I have 5 gates and a moving car. I would like to know in which gate the rc car just past by. The gates does not have a power source. First I thought I can use rfid to identify the gate number from the car, however this requires to much power in order to read the passive tags from a 20cm distance. The other idea is to use something like the bar-code scanner with my arduino. Can anybody recommends other easy to implement solution on an arduino?
I've used RFID sensors and tags in a product. The RF tags we used are for short-range stuff. The UHF tags are used for detecting objects from further away, such as containers on lorries from 15 m away.
The UHF readers are off-the-shelf and readily available. You will get a code from each tag so you can tell vehicles apart.
The downside is that the readers are expensive. You don't mention a budget so I'll leave you to weigh this up.