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.)

I am experimenting with hand-made antennas, and the maximal achievable range is around 4 cm. For my thesis, I need antennas to achieve ranges in the order of 50 cm. Does anybody have any idea if other commercial HF PCB antennas would work with Proxmark?

I noticed that there're already some posts about this on the forums.. but nobody replied! Are the questions that hard? Or that dumb? :-).

Guys, any info on that would help...I've very little knowledge on antenna's design.

Thanks.

does anyone know the internal impedance of the proxmark3 on the antenna ports? also I'm curious as to whether anyone has checked out good working antennas designs in a network analyzer to determine what a good matching impedance is (discounting parasitics)? I'm interested in designing a better performance antenna for the 13.5Mhz tags than the coil of wire you massage to get to work.

The faint gradings on the ruller on top are spaced at 1 mm from each other.

Finally, I got the idea of trying a rectangular antenna the size of the credit card. And it works like wonder. This is the final result:

You can't really see the wires because i covered them with white tape so they are not loose but the coil has 2 windings, like shown in this image:

As for results (on board with C35 = 100pF) , i get

# HF antenna: 11.47 V @    13.56 MHz

with no tag, which seems modest I know, but when I put the tag (Calypso ISO 14443 B credit card sized) on top it goes like this:

# HF antenna:  2.19 V @    13.56 MHz

a whole 9.28 V lower. In my ignorance for physics I say that because the coupling with the tag antenna has a high impact, this can only be a good thing.

Where before, with the same ~12V on the antenna with no tag and 8V with tag, I managed to read the tag 2/3 of the times, now it's 100% success.

At first I used a piece of wirewrap "green wire" and rolled a 5 turn aircoil 43mm diameter, then experimentally played around with adding or removing a turn while issuing the tune command to get a voltage reading. It mostly sat around 1.3V except when I let the coil turns lose and unravelled and the coil looked like a deformed spring the voltage jumped to over 10V but that was not really an option for an antenna. I then returned to the 43mm diameter coil with 4 turns and taped the coil with sellotape to keep it together then started deforming it to see what difference that made. It looks like I got lucky as squashing it to an elongated and slighlty rectangular shape moved the voltage to about 16V.

This is how I ended up with this shape. It used to be straighter but the coil has been through a lot. It's soldered direct to the test pads as somebody forgot to order the mating hirose connector when buying the parts...

The picture below is a typical setup where a RFID snapper card is sandwitched between the proxmark3 antenna and a snapper feeder (card reader, the black thing that looks like a USB flash key)

While in this close proximity, I issue the hi14asnoop command on the prox, then drive the snapper feeder with some python script for example issuing four consecutive list card commands in my python shell, like so:

Then stopping the snoop (press the prox button) and issuing the hi14alist command we can see what the prox snooped. Note that the card's UID changes every time, so it moves through UIDs 086B64BE, 08DC78E7, 08E743D1, 0841B329 and these UIDs in the snooped prox output match the returned values in the python debug output.

Finally for completeness I took Roel's idea of using a toilet paper roll, cut a slice and wound 150 turns of 0.125mm wire on it. I knew people had success in the past with around 100 turns so I started high and removed turns to get the tuning right. With 150 turns I used to get 45V on 125khz and about 20V on 136khz and as I removed turns these numbers moved closer to each other. There isn't much point going higher than 40V as the zenners will clip the voltage so I removed enough turns (lost count) until tune reported 29V at 125khz and 30V at 136khz. The picture below shows the final coil, sellotape is holding the coil to the TP roll and in the picture it's not actually soldered to the board as it's a little cumbersome to carry that around so I only fit it when needed. Currently I'm not doing any LF work so this coil isn't needed but it has successfully read some HID tags I have (in raw data mode).

hitune

command which shows only the HF tuning but continuously. Go tweak those antennas

> hitune
#db# Measuring HF antenna, press button to exit
#db# 11247 mV
#db# 11214 mV
#db# 11214 mV
#db# 11214 mV
#db# 11182 mV
#db# 11182 mV
#db# 11182 mV
#db# 11182 mV
...

This uses the 'sternzwirn' cotton reel which is a popular cotton supplier here in Hungary and I believe the rest of Mitteleuropa :-) google 'sternzwirn'  and you'll find suppliers of this reel for around 1-2 Eurotokens.

