How to protect Boron Cellular modem when Antenna is disconnected?

I read that you should never have the boron running without an antenna connected.
I have an enclosure that allows for an external antenna which could be powered up without the customer having installed the antenna. I see that the BLE antenna allows both the on chip antenna and the external, could I rig a Y-adapter and use an ‘internal’ antenna inside my enclosure to ensure that it never doesn’t have an antenna plugged in?

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HI @tunahammer -

Interesting question indeed. I am just not sure what the effect then would be if they do actually connect the external antenna. Would you then in essence have 2 antennae connected simultaneously?

Personally I always try to find a solution where the device could not be powered on if everything was not connected, sort of like a dead man’s switch if you want. I recently kept the EN pin LOW on a Voltage regulator using couple of MOSFETs and Hall Effect sensor, until said external device was present which then flipped the HAS and latched the MOSFET circuit pulling the EN pin HIGH on the Voltage regulator turning the device on.

It might not be to answer to your case, but is generally how I approach things if needed. Then again… what do I know :grinning_face_with_smiling_eyes:

Good Luck!


Is it absolutely necessary to have the external antenna option? Unless the enclosure is metal, these PCB adhesive antennas are as strong (if not stronger) than most ducky antennas when it comes to LTE-M.

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I agree with @LloydChristmas - those flex antennas are actually really good. But I have had the occasional instance where the device would be inside i.e. metal enclosure. In these cases we used external antennas.

Also note (I stand to be corrected and probably depends on your country) but when you use any antenna other than the flex ones (which already carries certification thanks to efforts from Particle’s side) you might have to get this done yourself with the specific antenna you use. .



Those flex antennas are great - but what do you do if an external antenna is necessary to not damage the Boron?

Hi @AHolla -

Welcome to the forum!

I would say first we need to establish exactly what damage (if any) could be caused by starting up a Boron with no Antenna connected. In my experience, we have not had any problems caused by this. Maybe we were just fortunate :slight_smile:

In terms of how I approach such matters, I usually try to find some hardware solution to keep the device from starting up if all peripherals aren’t connected. Easier said than done with something like and antenna where you do not have any form of power or ground wires running that you could use to toggle either interrupts or EN pins. I would probably construct a custom bracket that would allow from placement of some sensor to detect the presence of the antenna, could be as simple as a Reed Switch.

Let me see whether I can confirm the “damage” that can be caused, I will let you know as soon as I find out. Maybe someone else can shed some light in the meantime.

Kind Regards, Friedl.