RFID Senior Project


I am writing this post to inquire the bright minds on this forum about an RFID design project. I am taking a senior design class where our project idea is an RFID Inventory System. We are aware that these systems exist, however our idea differs in the sense that our reader will emit a constant field and when the tagged items are brought in range of that field, the system will register it. So rather than bringing the reader to the item and individually scanning it, our idea brings the items all at once to the reader. This brings up some questions, the most pressing being which range to use, 13.56MHz or the UHF range (800-960 MHz). We are leaning towards the 13.56MHz range for purely cost reasons, however our research seems to indicate that achieving our 1-2m range would be difficult. This explains our other option of the UHF which gives us increased range at a price.

Also, given our $600 budget, we are hoping to build our own reader, similar to the famous (infamous?) Arduino example here (http://playground.arduino.cc/Main/DIYRFIDReader). We would change the values to fit our required range, which leads to our second question about the antenna? None of our research was able to show a relation between the antennas design and its reading range. Is it possible to design an antenna in the 13.56 MHz range that can read a 13.56 MHz passive RFID tag up to 2m away? If we had to design the antenna in the UHF range, how could we ensure it would not read farther than 2m?

I have read many of the forum posts on here about RFID, and have seen the bright minds that respond to them. I am eager to learn and hear what you have to say, and I anxiously await your responses. Thank you!

How do you keep mulitple RFID tags from responding at one time? I would think that would interfere with the readings.

Maybe start by testing with this: http://www.adafruit.com/products/789

Thanks for that link CrossRoads,

That shield looks cool, unfortunately the built in antenna limits our range to 4 inches. This could possibly be overcome with an exterior antenna which leads back to one of our original questions about antenna design.

and you know this from what?

melonsdg01: and you know this from what?


thanks, you guys are about as helpful as a bag of sand

Just because you don't like the answer...

Using Google on "maximun rfid read range" I see: 13.56 MHz. High Frequency (HF) Passive RFID Tags - maximum read distance of 1.5 meters (4 foot 11 inches) - usually under 1 meter (3 feet) and you can use a single or multi port reader plus custom antennas to extend the read range to longer tag read distances or a wider RFID read zone. To obtain more than 1 meter you need a reader with more than 1 watt RFID output power. 860 ~ 960 MHz. Ultra High Frequency (UHF) Passive RFID Tags - minimum read distance of over 1 meter or 3 feet. Gen2 tags can have a read range of up to 12 meters or 37 feet, however new generation of IC's plus antenna designs are now pushing this distance to over 15 meters!

which would suggest maybe you want the 800-960 over the 13.56. Disclaimer: not a "bright mind" with regard to RFID.

melonsdg01: thanks, you guys are about as helpful as a bag of sand

If this is truly a Senior project then you better shape up and start acting like a senior. If you ask the impossible be prepared for the answer.

For an inventory system you need to be able to read multiple tags in a field. While there are some 13MHz tags that will do that they are specialized and you are better going for the higher frequency.

If you ask the impossible be prepared for the answer.

and that answer would appear to be the sarcastic wit of a geriatric. Interesting in how only after making a berating comment, was a helpful opinion offered.

In keeping with this observation, any thoughts on controlling an antenna read range thou bags of sand?

You started this attitude in reply #4 that sets the tone. Guess what, you are asking someone for something you don't have, if you had any smarts you would be polite about it. I know about RFID because I used to design them for a living. I am happy to shair this knowlage with any one who asked nicely. So that's you ruled out isn't it.

Grumpy_Mike: You started this attitude in reply #4 that sets the tone.

Tell me how you can interpret "tone" through text?

Is it that much of a stretch to think that I'd expect a detailed answer to a question as long and detailed as mine was? I had established I wasn't thoroughly familiar with antenna theory, so is it out of line to ask for more information about the answer rather than take it at face value?

JohnLincoln didn't misunderstand my reply as he posted a source where he got his information from, which was helpful.

You immediately assumed the negative, which is a common characteristic of people like you. Negativity begets negativity.

Good luck with your project.

I think you've probably got what you're going to get from here.