It will be recalled (blog article, April 30, 2026) that recently I had a luggage tracking tag get knocked loose from my suitcase and the tag ended up at an airport in Portugal. Thanks to comments from loyal readers, I was inspired to try harder on this.
Until now my way of attaching a luggage tracking tag to my luggage was nylon cable ties. Readers asked, why not simply place the tag inside the luggage. Then it cannot get knocked loose. The answer to this, as any of your amateur radio friends or electrical engineer friends will tell you, is that putting the tag inside the suitcase necessarily attenuates the radio signal (which is Bluetooth Low Energy) and means that if anyone’s phone is going to detect the lost suitcase, it would need to be closer to the suitcase to pick up the signal.
To say this another way, if you want to minimize how many hours or days pass before somebody’s phone picks up the signal, you would be daft to place the tag anywhere inside the suitcase. The correct place for the tag is outside the suitcase.
At the time of the previous blog article, what I did was to repeat my previous mistake of relying on nylon cable ties. And rather predictably, yet another tracking tag went on walkabout, this time to a resting place at San Francisco airport.
After my posting of the previous blog article, alert reader Debra M. Konnerth suggested I use stainless steel cable.
This prompted me to realize that in my toolbox I already had some ¹⁄₁₆-inch cable made of 304 stainless steel, and matching crimping sleeves. In the photo you can see the bolt cutter (top left) with 18-inch handles, and the swaging tool (bottom left) with 16-inch handles. You can see the ¹⁄₁₆-inch cable at bottom right and the crimp sleeves at top right.
As you will see from the photo at the top of this article, I chose to use two sleeves.
Now let’s see if this tracking tag gets knocked loose.
Thank you as always for the helpful suggestions in the comments in the previous article.
Well now for the price of one more tag you can run an experiment next time you fly. Put one inside as well, and see how often you only see the one on the outside.
Of course you are right about this. I guess a thorough study would be across several flights in which the two tags would trade places being the “inside tag” and the “outside tag”. The goal being to minimize the effects of manufacturing differences in the batteries powering the two devices, and in the devices themselves. But you are right that one could do productive experiments.
I have often been on a flight, seated as usual in the passenger cabin, and my phone has been able to pick up the tracking tag on my suitcase that is in the luggage hold in the belly of the airplane.
The thing is that as a radio amateur, I have accumulated quite a bit of experience with devices that are sufficiently analogous that I would not need to do any experiments here to predict with high confidence the outcome of this kind of experiment. For example the tags used in LoRa mesh systems (see https://mesh.oppedahl.com/) use the same wavelengths as the luggage trackers (2.4 GHz) and the same modulations (Bluetooth Low Energy). The nodes that connect with them report RSSI and SNR and noise floor.
Doesn’t the impact of having the tracking tag on the inside of the luggage on the ability of other devices to detect the tag depend on the materials from which the luggage is constructed?
I would expect suitcases made of conventional resin-based materials to be nearly transparent at 2.4 GHz; the hard-shell aluminum suitcases to be fairly efficient shields (only fairly because some don’t have conductivity where the clam-shell elements mate); and carbon-fiber items to have significant attenuation (but hard to predict because the weave and grain vary among makers).
I have tested a 2.4 GHz WiFi device inside and outside a laptop bag. No difference in signal strength (as measured by the WAP in the device-to-WAP direction) was apparent, at least within the limitations of my unsophisticated testing methodology. If there was an attenuating effect of placing the device in the laptop bag, it was confounded by the much larger effect from small displacements of the device. (My RF testing world headquarters 🙂 is advantageously equipped with extensive RF shielding embedded in the walls and ceilings. )
Of course you are right that the materials choices made by the luggage maker can make a big difference.
My bags these days are all carbon fiber and yes, I would expect it to be a little bit of a faraday cage.
Nylon zip ties are not remotely as strong as one might think — that’s why the ones used as handcuffs by the police are so massive.
Steel wire should hold up better, but the smaller the loop, the less likely it is to get snagged on something. (Snugly cinched leather and plastic tags have never failed me, over decades of travel.)