If anybody else is trying to make one and doesn’t know which capacitor to use, you can figure out the correct inductance using that calculator I made, or one you find online.
Once you have an idea of the inductance, you can figure out which capacitor to add to make it resonate at 13.56MHz using this.
Sorry I didn’t deliver on the crucifixion. Fuck up better next time and I’ll be back.
I guess you could describe it that way, for some types of transponders anyway. Particularly the small implantable kind. I don’t think you would get any difference in range if you were talking about a full size card, in fact you might get slightly less range with a full size card. It’s more of a magnetic field concentrator then booster or extender.
I suppose the same principle applies to LF? Approximately what value should the capacitor be for let’s say one of those cheap EM4100 keyfob antenna? I don’t have a LCR meter
Not that I have seen on the forum.
I have a few “Bullseye” stickers that I considered using, but went with the copperr wire because I had ceramic caps, and I wasn’t going to achieve the low profile I was after for the whole thing plus the stronger mechanical bond (solder) onto the foil would actually become the weak point; also they may be fine secured in phone case etc, but the stickers are not very robust.
I decided it was a better experiment than a “product”
Amal did look at / consider a sticker
and Satur9 at a flexible pcb version , but thats probably down the list for both of them
I haven’t messed with designing any stls, but I’ve got a filament and resin printer to make a mold. And I’ve got some flexy resin if anyone wants to send a design and I’ll ship.
Would be nice having a custom phone case for it.
I do have the components lying around, I can make the antennas. What I don’t have is the latest Iphone to see what the best shape is in terms of performance.
If you want to give it a go I can make a batch of generic copper ones and you bend them in whatever shape works.
Edit: I have tiny smd caps so you can fit everything in 1mm resin for sure
Maybe. I’ll look to see if I can find some friends with iphones and ask to test out some flexy and filament prints if I can find an STL and figure out how to engrave a space for it.
ordered some HF fobs and 22 pF capacitors and what do you know, this actually works! My previously almost unusable phone can read my apex from a few cm away now!
. Thanks!