Take a hirose connector stripped from a cable and tinned like so -

Attach the wire to the eyelet (this is from the hirose cable) -

Wrap around the lugs, weave around, up and down, around and around (4 complete turns) and solder to the hirose connector add a blob of hotglue and electrician's tape for cosmetic appeal -

Enjoy your antenna, it gives very good results and the whole antenna is sturdy and doesn't lose the shape.

-- pytey

Since I began to do some ISO-14443b work, I noticed that my antenna is very sensitive to the location of where it's placed, and that it needs a fair amount of mV to successfully snoop a communication.

I decided to start this topic so people can share their antennas setup and the antenna tuning with the rest of the people. Then, maybe I will benefits from the setup of somebody else, or maybe somebody else will benefit from my setup!

To begin, here is the shape of my 13.56mHz antenna (the hands are quite hairy, they are not mine btw :-):

And here is the tuning that I was able to achieve (old version of 'tune', I know ... ;-)):

> tune
# LF antenna @   0 mA /     0 mV [1273 ohms] 125Khz
# LF antenna @   0 mA /     0 mV [1187 ohms] 134Khz
# HF antenna @  54 mA / 12697 mV [235 ohms] 13.56Mhz

Admission: I'm not good with electronics, so I'm probably doing something wrong here.  Hence the question.  I'm building this antenna to use with a Proxmark3 that my department bought.

So, I'm following the instructions given at:

http://code.google.com/p/proxmark3/wiki … se_antenna

I've tried twice, getting pretty precise with the measurements (starting high and working my way down), but each time I've only been able to get about 3V out of the antenna.  My real question is whether I'm doing something fundamentally wrong, since I don't quite understand part of the directions. 

Here's what I'm doing.  Once I've stripped the cable and cut out the white and red wires, I've got just the green and black.  I trim them to length and strip the ends.  Then, the instructions say to "Make an antenna coil of 3 windings using the green cable. Connect the green cable with the black one and tape them together so they won’t unwind."  At this point I get confused, because the green wire is only 19cm, clearly too short to make 3 coils.  So, instead, I twisted the ends of the green and black together to make one big loop, taped them to make sure they'd stay together, and then doubled my new big loop three times, so that the antenna looks, as far as I can tell, basically like the one in the picture.

Is this basically what I should be doing?  I'm so ignorant about electronics and all that I'm not even sure that I'm right to connect the black and green wires together in a loop like that, so feel free to tell me if I'm being really stupid here.  As I tried this repeatedly, starting with each wire slightly too long, making the coils, tuning, cutting them shorter, making the coil, tuning, etc. the voltage basically just hovered slightly below 3V, and tune just told me that my antenna was marginal (and it seemed to be missing signals when attempting to communicate with a card).

Am I doing something fundamentally wrong, or should I just keep trying until I get it just right?

Thanks in advance!
Adam

  I am having quite a lot of trouble reading type B tags: no matter what I do the hi14read command does not do much, and hi14snoop sometimes gives good results, but is very sensitive to the probe's placement. I suspect my home-made antenna, actually...

  Does anyone else have experience on 14443 type B modulation with the Proxmark ?

Ed

Anyone kmows how can I home made it easily?.

Or, anyone knows if commercial antennas like these:

http://www.feig.de/files/FEIG_DOCS/OBID … _310_e.pdf

works with proxmark?.

Thanks.

# LF antenna @   0 mA /   123 mV [1273 ohms] 124k
# LF antenna @   0 mA /     0 mV [1187 ohms] 134k
# HF antenna @   1 mA /    99 mV [90 ohms]

No matter what I do (turn more coils, shorten the wire length, etc), I am unable to get any voltage on my HF readings. Is there some steps that I have missed out? Thanks in advance!

I have this situation that I need to read the card transmission. In the wall is a small hole where i can put card.
It can not be read the transmitting antenna wire because there is not expected to enter.
I tried to connect Proxmark directly into the card, but does not work. I cut off RFID antenna from other card, sticked it on card, connected to proxmark - unfortunately does not work.

Do you have any idea how to read the transfer in the wall where I have a small hole?
Any idea how to make bulit-in antenna ?

http://www.proxmark.org/files/index.php … nts/HOWTOs