed will go down in order to maintain a stable connection.
From memory Wifi power is inverse-square.
i.e. as you double your distance from the AP you get a 1/4 of the power at the node; then faster if not line of site.
Of course this is linked to how good the signal is to start with.
With most systems, the best option is always to test with the gear you would like to use.
Hi Michael
I think the it would be a brave soul who would answer the original question with any degree of certainty.
How true.
That is why with serious systems a radio survey is usually done as you mention here
This will either confirm or disprove path calculations or predictions. One curly one with point to point systems is âFade Marginâ, ie; how much do you need over and above the expected threshold to allow for worst case fades. The design engineers have to come up with some sort of figure which depends on lots of things, including your position on the planet and direction of propagation.
I donât think you can worry about much of this in trying to establish an answer to this query but these things are there and it does no harm to get an appreciation of what is involved here.
Cheers Bob
Thanks Bob. I plan to do a lot of component testing and see how far I can push performance so I have confidence that high demand and reliable connectivity is well below max testing thresholds. I needed a bit of a starting point so I donât waste time and money od devices that havo no chance to cut it!
Cheers
Macka
Hi Rod
Just a starting point. I would make sure to get a device with a decent antenna. Not sure how these PC board antennas perform and I donât think there is too much published. This really is a key component in any communications system.
There is an old saying that you can have the best transmitter or receiver in the world but if you have not got a decent antenna to go with it you might as well have a piece of string. In other words you are wasting your time.
Cheers Bob
Agreed Bob.
Jane made a good suggestion, Seeed Studio XIAO ESP32-C3, with external antenna. Most of my devices in my system will be direct line of sight, through shade cloth or greenhouse film and relatively free of intense WIFI traffic. As long as I can get to 30m range all will be good. I also concur; my research seems to indicate most devices with copper track antennas have poor range or reliability issues.
Thanks heaps
Hi Rod
I think the âexternal antennaâ bit here will be important.
The 30m could be questionable though. This is something you might have to âsuck it and seeâ.
If it is only a single path and both ends are fixed ie; not mobile or moving around you might have to consider directional antennas. I think Yagis are available for this kind of use. At a minimum you should use external vertical rod or whip antenna, probably at both ends. These will be omni directional and as such will waste a lot of power transmitting in unwanted directions.
Remember antenna characteristics are the same for both transmitting and receiving.
For best results both antenna polarities should be the same (horizontal or vertical)
If using a mixture of antennas say a Yagi and Whip the whip will be vertical so the Yagi should be rotated vertical to match
Cheers Bob
I would be inclined to run some tests if you have the devices already.
While not the distance you are talking about⌠this is an example.
ESP32 S3 - PCB Antenna (not ceramic or external).
Inside PLA project box, sitting behind a 3.2" LCD touch screem; but back a little bit of to one side a bit⌠i.e. not perfect, but not worst case either.
Im about 15M from the Access Point and the signal is going via 2 internal walls to get to the Access Point.
The following image is the report from the WiFi AP
Note: the 7h up time was due to me resetting it this morning, not that it lost connection.
but -48 dBm is very good. and the 60-70Mbs on a single channel 2.4Ghz is damn good.
I am impressed to see that Unexpected Maker (who Core is a stockist of) latest âseries Dâ of ESP32-S3 boards incorporate both onboard and external antenna options into a single board, with user controlled (via code) RF switch to select the antenna output for each project. Of course the S3 is more processing power than you need ⌠but there are certainly more boards with u.FL connectors than there used to be.
I know I have said it before ⌠I understand the use of unidirectional antenna on a Wireless Access Point - but most of the individual devices are expected to connect to only one WAP, and so Iâm surprised that small directional antennas are not readily available. Yes, there are YAGI and other directional antennas, but they are designed big for long distances.
Hi Donald
They are. I just had a quick Google and found quite a few that are rather large. About 50cm plus for a gain of about 16db (i ??) Unfortunately with Yagi style antennas gain comes with length. That is physics and there are no short cuts. 16db is quite a bit of antenna gain though and depending on the distance required could be somewhat an overkill.
I did not search further than 1 google page but I donât see why smaller (with corresponding less gain) would not be available. Ebay seem to have quite a few etched on a double sided PCB. Most have a claimed gain of 10db but I think even if this were dbi the 10 could be questionable.
This is a very interesting web site I would suggest you have a look at.
A TI application note with all the design figures and details. Something you could make up yourself if you are conversant with PCB manufacture. This is a Yagi with a quoted gain of 7.2dbi which is believable. Size is 100mm x 150mm which is very manageable.
Cheers Bob
Thank you Bob for that link !!!
Previously when i looked on AliExpress i saw so many different styles claiming directional - but without any documentation to suggest which direction to point them - that I couldnât trust any of them. However this TI application note provides that confidence.
As it happens my Greenhouse is within reach with its ESP32âs on-board antenna, so i didnât need to go down this path ⌠but it is reassuring to know that small directional antennas are available.
Hi Donald
Yes AliExpress and other similar are pretty stingy when it comes to important documentation. I have made a couple of purchases from here but I mainly avoid for that reason. Even components are unbranded and mostly unmarked in any form.
With this particular link the same definitely cannot be said of TI. The amount of info in fact could be said to be overwhelming. There might possibly be something but I canât see anything they havenât covered. Fairly typical of TI data in general. The results tabulated seem to be actual measured figures.
