Proxmark3 community

bushing

Contributor

Registered: 2008-10-14

Posts: 42

PCB antenna for HF range

(from another thread)

That antenna is tailored for a PN53x chip. That particular chip has an output stage that has two drivers and a common point hence the three pins. Think of it as two loop antennas sharing a common ground. o-uuu-o-uuu-o where the o are the pins and u are coils

Yeah, I can see that -- does that mean I could just ignore one of the pins, or remove one of the two circuits?  Or is there a better way to do this?

I made a bunch of the LF antenna PCBs for CCC and was very pleased with how they turned out -- it would be nice to repeat the same with an HF antenna, or better yet, one PCB that can do both.   My first naive thought would be to take the LF PCB design, calculate / measure the total trace length, and then divide that length by 13.56MHz/125KHz =~ 100 -- then make a PCB with roughly the same shape, but fewer turns.  To make one antenna that could do both, I would just interleave the turns of the coil.

I have the strong suspicion that that won't work like I hope it will!  If nothing else, when testing the LF antenna PCBs I noticed that the measured voltage read back using the 'tune' command dropped significantly if the antenna under test was sitting on top of another antenna -- I suppose that other antenna is absorbing some of the energy radiated by the unit under test, and that the same would happen if I had two interleaved coils.

Anyone have any guidance they could give me?  It's a bit hard to really experiment with this stuff on PCBs, since it's harder to change the trace-length and geometry on an already-manufactured PCB than it is to trim some wire or bend the loop into a different shape.

(And yes, I did Google this -- all I come up with is a bunch of people telling other people to search Google, and some app notes with scary math.)

iZsh

Contributor

Registered: 2010-01-02

Posts: 95

Re: PCB antenna for HF range

I found this paper to be interesting: ANTENNAS FOR LOW POWER APPLICATIONS. By Kent Smith
http://www.rfm.com/corp/appdata/antenna.pdf

Otherwise, the mikey ppl are using this antenna (the bigger one):
http://www.sonmicro.com/en/index.php?op … &Itemid=72

But as most designed I found for RF, we need a common ground, and the proxmark doesn't provide one. I don't know anything about antenna, so I don't really know if it's really an issue though.

d18c7db

Contributor

Registered: 2008-08-19

Posts: 292

Re: PCB antenna for HF range

The new revised PM3-LCD has common ground antennas.

Bushing, do you have a proven PCB design that is known to work with the PM3?

BKone

Contributor

From: Düsseldorf, Germany, Europe

Registered: 2009-12-29

Posts: 6

Re: PCB antenna for HF range

Hello all,

what about the antenna used by Mikey-card?
http://www.sonmicro.com/en/onlinestore/ … &Itemid=43

Could this antenna used with PM3? If so it would be very cheap: 3$ plus shipping.

Best regards from Germany

BKone

bushing

Contributor

Registered: 2008-10-14

Posts: 42

Re: PCB antenna for HF range

Bushing, do you have a proven PCB design that is known to work with the PM3?

No, I started this thread to try to *find* one.

I'd be happy to have a few different cheap prototypes made, if we had some good candidates.

rule

Member

Registered: 2008-05-21

Posts: 417

Re: PCB antenna for HF range

Hey Bushing,

I played around with these antenna's, they cost around 2$ each:
http://www.sonmicro.com/en/index.php?op … &Itemid=72

Minimum order is around 100, but if you ask friendly you can get a batch of 30 or something.
It would be good to calculate the best capacitor values for these antenna's. I have still one laying around I guess, so let me know if you want me to send it to ya

Cheers,

  Roel

iZsh

Contributor

Registered: 2010-01-02

Posts: 95

Re: PCB antenna for HF range

Did you manually soldered the antenna ground to the pm3 ground?

difr

Member

Registered: 2010-04-10

Posts: 3

Re: PCB antenna for HF range

An update regarding the RFID Antennas from SonMicro:

There's no minimum purchase quantity, but you must spend at least $90 in their shop.
ie. you could buy 6 of their antennas + a reader module

They have 3 types of 13.56MHz antenna:
http://www.sonmicro.com/en/onlinestore/ … &Itemid=43

13.56 MHz PCB Antenna 55x55mm                                                PA1356-1     $3.00    
13.56 MHz PCB Antenna 45x50mm                                                PA1356-3     $3.00    
13.56 MHz PCB Antenna 26x45mm    WITH Pin Headers (Standard)     PA1356-4     $3.00    

Also, 3 types of 125kHz antenna
http://www.sonmicro.com/en/onlinestore/ … &Itemid=43

125 KHz RFID Antenna 65x35mm   with connector (+ $0.30)             IND125-1     $3.50    
125 KHz RFID Antenna 90x45mm   with connector (+ $0.30)             IND125-2     $3.50    
125 KHz RFID Antenna 40x15mm   with connector (+ $0.30)             IND125-3     $3.50    

I'd be interested in trying them, but I can't justify $90 worth of antennas, and I don't need anything else from there :-)
.

jonor

Contributor

Registered: 2009-09-17

Posts: 97

Re: PCB antenna for HF range

@bushing have you found a solution at your problem?
There is user laser sell PCB antenna for 13.56MHz but I don't understand if is working.