RF transmission interference due to titanium

[hatman9]

I am going to be testing an 13.56MHz RFID chip soon to see if a reader can sucessfully read thru a 1/4th inch thick titanium case with a 3/16ths inch diameter hole cut in it at a distance of 3 inches (i know its a horrible waste of a nice piece of titanium :sad: but my boss already drilled it)

What I want to know is:
1) if anyone has had experience with titanium-RF interferience
2) what I should expect to see, and will the interferience be too great with even a larger sized hole
3) if changing to 125kHz RFID would increase reliability of signal transmission

 

[biff44]

Won't work for an electromagntic field--hole is too small.

It might work if you try talking over a purely magnetic field. I would go with a lower frequency RFID (100 KHz) and try to drive a coil of wire in lieu of an antenna. Or you might actually have to pass a current into the titanium, which being paramagnetic may pass a chaning magnetic field thru it. Not sure, though.

 

[hatman9]

it is using a coil of wire, my bad for misstating.

 

[FvM]

In a short, to penetrate 1/4" titanium, you need to go to low kHz frequencies. Magnetic field attenuation at 125 kHz will be already much too high. Skin depth can give you a first idea of AC magnetical field penetration in metals. Skin effect - Wikipedia, the free encyclopedia

 

[hatman9]

*UPDATE*

someone had a 134kHz rfid tag and reader, and I found that I am able to read thru the hole in titanium.
it should be noted tho that it doesnt work if the tag is held against the titanium, only when it is held about 1/4th of an inch away. the reader can be held right up against the titanium to about half an inch away.

I am recomending not to order the reader, and try to rework the system to implement a 134kHz or lower freq setup