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Well 13.56 MHz are close range tag <10cm or so and always used in smart card, auto immobilizer.. For 125 kHz are use for long range tag (can be detected up to 1 meter). It is used in animal identification and others..
Well, the existance of so many standards make the difference blurry. Both are close range, the vast majority of the readers works up to 10cm, and of course, there are complex readers which are able to read from higher distances. The difference is at the performed functions (besides the operating frequency). Most of the 125khz cards are read only, meaning they have a unique code hardwired, the reader get the code in clear form, and that's all. The 13,56mhz are more complex cards. Some of them have advanced functions like reading/wwriting data, communication using encrypted protocols, etc. They are more suitable for ticketing, secured access, etc. The difference in the operating frequency imposes a difference in the reader construction. For example, the antenna for 125khz reader is made with copper wires, due to the relatively low frequency, but the antenna for 13,56mhz can be made directly on the PCB with traces. Also, you can use the search function:
Read distance for both is roughly related to coil size. We all call them "antennas", but they really are not antennas. At those two frequencies, RFID works by inductive coupling, like a transformer. If you have a large read distance (several meters), then at least one of the coils (usually, the reader) is large. Each coil is resonated at the operating frequency with a capacitor. (I think that is the case with 125 kHz, most of my playing has been at 13.56 MHz).
You get into a real antenna at 900 MHz where the wavelength is a few CM. Now, you can get 10+ meters range with small tags and readers. In all cases, you do run into problems with nearby objects, esp. if made of metal.
You're absolutely right about the "antennas", I am sorry for the term confusion. As a matter of fact, one such coil I use for 13,56 is made on multilayer PCB and it is shielded on top and bottom layer, so only inductive coupling with it is possible. 125 khz coils works at resonance, as well as 13,56. The main problem which I experienced in the past with ranges over 10cm was an increased performance demand from the analog part, because the modulation level can be quite low compared with the level of the resonant carrier. One other issue which I think it can be a problem (however I don't know if in practice remains true) is the posibility to de-tune the resonant circuit if metalic objects are present nearby the reader coil.
Hi pisoiu -- Detuning can be a big problem. Apply a tag to a cardboard box, or to a metal barrel, and you get two really different resonant frequencies. In a grocery cart, is the RFID tag sitting next to the metal grill of the cart, or next to a big bottle of soda or 12-pack of beer cans? RFID has a huge potential, but this is one of the downsides that RFID proponents tend to keep silent about. As I have stated in other postings on EDABoard, I think it is very important to point out both weaknesses and strengths. The detuning problem is a weakness. I do have a partial solution for 900 MHz RFID, which I can post if there is interest. For 13.56 MHz, it remains a tough problem.
The two types of tags are very much different. Here i give a easy to read comparision ,please refer to RFID Handbook, or AIMS global website for more details.
( 125 Khz 13.56 Mhz
1. Range : Less(few cms) More (around 1 Meter)
2.Technology: Vicinity coupling Near field coupling
3.Antenna : Quite large Compact
4. Use : Limited Wide applications
5. Cost : Cheaper Some what costlier than 125Khz
Apart from these there some technical differences like effect of interference etc...but that needs specialised reading.
( oops , the message is not displayed quite like i wanted it to be....the spaces are erased ,hence the tabular look is visible no more ,please try to understand it as it is )
Yes, I think it will be interesting for many, but perhaps it should be done in a new topic. However, one of the advantages of both 125khz and 13,56mhz are the use of passive transponders. Is your 900MHz sollution keeping this advantage? To be sincere, this idea stays from a long time in my memory cells...to insert my bag full of stuff in a coil reader and to see at a display how much do I have to pay, without unloading anything..., but it seem that metallic objects are troublesome..
1- You can send more data with more speed by 13.56 MHZ tag
2- Antenna of 13.56 MHZ reader is smaller than 125KHZ
3- 125 khz is better for the place which is near metal
However 125khz tag are going to be vanished and discontinued
Smart - why do you think that 125KHz tags are going to go away? Do you think that an entire industry and huge deployed base of tags and readers is just going to vanish without a solution? (really, I am not being sarcastic!)
i need to know what is suitable for a product serialization in a warehouse using RFID tags a and reader ,( 125 Khz , 13.56KHZ , 900 MHZ ).
the RFID should be relativly cheap and all RFID tags should be read without problems from a range of at least 2 meters