How to Design 1-3/4 Inch Square PCB Antennas for SM130 RFID Reader Chessboard Project

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#1 21681277 07 Dec 2018 14:55

Haley Dumphy Haley Dumphy

Anonymous

Post #1
21681277 07 Dec 2018 14:55

I just bought the SM130 RFID reader which requires an external antenna. I also bought the external antenna shield that contains extras e.g. xbee, etc. What I need is to make 64 antennas for a chessboard using only one reader module. I have devised a way to make this concept work based on some info from an essay, but I think it is not enough to support my idea. So is there any advice can give me and most important is how to deal with it.

At a world, Can someone help in the process of making a 1-3/4 inch square pcb antenna for the sm130?

Help is appreciated.

Best regards.

Helay
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#2 21681278 07 Dec 2018 15:00

Haley Dumphy Haley Dumphy

Anonymous

Post #2
21681278 07 Dec 2018 15:00

By the way, I have a small question, what I have read is about Integrated Laminate Substrates and Passive Devices, is there anyone can recommend me more material or articles about RFID. Thanks a lot.
#3 21681279 08 Dec 2018 05:36

David Ashton David Ashton

Anonymous

Post #3
21681279 08 Dec 2018 05:36

There is a bit of info about designing 13.56 MHz RFID antennas herehttps://electronics.stackexchange.com/questions/377706/on-board-13-56mhz-rfid-antenna-design
Not a lot of detail but it may give you some pointers.There is a 55x55mm PCB antenna here for $2.50 each:https://shop.sonmicro.com/PA1356-1
This company also does some RFID products including an evaluation kit with antennas:https://shop.sonmicro.com/SM1250-EK
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#4 21681280 08 Dec 2018 06:44

Elizabeth Simon Elizabeth Simon

Anonymous

Post #4
21681280 08 Dec 2018 06:44

If you are going to have 64 antennas in near vicinity of each other, you will likely have problems with interaction between the antennas. You will also need an antenna switch to select which antenna you want to use.
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#5 21681281 10 Dec 2018 01:34

David Ashton David Ashton

Anonymous

Post #5
21681281 10 Dec 2018 01:34

I'm envisaging a system with 64 reader antennas, only one of which is switched to the reader electronics at any one time. So the reader would"Scan" the board one square at a time. So interference between antennas would not be a problem.I can however see a problem when two pieces are on adjacent squares, or an empty square has a piece on an adjacent square. you may get false responses. This would have to be controlled with transmit power level in the reader, perhaps?
#6 21681282 10 Dec 2018 23:16

Elizabeth Simon Elizabeth Simon

Anonymous

Post #6
21681282 10 Dec 2018 23:16

@davi_d,Yes, the false response rate would have to be addressed but what I was thinking was that any metal in the near field of an antenna can disrupt the tuning so you need to be aware of the presence of other antennas when you design them.
The best way to avoid the problem would be to make the antenna sufficiently directional that it wouldn't matter. This would have the beneficial side effect that it would also reduce the false response rate.In this case you are trying to fit an antenna into dimensions that are a small fraction of a wavelength which implies the use of a multi-turn coil. A multi-turn coil will be directional but I wouldn't know by how much without modeling it.
#7 21681283 11 Dec 2018 02:26

David Ashton David Ashton

Anonymous

Post #7
21681283 11 Dec 2018 02:26

Hi Elizabeth. The impression I get from what I have read is that RFID / NFC is more an inductive coupling technique than pure RF transmission - I recall one thing had about a 10:1 inductance range for the coil.I don't know if readers have an SSI (Signal Strength Indication) - if so it should be a simple matter to only take account of responses that have an SSI corresponding to a piece right on the square.
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#8 21681284 11 Dec 2018 04:16

Elizabeth Simon Elizabeth Simon

Anonymous

Post #8
21681284 11 Dec 2018 04:16

@davi_d,You're probably right that it's more inductive coupling than pure RF. If so, then all you need is a coil etched on the PCB that fits inside the square.
On the other hand, switching the antennas in the array without spreading the RF around could get interesting.
#9 21681285 12 Dec 2018 02:00

David Ashton David Ashton

Anonymous

Post #9
21681285 12 Dec 2018 02:00

All - this user seems to reference Kynix a lot and never replies to any advice given on posts.I suspect the object is advertising.
#10 21681286 05 Jan 2019 12:21

Haley Dumphy Haley Dumphy

Anonymous

Post #10
21681286 05 Jan 2019 12:21

Thank you for all guys advice, but I think I get a little useful information. I am really busy recently, and I get so many ideas from the online friends, I will arrange them in my free time.
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Topic summary

The discussion focuses on designing 1-3/4 inch square PCB antennas for a chessboard project using a single SM130 RFID reader module with 64 antennas. Key challenges include antenna interaction due to proximity, requiring an antenna switching mechanism to select one antenna at a time and avoid interference. The system concept involves scanning the board square by square, but false responses may occur when adjacent squares have active tags, which could be mitigated by adjusting the reader's transmit power or using signal strength indication (SSI) to filter responses. The antennas operate primarily via inductive coupling at 13.56 MHz, suggesting the use of multi-turn coil PCB antennas within the limited size constraints. Directional antenna design is recommended to reduce interference and false reads, though modeling is necessary to determine effectiveness. References to external resources include a 55x55 mm PCB antenna and RFID evaluation kits from SonMicro. Additional requests for RFID design materials and articles were made. The discussion also notes the importance of considering metal presence near antennas as it affects tuning and performance.
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How to Design 1-3/4 Inch Square PCB Antennas for SM130 RFID Reader Chessboard Project

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