As I said there are similar antennas on Ebay with the same number of elements but somehow quote 10.5dbi which I think is a bit optimistic as TI MEASURE 7.2dbi for pretty much the same thing. The gain of a Yagi is pretty much controlled by the number of elements and thus the length and there is really no magic way around that. Even stacking 2 Yagis with the optimal spacing and phasing will only increase total gain by 3db. If you stack again to result in 4 Yagis only increases by a further 3db. So to get a 6db increase the antenna size has to increase by 4 and everything has to be going right at that.
Cheers Bob
Just keep in mind that 2.4 Ghz wifi is spread spectrum, as such you donât need a lot of power for it to work. Line of site can go a fair distance.
that said when looking at external antenna dont for for the total budget.
TX Power minus connectors and coax plus antenna gain.
The lost in the coax is normally ok as long as you keep it as short as you can and use a good low loss coax.
Also, with wifi the âpower is meant to be measure at the antennaâ Equivalent Isotropically Radiated Power (EIRP)
Some googled (not verified) numbers.
20 dBm (100 mW) in Europe (ETSI) and Australia
The maximum transmit (TX) power of the ESP32-S3 Wi-Fi module is 20m
So if the TX of the ESP32 is already 20dbm and you have 0.5 dbm loss in the coax and 6 dbm Gain your net gain of 5.5 dbm will put you over the limit.
As such, in theory you are meant to lower the TX power from the transmitter such that at the antenna its the 20dbm. Why do this⌠simple a high gain antenna will pull in weaker signals⌠thus letting each end âhearâ more
Hi Michael
I am not totally familiar with WiFi requirements. For instance I thought that TX power was just that, TX power INTO the antenna.
If it is EIRP then I would understand references to reduce the actual TX power, I assume the idea here is to reduce TX power to get the EIRP down to the legal maximum although I donât quite know just how the hobbyist would measure this. You would have to go with published antenna figures IF YOU CAN FIND ANY. This would depend on the antenna manufacturer and vendor. The cable attenuation figures should be readily available that is if you can find out what cable it is you are using.
OK, letâs say we have that sorted. We have the legal EIRP by reducing TX power. So we have lost a bit.
One important point. Any antenna has a set of characteristics which behave EXACTLY the same for TX and RX.
So even though we have had to reduce TX power into the TX antenna if we are using directional units such as Yagis t would be reasonable to assume that we have a need for directional properties and we would use the same antenna at both ends of the path. This means that the net gain from antenna - cable loss is still available at the RX end so as you say the RX end will âhearâ a bit more.
So even though we may have had to reduce TX power we still have a net gain overall. And we have kept the RF energy where we want it without scattering it around useless directions. That is how we get an apparent gain. The antenna is passive so does not amplify anything to increase power it just manages what is given to it more efficiently.
Cheers Bob
I have used a seeedstudio esp32 c6 (?similar to C3) about 50m away from the house in plastic shed. There are no trees in the way. I did not use the external antenna. The router is is in the house and the signal would have to pass a cupboard door, living room and window. I did not expect it to work so just try it and see.
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Yeah. The eirp i beleive is to allow for a fair range v allowing many users.
The esp32 at max power should be just under 20 dbm. So if adding a 6 dbm gain drop the esp to 20-6=14dbm TX power.
Of course like many of these things, is normally only policed if there is a reported issue. So an attempt to do the right thing will go a long way. I have seen plenty of people put their home wifi into US country code that allows for higher signal levels. At work i have been imvolved with requests for us to lower our power to help the business next door. We have always been within spec, which their reports stated, so people do check when they have issues.
The issue i see with 2.4ghz is it goes too far. We have some APs that have so mach co channel interferqnce from other APs that it cant keep a stable signal. Our AP software reoprts over 10,000 other 2.4ghz AP that we can hear that are not oursâŚ
Hi Michael
All so very true. There are lots of 2.4G signals around, even the humble microwave oven. Although if an oven leaks too much RF out of the âboxâ it really should be discarded as unsafe.
Even my after market reversing camera is 2.4G with the TX at rear and a RX unit up front. When reversing out of my driveway I get all sorts of interference from local signals but I recognise it for what it probably is (local WiFi) and live with it. Does no real harm.
Adjacent channel interference is closely monitored and strictly controlled by the licensing authority. Usually caused by incorrect modulation producing out of band sidebands. This was so with the old analog TV system and an area that was closely monitored was a little known TV channel between 9 and 10 known as CH 9a or CH 9and a half. This is where the old VHF aircraft DME was located. If CH 9 over deviated the sound TX or CH10 vestigial sideband filters malfunctioned would cause unwanted sidebands in that reserved area could cause all sorts of problems. CH 10 operating frequency was actually shifted up by 1MHz to help this isolation. Frequency allocations were such there was no CH11 anywhere a CH 10 so sheer distance provided this particular separation.
I have not checked completely but to my knowledge there is still nothing in that slot, 202 - 209MHz even though the modern DME has shifted out of that area, much to the disappointment of most commercial airline pilots I believe.
I am interested now so will have a look later
Cheers Bob
All I want to do is put some sensors around my greenhouse to ping environmental readings back to a central device with WiFi. The question was âwhat sort of range I can expect from an esp32 board?â. Thank you, Stuart, you seem to have achieved more than what I am wanting to do coz I wonât have any walls, windows, living rooms or cupboards in the way and the longest distance is most likely to be less than 30m. All I was asking for was what real distances members had actually achieved.
