Thanks for the detailed response, seems like you are very knowledgeable in this area. I guess the issue I have is that this product is intended to connect to WIFI in a residential home… so I have no idea what WIFI router/receiver the product will connect to and therefore can’t really do a link budget calculation or some of the more detailed analysis.
Is there anyway one could get a sense if the PCB trace antenna on a module is good enough to work with a typical WIFI router/receiver in such a situation? Or do I basically have to built it and test to see?
Thank you for the information, this was very helpful. This product is intended to connect to WIFI in a residential home. The enclosure is to be made of plastic. Sounds like the PCB antenna on the ESP32 should be sufficient… would you agree, or am I missing something?
Is there anyway one could get a sense if the PCB trace antenna on a module is good enough to work with a typical WIFI router/receiver in such a situation? Or do I basically have to built it and test to see?
The short answer is: Yes, build it and try it out.
The longer answer is that a good PCB trace antenna implementation isn’t really inferior to your other antenna options. The only catch is that you need to carefully observe any implementation details and avoid detuning it with nearby components or enclosure walls. Most vendors will provide a reference design with some guidelines (PCB material, nearby ground plane requirements, keep-out areas around antenna). Always start with that.
The reality is that you can’t make an IoT device work in every possible user scenario. I prefer to set a reasonable benchmark against my phone. If I can stream YouTube on my phone over WiFi in a certain location, my low-bandwidth IoT device should also work there. Your phone has the advantage of a highly optimized, sensitive front-end, but your IoT device has the advantage of ultra-low bandwidth.
Users can generally understand that if their phone can’t get WiFi in a location, it’s unreasonable to expect any other device to work there. On the other hand, they’re not going to be happy if their phone works fine but your IoT device cannot.
Thanks Tom… that makes sense. Appreciate the feedback as I’m new to IoT and wireless design and wasn’t sure how to go about making such a decision. When would it be appropriate to use a u.fl/IPEX style antenna? If you have some crazy long distance requirement or if your in a metal enclosure? Seems to me like there is no real advantage to using these… but what the hell do I know?!?
When you have too many variables you don’t understand: “When in doubt, test it out.” and apply the old engineer’s adage: “when in doubt, build it stout, out of things, you know about” or in this case, over design a bit.
You might also consider populating the board with both options. Place the antenna you want on the board, and have an MCX there as well. There’s probably a DC blocking cap in line before the antenna. Place it so that it can feed either the antenna or the MCX.
OTOH, just to play Devil’s Advocate, there’s something to be said for the approach of building your proof-of-concepts shoddily - if it works ok then, it can only get better
Offered in the same spirit: One of my favorite, and almost certainly apocryphal stories is about the guy who value engineered a product by removing parts until it stopped working - then added the last part removed back in and shipped.
My preferred mode is to overbuild and trim. Not quite the same thing, but sorta kinda. I’d like to get to functional and then see how much I can shoddy it up.
Customers always seem to want it good, fast AND cheap. Most will settle for good and fast, albeit often grudgingly. I’ve not met one yet that will settle for fast, cheap and non-functional. They may accept the risk, but rarely if ever accept the (non) results.
Really? That sounds like an urban legend to me… Take 3.3v to 5v level shifters, I’m sure you can take them out in 99% of projects and it will continue working. Question is for how long and what happens the day the 5v supply runs at max spec’d voltage. Or take ESD diodes, every circuit works great without. Fuse of any type: out. That doesn’t make much sense.
What makes a lot of sense to me is the concept of throwing everything you may need in and then once it’s working figuring out how to simplify. It often means that when one part of the circuit changes 'cause you didn’t really understand the datasheet/requirements/timing/whatnot then other parts don’t have to change 'cause they’re robust and self-contained. And then later once it’s all working you can see redundancies or defenses that are not needed and pull them out.
I never, ever want to ship something that only barely works, or is shoddy. But validating concepts by building the first test prototype(s) sloppily is a way of ensuring that there’s plenty of margin and that after the design is refined and built using good practices, it will be bulletproof. Using the best materials and best practices on the first go-round tells you nothing about margin - it may work only because you built it so carefully.
I think where we differ (and I suspect not really) is that I overbuild, test, and measure the margin to know how much I have to work with.
It’s a rare project I have much time to spare on, and any time reserve I do have to spare, I want to retain for dealing with “unkown unknowns.”
Of course I also build as many alternatives as I can reasonably get away with. One that I know will work and some that might work and offer other advantages like cost or size/weight/power.
Some of this is a reaction to working for a company a while ago that always picked one path for a project in the name of ‘efficiency.’ We had a lot of expensive do-overs and delays. I did not find that very efficient overall.
Sure, I design the heck out of something once I’ve decided on an approach. But my initial test is often a bodge of clip leads, substitution boxes, bits of boards from other projects, and junkbox components. If it feels too finicky I may look for another approach; if it works or I can easily see what’s needed to make it work, then on to proper design.
I believe you may be describing “Muntzing”. Building a “works well enough” product for the biggest audience of “80%” customers. A fascinating read which you can find and discussed all around the web.
If you’re using a module with an integrated antenna, the performance will likely be very poor. Often this is OK for BLE products. The reason is because simply mounting the module onto a PCB will detune the antenna. Plastic enclosure also detunes the antenna. In order to get datasheet performance, you need to do exactly as they did in the datasheet.
So use the u.FL or spin your own embedded antenna that’s external to the module, if performance is important at all.
Tuning the antenna will often matter more than the antenna design itself. Just recently I improved the sensitivity of a BLE device by 20dB, just be re-tuning to account for the plastic enclosure.
Ah! Yeah, I do this too. What I was responding to had me in an RF PCB mindset, and that’s a bit different case. Even so, I often do something similar with RF. I’m sitting here digging through a ziploc full of SMA jumpers to string together some connectorized modules to make a measurement. I’ll often sim stuff first where I have the tools to get past the egregious logic errors and oversights, but have a lot of elephant’s nest concept proofs as well.
I have a friend who’s best described as an “antenna whisperer.” He’ll do the occasional sim, but mostly he will bodge something together, or do a quick PCB and trim and tweak that. He claims (and I’ve witnessed) he can usually do that and have results before the first sim is complete. He’s not a hacker - he just has such a good intuitive understanding of what’s going on that he doesn’t get much added value from the sims.
Yup, though I think the legend has grown a lot with the telling. I’m dating myself, but I’ve actually repaired a Muntz TV though they were mostly out of the TV manufacturing business by then. Madman Muntz was undeniably a character though. I think Muntz Stereo still has stores in the LA area.
Man, this thread has drifted. Shutting up now sir.
