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I want to build a GPS tracker to put on my bike and I would like to use the smallest components to do it. The idea is to send the GPS coordinates to an HTTP server every minutes.

The problem is all the components I found for GSM or 3/4G are all too big (around 50x50 mm).

Does it exist smallest components? Or does it exist alternatives to send data to a server?

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  • \$\begingroup\$ Let's take a look at everything you need: A GSM antenna, GSM chip, the power management for such (as sending/receiving cellular data is power hungry), a GPS, GPS antenna, and a microcontroller to coordinate it all. Don't forget the battery. It seems that a 50mmx50mm solution for all of that (minus the battery I'm guessing) seems pretty remarkable, considering 50mm is about 2", so you are talking about a 4 square inch board. \$\endgroup\$ – Ron Beyer Dec 28 '19 at 16:42
  • \$\begingroup\$ @RonBeyer 50mm x 50mm is what I found only for the GSM chip. I didn't take into account the other components. Indeed, if the final result can have this size, it can be ok. Let's say, if it fits and can be hide on a regular bike, it's perfect. \$\endgroup\$ – Pierre Dec 28 '19 at 16:45
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    \$\begingroup\$ Any "correct" answers will be out of date in a month hence voting to close. \$\endgroup\$ – Andy aka Dec 28 '19 at 17:50
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Since product recommendation questions are off-topic, I'll answer the underlying question of

How small could a fully functional 2G/3G/4G module possibly become?

The answer to that lies in physics:

The wavelengths involved in these microwave cellular standards are in the range of 10 to 30 cm.

Efficient antennas are typically in the order of ΒΌ of the wavelength, but using very narrowband designs, or very high \$\varepsilon\$ chip antennas, you can maybe shrink them down to a couple of centimeters.

Below that, you simply can no longer efficiently capture (or emit) radio wave energy, and thus, can't communicate with the network.

So, antennas set a natural lower boundary for what is possible, size-wise.

You could of course try to move the antenna off-board (which might be very wise, if you plan to mount things e.g. in a pipe), but vibration-safe RF connectors are way more complex, expensive, and possibly not even significantly smaller than antennas.

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