Increasing RFID card range without modifying transceiver? - Page 1
Forum section: electronics / beginners

author: frenky
author_rank: Unknown
timestamp: March 09, 2016, 02:07:06 pm
content: At work we have a ramp for parking that opens when you put passive RFID card near the card reader.This is very inconvenient when it's raining or snowing because car gets all wet.If only there was a way to increase range of the RFID card so much that I wouldn't need to open window? Let say 2 feet (cca 60cm).Doing anything to the reader unit is of course out of the question.I was looking at this:Quotehttp://www.priority1design.com.au/rfid_design.htmlSo the question is:Could the card to modified in a way that would draw the same amount of power from the reader field, just from further away?

author: viperidae
author_rank: Frequent Contributor
timestamp: March 09, 2016, 09:08:18 pm
content: Tape the card to a stick, wind the window down just a bit and poke the stick & card combo out the window.It'll stop your arm getting rained on and stop most of the rain and snow getting in your car.Sometimes more technology isn't always the answer.I guess the other answer would be to copy the RFID card to an active card that has a battery. The problem you've got is the chip in the card needs to get its power from the reader. The power will be too small as you get too far away.

author: uncle_bob
author_rank: Unknown
timestamp: March 10, 2016, 01:14:31 am
content: Quote from: frenky on March 09, 2016, 02:07:06 pmHiIt's actually quite simple. All you need is a high gain antenna on top of the car and the ability to steer it directly towards the reader. If it's a multi element Yagi should do the trick pretty well.First step would be to work out which RFID band the card is operating in.If it's in near field on the normal reader, you will find that things drop off pretty fast. 2" to 10 feet could easily be a 20 log (2/120) = 35 db sort of issue. You have loss in both the "forward" and the "reverse" directions so the total distance adds up pretty fast. Why 10' ... If it is a 13.5 MHz system ... it will be a pretty big antenna.Bob

author: viperidae
author_rank: Frequent Contributor
timestamp: March 10, 2016, 08:33:59 am
content: frenky, I thought passive RFID used inductive coupling to power the tag, hence why they use a coil and not an antenna.Can you inductively couple to a yagi antenna?

author: Rerouter
author_rank: Super Contributor
timestamp: March 10, 2016, 08:47:48 am
content: Figure out what the card type is, and build a repeater, your device reads the code in, then punches it at the reader outside at a much higher power,

author: generic_username
author_rank: Regular Contributor
timestamp: March 10, 2016, 01:34:40 pm
content: viperidae's idea might be the best practicable sollution.even with active types it is not easy to get past 0.1m.So either try uncle_bob's sollution or try the stick -I'd try the stick

author: tigrou
author_rank: Regular Contributor
timestamp: May 29, 2022, 06:48:08 pm
content: I was going to ask the exact same thing for the exact same reason.One day a guy with a forklift saw me entering the parking lot and use some sort of remote to open the gate (letting me enter without me to use RFID card)I'm wondering if it's using a different technology than RFID or if it's RFID powered by some battery (increasing overall range).