Zooz ZST10 USB Stick; External Antenna

Curious if someone smarter than me in this area has any ideas. I have a Zooz Z-Wave stick that I was curious about swapping to an external antenna. Cracked it open and they're using a coil antenna with a single connection. My idea was to solder on a U.FL to SMA connector, but was unsure if I needed to be making a special consideration for the antenna. A quick Google says the ground path really only comes into effect for 1/2 wavelength antenna, so maybe a full length would be it?

just a guess but don't those two pads look like a place for a surface mount U.FL connector?

Screenshot 2023-05-13 at 2.55.20 PM

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You might be right. Ooo...I also presume if so, then it's a switched circuit so I don't even need to remove the coil antenna.

Doesn't look switched to me, just a 50ohm matching circuit from the chip then another to match to the coil antenna.. but that's just wild guesses really.

The more I look, the more this looks like U.Fl:

Screenshot 2023-05-13 at 4.02.03 PM

My guess is that you'd want to remove the coil antenna.

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Thanks man!

Got a chance to test this out. I opted to add a lead wire vs having to heat the coil antenna to get it straightened out. I also wanted to keep the coil intact in case this little experiment didn't pan out.

Using a full-wave antenna I was able to get some nice bumps in signal.

Coil antenna:


Device 2 is a ZEN21 that's about 12' from the dongle in the same room.
Device 3 is a ZEN22 on the opposite side of the house.
Device 4 is a GE Fan Switch in the same box as the ZEN22.

I just realized all three devices are 500 series chips. Probably should have tossed in a 700 for good measure, but too late now.


With a little 3D printer magic, we've got a case.

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Download the Hubitat app