Update: I switched from nylon ties to steel cable to attach a luggage tracking tag to a suitcase. See blog article.)
I use luggage tracking tags. As you can see from the map at right, it looks like my medium-sized suitcase is at Porto Airport in Portugal. Actually the suitcase is with me right now at home in the mountains of Colorado. What explains this?
I use Tile tags to track my luggage. So far they have worked perfectly in the way that umbrellas work. As is well known, the mere fact that you went to the trouble to carry an umbrella tends to reduce greatly the risk of an unexpected rainfall. And, in the years since I started using Tile tags to track my luggage, not once has an airline lost any of my luggage. The tags do not cost very much money, and I feel it has been money well spent.
(Tracking tags have a “network effect”. What you want to do, if you are smart about it, is to use tags from some ecosystem that has many other users. You want it that somebody else’s smart phone might detect your lost suitcase and report it to the cloud, so that you can learn the location of the suitcase. There are two ecosystems that have enough users to make it work — the Apple airtag system, and the Tile system. I prefer Tile.)
On a recent trip something odd happened. I was on a flight from Colorado to California, and I clicked on my phone to see where my suitcase was, and was astonished to see that the suitcase was somewhere in Illinois. Upon my arrival in California, I was greatly relieved when my suitcase arrived on the baggage carousel as if nothing were out of the ordinary.
A week or so later, I clicked on my phone to see where my suitcase was, and I saw what you see above. The suitcase had come to rest at Porto Airport in Portugal.
I think the alert reader will arrive at the same explanation that I have arrived at. What must have happened is that the tag got snagged on something in the cargo hold of the airplane. And the tag got knocked loose from the suitcase. And, in the belly of the airplane, the tag then went on walkabout, first to Illinois and then to Portugal. Eventually somebody went in with a broom and swept out the cargo hold, and the tag is now somewhere in a trash heap in Portugal.
When I looked at the suitcase recently, indeed the tracking tag was missing from the suitcase. I have just now attached a new tracking tag to that suitcase.
That’s why I put the tracking tag IN my luggage 🙂
Ah but the signal travels much further (and thus is much more likely to be detected) if the tag is outside the suitcase.
My tracking tag lives inside a stick-on, screw-top tag holder that I affixed to the inside surface of my suitcase’s (plastic) shell. What’s nice is that my suitcase has a zippered lining attached to that shell so that, once I zip-close the lining, the tag holder underneath remains unseen but accessible (for battery replacement, etc.).
I was not aware that concealing the tag inside the suitcase would significantly reduce its ability to communicate. Doesn’t the tag manage to work through greater barriers to its signal, such as airplane fuselages? I didn’t think that a plastic suitcase shell would add much of a communication burden.
Every layer of material cuts the signal strength by some amount. In your case you are adding two layers of material — the suitcase itself, and the tag holder.
It does not shed much light on the question to do, say, a single test in which the tag inside the suitcase manages to send a signal that is picked up by a cell phone that is ajacent to the suitcase.
When the time comes for a suitcase to be “found” at some random airport, what you want very much is that a smart phone that happens to be, say, 30 feet away is able to pick up the signal. And that smart phone is what sends the happy news to the cloud and thence to you.
But the suitcase itself might cut the signal enough that the smart phone that you hope will find your suitcase will now need to be within, say, 27 feet instead of 30 feet. And the tag holder might cut off another two feet of range.
Yes, hopefully no matter how many barriers one places between the tag and the outside world, eventually somebody’s smart phone will happen to be so very close to your suitcase that it picks up the signal. And that is when you find out where your errant suitcase went.
Seems to me that there is a choice here between (a) reducing the effective range of the tag by some unknown amount by placing the tag inside the suitcase, and (b) placing the tag outside the suitcase and risking its loss or theft. Out of curiosity, I searched for online resources on the subject. Most recommended keeping the tag inside the suitcase for the reasons mentioned but no one seems to have experimented with how much doing so cuts the signal. I suppose that you could experiment with the tags, keeping one inside a suitcase and one in your preferred preferred tag holder outside the same suitcase, to see if there is any difference in tracking ability.
Talk to any radio amateur among your acquaintances. They will back me up when I say that there is no need to do such experiments to find out the answer. I already know the answer and your radio amateur friends already know the answer. Any layer of material between one antenna and another antenna will attenuate the signal. It is quite predictable that adding a layer of material will reduce how far away the cell phone can be and still pick up the signal.
And if the suitcase happens to be damp (suppose it gets a bit of rain on it while being loaded on or off the airplane) the dampness will further attenuate the signal.
I urge all readers to get a ham radio license and hang out with a few other hams and gain experience with stuff like this.
Is there some reason you can’t place your tag inside the suitcase? Does that interfere with the location abilities? I use Apple Airtags, and I usually just drop one inside my luggage when I travel. I have not noticed any dropoff in the Airtag’s ability to report its position, and keeping it inside would seem to make it at least somewhat more difficult for a bad actor who wanted to take my suitcase to dispose of it.
Ah but the signal travels much further (and thus is much more likely to be detected) if the tag is outside the suitcase. Talk to any radio amateur in your acquantance and they will back me up on this.
Might I inquire what you use to attach the tag to your luggage that allowed it to decide to depart your suitcase and travel independently? I’m thinking I have a solution. 😉
thank you for posting. I used two nylon cable ties.
Since then I have wondered if maybe I should use duct tape.
My last trip to Colorado, I had to change planes in LAX. There United decided my luggage had to wait for another jet, while I happily made my connection to Aspen. Then I saw my bag in Nebraska as the flight it was on to Denver was diverted for weather. It eventually made its way to Denver then Aspen. All inside the bag.
Carl is correct, but maybe he should have used metal cable ties.
WA0KAN
Agreed. Metal cable key chains for example.