I have an Apex Flex and currently an S21+, It used to read OK, a bit of lining up, then muscle memory lead to faster and easier reads, I made a resonant repeater coil that lived between my phone case and phone, this improved my reading noticibly, I then modded it to a different form factor ( irrelevant to this discussion ) but it wasn’t tuned particularly well, so it didn’t perform as well as I had hoped.
Here’s a few examples if you want to go that path
Then @hamspiced made these
Here’s the video
I HIGHLY recommend these, I had noticeable improvements on the ones I made, but @Hamspiced ones are even GOODERER. When reading my ApexFlex, it’s simply…simple
Here’s his Tinide store for a fully built and tuned one
- The only thing I am not sure of is, due to the iPhone NFC antenna location, I’m not sure if they will work or fit well in the iPhone case
I’m not sure if @hamspiced can test that for you (I don’t have an iPhone or access to one or I would do it myself) , but I think he has a Pixel, but MAYBE access to an iPhone?
If not, maybe a make your own:
What may fit better in the iPhone is something like one of these
LINK
and a 22pf capacitor
Pretty cheap solution
NB: You might get lucky with the tuning, or you may need a VNA., which makes it mor expensive than just buying a #HammyResonantRepeaterJammy™
Anyway, just some thoughts and options for you to consider