Sensing proximity (around 1 meter) without a proximity sensor, maybe RDIF ???

Other Hardware Sensors
1

Hi,
I'm interested in developing an device with arduino that can detect proximity to an object/place without touching the object.
This is like registering race participants completing the race at the finish line, but the registration is made not by a device at the finish line, but by a device that each participant has on itself.
So, the device (arduino, preferable) should be able to sense the close proximity (max 1 meter) from a place, without touching the point or coming too close to it.
I know that hall sensors can be used, but their range is way too short.
I'm thinking about RFID, but I never used them and I need help (pointing) to the right direction for a range of max 1 meter.
I'm also open to any other suggestions that may accomplish the same goal, the cheaper the better

Thank you for your attention.

2

For accuracy of time registration it's going to be MUCH easier and cheaper to have the runners carry a passive tag, and some kind of security gate at the start and finish where they walk through, and which registers when which tag passes through. A passive RFID tag will do. Those things are cheap enough to be disposable nowadays (it's used for tagging air luggage)

3

Yes, I know what say say, but in my case I prefer to have the individual device register the event as it will need to do some other custom actions.
If I use passive RFID tags, can that trigger an action on the arduino?

4

An Arduino can be interfaced to an RFID reader, and take various actions when a tag is read.

There will be time lags and possibly interference between tags, so resolving "photo finish" races is probably out of the question.